2.著色器和編程

1.創(chuàng)建著色器
GLuint glCreateShader(GLenum type);
type: GL_VERTEX_SHADER(頂點(diǎn)著色器)、GL_FRAGMENT_SHADER(紋理著色器)
2.刪除著色器
void glDeleteShader(GLuint shader);
shader:要?jiǎng)h除的著色器句柄
3.著色器源碼
void glShaderSource(GLuint shader, GLsizei count, const char ** string, const GLint * length);
shader:著色器對(duì)象句柄
count:著色器源碼的字符數(shù)
string:指向著色器源碼字符串矩陣的指針
length:長(zhǎng)度
4.編譯著色器
void glCompileShader(GLuint shader)
shader:著色器句柄
5.debug信息輸出
void glGetShaderiv(GLuint shader, GLenum pname, GLint *params)
shader:著色器句柄
pname:要查詢的信息 GL_COMPLE_STATUS(編譯是否完成)、GL_DELETE_STATUS(著色器是否被刪除)、GL_INFO_LOG_LENGTH(編譯信息)、GL_SHADER_SOURCE_LENGTH(著色器源碼)、GL_SHADER_TYPE(著色器類型)
p
6.獲得調(diào)用日志,在使用glGetShaderiv(GL_INFO_LOG_LENGTH),分配足夠的字符串來(lái)儲(chǔ)存info log
void glGetShaderInfoLog(GLuint shader, GLsizei maxLength, GLsizei *length, GLchar *infoLog);
shader:著色器句柄
maxLength:日志緩存大小
length:
infoLog:日志內(nèi)容

例:裝在著色器
GLuint loadShader(GLenum type, const char *shaderSrc)
{
   GLuint shader;
   GLint compiled;
   shader = glCreateShader(type);
   if(shader == 0)
   return 0;
   //Load the shader source
   glShaderSource(shader, 1, &shaderSrc, NULL);
   //compile the shader
   glCompileShader(shader);
   //check the compile status
   glGetShaderiv(shader, GL_COMPILE_STATUS, &compile);
   if(!compiled){
      GLint infoLen = 0;
      glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
      if(infoLen > 1){
          char *infoLog = malloc(sizeof(char) * infoLen);
         glGetShaderInfoLog(shader, infoLen, NULL, infoLog);
         //輸出log
        free(infoLog);
     }
     glDeleteShader(shader);
     return 0;
   }
    return shader
}

7.創(chuàng)建源程序
GLuint glCreatePrograme();
8.刪除源程序
void glDeleteProgram(GLuint program);
program:要?jiǎng)h除的項(xiàng)目句柄
9.鏈接著色器(頂點(diǎn)/片段)到項(xiàng)目
void glAttachShader(GLuint program, GLuint shader);
program:項(xiàng)目句柄
shader:這色器句柄
10.分離著色器
void glDetachShader(GLuint program, GLuint shader);
program:項(xiàng)目句柄
shader:著色器句柄
11.鏈接項(xiàng)目
void glLinkProgram(GLuint program);
program:項(xiàng)目句柄
12.檢查鏈接的結(jié)果:
void glGetProgramiv(GLuint program, GLenum pname, GLint *params);
program:項(xiàng)目句柄
pname: 要查詢的信息
GL_ACTIVE_ATTRIBUTES
GL_ACTIVE_ATTRIBUTES_MAX_LENGTH
GL_ACTIVE_UNIFORMS
GL_ACTIVE_UNIFORMS_MAX_LENGTH
GL_ACTIVE_SHADERS
GL_DELETE_STATUS
GL_INFO_LOG_LENGTH
GL_LINK_STATUS
GL_VALIDATE_STATUS
params:保存查詢結(jié)果的整形指針
13.檢查項(xiàng)目當(dāng)前的執(zhí)行狀態(tài)
void glValidateProgram(GLuint program);
program:項(xiàng)目句柄
14.開(kāi)始使用program
void glUseProgram(GLuint program);
program:項(xiàng)目句柄

例子:創(chuàng)建、連接著色器、鏈接項(xiàng)目
//create the program object
programObject = glCreateProgram();
if(programObject == 0){
     return 0;
}
glAttachShader(programObject, vertexShader);
glAttachShader(programObject, fragmentShader);
//link the program
glLinkProgram(programObject);
//check the link status
glGetProgramiv(programObject, GL_LINK_STATUS, &linked);
if(!linked){
     GLInt infoLen = 0;
     glGetProgramiv(programObject, GL_INFO_LOG_LENGTH, &infoLen);
    if(infoLen > 1){
       char * infoLog = malloc(sizeof(char) * infoLen);
      glGetProgramInfoLog(programObject, infoLen, NULL, InfoLog);
      //輸出log
     free(infoLog);
    }
    glDeleteProgram(programObject);
    return FALSE;
}
//use program 
glUseProgram(userData->programObject);

15.查找常量的細(xì)節(jié)
void glGetActiveUniform(GLuint program, GLuint index, GLsizei bufSize, GLsizei *length, GLint *size, GLenum *type, char * name);
program:項(xiàng)目句柄
index:被查詢常量的索引
bufSize:緩存大小
length:數(shù)目
size:1
type:GL_FLOAT, GL_FLOAT_VEC2, GL_FLOAT_VEC3, GL_FLOAT_VEC4 GL_INT, GL_INT_VEC2, GL_INT_VEC3, GL_INT_VEC4, GL_BOOL GL_BOOL_VEC2, GL_BOOL_VEC3, GL_BOOL_VEC4, GL_FLOAT_MAT2, GL_FLOAT_MAT3, GL_FLOAT_MAT4, GL_SAMPLER_2D, GL_SAMPLER_CUBE
name:
16.得到常量的地址
GLint glGetUniformLocation(GLuint program, const char * name);
program:項(xiàng)目句柄
name:常量的名字

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