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在哪公司建设网站,移动互联网应用程序指的是什么,WordPress网站转HTPPS,网站图片怎样做seo优化再回顾下镜面部分的分割求和近似法 现在关注第二部分 最后可化为 也就是说#xff0c;这两部分积分可以获得F0的系数和F0的偏差。 这两个值可以存储到BRDF积分贴图的RG部分。void main() { vec2 integratedBRDF IntegrateBRDF(TexCoords.x, TexCoords.y); FragColor …再回顾下镜面部分的分割求和近似法 现在关注第二部分 最后可化为 也就是说这两部分积分可以获得F0的系数和F0的偏差。 这两个值可以存储到BRDF积分贴图的RG部分。void main() { vec2 integratedBRDF IntegrateBRDF(TexCoords.x, TexCoords.y); FragColor integratedBRDF; } 再看函数vec2 IntegrateBRDF(float NdotV, float roughness) 可知积分贴图的横坐标是NotV,纵坐标是粗糙度。 查看这个RG是如何计算的。 循环采样后A / float(SAMPLE_COUNT); B / float(SAMPLE_COUNT); return vec2(A, B); 即A,B分别是F0和系数和F0的偏差也就是积分贴图的RG部分。结合公式在对每个采样向量中 float Fc pow(1.0 - VdotH, 5.0); A (1.0 - Fc) * G_Vis; B Fc * G_Vis; 继续向下float G GeometrySmith(N, V, L, roughness); float G_Vis (G * VdotH) / (NdotH * NdotV); 可知使用BRDF的几何函数处理了采样向量。继续向下vec2 Xi Hammersley(i, SAMPLE_COUNT); vec3 H ImportanceSampleGGX(Xi, N, roughness); vec3 L normalize(2.0 * dot(V, H) * H - V); 类似于预过滤环境贴图也是通过低差异序列进行重要性采样获取采样向量。 在c部分。 设置brdf积分贴图为512x512,纹理设置为GL_RG texture-setSourceFormat(GL_RG); 运行结果如下 代码如下 #include osg/TextureCubeMap #include osg/TexGen #include osg/TexEnvCombine #include osgUtil/ReflectionMapGenerator #include osgDB/ReadFile #include osgViewer/Viewer #include osg/NodeVisitor #include osg/ShapeDrawable #include osg/Texture2D #include osgDB/WriteFile static const char * vertexShader { “in vec3 aPos;\n” “in vec2 texcoord;” “varying vec2 TexCoords;\n” “void main(void)\n” “{\n” “TexCoords texcoord;\n” “gl_Position ftransform();\n” //“gl_Position view * view * vec4(aPos,1.0);” “}\n” }; static const char psShader { “#version 330 core \n” “out vec2 FragColor; \n” “in vec2 TexCoords; \n” \n “const float PI 3.14159265359; \n” “// —————————————————————————- \n” “// http://holger.dammertz.org/stuff/notes_HammersleyOnHemisphere.html \n” “// efficient VanDerCorpus calculation. \n” “float RadicalInverse_VdC(uint bits) \n” “{ \n” bits (bits 16u) | (bits 16u); \n bits ((bits 0x55555555u) 1u) | ((bits 0xAAAAAAAAu) 1u); \n bits ((bits 0x33333333u) 2u) | ((bits 0xCCCCCCCCu) 2u); \n bits ((bits 0x0F0F0F0Fu) 4u) | ((bits 0xF0F0F0F0u) 4u); \n bits ((bits 0x00FF00FFu) 8u) | ((bits 0xFF00FF00u) 8u); \n return float(bits) * 2.3283064365386963e-10; // / 0x100000000 \n “} \n” “// —————————————————————————- \n” “vec2 Hammersley(uint i, uint N) \n” “{ \n” return vec2(float(i) / float(N), RadicalInverse_VdC(i)); \n “} \n” “// —————————————————————————- \n” “vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness) \n” “{ \n” float a roughnessroughness; \n \n float phi 2.0 * PI * Xi.x; \n float cosTheta sqrt((1.0 - Xi.y) / (1.0 (aa - 1.0) * Xi.y)); \n float sinTheta sqrt(1.0 - cosThetacosTheta); \n \n // from spherical coordinates to cartesian coordinates - halfway vector \n vec3 H; \n H.x cos(phi) * sinTheta; \n H.y sin(phi) * sinTheta; \n H.z cosTheta; \n \n // from tangent-space H vector to world-space sample vector \n vec3 up abs(N.z) 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0); \n vec3 tangent normalize(cross(up, N)); \n vec3 bitangent cross(N, tangent); \n \n vec3 sampleVec tangent * H.x bitangent * H.y N * H.z; \n return normalize(sampleVec); \n “} \n” “// —————————————————————————- \n” “float GeometrySchlickGGX(float NdotV, float roughness) \n” “{ \n” // note that we use a different k for IBL \n float a roughness; \n float k (a * a) / 2.0; \n \n float nom NdotV; \n float denom NdotV * (1.0 - k) k; \n \n return nom / denom; \n “} \n” “// —————————————————————————- \n” “float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness) \n” “{ \n” float NdotV max(dot(N, V), 0.0); \n float