Adrian Got Shadow Mapping

I've finally finished adding another feather in the HD league. Shadows are a good way of showing the object positions etc in the world. I've finally added the ShadowMapping pass to our codebase and have actually cleaned up the code a little to treat the Shaders as objects rather than just the GLuint handles. Any way It's far from perfect, the aliasing effect is pretty evident.. the depth map is pretty high res (equal to the size of the rendering buffer) but the artifacts are there because of the huge frustum size that i had to specify for the light so as to fit the whole map.

Any way It's a good start. Ill' be looking out for ways to fix this but for now I think this is a good feature to have. Finally one of the games i created.. has shadows :D

It took me a while to get the thing working.. i was stuck with various silly problems.. but im' glad i got it done. For some tech details.. here is the sequence that i use to get the shadow rendering done. (Note .. the shadow map is rendered before every frame even for the static objects (map) but that's the only solution when we don't have a proper terrain etc to do shadow mapping offline and use that.)

• Create FrameBuffer with DepthBuffer only
• Enable and Set PolygonOffset(1.0, 1.0) // generally used value.
• Render The scene you want to get a shadow of (map + hero) from lights perspective
  
• Store the light matrix.(Light_MVP)
• Disable PolygonOffset
  
• Use Vertex and Fragment shaders for setting the color based on shadow map. (depth buffer sent as texture and is the ShadowMap)
• Send the Light_MVP to shader using mat4 uniform variable. (not using the texture matrix hack, coz this is cleaner to me).

You can check out the code @code.google.com/p/adrian

Post Processing

If you have seen my prev post, you already know iv'e been hard at work creating something using the GLSL Shaders. Well iv'e been adding a Post-Processing pipeline to Adrian's graphics engine. And i'm really excited about the results iv'e achieved with it .. So without further ado.. here are the screenies..



I know the toon shader has been done a million times now.. but the special thing about this one is ... it is done as a post-process step instead of while rendering. I know it sux.. but if you can achieve one more effect during post processing its just icing on the cake .. isn't it? :D

GLSL MultiTexture CheckList

Most of the tutorials about glsl cover the GPU side of things and generally leave out the host (CPU) side of the code to your imagination.. well not exactly .. but they assume you get it right. Turns out.. its' not that straightforward afterall.. or atleast not for me. So Here is a check list you need to see for getting multi texturing (multiple uniform variables in Fragment shader) to work.

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, tex0id); // general texture bind call we all know and love.
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, tex1id);

glUseProgram(program); //program is the shader program you create using glCreateProgram() call.
GLint h0 = glGetUniformLocation(program, "tex0");
GLint h1 = glGetUnifromLocation(program, "tex1");
glUnifrom1i(h0, 0); //first texture sampler
glUniform1i(h1, 1); //second texture sampler.

The code for Fragment Shader corresponding to the above cpu code is as follows

uniform sampler2D tex0;
uniform sampler2D tex1;
void main()
{
gl_FragColor = texture2D(tex0, gl_TexCoord[0].st) + texture2D(tex1, gl_TexCoord[0].st);
}

So Now the check list:

• Use glActiveTexture for each texture unit
• Use 0, 1, .. texture unit index while assigning values to uniform values.
• Call glUseProgram() before trying to set uniform values.
• Bind texture with texture id for each glActiveTexture.

I know this might look silly but iv'e seen a lot of people asking for this particular problem.. and sadly.. I struggled to get this right too... and this is a post to make sure i dont' ever have to go through that pain again...

Adrian v1.0 RELEASED!

At last I ironed out the bugs in the 1.0 branch and was able to release Adrian both for Windows and Linux. You can download the Linux version or the Pre-Compiled Windows Version.

Hope you guys enjoy the game. Do report any bugs you find here.

Source code is licensed under GPLv3 and the SVN repository is located here.

Here are some screenshots from the game (scaling them reduced the quality here)

New Model Loader

One of the sore points of the original game was that buildings attributes were handcoded. This was a very tedious effort. Also not to mention the results were not too appealing always, and the visual complexity of the objects was exceedingly little. But now by leveraging a third party Model loader, the loading of almost all formats has become a simple cake walk.

Thanks to ASSIMP, hosted at http://assimp.sourceforge.net/, we were able to load not just MD2, but even open source models like Collada etc. This has opened up a whole new array of resources for us. Also it lets us do away with the current MD2 loader which is pretty brittle. Even Skeleton animation can be included too if required.

However, Release 1.0 will be shipped without this feature.

Showstopper resolved - Release on track!

The showstopper with the windows release has been successfully resolved. The issue turned out to be a simple bug. Basically we have a structure which has an embedded vector STL class in it. What the code was doing was to create the structure, and before assigning contents to it, was simply memsetting the entire structure to 0. While this is normal operation in any C code, in C++ this can cause very weird bugs. More technical details can be had in the bug report or in my blog.

Now I have created a 1.0 branch to release Adrian, This branch will contain some basic bug fixes. The plan is to release it this Sunday. The trunk will continue to experiment with new features meant for 2.0 like new model loaders etc.

What is blocking Adrian Release

Currently we have done many improvements to the old game, but unfortunately unable to release, since the windows Release configuration crashes unexpectedly. The Debug configuration runs perfectly. The Linux version is running very well too. Some thing appears rotten there.

The problem occurs in some list handling in the MD2 model loading code. So we have two options - debug it or use a more professional loader. Basically we have seen a good open source model loader based on the BSD license at http://assimp.sourceforge.net/. This will be hopefully solve the woes. But I guess it pays to debug what the problem is with the existing code too, but not by blocking the release indefinitely. Technical details are tracked in this issue report.

So that is exactly what was blocking the release. I cant wait to populate the downloads section with the first "official" Beta release version of our game!