3D DirectX10 Free Look Camera (Timer based)

Introduction: Camera Basics

Okay so I promised I’d write a tutorial on writing a simple freelook camera, this tutorial doesnt only apply to DirectX10 but to any graphics API. Okay so the simplest possible camera we cam implement short of a first person style camera is a free look camera, without roll, so basically only two degrees of freedom: left/right and up/down, we are also going to implement some basic movement controls forwards/backwards and Strafe Left/Right.

First things first, as usual I’m not going to go into major detail about viewing and projections, if you want more info check out: http://en.wikipedia.org/wiki/Graphical_projection and http://en.wikipedia.org/wiki/3D_projection . Okay now to view any 3D scene we need a virtual camera with a field of view (FOV- theta) and near (a) and far (b) view planes, these together form a view frustum as show in figure 1. This frustum defines what is visible in the scene, all geometry clipping and hidden surface removal is based on this frustum.

Figure 1 - view Frustum (courtesy DX10 docs)

Now the shape of this frustum is controlled by the projection that we we to employ, there are several types of projective but chances are you will end up using a perspective projection. Now the projection is attached to our virtual camera (think of the projection as a camera lens), to orient ourselves in a scene we need to know the position that we are viewing the scene from, the direction in which we’re looking and which way is up (shown in figure 2), now this up direction is very important for movement calculations and obviously to display the scene the right way up   These three parameters are called the eye position, the view vector and the up vector.

Figure 2 - Virtual Camera

For a free look camera, we need the up vector to be in the direction of the camera top, if we were doing a first person camera where the viewer is stuck on the ground then the up direction will always be towards the sky. So in conclusion to view a scene, you need a virtual camera positioned somewhere in a scene (pos/up/view) with some sort of lens (projection).

Now I need to quickly explain what happens to an object’s vertices when it travels through the rendering pipeline. When a object’s vertex gets sent down the rendering pipeline it has a position in its own model space, this position is now moved to wherever the object is required to be in the world by multiplying the vertex by the world matrix for the object. Now if you run through the world you would think of it as the world standing still and the camera moving, but for now it is beneficial to think of it in the opposite way, that the camera is stationary and its the world that’s moving. Cause mathematically that is exactly whats happening.

The camera never moves, the worlds position is just adjusted to give that impression. So we’ve positioned our object in the world, the next step it move it according to our view point, if we want to looking to the left of the object, we need to move the entire world to the right, so we multiply the vertex position with the view matrix to move it as necessary. Remember each object will have its own world matrix but used the exact same view matrix, the last step is to convert from 3D to the 2D image that is displayed on the screen, the camera lens does that just like it does in a real camera, the vertices are flatten to the near viewing plane by multiplying the vertex by the projection matrix. The entire process is show below in figure 3.

Figure 3 - Vertex Transformations

The Camera Body: The Container Class

Figure 4 - Camera Class

Figure 4 shows the class structure for our camera, source code is below, we have the two matrices: view and projection, we have function to position the camera, change the view and so on… #define TWO_PI 6.283185307179586476925286766559 #define DEG_TO_RAD 0.01745329251994329576923690768489 class camera { /******************************************************************* * Members ********************************************************************/ private: //view parameters float heading, pitch; //in radians //matrices D3DXMATRIX viewMatrix; D3DXMATRIX projectionMatrix; D3DXMATRIX rotationMatrix; //view vectors const D3DXVECTOR3 dV, dU; //default view and up vectors D3DXVECTOR3 eye, view, up; //movement vectors and movement toggles D3DXVECTOR3 forward, strafeRight; int movementToggles[4]; //fwrd, bck, strfLft, strfRght //camera timer for movement HRTIMER::timer camTimer; /******************************************************************* * Methods ********************************************************************/ public: //constructor and destructor camera(); virtual ~camera(); //set projection methods void setPerspectiveProjection( float FOV, float aspectRatio, float zNear, float zFar ); //camera positioning methods void setPositionAndView( float x, float y, float z, float hDeg, float pDeg ); void adjustHeadingPitch( float hRad, float pRad ); void setMovementToggle( int i, int v ); //update camera view/position void update(); //get methods D3DXMATRIX& getViewMatrix() { return viewMatrix; } D3DXMATRIX& getProjectionMatrix() { return projectionMatrix; } private: //create view, forward, strafe vectors from heading/pitch void updateView(); };

The Camera Lens: Creating the Projection Matrix

Lets do the easiest thing first, creating the camera lens or projection matrix. Almost all graphical APIs have a helper functions to create this matrix for you. To create a left handed perspective projection  in D3D10, the function you need is: D3DXMatrixPerspectiveFovLH( outputMatrix, FOV, aspectRatio, nearPlane, farPlane)… The code to create this matrix is:

void camera::setPerspectiveProjection(float FOV, float aspectRatio, float zNear, float zFar)
{
	//convert FOV from degrees to radians
	FOV = FOV * (float) DEG_TO_RAD;

	D3DXMatrixPerspectiveFovLH( &projectionMatrix, FOV, aspectRatio, zNear, zFar );
}

I’m setting the projection matrix’s FOV using a degree parameter, since I only do it once and its easier to visualize a degree based FOV its fine, the helper function requires radians, so I simply convert to radians using the constant defined in the class header file. The aspect ratio is the ratio of width:height for your display window. If your window is 640×480 then the aspect ratio is 640:480 -> 4:3 or numerically 1.3333333333…

The Camera: Creating the View Matrix

Since we are using a camera with only 2 degree of freedom (axes of movement) ->heading (left/right) and pitch (up/down),  we store the direction in which we’re facing as a angle on each axis. These angles are stored as radians. The final view vector is calculated from these two variables and original position of the view and the up vector is adjusted accordingly. This mean that to get an accurate up vector we need to initialize the camera with correct values when we create it, so that the up vector is valid once the view changes. so the constructor for the camera class is:

camera::camera():	dV( D3DXVECTOR3(0,0,1) ),
					dU( D3DXVECTOR3(0,1,0) ),
					eye( D3DXVECTOR3(0,0,0) ),
					view( D3DXVECTOR3(0,0,1) ),
					up( D3DXVECTOR3(0,1,0) ),
					forward( D3DXVECTOR3(0,0,1) ),
					strafeRight( D3DXVECTOR3(1,0,0) ),
					heading(0),
					pitch(0)
{
	//set matrices to identity
	D3DXMatrixIdentity( &viewMatrix );
	D3DXMatrixIdentity( &projectionMatrix );

	//initialize movement toggles
	movementToggles[0] = 0;
	movementToggles[1] = 0;
	movementToggles[2] = 0;
	movementToggles[3] = 0;
}

This always initializes our camera at the position (0,0,0), facing the positive z axis. *NOTE: we will discuss the movement toggles later on. We also set our default view and up vectors to (0,0,1) and (0,1,0) respectively. We will use these default vectors to calculate the new view vector from the heading and pitch parameters when the view changes. So how do we adjust the view? Well we simple modify the heading  and pitch parameters and run the updateView() function which we’ll define later. Just to be safe we add hard limits to the values of the heading and pitch (0~2pi) just so over the course of the program we don’t overflow the variables.

void camera::adjustHeadingPitch( float hRad, float pRad )
{
	heading += hRad;
	pitch += pRad;

	//value clamping - keep heading and pitch between 0 and 2 pi
	if ( heading > TWO_PI ) heading -= (float) TWO_PI;
	else if ( heading < 0 ) heading = (float) TWO_PI + heading;

	if ( pitch > TWO_PI ) pitch -= (float) TWO_PI;
	else if ( pitch < 0 ) pitch = (float) TWO_PI + pitch;
}

We also said we would be adding movement controls: forwards, backwards  and strafing. To move we will need to know which direction is forward ( hint: the view vector ) and which way is directly right, backwards and left are obviously in the direct opposite direction. We now have the two unit vectors forward and strafeRight which also need to be updated as soon as the view changes. As we said forward is easy as it is the view vector and backward is the negative forward vector. How do we calculate the right vector? Well we have the forward direction and the up direction so right should be ortogonal (90 degrees) to both of them (ie the x axis, if forward is the z axis and u is the y axes), hm, we have two vectors and need to get another vector orthogonal to them, if we think back to basic calculas and we suddenly remember that the cross product of two vectors gives us an orthogonal vector, wiki the cross product for more details. We also need to unsure that the movement vectors are unit vectors to ensure consistant movement.

