This document discusses pixel shaders and GPU programming. It begins by defining what a shader is and describing the basic entities and traits involved in shader programming. It then covers the different types of shaders including pixel shaders, vertex shaders, and geometric shaders. The document discusses the graphics pipeline and how shaders are used. It introduces Cg as a programming language for shaders and provides examples of loading and using pixel shaders in OpenGL.

1. Pixel shaders: programming the GPUBy: Venkata Nanda Kishore

2. What is a Shader?Set of Software InstructionsDegree of FlexibilityTraits of an entity

3. Entities,Traits And DegreeEntities: Pixels Vertices Geometric shapesTraits: Pixels: z-buffer, alpha values etc.Vertices: Texture co-ordinates, Color

4. Types of ShadersInitially, Shaders are just pixel shadersTypes of Shaders:Pixel Shaders

5. Vertex Shaders

6. Geometric ShadersBut the name remained as it was!

7. GRAPHICS PIPELINEGeometric ShadersRasteriserVertexShadersPixel Shaders

8. Effect of ShadersReplaced hard coded effectsGives a programmable alternativeFixed Function PipelineProgrammable Function Pipeline3.Parallel Programming

9. Programming ShadersHLSL (Direct 3d)GLSL (OpenGl)Cg(Nvidia + Microsoft)

10. CgWhat is Cg?Is it similar to C?Is it the right question?Can we use it as a general programming language?

11. Background of CgUse of Assembly level languageWhat is assembly level?What is high level,low level and middle level?How easy is it?

12. Example of assembly level languagefib: movedx, [esp+8]cmpedx, 0 ja @f moveax, 0 ret@@: cmpedx, 2 ja @fmoveax, 1ret @@: push ebxmovebx, 1movecx, 1 @@: lea eax, [ebx+ecx] cmpedx, 3 jbe @f movebx, ecxmovecx, eaxdecedxjmp@b@@: pop ebx ret

13. Advantage of CgPortableEasyOptimize the code

14. Games that Use CgHIT MAN : Blood MoneyBATTLE FIELD 2FAR CRYRACERAnd many more

15. Syntax and Semantics(1)Data Types:int, float, half, fixed, bool, sampler*Operators: Arithmetic and logical operators as in CAdditional: arithmetic operations for vector and matrix operrations

16. Syntax and Semantics(2)Functions and Control Structures: Similar to CStandard Cg Library: Specialised GPU programming tasksEg. Texture Mapping functions tex1D and tex2DCg Runtime Library:Can be used with OpenGl or DirectX

17. Example ShaderstructVertIn //Input vertex{ float4 pos : POSITION; float4 color : COLOR0; }; // output vertexstructVertOut{ float4 pos : POSITION; float4 color : COLOR0; }; // vertex shader main entryVertOutmain(VertIn IN, uniform float4x4 modelViewProj) { VertOut OUT; OUT.pos= mul(modelViewProj, IN.pos); //positionOUT.color= IN.color; // copy input color to outputOUT.color.z= 1.0f; // blue component of color = 1.0freturn OUT; }

18. Loading Pixel Shaders in OpenGL1.Loading extensions:glEnable(GL_FRAGMENT_PROGRAM_ARB);2.Create Shader Number:glGenProgramsARB(1, &shader_num); glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, shader_num);

19. Actually Loading the ShaderglProgramStringARB(GL_FRAGMENT_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB, strlen(program_string), program_string);glDisable(GL_FRAGMENT_PROGRAM_ARB);http://joshbeam.com/articles/cg_pixel_shaders_in_opengl/