Introduction to 3D Game Programming with DirectX 9 源码

//////////////////////////////////////////////////////////////////////////// // // File: diffuse.txt // // Author: Frank Luna (C) All Rights Reserved // // System: AMD Athlon 1800+ XP, 512 DDR, Geforce 3, Windows XP, MSVC++ 7.0 // // Desc: Vertex shader that does diffuse lighting. // //////////////////////////////////////////////////////////////////////////// // // Global variables we use to hold the view matrix, projection matrix, // ambient material, diffuse material, and the light vector that describes // the direction to the light source. These variables are initialized from // the application. // matrix ViewMatrix; matrix ViewProjMatrix; vector AmbientMtrl; vector DiffuseMtrl; vector LightDirection; // // Global variables used to hold the ambient light intensity (ambient // light the light source emits) and the diffuse light intensity (diffuse // light the light source emits). These variables are initialized here // in the shader. // vector DiffuseLightIntensity = {0.0f, 0.0f, 1.0f, 1.0f}; vector AmbientLightIntensity = {0.0f, 0.0f, 0.2f, 1.0f}; // // Input and Output structures. // struct VS_INPUT { vector position : POSITION; vector normal : NORMAL; }; struct VS_OUTPUT { vector position : POSITION; vector diffuse : COLOR; }; // // Main // VS_OUTPUT Main(VS_INPUT input) { // zero out all members of the output instance. VS_OUTPUT output = (VS_OUTPUT)0; // // Transform position to homogeneous clip space // and store in the output.position member. // output.position = mul(input.position, ViewProjMatrix); // // Transform lights and normals to view space. Set w // componentes to zero since we're transforming vectors // here and not points. // LightDirection.w = 0.0f; input.normal.w = 0.0f; LightDirection = mul(LightDirection, ViewMatrix); input.normal = mul(input.normal, ViewMatrix); // // Compute cosine of the angle between light and normal. // float s = dot(LightDirection, input.normal); // // Recall that if the angle between the surface and light // is greater than 90 degrees the surface recieves no light. // Thus, if the angle is greater than 90 degrees we set // s to zero so that the surface will not be lit. // if( s < 0.0f ) s = 0.0f; // // Ambient light reflected is computed by performing a // component wise multiplication with the ambient material // vector and the ambient light intensity vector. // // Diffuse light reflected is computed by performing a // component wise multiplication with the diffuse material // vector and the diffuse light intensity vector. Further // we scale each component by the shading scalar s, which // shades the color based on how much light the vertex received // from the light source. // // The sum of both the ambient and diffuse components gives // us our final vertex color. // output.diffuse = (AmbientMtrl * AmbientLightIntensity) + (s * (DiffuseLightIntensity * DiffuseMtrl)); return output; }