To create the new view and up vectors, we first create a rotation matrix which will rotate any point/vector by the degrees on each axis that we specify, we then rotate the default view and up vectors (du & dv) to get the new view and up vectors. Easy Peasy…

We now have all the info necessary to create our updateView() function.

void camera::updateView()
{
	//create rotation matrix
	D3DXMatrixRotationYawPitchRoll( &rotationMatrix, heading, pitch, 0 );

	//create new view and up vectors
	D3DXVec3TransformCoord( &view, &dV, &rotationMatrix );
	D3DXVec3TransformCoord( &up, &dU, &rotationMatrix );

	//create new forward and strafe vectors
	D3DXVec3Normalize( &forward, &view );
	D3DXVec3Cross( &strafeRight, &up, &view );
	D3DXVec3Normalize( &strafeRight, &strafeRight );

	//take into account eye position
	view = eye + view;

	//update view matrix
	D3DXMatrixLookAtLH( &viewMatrix, &eye, &view, &up );
}

Statically Positioning our Camera

void camera::setPositionAndView(float x, float y, float z, float hDeg, float pDeg)
{
	//set eye coordinates
	eye.x = x;
	eye.y = y;
	eye.z = z;

	//set heading and pitch
	heading = hDeg * (float) DEG_TO_RAD;
	pitch = pDeg * (float) DEG_TO_RAD;

	//update view
	updateView();
}

This simply positions the camera on a location and set the view according to the heading/pitch params specified.

Moving our Camera

There are two ways to move the camera, incrementally step by by, i.e. on each update (frame) we move the camera by a fixed amount  but there is a massive problem with this, variable framerates! Imagine if we moved the camera by 1 unit every frame, on a midrange PC getting around 45 frames per second  we will be moving at 45units a second, but now comes a guy with a monster machine and runs the game at 75 frames per second and our movement speed has increased as well, this is unacceptable and would ruin any game. I dont know if any of you remember how quake3’s physics was reliant on the FPS, and so guys getting higher FPS rates could run faster and jump further than guys with lower FPS rates. So how do we correct this? We need to ensure a fixed movement rate based on time and not frames, so we do just that, we make movement timer based! We firstly add movement toggles, which get activated when a player pushes a movement key, and deactivated when he releases it, this is necessary to ensure that if a player pushes both forward and back the camera doesnt move and then when he releases a single key it immediately starts moving in the still active direction.

The to work out the distance moved between updates, we create a simple timer and check the elapsed time in seconds, we then multiply this time by the movement rate per second. Both of these functions are shown below:

/*******************************************************************
* set camera movement toggles
********************************************************************/
void camera::setMovementToggle( int i, int v )
{
	movementToggles[i] = v;
}

/*******************************************************************
* update camera view and position - timer based for fluid movement
********************************************************************/
void camera::update()
{
	//get current elapsed time
	float t = (float) camTimer.getElapsedTimeSeconds();

	//update position - 1.5 unit per second
	eye +=	 t * ( movementToggles[0] + movementToggles[1] ) * 1.5f * forward +
			 t * ( movementToggles[2] + movementToggles[3] ) * 1.5f * strafeRight;

	//update view
	updateView();

	//reset timer
	camTimer.reset();
}

This update function is what gets called from the main game loop, also the reason why updateView() is declared private. On each frame update, you will process input, set the movement toggles appropriately, run the adjustHeadingPitch() function and then run the update() function to create the new view matrix.

NOTE: The timer used is based on my silly encapsulation of the tick timers in the windows API, look at my High Resolution Timers entry.

Conclusion

So there we have it, a super simple super basic free look camera implementation in less than a 100 lines of code. In the next blog entry I will be covering how to give the camera mouse control using Windows Raw Input. With those two tutorials you will have all the tools to create a basic input system for your game!!!

Hoep you enjoyed it!

My Thoughts on Dragon Age: Origins

I have been nervously awaiting Dragon Age: Origins, I’ve been following all related news and so on for months, so when the release date finally drew near I was super excited. The game launched on the 9th of November here, a monday, so I ended up taking 2 days leave just so me and the game could spend some quality time together. Now before I continue, I do need to state for the record I am a huge Baldur’s Gate / Original Fallout fan, those two series are my top two games of all times, basically that means that any future RPG will be compared to those games, and boy do they set the bar high!

We got the game a few days after the rest of the world so I read through several reviews, most of them giving the game great scores! (“Yay!” I thought, but then remembered that fallout 3 also got great scores and the moment died) Then I read the bit-tech.net review (I honestly value those guys opinions – they are definitely one of the better review sites on the net – well their hardware reviews need work) and in that review they said the game was good but nothing new or special, that it brought nothing to the table and yeh… I was honestly a little ticked off by that since in the last 5 years there have been a lot of games that tried doing the same old stuff and failed miserably, the witcher & mass effect are the only RPGs in the last 5 years that I felt did things right, I dont mind if its the same concepts and stuff, just do it right! I’m so tired of devs being forced to bring new elements to the table and in many cases have those exact elements sink the game.

So how did I find the game?! well I technically finished it twice in the space of 5 days. I really didn’t get much sleep, I think I sunk around 50+ hours into it, and how do i feel about it? Well, I love it!! This game is exactly what I expected and much much more! It is everything baldur’s gate 2 was and more. (Yes,unfortunately the world is smaller, but its understandable since created 3D environments is a lot harder than drawing a few sprites).

I’m not going to go into too much detail regarding the game since there are a million detailed reviews out there to read, simple this will be a brief overview of what I loved/disliked about the game.

What they did right

To start the new character system at first glance looks very simple and scaled down, with not a lot of customization options, so I thought this might be a bad thing then I remembered how much I disliked the D&D 3rd edition rules just for the opposite reason, where there was no real specialization, ie. i could get a lock picking, plate wearing, archer mage who would be terrible at all those thing but the combination was still possible. The new character system in DA is simple and specialized and I love that about it, from when you create the character you can already see the bigger picture, although on the first play through I did make a few mistakes in my character build that made me play through again.

The combat is tactical and involved, its not simple point at the enemy and chill, you need to be constantly on your toes watching what the enemy is doing and responding to it, the whole combat tactics section was awesome, in it you can set up condition that control your characters, for example if you’re magic resistant templar sees a mage on the battlefield that must be his priority target, or if your fighter encounters an enemy with high armor should use a armor piercing ability. There is also a nice feature that when a player attacks and enemy from behind he gets large bonuses to his hit chance and damage, this has been present in other RPGs but it was usually restricted to rogue/thieves and backstabbing, here its open to anyone so character positioning is very important. There is also a heavy reliance on traps and poisons, the poisons/traps available are quite varied and mixing them up in battle is pretty damn awesome, leading an enemy through a grease trap you laid then finishing him off with some crow poison… All characters should have at least one level of poison making so they can make use of the poisons.

