这里以演示如何编译Vertex Shader为例,其他类型的Shader类似。

1,先用io流读取shader文件

std::stringstream code;
code << inFile.rdbuf();
inFile.close();
string codeStr(code.str());

2,创建空白Shader对象

GLuint vertShader = glCreateShader( GL_VERTEX_SHADER );

3,编译Shader代码到Shader对象中

// Load the source code into the shader object
const GLchar* codeArray[] = {codeStr.c_str()};
glShaderSource(vertShader, 1, codeArray, NULL);

// Compile the shader
glCompileShader( fragShader );

4,Shader链接
4.1 创建program对象

// Create the program object
GLuint programHandle = glCreateProgram();

4.2 附加Shader对象到program对象中

// Attach the shaders to the program object
glAttachShader( programHandle, vertShader );
glAttachShader( programHandle, fragShader );

4.3 链接program

// Link the program
glLinkProgram( programHandle );

4.4 使用program对象

glUseProgram( programHandle );

5,创建并绑定buffer对象

绑定buffer的意义:当渲染(Rendering)的时候,着色器(shader)每当被执行时,OpenGL从这些buffer中拉取属性(attribute)数据给这些着色器。

// Create and populate the buffer objects
GLuint vboHandles[2];
glGenBuffers(2, vboHandles);
GLuint positionBufferHandle = vboHandles[0];
GLuint colorBufferHandle = vboHandles[1];

glBindBuffer(GL_ARRAY_BUFFER, positionBufferHandle);
glBufferData(GL_ARRAY_BUFFER, 9 * sizeof(float), positionData, GL_STATIC_DRAW);

glBindBuffer(GL_ARRAY_BUFFER, colorBufferHandle);
glBufferData(GL_ARRAY_BUFFER, 9 * sizeof(float), colorData, GL_STATIC_DRAW);

6,开辟Array数组并填充其数据

// Create and set-up the vertex array object
glGenVertexArrays( 1, &vaoHandle );
glBindVertexArray(vaoHandle);

glEnableVertexAttribArray(0);  // Vertex position
glEnableVertexAttribArray(1);  // Vertex color

glBindBuffer(GL_ARRAY_BUFFER, positionBufferHandle);
glVertexAttribPointer( 0, 3, GL_FLOAT, GL_FALSE, 0, (GLubyte *)NULL );

glBindBuffer(GL_ARRAY_BUFFER, colorBufferHandle);
glVertexAttribPointer( 1, 3, GL_FLOAT, GL_FALSE, 0, (GLubyte *)NULL );
glBindVertexArray(0);

只愿君心似我心,定不负,相思意。---李之仪《卜算子》