A GLSL Framework

自http://nehe.gamedev.net/article/glsl_an_introduction/25007/

一、 一个最简单的着色器程序

Ambient Shader, 所有的像素点都渲染为一种指定的颜色

void main() 
{ 
    // Transforming The Vertex 
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; 
}

Void main() 
{ 
    // Setting Each Pixel To Red 
    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0); 
}

二、如何在你的OpenGL程序中使用GLSL

GLSL需要以下四个扩展支持：GL_ARB_shader_objects，GL_ARB_shading_language_100，GL_ARB_vertex_shader，GL_ARB_fragment_shader

要想使用GLSL着色器，首先传递着色器源码给一个着色器对象，编译着色器源码，链接着色器到一个程序对象。

着色器对象表示你的源码，而程序对象表示一个可用的渲染管道线。

 

GLhandleARB glCreateProgramObjectARB();
GLhandleARB glCreateShaderObjectARB(GLenum shaderType); //shaderType可以为GL_VERTEX_SHADER_ARB或GL_FRAGMENT_SHADER_ARBvoid glShaderSourceARB(GLhangleARB shader, GLuint number_strings, const GLcharARB** strings, Glint * length);
void glCompileShader(GLhandleARB shader);
void glAttachObjectARB(GLhandleARB program, GLhandleARB shader);
void glLinkProgramARB(GLhandleARB program);
void glUseProgramObjectARB(GLhandleARB program);

char * my_fragment_shader_source; 
char * my_vertex_shader_source; 
  
// Get Vertex And Fragment Shader Sources 
my_fragment_shader_source = GetFragmentShaderSource(); 
my_vertex_shader_source = GetVertexShaderSource(); 
  
GLenum my_program; 
GLenum my_vertex_shader; 
GLenum my_fragment_shader; 
  
// Create Shader And Program Objects 
my_program = glCreateProgramObjectARB(); 
my_vertex_shader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB); 
my_fragment_shader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB); 
  
// Load Shader Sources 
glShaderSourceARB(my_vertex_shader, 1, &my_vertex_shader_source, NULL); 
glShaderSourceARB(my_fragment_shader, 1, &my_fragment_shader_source, NULL); 
  
// Compile The Shaders 
glCompileShaderARB(my_vertex_shader); 
glCompileShaderARB(my_fragment_shader); 
  
// Attach The Shader Objects To The Program Object 
glAttachObjectARB(my_program, my_vertex_shader); 
glAttachObjectARB(my_program, my_fragment_shader); 
  
// Link The Program Object 
glLinkProgramARB(my_program); 
  
// Use The Program Object Instead Of Fixed Function OpenGL 
glUseProgramObjectARB(my_program);