The armor/damage system needs special mention, this is probably the first game I cnat think of where armor does not affect a character chance to be hit score, a character’s armor and defense are entirely seperate entities and honestly thats exactly how it needs to be, armor only reduces the amount of damage taken when hit, so it is there to help out low dex characters like fighters that do tend to be hit a lot, and it also allows a mage to wear light robes and and end up being more protected than my fighter wearing the heaviest armor possible. And to counter that each weapon has an armor penetration number, so certain weapon types are better against certain targets.

I could go on and on about how elegant and well implemented the combat system in the game is but i wont   There have been complaints regarding the difficulty but I personally loved it,  I can understand that the average console player was probably tearing his hair out during some sections of the game, and that they’re probably not used to having to plan ahead and that the slow pace of combat would probably be frustrating, but that just made the game so much better for me. A lot of the battles that I kept losing over and over ended up being easily won once I changed tactics and I like the idea that the reason I was losing was because I wasn’t thinking.

The  character design is excellent, not really much to say in that regard, the character interaction is very mass effect’ish (most recent example) and that’s a good thing, bioware have improved the inter party dialogue with each game they make just making it better and better. The world/mythology they created is also excellent, and very detailed, its really nice to discover a new world. Half the enjoyment of the game for me was reading all the info about the world lying around in books and scrolls. The overall writing quality in the game is excellent and I cant wait to revisit the world they created Movement is achieved by means of a world map (BG style), I personally prefer this as this allows for more detailed locations than in a free roam game, I’d rather have less unique locations then tons of the same dungeons/subways (cough fallout3/oblivion cough).

The size of the world is a little small, but it still provides you with plenty of characters to meet and areas to explore, even so with the small world it still took me around 35hrs to finish the game the second time round, and that’s with me rushing through through the first half. Granted around 5hours of that was watching loading screens :/

What they did wrong

While I was praising the earlier character and combat systems, they aren’t perfect. The main concern for me was the lack of detailed info on the effects of abilities and spells. Getting told that this ability boosts damage at the cost of defence doesn’t particularly help especially when you don’t know by how much, you end up having to write down the character stats then enable the ability and check the differences. Also there was absolutely no display available for a characters missile defense score or for his attack speed. The lack of any sort of attack speed indicator on weapons is honestly unacceptable, and the fact that certain abilities seem to affect this attack speed with absolutely no mention of it is also unnacceptable (ie. I swear powerful swings slows down the attack rate, but it might just be me imagining things). Also info that’s missing is the level of skill required to lock pick certain items / disarm traps / etc. and most importantly the amount of damage spells do, players are left totally in the dark regarding that – descriptions state: spell does moderate damage over a short period (WHAT THE HELL DOES THAT MEAN – what does moderate mean? moderate at level 5 is different to moderate at level 15).

What I would have liked to see when a player mouse overs a score like attack, is the base attack score, the additional attack score from attributes, then each item and buffs contributions to the score. Its frustrating when your character has 3 or more effects on him and you cant tell what the hell each one does, apart from that it affects a certain score. Also add the damn attack speed on weapon descriptions, I want to clearly see exactly how much faster a long bow is compared to a short bow, I also want to see exactly how much faster enabling rapid fire on an archer is compared to his standard attack. The game combat system is very intricate and detailed and then hiding all the elegant maths from the player is simply not on. I cant imagine that any player would be scared off by the numbers if anything it would probably improve the experience. Currently playing the game feels like you’re driving a car with gauges telling you your battery voltage, oil pressure, tire pressure, outside temperature and a million other non essential things in detail, and then having your speedometer have three sections marked: slow/fast/very fast, not really very useful…

Another problem for me was the loading times, my machine at home is by no means low end or even mid range, its well up in the high end bracket and even so the load times were a bit ridiculous, ranging from 10s to 2minutes for even the smallest areas, and it may be my imagination but they seems to deteriorate over time, starting out reasonably quick and gettign progressively worse over time. Another thing is the the mini transitions between main areas and sub areas in thsoe main areas also take long but it seems like that’s due to some sort of race condition / thread blocking since during each transition I can see my CPU load meters lock at 100% for both cores for a few seconds, once they unlock the loading starts and the transition occurs quickly. So if they can fix that problem the load times should decrease by a fair bit.

Conclusion

I know i barely went into any detail about the game and what its about and so on but like I said there are a ton of other places to check up on that, while like people have said the game isn’t anything revolutionary or new, it’s an old concept done right! Change isn’t always a good thing, take an old concept and improve on it, do it right, take the effort to make a good solid game that people enjoy playing rather than some half assed proof of concept BS or some watered down consoletard game (cough COD:MW2 I’m looking at you cough). It’s also really good to know that there are companies out there that care about PC gamers. Bioware and EA, thank you so much for Dragon Age, this game is by far the game of the year for me!!! You are welcome to my money any time in the future.

Basically this game is Baldur’s Gate 2, just not using the D&D rules and not set in the forgotten realms! If you liked BG then you’ll love this!! Honestly this is a game worth buying so go out and buy it if you haven’t already!!!

October Update! Exciting News!!!

I’ve had a rough few months, and have finally started to recover! In the middle of last year I ended up burning from stress and trying to juggle a million things at once, and I’m finally starting to feel like I’ve recovered. I’ve spent the better part of the day cleaning up the blog layout and the content of several of my popular blog posts just to make it easier to read.

I’ll be writing up a few new tutorials soon! As a sneak peak the upcoming tutorials cover: windows RAW input, how to write a 3D free look camera, an introduction to pathfinding and a tutorial on an efficient implementation of A*.

In other news I’ve had a bit of a career change, I’ll be lecturing the final year and honors level graphics courses, 3D graphics is one of my key interests second only to AI, and this gives me the opportunity to focus on it full time! This also mean that in setting up the course content for next year, a few more DX10 tutorials will pop up And I’ll finally get the time to do and show some more advanced techniques like bump-mapping, anti-aliasing and maybe even occlusion culling. I’m pretty damn excited!!!

Also in the pipeline is a complete upgrade for my slightly less monstrous machine, once the upgrade is complete it will be back in the realm of monstrous I cant wait!! I’ll post photos of the work-log and everything once I get all the parts in, I cant believe that I’m forced to import components due to lack of local suppliers or if there is a supplier with stock then I have to deal with absolutely insane prices.

I don’t know how much free time I’ll have in the next few days since I have one last deadline to complete at my current work, but once that is done I’ll write that camera tutorial!

In other news my master’s thesis is going well, I’ve completed my literature survey and have developed a very basic pathfinding framework to test various algorithms with, but the actual writing of the thesis is whats killing me. Writing has never been a strong point of mine, I know what I want to say but I struggle to put it into words and ironically I have a pretty large vocabulary so even that isn’t an issue. I’m never really happy with anything I write, but i guess that’s the nature of being a little bit of a perfectionist.

Downtime

I havent really updated this blog in forever, I’ve been swamped with work. Its not helping matters that my band is also completing our full-length album release so thats also taking up a fair chunk of my time.

The last few months have been crazy, I’ve been reading so much about pathfinding in games and I’ve learnt so much, I’ve started writing my masters thesis but I’m finding it extremely difficult and time consuming, writing has never been a strong point, never mind academic writing. I’ve spent around 2 weeks writing and re-writing and only have 3 completed pages of my introduction.

