内置函数
radians(degree) : 角度变弧度; degrees(radian) : 弧度变角度; sin(angle), cos(angle), tan(angle) asin(x): arc sine, 返回弧度 [-PI/2, PI/2]; acos(x): arc cosine,返回弧度 [0, PI]; atan(y, x): arc tangent, 返回弧度 [-PI, PI]; atan(y/x): arc tangent, 返回弧度 [-PI/2, PI/2]; pow(x, y): x的y次方; exp(x): 指数, log(x): exp2(x): 2的x次方, log2(x): sqrt(x): x的根号; inversesqrt(x): x根号的倒数 abs(x): 绝对值 sign(x): 符号, 1, 0 或 -1 floor(x): 底部取整 ceil(x): 顶部取整 fract(x): 取小数部分 mod(x, y): 取模, x - y*floor(x/y) min(x, y): 取最小值 max(x, y): 取最大值 clamp(x, min, max): min(max(x, min), max); mix(x, y, a): x, y的线性混叠, x(1-a) + y*a; step(edge, x): 如 x smoothstep(edge0, edge1, x): threshod smooth transition时使用。 edge0<=edge0时为0.0, x>=edge1时为1.0 length(x): 向量长度 distance(p0, p1): 两点距离, length(p0-p1); dot(x, y): 点积,各分量分别相乘 后 相加 cross(x, y): 差积,x[1]*y[2]-y[1]*x[2], x[2]*y[0] - y[2]*x[0], x[0]*y[1] - y[0]*x[1] normalize(x): 归一化, length(x)=1; faceforward(N, I, Nref): 如 dot(Nref, I)< 0则N, 否则 -N reflect(I, N): I的反射方向, I -2*dot(N, I)*N, N必须先归一化 refract(I, N, eta): 折射,k=1.0-eta*eta*(1.0 - dot(N, I) * dot(N, I)); 如k<0.0 则0.0,否则 eta*I - (eta*dot(N, I)+sqrt(k))*N matrixCompMult(matX, matY): 矩阵相乘, 每个分量 自行相乘, 即 r[i][j] = x[i][j]*y[i][j]; 矩阵线性相乘,直接用 * lessThan(vecX, vecY): 向量 每个分量比较 x < y lessThanEqual(vecX, vecY): 向量 每个分量比较 x<=y greaterThan(vecX, vecY): 向量 每个分量比较 x>y greaterThanEqual(vecX, vecY): 向量 每个分量比较 x>=y equal(vecX, vecY): 向量 每个分量比较 x==y notEqual(vecX, vexY): 向量 每个分量比较 x!=y any(bvecX): 只要有一个分量是true, 则true all(bvecX): 所有分量是true, 则true not(bvecX): 所有分量取反 texture2D(sampler2D, coord): texture lookup texture2D(sampler2D, coord, bias): LOD bias, mip-mapped texture texture2DProj(sampler2D, coord): texture2DProj(sampler2D, coord, bias): texture2DLod(sampler2D, coord, lod): texture2DProjLod(sampler2D, coord, lod): textureCube(samplerCube, coord): textureCube(samplerCube, coord, bias): textureCubeLod(samplerCube, coord, lod):
内置常量
const mediump int gl_MaxVertexAttribs = 8; const mediump int gl_MaxVertexUniformVectors = 128; const mediump int gl_MaxVaryingVectors = 8; const mediump int gl_MaxVertexTextureImageUnits = 0; const mediump int gl_MaxCombinedTextureImageUnits = 8; const mediump int gl_MaxTextureImageUnits = 8; const mediump int gl_MaxFragmentUnitformVectors = 16; const mediump int gl_MaxDrawBuffers = 1;
内置变量
const mediu mp int gl_MaxVertexAttribs = 8; const mediump int gl_MaxVertexUniformVectors = 128; const mediump int gl_MaxVaryingVectors = 8; const mediump int gl_MaxVertexTextureImageUnits = 0; const mediump int gl_MaxCombinedTextureImageUnits = 8; const mediump int gl_MaxTextureImageUnits = 8; const mediump int gl_MaxFragmentUnitformVectors = 16; const mediump int gl_MaxDrawBuffers = 1;
精度
ighp, mediump, lowp
定义
默认:无修饰符,普通变量读写, 与外界无连接; const:常量 const vec3 zAxis = vec3(0.0, 0.0, 1.0); attribute: 申明传给vertex shader的变量;只读;不能为array或struct;attribute vec4 position; uniform: 表明整个图元处理中值相同;只读; uniform vec4 lightPos; varying: 被差值;读写; varying vec3 normal; in, out, inout;
外部调用
1、uint CreateShader(enum type) : 创建空的shader object; type: VERTEX_SHADER, 2、void ShaderSource(uint shader, sizeicount, const **string, const int *length):加载shader源码进shader object;可能多个字符串 3、void CompileShader(uint shader):编译shader object; shader object有状态 表示编译结果 4、void DeleteShader( uint shader ):删除 shader object; 5、void ShaderBinary( sizei count, const uint *shaders, enum binaryformat, const void *binary, sizei length ): 加载预编译过的shader 二进制串; 6、uint CreateProgram( void ):创建空的program object, programe object组织多个shader object,成为executable; 7、void AttachShader( uint program, uint shader ):关联shader object和program object; 8、void DetachShader( uint program, uint shader ):解除关联; 9、void LinkProgram( uint program ):program object准备执行,其关联的shader object必须编译正确且符合限制条件; 10、void UseProgram( uint program ):执行program object; 11、void ProgramParameteri( uint program, enum pname, int value ): 设置program object的参数; 12、void DeleteProgram( uint program ):删除program object;