OpenGl 4.x for Mac开发环境配置

概述

不同平台OpenGL开发环境的配置大同小异，我认为可以分为4部分：
1. OpenGL库：Mac OS X、Windows已经预安装，可以直接使用，linux和unix则需要自己安装，安装方法自行Google，在此不做详解。
2. OpenGL扩展库：GLEW提供了高效的运行机制,来决定哪个OpenGL扩展在目标平台上是否支持。它将OpenGL核心和扩展功能暴露在一个头文件，以供使用。安装方法自行Google，在此不做详解。
3. 应用程序框架：OpenGL是一种应用程序编程接口，本身不具有创建窗口、接收外设事件等功能，所以需要第三方软件库。目前应用较广泛的有GLUT和GLFW等，安装方法自行Google，在此不做详解。
4. 其他实用工具库：

Mac OS X平台通用步骤：

1. 链接GLUT.framwork和OpenGL.framwork库。
2. 导入GLEW扩展库。

---

基于xcode7的示例：

1. 链接GLUT.framwork和OpenGL.framwork库。
   
2. 导入GLEW扩展库。
   
   
3. 基本配置已经完成，引用OpenGL编程指南（第8版）的triangles实例，来展示一个OpenGL应用的基本结构。

triangles.cpp

#include 
#include 

#include 
#include 
#include "LoadShaders.h"

#define BUFFER_OFFSET(x)  ((const void*) (x))

enum VAO_IDs { Triangles, NumVAOs };
enum Buffer_IDs { ArrayBuffer, NumBuffers };
enum Attrib_IDs { vPosition = 0 };

GLuint VAOs[NumVAOs];
GLuint Buffers[NumBuffers];

const GLuint NumVertices = 6;

void init(void)
{
    glGenVertexArrays(NumVAOs, VAOs);
    glBindVertexArray(VAOs[Triangles]);

    GLfloat vertices[NumVertices][2] = {
        { -0.90, -0.90 },
        {  0.85, -0.90 },
        { -0.90,  0.85 },
        {  0.90, -0.85 },
        {  0.90,  0.90 },
        { -0.85,  0.90 }
    };

    glGenBuffers(NumBuffers, Buffers);
    glBindBuffer(GL_ARRAY_BUFFER, Buffers[ArrayBuffer]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    ShaderInfo shaders[] = {
        { GL_VERTEX_SHADER, "/Users/LXY/Desktop/test_opengl/triangles.vert" },
        { GL_FRAGMENT_SHADER, "/Users/LXY/Desktop/test_opengl/triangles.frag" },
        { GL_NONE, NULL }
    };

    GLuint program = LoadShaders(shaders);
    glUseProgram(program);

    glVertexAttribPointer(vPosition, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));

    glEnableVertexAttribArray(vPosition);
}

void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT);

    glBindVertexArray(VAOs[Triangles]);
    glDrawArrays(GL_TRIANGLES, 0, NumVertices);
    glFlush();
}

int main(int argc, const char * argv[])
{
    glutInit(&argc, (char**)argv);
    glutInitDisplayMode(GLUT_3_2_CORE_PROFILE | GLUT_RGBA);
    glutInitWindowSize(512, 512);
    glutCreateWindow(argv[0]);
    glewExperimental = GL_TRUE;
    GLenum err = glewInit();
    if (GLEW_OK != err) {
        fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
    }
    fprintf(stdout, "Status: Using GLEW %s\n", glewGetString(GLEW_VERSION));

    if (GLEW_VERSION_4_1) {
        std::cout << "Yay! OpenGL 4.1 is supported!" << std::endl;
    }

    init();

    glutDisplayFunc(display);

    glutMainLoop();

}
}

LoadShaders.h

//////////////////////////////////////////////////////////////////////////////
//
//  --- LoadShaders.h ---
//
//////////////////////////////////////////////////////////////////////////////