Its and interesting field and I have a few ideas on extending a few common algorithms to provide faster and better quality results, but as with all things research related there is always the chance that my “optimizations” might end up making things worse, as Adam Savage says “Failure is always an option”.

Looking at the directx 11 specs, tech demos, etc I cant help but feel excited, I kinda just wanna lock myself in a room and play with it My directx 10 tutorials kinda stopped coming as my workload increased and I’m sorry about that, I’ll try my best to find the time to perhaps write a new tutorial or two.

Anyways I had a bit of time before a meeting at work and realized I havent touched this blog in a while so decided to show it some love

The “Perfect” Post Apocalyptic RPG

 Before I continue I just need to state for the record that I am a fallout (originals) fanboi. In my opinion Fallout 1/2 are the pinnacle of post apocalyptic cRPGs, actually probably the pinnacle of cRPGs in general, I can’t think of a single cRPG I’ve played through more times that the fallout games. Baldur’s Gate 1 and 2, are probably second on my list. In the last decade there hasn’t been a single game that has even come close to removing them from the top spots on the list of my all time favorite games.

So I’ve been thinking a bit about some of the recent games I’ve played and all the things that I liked and I found lacking in them. So I’m gonna outline what I feel the games did right and what they did wrong. Then I’m gonna give a basic description of what I feel would make my perfect post apocalyptic (gonna refer to it as PA from now on) RPG.

Let’s start with the classics:

Fallout 1/2

What They Did Right

Um, pretty much everything… haha, okay typical fanboi comment aside, what made those games that great? One thing stands out above everything else, the writing! Yes the setting design and the art style was amazing as well but it got outshined by the quality of the writing. The depth of characters, the locations, the back stories, the quests, the little jokes thrown in randomly, all these things fleshed out the game. Ironically the weakest story in both games was the main plot. I played those games just for the dialogues and the characters. The only other game that came close to the depth of the world and the dialogue was Baldur’s Gate 2.

Let me just go on a little bit of a rant now, to a large extent during the time period that the games were made, gaming was still a small exclusive past time. Most gamers of that period were male, and older, and usually a little geeky. There was no massive casual gaming culture as we knew , the console age was just starting and PC games were still in large, the smart gamers choice. I kinda feel that this contributed greatly to the depth of writing present in the original fallout games, when there was more focus on that sort of thing, and much less focus on large explosions, instant action and shiny graphics in games. Storylines were appreciated and dialogue sequences weren’t skipped just to get to the next level of killing hordes of nazi/aliens/etc. I miss those days, but maybe that’s just me.

Let’s move onto the combat and character systems in Fallout, the combat was a slow strategic affair, more a kin to a game of chess rather than a quake deathmatch. That again was indicative of the times, turn based combat was pretty common in games at the time and so no one complained. I personally loved the slower more thoughtful approach to combat. It made battles all the more epic since at the end you felt like you had not only outgunned your opponents but out thought them as well.

The character system was the now familiar SPECIAL system, which was based if I recall correctly on the GURPS system. I’m not gonna go into detail about the system, but it was basically a standard DnD style character attributes system. In addition to the character stats you had a list of skills, ranging from combat skills to dialogue skills, and perks. Anyone that’s played fallout3 will be familiar with both these. I really preferred the more open approach to character development found here in comparison to the rigid DnD character systems that pigeonholed your character from the start.

Another excellent design feature in the fallout games was the option to not fight! You could make it through a massive part of the game without firing a shot. This allowed me to replay the game several times with entirely different experiences. I played as a standard gunfighter character that just slaughtered everyone, then I played as a smooth talker, and realized how much additional depth the game had, and how much content I had missed out on by just gunning my way through everything. The level design was also excellent, there was no repetition between areas, you never got bored exploring. Items were also pretty scarce and so you had a sense of achievement when scavenging. There were tons of different weapons, different ammo types, different armors, etc.

The enemies were varied and tough, at no point did I feel like a god prancing through the world invulnerable, there was always some brotherhood of steel paladin or some super mutant to cut me back down to size.

What They Did Wrong

I honestly can’t really think of anything to complain about here. There were several glitches with quests not working properly and other miscellaneous bugs but those are not design problems. Design wise I can’t think of anything that could have been better. So

I’ve fanboi’d myself out so let’s move onto the best modern PA games: Fallout 3 and STALKER, seeing as we’re in a fallout mood we’ll start with fallout 3.

Fallout 3

What They Did Right

Their world design on the surface is excellent, wandering out in the DC wasteland from a first person viewpoint was excellent. I found the experience quite immersive. The various locations were quite well designed as well but there was some pretty major problems in regards to the world when you look at it in a little more depth, but I’ll get to that. The first person view and the graphics were again quite good and really help immerse the player in the environment, I found the combat system fun (it had some problems) for the most part, and really didn’t mind the VATS add on, it was fun blowing off parts in slow motion.

What They Did Wrong

(WARNING: bethesda fans should stop reading now)

When will bethesda realize that p&p RPG systems DONOT work well in first person? The obviously didn’t learn the lesson from morrowind or oblivion. Why bother giving the player the illusion of aim, when it had no effect on damage. How many times was the player stormed in oblivion by an enemy with 6 arrows sticking out his face? Seriously, it just shatters any immersion the player has with the game. The same happens in FO3, it didn’t matter if you shot someone in the face or in the foot, emptying a clip into an enemies face at close range only to have them still come at you is just stupid! Having a PnP character system in a realtime FPS game is stupid, what is it used for? just calculating whether you hit and how much damage you did? Uh, that’s what aim and distance is for, seeing as its already an FPS and chances are they already do an intersection test to see whether they should run a weapon hit check. Shooting a monster at point blank range and not hitting is ridiculous, and just ruins that sense of immersion once again.

The locations in the game while well designed from the outside lacked any sort of depth, a settlement with 6 people in it? seriously? Even megaton with its masses of people (read 20) only had 3 or 4 worth talking to. Just like every other recent bethesda game, there was a massive lack of depth. The levels were repetitive, if I had to see another sewer / subway I was going to scream. They just made a shallow simple hack and slash game and called it fallout. Yeh, it was fun for a while, until I ran through my bazilionth tunnel.

Also there were some consistency issues I had with the game, they’d be destroyed building and cars everywhere, the aftermath of a nuclear attack, and yet all the cars energy packs seem to have made it out okay, even though the cars themselves were destroyed. Also the addition of the nuke launcher?! Seriously?! I cna only think both those items were added in for the console “instant gratification” players take like “lotsa splosions!”. Weapons were not varied enough, and also items were everywhere, I don’t think I ever ran out of stimpacks or ammo. Obviously in a desolate wasteland, every single fridge or box will have tons of ammo and stuff in it, since no-one would bother looting (sarcasm!). Power armor was strewn everywhere, you never struggled for weapons or armor. Then they threw in a half baked recipe system that never really worked, the items you made were mediocre at best and you never really needed them anyways, again another stupid left over from oblivion.

The enemies were ridiculously easy to kill, supermutants going down with something ridiculous like three shots from a hunting rifle. I think by around level 14, nothing in the game could touch me, I’d maxed out my gun skills, my speech skills, my repair skills, and was busy maxing out my energy weapons skills. The quests were simple and linear, no back stories, no depth: “fetch me 30 nuka cola bottles”, why? because the NPC collects them of course. Why would I even give a damn? The moral choices were clear as night and day with the exceptions of the ghouls and tenpenny tower (kudos on that one guys). The characters were shallow and uninteresting. Trying to talk your way through things was pointless, it always boiled down to a fight. I honestly got bored 3/4 of the way through and didn’t bother finishing it.