NdotL max(dot(N, L), 0.0); \n float ggx2 GeometrySchlickGGX(NdotV, roughness); \n float ggx1 GeometrySchlickGGX(NdotL, roughness); \n \n return ggx1 * ggx2; \n “} \n” “// —————————————————————————- \n” “vec2 IntegrateBRDF(float NdotV, float roughness) \n” “{ \n” vec3 V; \n V.x sqrt(1.0 - NdotV*NdotV); \n V.y 0.0; \n V.z NdotV; \n \n float A 0.0; \n float B 0.0; \n \n vec3 N vec3(0.0, 0.0, 1.0); \n \n const uint SAMPLE_COUNT 1024u; \n for (uint i 0u; i SAMPLE_COUNT; i) \n { \n // generates a sample vector that’s biased towards the \n // preferred alignment direction (importance sampling). \n vec2 Xi Hammersley(i, SAMPLE_COUNT); \n vec3 H ImportanceSampleGGX(Xi, N, roughness); \n vec3 L normalize(2.0 * dot(V, H) * H - V); \n \n float NdotL max(L.z, 0.0); \n float NdotH max(H.z, 0.0); \n float VdotH max(dot(V, H), 0.0); \n \n if (NdotL 0.0) \n { \n float G GeometrySmith(N, V, L, roughness); \n float G_Vis (G * VdotH) / (NdotH * NdotV); \n float Fc pow(1.0 - VdotH, 5.0); \n \n A (1.0 - Fc) * G_Vis; \n B Fc * G_Vis; \n } \n } \n A / float(SAMPLE_COUNT); \n B / float(SAMPLE_COUNT); \n return vec2(A, B); \n “} \n” “// —————————————————————————- \n” “void main() \n” “{ \n” vec2 integratedBRDF IntegrateBRDF(TexCoords.x, TexCoords.y); \n FragColor integratedBRDF; \n “} \n” }; int main() { int imageWidth 512; int imageHeight 512; osg::ref_ptrosg::Vec3Array vertices new osg::Vec3Array; vertices-push_back(osg::Vec3(-imageWidth, 0.0f, -imageHeight)); vertices-push_back(osg::Vec3(imageWidth, 0.0f, -imageHeight)); vertices-push_back(osg::Vec3(imageWidth, 0.0f, imageHeight)); vertices-push_back(osg::Vec3(-imageWidth, 0.0f, imageHeight)); osg::ref_ptrosg::Vec3Array normals new osg::Vec3Array; normals-push_back(osg::Vec3(0.0f, -1.0f, 0.0f)); osg::ref_ptrosg::Vec2Array texcoords new osg::Vec2Array; texcoords-push_back(osg::Vec2(0.0f, 0.0f)); texcoords-push_back(osg::Vec2(1.0f, 0.0f)); texcoords-push_back(osg::Vec2(1.0f, 1.0f)); texcoords-push_back(osg::Vec2(0.0f, 1.0f)); osg::ref_ptrosg::Geometry quad new osg::Geometry; quad-setVertexArray(vertices.get());quad-setNormalArray(normals.get()); quad-setNormalBinding(osg::Geometry::BIND_OVERALL); quad-setTexCoordArray(0, texcoords.get()); quad-addPrimitiveSet(new osg::DrawArrays(GL_QUADS, 0, 4));quad-setVertexAttribArray(1, vertices, osg::Array::BIND_PER_VERTEX); quad-setVertexAttribArray(2, texcoords, osg::Array::BIND_PER_VERTEX); osg::ref_ptrosg::Texture2D texture new osg::Texture2D; texture-setSourceFormat(GL_RG); texture-setFilter(osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR); texture-setFilter(osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR); texture-setWrap(osg::Texture::WRAP_S, osg::Texture::CLAMP_TO_EDGE); texture-setWrap(osg::Texture::WRAP_T, osg::Texture::CLAMP_TO_EDGE); osg::ref_ptrosg::Geode geode new osg::Geode; geode-addDrawable(quad.get()); osg::ref_ptrosg::StateSet stateset geode-getOrCreateStateSet(); stateset-setTextureAttributeAndModes(0, texture.get());//shaderosg::ref_ptrosg::Shader vs1 new osg::Shader(osg::Shader::VERTEX, vertexShader); osg::ref_ptrosg::Shader ps1 new osg::Shader(osg::Shader::FRAGMENT, psShader); osg::ref_ptrosg::Program program1 new osg::Program; program1-addShader(vs1); program1-addShader(ps1); program1-addBindAttribLocation(aPos, 1); program1-addBindAttribLocation(texcoord, 2);osg::ref_ptrosg::Uniform tex0Uniform new osg::Uniform(tex0, 0); stateset-addUniform(tex0Uniform); stateset-setAttribute(program1, osg::StateAttribute::ON);//osgDB::writeImageFile(*image, strBRDFLUTImageName); osgViewer::Viewer viewer; viewer.setSceneData(geode.get());bool bPrinted false; return viewer.run();}