Davidtse

Hello,

 

My name is David Tse and I am have recently dropped out of college to start a game development company called Subsurface Games. I graduated from high school last year(may 2012) and made it a few months in college before I decided it was a waste of my time and that it was time for me to go make games. Right now I am the only one working on the game apart from a few contract artists. I am making a zombie survival shooter that is set in a procedural open world. The idea of the game is what would you do in the zombie apocalypse. you have to scavenge the unlimited procedural open world for food, water and guns to survive. You can enter every single building in the world to find supplies or build a fort to survive.

 

I am making a 3D game engine completely from scratch for this project using OpenGL and C++. The only libraries I am really using are SpeedTree for vegetation and PhysX for physics, cloth, and destruction. I have also started a development blog for this game where I post game updates and other behind the scenes stuff. When the game reaches the alpha stage(it is currently in pre-alpha) people who pre-order the game will be able to download the game and play it before its done.

 

I hope you guys can check out the blog and tell me what you think about the idea for the game, and the current state of the engine/game. Here is a link to the blog/company website: http://www.subsurfacegames.com/, and here is the latest video that I posted to the blog:

 

 

Thanks,

David

Hello, I am in the process of converting to a deferred renderer, and I am a little stuck at position reconstruction from depth. I have been reading alot about it. I have read all of MJP's blog posts and the thread that started them, and feel like I have a somewhat solid understanding of how it works, but my implementation has some issues. If some of you could give me some insight into my problems I would appreciate it.

 

I have tried many variations on the way I am at right now, but this one gets the closest results to what it should be.

 

First I get the frustum points in I think camera space:

 

Vector3f NearCenterPosition = Look * nearplane;
Vector3f FarCenterPosition = Look * farplane;
float angle = fov*0.0174532925; 
float NearHeight = 2*(tan((angle)/2)*nearplane);
float NearWidth = NearHeight *  (aspectratio);
float FarHeight = 2*(tan((angle)/2)*farplane);
float FarWidth = FarHeight * (aspectratio);  
FrustumPoints[0] = cml::normalize(FarCenterPosition - Right*(FarWidth/2) - Up*(FarHeight/2));
FrustumPoints[1] = cml::normalize(FarCenterPosition - Right*(FarWidth/2) + Up*(FarHeight/2));
FrustumPoints[2] = cml::normalize(FarCenterPosition + Right*(FarWidth/2) - Up*(FarHeight/2));
FrustumPoints[3] = cml::normalize(FarCenterPosition + Right*(FarWidth/2) + Up*(FarHeight/2)); 

 

Then I pass those to my lighting shader as a uniform. Then I give each vertex of the full screen quad an index into these frustum points

 

 

Vector3f FullScreenVert1 = Vector3f(1.0,   -1.0, 0.0);
int FullScreenVert1FurstumIndex = 1;

Vector3f FullScreenVert2 = Vector3f(1.0,   1.0, 0.0);
int FullScreenVert2FurstumIndex = 0;

Vector3f FullScreenVert3 = Vector3f(-1.0,   1.0, 0.0);
int FullScreenVert3FurstumIndex = 2;

Vector3f FullScreenVert4 = Vector3f(-1.0,   -1.0, 0.0);
int FullScreenVert4FurstumIndex = 3;

 

In the lighting vert shader I just index into the frustum points and pass it into the pixel shader.

 

Lighting Vert Shader:

 

 

out vec3 CameraRay;
void main(void)
{  
	CameraRay =  FrustumPoints[ index ];   
         ...
}

 

Then in the lighting frag shader I first convert the depth to a linear using:

float DepthToLinear(float depth)
{ 
	vec2 g_ProjRatio   = vec2( ViewClipFar / (ViewClipFar-ViewClipNear), ViewClipNear / (ViewClipNear-ViewClipFar) );
	return g_ProjRatio.y/(depth-g_ProjRatio.x);
}

 

Finally I get the world position by multiplying the interpolated camera ray with the linear depth and the view clip far.

 

vec3 WorldPosition = CameraPosition - ( CameraRay * (LinearDepth*ViewClipFar ) ) ;

I know your supposed to add the camera position, but subtracting like this gets closest to the desired results. I am comparing it to just outputting the pixel position in the G-buffer pass.

 

Here are some screenshots showing the comparisons.

 

The Correct Results, what I am expecting:

http://farm9.staticflickr.com/8075/8301716099_44e9f527dc_k.jpg

 

Depth reconstructed results:

http://farm9.staticflickr.com/8213/8301716005_9d86ec6cc4_k.jpg

 

Also when I move the camera higher up the z value of all the world positions increases turning the green light blue and the yellow white, ect. When I turn the camera up the "horizon line" where the z value changes from 0 to 1 moves down, and when I look down it moves up. Then when I move the camera in the x and y cross slowly creeps in the oposite direction of the movement. I thought this might be because of the subtracting the cam pos, but when I add the camera position it moves twice as fast in the other direction. If you need more information on the behavior of the implementation just let me know. Its hard to explain and show in screenshots, but hopefully you can see what I'm doing wrong from the code. Any help is greatly appreciated.

 

I should also mention that my engine uses Z as the up axis.

 

Thanks,

David

 

Hello everyone, I recently implemented shadow mapping in my engine and im trying to get it too look just right. When I added a sphere to the scene I noticed there where seams in the self shadowing along the polygons of the underlying mesh and it was not the smooth self shadowing I was expecting for a sphere. I didn’t really notice this before because I was using more complex models with more dense geometry. here is a picture of what i'm talking about





Im not sure why this would be the case I would think there should be a nice smooth line on the part of the sphere that is in shadow. it must be a problem with something in my shaders here is how I do the shadowing.

(glsl)
Vert Shader:

ProjShadow = TextureMatrix * WorldMatrix * in_Position;

Frag Shader:

float depth = textureProj(ShadowMap, ProjShadow).x;
float R = ProjShadow.p / ProjShadow.q;
R += 0.0005;
float shadowValue = (R <= depth) ? 1.0 : 0.0;

If anyone knows what I am doing wrong and could help me out I would really appreciate it.

Thanks, David