The game can be simply described as a PA hack and slash, they might as well have foregone the quests entirely and just gone the diablo route. All in all it was a fun, simple, flashy, repetitive game without any sort of depth.

STALKER: SOC and CS

What they did right

 (I do realize stalker is not an RPG but it had a lot of RPGesque elements)

No stupid character system to calculate hits and so on, these guys were smart enough to realize that FPS and hit checks don’t work so well. You shoot a guy in the head he goes down, shoot him in the body, you’ll need to shoot him again.

Amazing environment, beautifully done, I don’t think any game has managed to capture that sense of desolation and abandonment as well as STALKER did.

 Excellent weapon range and customization options, excellent item range and artifact options. Pretty much every aspect in regards to weapons and items in the game was excellent. Items were scarce, health packs were pretty rare, various ammo types were extremely rare, artifacts were obviously rare, basically everything you carried, you had worked hard to acquire.

 The enemies were tough from the start till the end, you never once felt overpowering and untouchable.

What They Did Wrong

Infinite enemies, that was the one thing that pissed me off about both games, you’d killed everything in an area leave, come back literally 3 minutes later and the area would be repopulated with enemies. It just made the game annoying especially when travelling across multiple areas, you’d have geared up at a vendor, then by the time you got to your objective you’d be at half health with no health packs and no ammo.

CS introduce a broken faction system, which was interesting if it had worked! I should put this in the things they did right but since it never really worked I have no idea what it was supposed to do.

Terrible incomprehensible storyline and endings, I finished both games and really have no idea what the hell was going on. I had to go read the damn wikipedia page to get an idea of the storyline I had just played. I’ll put it down to a poor translation from russian to english. The game had so much potential for storytelling, tons of stalkers huddled around camp fires that could tell you rumors or interesting stories. They made use of it once or twice but not enough. The quests were all just fetch quests. Simple task / reward affairs, again so much potential especially in regards to the faction system. I really felt that having quests to go weaken enemy factions strongholds would have been excellent, so much potential for inter faction politics. Instead they made a open world FPS till you reached a certain point, where you couldn’t go back and followed a per defined route to an end mission that left you entirely unsatisfied. It’s like being led to a candy store through a rough ghetto, only to go inside and be given a stick of celery.

So now we come to my perfect PA RPG

My personal perfect PA RPG

Okay, so after lots of thinking, I actually think STALKER is an excellent base for a great PA RPG, but with some heavy modifications. Let’s just take stalker as a based and fallout’ify it a bit This is not going to be a full design doc, that I’m working on in my spare time but rather an idea of the things that I think would make a great game.

The World

The world present in stalker was excellent, it was well designed but severely underused. There were so many areas that could have been excellent little sub plot triggers or quest locations. Like the pump house in Clear Sky, great location, well modeled and designed and absolutely no reason to be there.

The world should be just like the stalker world, open and varying, there was next to no repetition across areas in stalker, unlike in the “seen one subway tunnel seen em all” fallout 3.

The Gameplay

Fallout 3 made me see that FPS is an excellent format for a PA game, you want to be able to feel that sense of destruction, emptiness, hopelessness that would be present in such a world, where fallout 1/2 portrayed that feeling through the rich writing, fallout 3 out did them in that regard with the magnificent vistas of destruction (pity that was all there practically was, an outside image).

In regards to the character system, I don’t think that a strict pen and paper style character system has any place in a first person game, it’s too restrictive and like I mentioned tends to destroy some of that sense of immersion. I’d suggest a system of skills, where you can increase the skills with each level. I’d also suggest reducing the number of skills to the bare minimum:  light weapons, heavy weapons, first aid, repair, speech, electronics.

I’d suggest health to remain the same as when the player starts out, so that the game is equipment based more so that stat based. I’d like to struggle to acquire my equipment and know that without it I’m pretty much as vulnerable as at the start of the game.

The combat system should also be a bit modified, I think that in additions to the skills there should be a proficiency list of all the weapons in the game. When you first find a weapon you should not have any skill in using it, an M4 is nothing like an AK so the assumption made in most games so far is that it is. I’d suggest introducing a system similar to that in dungeon siege 2, where the more you use a weapon type like an M4 the more proficient you get in using it. Start off with a massive crosshair and insane recoil and slowly reduce both these with use.

The weapons skills should affect the learning rate of each weapon. This game mechanic will further tie you to certain weapons and make the game inventory centric.

Characters shouldn’t be able to master all the weapons in the game, and so it should give them incentive to replay with different load outs. I’d also suggest various levels of specialization (beginner, intermediate, expert, marksman, etc) with each weapon, so once you cross over into a new level you unlock a special function like automatic fire, or three round burst, or allows you to use different ammo type…

The Weapons, Armor and Items

The range available in stalker was excellent, and the upgrade/customization system present in Clear Sky was the best I’ve seen in any game to date. I’d say keep a similar range of weapons. Perhaps add in some more ammo types and armors. Add in helmets and add helmet customizations. Perhaps even add extras like pants, boots etc, which affect things like stealth, stamina, etc… This adds the option for random generation of items (diablo style).

Players like customization, and the game should provide them to create entirely custom characters and loadouts. Have character skills affect the efficacy of items, good first aid gives you more health from health packs, better repair better repairs items, pretty much the way the fallout games handled the link between skills and items.

The Enemies

Enemies should be like the player, and their difficulty should depend on their equipment and skill sets as well, ie. a tough enemy must have high end armor and be at the max weapon level with a good quality customized weapon while an easy enemy must be wearing light armor and still be figuring out which end of the gun the bullets come out of.

At no point should the player feel invincible or fragile, obviously with better equipment, the weaker enemies will pose no challenge. The player must also be rewarded for good aim, and as such feel that he can take down tougher enemies if gets the right shots in. Getting a lucky shot in always feels so rewarding. Perhaps add the VATS system in as well just for some spice, calculate the chance to hit based on distance and weapon skill.  

The Storyline / Quests

Now the most important part of any RPG is the story, the characters and the quest. I’d suggest making it a very open “main” plot, something like the player’s brother needs money for an operation and the player entered the zone to raise the cash. Something that is a goal to work towards but that doesn’t restrict the player from the start. The game should be all about exploring the game world, learning about all the characters, the back stories, the politics. The player should be able to leave a lasting effect on the world. Having an ending like fallout’s with a slideshow of all the areas you visiting and how your actions affected them would be amazing.

The game should be like a long TV action series,  lots of character, lots of dialogue, lots of action.

Try to avoid stupid things like simple fetch quests, make them a little bit more elaborate, it will take a bit of thought, but that’s what you’re paying your game designers/writers for.  Make it interesting, make the choices have consequences, ie, “if you do a job for boss a, against boss b, boss b’s thugs might rob you of your belongings” etc… I think that multi part elaborate quests are what should be done rather than simple boring task. I recently finished GTA4 and towards the end of the game, I didn’t even bother watching the cut scenes, cause they boiled down to 4-5minute speeches to tell you to go to “point x” and kill “person y”.  Keep things interesting.

The game shouldn’t be about instant gratification, it should be a game where the player sits down and can’t stop playing for hours. I hate it when I sit down with a game and after an hour I’m about to throw my keyboard out the window when I’ve been given my 45th go to the other side of the map and kill/fetch something quest (ie STALKER, far cry 2, GTA 4).