#ifndef __LOAD_SHADERS_H__
#define __LOAD_SHADERS_H__

#include 

#ifdef __cplusplus
extern "C" {
#endif  // __cplusplus

//----------------------------------------------------------------------------
//
//  LoadShaders() takes an array of ShaderFile structures, each of which
//    contains the type of the shader, and a pointer a C-style character
//    string (i.e., a NULL-terminated array of characters) containing the
//    entire shader source.
//
//  The array of structures is terminated by a final Shader with the
//    "type" field set to GL_NONE.
//
//  LoadShaders() returns the shader program value (as returned by
//    glCreateProgram()) on success, or zero on failure. 
//

typedef struct {
    GLenum       type;
    const char*  filename;
    GLuint       shader;
} ShaderInfo;

GLuint LoadShaders( ShaderInfo* );

//----------------------------------------------------------------------------

#ifdef __cplusplus
};
#endif // __cplusplus

#endif // __LOAD_SHADERS_H__

LoadShaders.cpp

//////////////////////////////////////////////////////////////////////////////
//
//  --- LoadShaders.cxx ---
//
//////////////////////////////////////////////////////////////////////////////

#include 
#include 

#define GLEW_STATIC
#include 
#include "LoadShaders.h"

#ifdef __cplusplus
extern "C" {
#endif // __cplusplus

//----------------------------------------------------------------------------

static const GLchar*
ReadShader( const char* filename )
{
#ifdef WIN32
    FILE* infile;
    fopen_s( &infile, filename, "rb" );
#else
    FILE* infile = fopen( filename, "rb" );
#endif // WIN32

    if ( !infile ) {
#ifdef _DEBUG
        std::cerr << "Unable to open file '" << filename << "'" << std::endl;
#endif /* DEBUG */
        return NULL;
    }

    fseek( infile, 0, SEEK_END );
    int len = ftell( infile );
    fseek( infile, 0, SEEK_SET );

    GLchar* source = new GLchar[len+1];

    fread( source, 1, len, infile );
    fclose( infile );

    source[len] = 0;

    return const_cast<const GLchar*>(source);
}

//----------------------------------------------------------------------------

GLuint
LoadShaders( ShaderInfo* shaders )
{
    if ( shaders == NULL ) { return 0; }

    GLuint program = glCreateProgram();

    ShaderInfo* entry = shaders;
    while ( entry->type != GL_NONE ) {
        GLuint shader = glCreateShader( entry->type );

        entry->shader = shader;

        const GLchar* source = ReadShader( entry->filename );
        if ( source == NULL ) {
            for ( entry = shaders; entry->type != GL_NONE; ++entry ) {
                glDeleteShader( entry->shader );
                entry->shader = 0;
            }

            return 0;
        }

        glShaderSource( shader, 1, &source, NULL );
        delete [] source;

        glCompileShader( shader );

        GLint compiled;
        glGetShaderiv( shader, GL_COMPILE_STATUS, &compiled );
        if ( !compiled ) {
#ifdef _DEBUG
            GLsizei len;
            glGetShaderiv( shader, GL_INFO_LOG_LENGTH, &len );

            GLchar* log = new GLchar[len+1];
            glGetShaderInfoLog( shader, len, &len, log );
            std::cerr << "Shader compilation failed: " << log << std::endl;
            delete [] log;
#endif /* DEBUG */

            return 0;
        }

        glAttachShader( program, shader );

        ++entry;
    }

#ifdef GL_VERSION_4_1
    if ( GLEW_VERSION_4_1 ) {
        // glProgramParameteri( program, GL_PROGRAM_SEPARABLE, GL_TRUE );
    }
#endif /* GL_VERSION_4_1 */

    glLinkProgram( program );

    GLint linked;
    glGetProgramiv( program, GL_LINK_STATUS, &linked );
    if ( !linked ) {
#ifdef _DEBUG
        GLsizei len;
        glGetProgramiv( program, GL_INFO_LOG_LENGTH, &len );

        GLchar* log = new GLchar[len+1];
        glGetProgramInfoLog( program, len, &len, log );
        std::cerr << "Shader linking failed: " << log << std::endl;
        delete [] log;
#endif /* DEBUG */

        for ( entry = shaders; entry->type != GL_NONE; ++entry ) {
            glDeleteShader( entry->shader );
            entry->shader = 0;
        }

        return 0;
    }

    return program;
}

//----------------------------------------------------------------------------
#ifdef __cplusplus
}
#endif // __cplusplus

result: