glLinkProgram crash on Intel

Armageddon · 2015-08-07T01:47:30

Hello, recently i stumbled on error with GLSL shader crashing on intel gpu(Bay Trail Graphics) in method glLinkProgram(ProgramID). Tested on Windows 10. Code compiles and works fine on two AMD gpu.. It's uber shader that computes lightning and texturing of mesh. It works fine if i specify only lights without shadows, if i add any light that use sampler2D with shadowmap, it crashes without any error on line glLinkProgram() indicating driver bug. Code of directional shadow light looks like: struct LightDirectional { vec3 Color; vec3 Direction; sampler2D ShadowTexture; vec2 ShadowMapSize; }; #if NUM_DIRECTIONAL_SHADOW > 0 in vec4 DirectionalShadowCoord[NUM_DIRECTIONAL_SHADOW]; //On Vertex Shader side, there is code that computes and specify this as 'out' uniform LightDirectional DirectionalShadow[NUM_DIRECTIONAL_SHADOW]; vec3 CalculateDirectionalShadow(int id, vec3 Normal, vec3 DiffuseColor, vec3 CameraVector, vec3 WorldPos) { float nDotL = dot(Normal, -DirectionalShadow[id].Direction); if(nDotL > 0.0) { float Shadow = CalcShadowTermSoftPCF(DirectionalShadow[id].ShadowTexture, DirectionalShadowCoord[id].xyz, 5, DirectionalShadow[id].ShadowMapSize); return CalculateLight(Normal, CameraVector, WorldPos, -DirectionalShadow[id].Direction, DirectionalShadow[id].Color, DiffuseColor, nDotL) * Shadow; } return vec3(0.0, 0.0, 0.0); } #endif //This method is called from void main() of mesh shader vec3 lighting(vec3 Normal, vec4 DiffuseTextureColor, vec3 CameraVector, vec3 WorldPos) { vec3 DiffuseAmount = vec3(0.01, 0.01, 0.01); //...Other kinds of lights #if NUM_DIRECTIONAL_SHADOW > 0 for(int i = 0; i < NUM_DIRECTIONAL_SHADOW; i++) { DiffuseAmount += CalculateDirectionalShadow(i, Normal, DiffuseTextureColor.rgb, CameraVector, WorldPos); } #endif //... Other kinds of lights return DiffuseAmount; } Is there any GLSL rule that forbids that kind of sampling texture in loop? If NUM_DIRECTIONAL_SHADOW is compile time define shouldn't it be unrolled by compiler? (That's sad there is no [unroll] like in hlsl) Is there any workaround to that issue? Best Regards

Graphics and GPU Programming Programming

Started by Armagedon August 06, 2015 08:55 AM

9 comments, last by Hodgman 8 years, 8 months ago

Hodgman

52,717

August 07, 2015 01:47 AM

Do you check for errors when compiling the shaders?
If you ignore any compilation errors, then I would expect the linking stage to crash in the driver, because you'll be feeding invalid data into the driver...

But how is it possible that it works correctly on two amd gpus(hd 7770, windows 10; hd 6470,. windows 7)? And both produces correct images?
If there were any mismatch between vertex and pixel shader there would be an error on amd gpus or at least they would produce incorrect image.

OpenGL is just a text document, specifying how drivers *should* behave. Sadly, in practice, no driver strictly follows every word of the specification...

NVidia in particular are famous for accepting blatantly invalid GLSL code and compiling it anyway. So it's very important to test your GL applications on every different graphics card driver that your customers might use :(

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glLinkProgram crash on Intel

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glLinkProgram crash on Intel

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