Conclusion

This rant got to be super long and I apologize, It isn’t as detailed as I’d like it to be but if it was it would take another 15 or more pages and I doubt you’d want to read that much. I hope that people would agree with some of the things I’ve said or might even have better ideas. The comment box is just below, please use it

Some C++ Debugging Advice – use #ifdef

If you are an experienced c++ programmer you can stop reading, nothing I cover here will be of any use to you. I’m just writing a little post on a simple little preprocessor trick that c++ programmers have been using for years. Using the #ifdef directive to tag blocks of debugging code.

So lets we have a function that does something like searching through a tree, while debugging we’d like to lets say have a counter to count all the nodes visited during the search but of course in the released version we don’t need this counter using up precious resources. lets have some example code:

double counter;

void treeSearch::visitNode(node* n)
{
	... some code ...
	counter++;
}

Some beginner programmers would probably do this:

bool debugMode = false;
double counter;

void treeSearch::visitNode(node* n)
{
	... some code ...
	if ( debugMode) counter++;
}

Yeh, that works but now every time you visit a node, the program evaluates an if statement, not to mention the memory for the counter has still been allocated. Yes in this case memory cost is pretty negligible but that is not always the case. So how can we improve upon this? The answer is by using basic pre-processor directives, more specifically conditional inclusions (#ifdef). Simply put these directives mark code for inclusion into the program during compile time if some condition is met.

so our code would now look as follows:

#ifdef _DEBUG
double counter;
#endif

void treeSearch::visitNode(node* n)
{
	... some code ...
	#ifdef _DEBUG
	counter++;
	#endif
}

So now those lines will only be included if _DEBUG is defined, what this means is that the counter variable and the code that increments it doesnt get compiled, and your program is as fast as possible and still has debugging functions. You can set the _DEBUG flag in your code manually by using the define directive: #define _DEBUG, or if your IDE supports it, multiple compile profiles, one of which defines _DEBUG before compiling. Visual studio by default defines _DEBUG when compiling using the Debug profile.

So that was a very simple and brief tutorial on something pretty much most C++ programmers know, but i posted it just in case some didnt

IE8 Brief Performance

so it got released yesterday and there’s a lot of speculation regarding performance, so I just briefly timed the load timed of a few of my favorite sites:

	ie	ff
wordpress	8	15
facebook	8.8	9.1
xs forums	9.6	13
cnn.com (uncached)	18	28.2
myspace	5	8
myspace login	27	26.7

IE8 seems to do okay, my tests arent super scientific or even done properly, just a quick test between the latest stable FF3 and IE8 on my machine. The memory usage of IE8 seems crazy tho: 60mb for two tabs across 2 processes. Earlier it was sitting at around 210mb for 3 tabs open with 4 processes running.

I’m sure they’ll be some in depth performance reviews in the future, and I’ll be looking forward to it…

My attempt at a DX10 game engine… Name Ideas

So I’ve started with developing the AI test bed for my masters experiments, and since I kinda wanted something that looked nice, I basically started developing a game engine without knowing it

I’ve been working on it for around a week now, and have a very basic renderer and a basic camera system going… The next step will be developing the scene graph and spatial data structures needed for rendering. I’ve been doing so much reading on scene graphs and so one that it’s coing out my ears and yet I’m not any closer to having an idea on a good solution. I could probably do my entire masters on scene graphs and spatial sorting.

Anyways I’m going to discontinue my DX10 tutorials since all the future tutorials will anyways be based off of my engine, so I’m going to start a new series of tutorials on building a very basic dx0 game engine.

The amount of files in the projects are growing and I need to come up wiht a nice name so i can start encapsulating the classes in namespaces, and have a nice uniform naming across the components, since the engine is going to be super super simple i was thinking as using one of the following as the engine name:

• Cimplicity
• basikEngine
• CimplEngine
• SimplEngine
• engineBasix

Any other suggestions?

DirectX 10 Tutorial 5: Basic Meshes

Since my car has been broken for the last two days, I’ve taken off work and have been working on my Masters degree, since part of my Masters involves building a small “game engine” for AI testing, I’ve been doing some more DX10 work, so its convenient for me to quickly slap together a few more tutorials.

Mesh Basics

I covered the basics of indexed buffers and the depth testing in the last tutorial, in this short tut, I’m going to cover the basics of directX meshes. A mesh is a data structure that contains all the vertex and index buffers needed to draw an object. It’s a neater method of drawing objects as we’ll see.

There are four steps to using meshes:

1. Create the mesh
2. Fill the Mesh with the index and vertex data necessary
3. Commit the mesh to the device
4. Draw the mesh

So let’s create a new mesh, first things first, we’ll define an ID3DX10Mesh* pointer called pMesh.

//create mesh
if ( FAILED( D3DX10CreateMesh( pD3DDevice, vertexInputLayout, 2, "POSITION", 8, 12, D3DX10_MESH_32_BIT, &pMesh) ) ) return fatalError("Could not create mesh!");

//vertices for a cube
vertex v[8];

v[0] = vertex( D3DXVECTOR3(-1,1,-1), D3DXVECTOR4(1,0,0,1) ); //front top left
v[1] = vertex( D3DXVECTOR3(1,1,-1), D3DXVECTOR4(0,1,0,1) ); //front top right
v[2] = vertex( D3DXVECTOR3(-1,-1,-1), D3DXVECTOR4(0,0,1,1) ); //front bottom left
v[3] = vertex( D3DXVECTOR3(1,-1,-1), D3DXVECTOR4(1,1,0,1) ); //front bottom right
v[4] = vertex( D3DXVECTOR3(-1,1,1), D3DXVECTOR4(1,0,0,1) ); //back top left
v[5] = vertex( D3DXVECTOR3(1,1,1), D3DXVECTOR4(0,1,0,1) ); //back top right
v[6] = vertex( D3DXVECTOR3(-1,-1,1), D3DXVECTOR4(0,0,1,1) ); //back bottom left
v[7] = vertex( D3DXVECTOR3(1,-1,1), D3DXVECTOR4(1,1,0,1) ); //back bottom right

//create indexes for a cube
unsigned int i[36] = { 	2,0,3,3,1,0,
						3,1,7,7,5,1,
						6,4,2,2,0,4,
						7,5,6,6,4,5,
						0,4,1,1,5,4,
						6,2,7,7,3,2 };

//insert data into mesh and commit changes
pMesh->SetVertexData(0, v);
pMesh->SetIndexData(i, 36);
pMesh->CommitToDevice();

Now we use D3DX10CreateMesh to create the mesh, the parameters are the d3d device, the vertex input layout, number of elements in the vertex layout, the name of the element that stores the vertex position, number of vertices, number of faces, mesh flag and finally the output mesh pointer.

There is a little trick here, remember how before we had triangle strips? Here we don’t, we have to specify every single triangle (referred to as a face in the mesh) by hand. So our index list looks a bit different from before.

To add the vertex data and index data, we simply use the mesh SET methods, a mesh can have multiple vertex buffers and so when you set a vertex buffer, you need to specify in which slot you wish to store it. The index data SET method simply takes the index array and the number of indexes in it.

The final step is to commit the mesh, every time you make a change to a mesh you need to commit it to the device before the changes will be taken into effect.

Drawing the Mesh

So how do we draw a mesh?

for( UINT p = 0; p < techDesc.Passes; p++ )
{
	//apply technique
	pBasicTechnique->GetPassByIndex( p )->Apply( 0 );
	pMesh->DrawSubset(0);
}

How simple is that? We use the draw subset method of the mesh interface to draw the mesh, the value given to the method specifies with attribute group to draw, attribute groups for meshes will be covered in a later tutorial, for now just specify 0. And that’s how to create and draw a basic mesh.

I’ve updated the draw code to render a bunch of spinning cubes just for fun:

Source Code

Source code: tutorial5.zip

DirectX 10 Tutorial 4: Indexed Buffers and Depth Testing

Okay so it’s been a while since my last tutorial, and I apologize for that. We dealt with textures in the last tutorial, and many of you might be wondering while I handled that so early? Well mainly because D3D 10 isn’t exactly an API designed for beginners, so a critical feature required for any scene rendering (depth testing or z-buffering) is done in D3D by use of a depth stencil texture, covering textures before depth testing makes sense in this case. Remember guys I’m not going to spoon feed you, these tutorials expect you to read the SDK docs for details on the variable types and the methods, these tutorials are just to give you a running start.

Indexed Buffers

Before I get to Depth Testing, let’s draw something a little more complicated that a quad, how about a cube. Using the same method as in tutorial 3 the code to draw a six sided cube is as follows:

//CUBE DRAW METHOD 1
//------------------------------------------------------------

//lock vertex buffer for CPU use
pVertexBuffer->Map(D3D10_MAP_WRITE_DISCARD, 0, (void**) &v );

//vertices for a cube
v[0] = vertex( D3DXVECTOR3(-1,-1,-1), D3DXVECTOR4(1,0,0,1) );
v[1] = vertex( D3DXVECTOR3(-1,1,-1), D3DXVECTOR4(0,1,0,1) );
v[2] = vertex( D3DXVECTOR3(1,-1,-1), D3DXVECTOR4(0,0,1,1) );
v[3] = vertex( D3DXVECTOR3(1,1,-1), D3DXVECTOR4(1,1,0,1) );
v[4] = vertex( D3DXVECTOR3(1,-1,-1), D3DXVECTOR4(1,0,0,1) );
v[5] = vertex( D3DXVECTOR3(1,1,-1), D3DXVECTOR4(0,1,0,1) );
v[6] = vertex( D3DXVECTOR3(1,-1,1), D3DXVECTOR4(0,0,1,1) );
v[7] = vertex( D3DXVECTOR3(1,1,1), D3DXVECTOR4(1,1,0,1) );
v[8] = vertex( D3DXVECTOR3(-1,-1,1), D3DXVECTOR4(1,0,0,1) );
v[9] = vertex( D3DXVECTOR3(-1,1,1), D3DXVECTOR4(0,1,0,1) );
v[10] = vertex( D3DXVECTOR3(-1,-1,-1), D3DXVECTOR4(0,0,1,1) );
v[11] = vertex( D3DXVECTOR3(-1,1,-1), D3DXVECTOR4(1,1,0,1) );
v[12] = vertex( D3DXVECTOR3(-1,-1,1), D3DXVECTOR4(1,0,0,1) );
v[13] = vertex( D3DXVECTOR3(-1,1,1), D3DXVECTOR4(0,1,0,1) );
v[14] = vertex( D3DXVECTOR3(1,-1,1), D3DXVECTOR4(0,0,1,1) );
v[15] = vertex( D3DXVECTOR3(1,1,1), D3DXVECTOR4(1,1,0,1) );
v[16] = vertex( D3DXVECTOR3(-1,-1,1), D3DXVECTOR4(1,0,0,1) );
v[17] = vertex( D3DXVECTOR3(-1,-1,-1), D3DXVECTOR4(0,1,0,1) );
v[18] = vertex( D3DXVECTOR3(1,-1,1), D3DXVECTOR4(0,0,1,1) );
v[19] = vertex( D3DXVECTOR3(1,-1,-1), D3DXVECTOR4(1,1,0,1) );
v[20] = vertex( D3DXVECTOR3(-1,1,-1), D3DXVECTOR4(1,0,0,1) );
v[21] = vertex( D3DXVECTOR3(-1,1,1), D3DXVECTOR4(0,1,0,1) );
v[22] = vertex( D3DXVECTOR3(1,1,-1), D3DXVECTOR4(0,0,1,1) );
v[23] = vertex( D3DXVECTOR3(1,1,1), D3DXVECTOR4(1,1,0,1) );

pVertexBuffer->Unmap();

//send vertices down pipeline
for( UINT p = 0; p < techDesc.Passes; p++ )
{
	//apply technique
	pBasicTechnique->GetPassByIndex( p )->Apply( 0 );

	//draw 5 quads
	pD3DDevice->Draw( 4, 0 );
	pD3DDevice->Draw( 4, 4 );
	pD3DDevice->Draw( 4, 8 );
	pD3DDevice->Draw( 4, 12 );
	pD3DDevice->Draw( 4, 16 );
	pD3DDevice->Draw( 4, 20 );
}

The code above produces the following cube (I’ve added rotation and moved the camera – take a look at the code for more details), noticed the depth problem, whatever face got drawn last is on top irrespective of whether it is obscure by another face.

Image 1 – No Depth Testing

So as you can see to draw our cube we need to define each vertex and add it to the vertex buffer, then call the draw method 6 times. Each draw call draws a single triangle list with 4 vertices, drawing each face. So in this method we send 24 vertices down the pipeline and use 4 draw calls. This is a little crazy just to draw a single cube with only 8 vertices. There must be a simple more efficient method of doing this and there is: indexing.

What indexing does is let you pass a vertex buffer containing all the key vertices down the pipeline, and also a list of the order the vertices must be drawn in. So for our cube you’ll send the 8 vertices down the pipeline followed by a list of the order to draw them in. It’ll be a bit clearer once you see the code and of course read the index buffer sections in the SDK docs.

//lock vertex buffer for CPU use
pVertexBuffer->Map(D3D10_MAP_WRITE_DISCARD, 0, (void**) &v );

//vertices for a cube
v[0] = vertex( D3DXVECTOR3(-1,1,-1), D3DXVECTOR4(1,0,0,1) ); //front top left
v[1] = vertex( D3DXVECTOR3(1,1,-1), D3DXVECTOR4(0,1,0,1) ); //front top right
v[2] = vertex( D3DXVECTOR3(-1,-1,-1), D3DXVECTOR4(0,0,1,1) ); //front bottom left
v[3] = vertex( D3DXVECTOR3(1,-1,-1), D3DXVECTOR4(1,1,0,1) ); //front bottom right
v[4] = vertex( D3DXVECTOR3(-1,1,1), D3DXVECTOR4(1,0,0,1) ); //back top left
v[5] = vertex( D3DXVECTOR3(1,1,1), D3DXVECTOR4(0,1,0,1) ); //back top right
v[6] = vertex( D3DXVECTOR3(-1,-1,1), D3DXVECTOR4(0,0,1,1) ); //back bottom left
v[7] = vertex( D3DXVECTOR3(1,-1,1), D3DXVECTOR4(1,1,0,1) ); //back bottom right

pVertexBuffer->Unmap();

//create indexes for a cube
unsigned int* i = NULL;
pIndexBuffer->Map(D3D10_MAP_WRITE_DISCARD, 0, (void**) &i );

//front face
i[0] = 2;
i[1] = 0;
i[2] = 3;
i[3] = 1;
i[4] = 0xffffffff; //start new strip

//right face
i[5] = 3;
i[6] = 1;
i[7] = 7;
i[8] = 5;
i[9] = 0xffffffff;

//left face
i[10] = 6;
i[11] = 4;
i[12] = 2;
i[13] = 0;
i[14] = 0xffffffff;

//back face
i[15] = 7;
i[16] = 5;
i[17] = 6;
i[18] = 4;
i[19] = 0xffffffff;

//top face
i[20] = 0;
i[21] = 4;
i[22] = 1;
i[23] = 5;
i[24] = 0xffffffff;

//bottom face
i[25] = 6;
i[26] = 2;
i[27] = 7;
i[28] = 3;

pIndexBuffer->Unmap();

//send vertices down pipeline
for( UINT p = 0; p < techDesc.Passes; p++ )
{
	//apply technique
	pBasicTechnique->GetPassByIndex( p )->Apply( 0 );

	//draw 5 quads - 29 indexes = 4 indexes x 6 faces + 5 breaks
	pD3DDevice->DrawIndexed( 29, 0, 0 );
}

Wow! That’s a lot of code! Well not really once you look at it, we add the 8 key vertices to the vertex buffer exactly as before. Then we map the index buffer in exactly the same way as the vertex buffer and start filling it with the indexes of vertices in the vertex buffer. So for the front face we’re telling it, draw the front bottom left vertex, then the front top left vertex, then the front bottom right and finally the front top right. Now whats the 0xffffffff mean? Well that indicates that a new line list or triangle list must be started at that point, It does the same job as calling a draw call for each face without any of the overhead.

So lets do some basic maths on what we saved by using indexing rather than the standard vertex buffer method. We had a vertex buffer filled with 24 vertices (each vertex weighing in at 224bits) so the vertex buffer 672bytes large. In the second case the vertex buffer is 224bytes, and we have an index buffer with 29 32bit ints (116bytes) so a total of: 340bytes. That’s nearly 50% reduction in memory used, not to mention we are only using a single draw call compared to 4 draw calls when using just a vertex buffer.

So how do we create the index buffer? Well in DX10 all buffers are the same so we create an index buffer the in the same manner we created a vertex buffer with a few minor changes:

//create vertex and index buffers (space for 100 entries)
//---------------------------------------------------------------------------------

//create vertex buffer
UINT numVertices = 100;
D3D10_BUFFER_DESC bd;
bd.Usage = D3D10_USAGE_DYNAMIC;
bd.ByteWidth = sizeof( vertex ) * numVertices;
bd.BindFlags = D3D10_BIND_VERTEX_BUFFER;
bd.CPUAccessFlags = D3D10_CPU_ACCESS_WRITE;
bd.MiscFlags = 0;

if ( FAILED( pD3DDevice->CreateBuffer( &bd, NULL, &pVertexBuffer ) ) ) return fatalError("Could not create vertex buffer!");

//create index buffer
//change buffer desc bytewidth to index type
bd.ByteWidth = sizeof( unsigned int ) * numVertices;

if ( FAILED( pD3DDevice->CreateBuffer( &bd, NULL, &pIndexBuffer ) ) ) return fatalError("Could not create index buffer!");

//set vertex and index buffers
UINT stride = sizeof( vertex );
UINT offset = 0;
pD3DDevice->IASetVertexBuffers( 0, 1, &pVertexBuffer, &stride, &offset );
pD3DDevice->IASetIndexBuffer( pIndexBuffer, DXGI_FORMAT_R32_UINT, offset );

We still use the createBuffer method to create the index buffer, we just change the bytewidth since the buffer stores 32bit unsigned ints. Once the buffer is created we bind it to the Input Assembly by calling the IASetIndexBuffer method ( all we need to specify is a pointer to the buffer, the format of the indexes, and the offset, in case we wish to use only a set portion of the buffer ).

Depth Testing (Z-buffering)

I’m not going to explain in depth what depth testing/depth buffering/z-buffering is (its covered in almost all beginner graphics tutorials), you guys can use google for that , but here’s a quick link to the basics: http://en.wikipedia.org/wiki/Z-buffer.

In DX10, depth testing is accomplished by making use of a depth stencil, there is a nicely detailed section in the SDK docs regarding the Output-Merger Stage, and here they cover how DX10 accomplishes the depth stencil test internally.

So lets just briefly go over what depth testing is, we have a depth buffer that stores the distance for each pixel in the screen to the camera, so for every pixel we draw from the pixel shader, we compare it’s distance to the camera to the distance stored in the depth buffer, if the new pixel is closer than the distance in the depth buffer then it is drawn and the depth buffer is updated with that pixels distance. That way we only draw the closest visible objects to the viewer, obstruction further objects.

So lets enable this in DX10:

//dx manager members
ID3D10Texture2D* pDepthStencil;
ID3D10DepthStencilView* pDepthStencilView;

bool dxManager::createRenderTargetsAndDepthBuffer( UINT width, UINT height )
{
	//try to get the back buffer
	ID3D10Texture2D* pBackBuffer;

	if ( FAILED( pSwapChain->GetBuffer(0, __uuidof(ID3D10Texture2D), (LPVOID*) &pBackBuffer) ) ) return fatalError("Could not get back buffer");

	//try to create render target view
	if ( FAILED( pD3DDevice->CreateRenderTargetView(pBackBuffer, NULL, &pRenderTargetView) ) ) return fatalError("Could not create render target view");
	pBackBuffer->Release();

	//create depth stencil texture
	D3D10_TEXTURE2D_DESC descDepth;

	descDepth.Width = width;
	descDepth.Height = height;
	descDepth.MipLevels = 1;
	descDepth.ArraySize = 1;
	descDepth.Format = DXGI_FORMAT_D32_FLOAT;
	descDepth.SampleDesc.Count = 1;
	descDepth.SampleDesc.Quality = 0;
	descDepth.Usage = D3D10_USAGE_DEFAULT;
	descDepth.BindFlags = D3D10_BIND_DEPTH_STENCIL;
	descDepth.CPUAccessFlags = 0;
	descDepth.MiscFlags = 0;

	if( FAILED( pD3DDevice->CreateTexture2D( &descDepth, NULL, &pDepthStencil ) ) ) return fatalError("Could not create depth stencil texture");

	// Create the depth stencil view
	D3D10_DEPTH_STENCIL_VIEW_DESC descDSV;
	descDSV.Format = descDepth.Format;
	descDSV.ViewDimension = D3D10_DSV_DIMENSION_TEXTURE2D;
	descDSV.Texture2D.MipSlice = 0;

	if( FAILED( pD3DDevice->CreateDepthStencilView( pDepthStencil, &descDSV, &pDepthStencilView ) ) ) return fatalError("Could not create depth stencil view");

	//set render targets
	pD3DDevice->OMSetRenderTargets( 1, &pRenderTargetView, pDepthStencilView );

	return true;
}

First we add two new members in the dxmanager class, a ID3D10Texture2D depth stencil pointer and a depth stencil view pointer. Then we create a new texture and assign it to the depth stencil pointer. After this we create a view to the texture by making use of a depth stencil view desc, sort of like the way we created texture views.

The final step is to modify the Output manager’s render targets to include the depth stencil, this automatically enables depth testing. Once we run the program, we get this result:

Image 2 – Depth Testing Enabled

So that’s basically it for this short tutorial, I’m sorry its so short and simple, I’m just flooded with other work right now. I’m going to be covering meshes and lighting in the next several tutorials.

Source Code

Source Code + VS2k8 project files:  tutorial4.zip