MAC OS下使用Xcode进行GLSL编程的配置过程

整理自之前使用的163博客原创文章。

GLSL项目中需要使用GLEW库，因此先要安装GLEW库和在Xcode中配置GLEW。要使GLEW在Xcode中被正确链接，又需要通过MacPorts来安装GLEW。下文以MacPorts-->GLEW-->GLSL的顺序来阐述。
环境：系统 OS X 10.9.2 (13C64)，工具 Xcode 5.1，图形卡 Intel Iris 1024 MB

1 MacPorts安装

MacPorts是与apt-get和yum类似的软件管理包，下载与系统对应的安装包后进行安装（安装过程中会联网进行更新，导致安装过程很久，建议断网安装）。安装之后打开终端运行

$ sudo port -v selfupdate

进行更新。如果更新时在如下状态下卡的时间很久，

--->  Updating the ports tree
Synchronizing local ports tree from rsync://rsync.macports.org/release/tarballs/ports.tar
receiving file list ... done
ports.tar

使用control+z终止更新，终端输入

$ sudo vim /opt/local/etc/macports/sources.conf

打开配置文件，更改最后一行的默认下载地址（参考“解决安装macports，不能更新的问题”，参考下载网址列表），如可修改为韩国镜像：

#rsync://rsync.macports.org/release/tarballs/ports.tar [default]
#http://www.macports.org/files/ports.tar.gz [default]
rsync://cjj.kr.rsync.macports.org/macports/release/tarballs/ports.tar

改好后wq保存退出，再次运行

$ sudo port -v selfupdate

进行更新，更新成功后会显示如下信息：

--->  MacPorts base is already the latest version
The ports tree has been updated. To upgrade your installed ports, you should run  port upgrade outdated

安装过程中遇到其它问题请戳：

Mac OS X Lion安装MacPorts（让你在Mac的Shell下更加游刃有余）

Mac中MacPorts安装和使用

Mac OS X中MacPorts安装和使用

2 GLEW库安装

glew库主要有如下三种安装方式：1）在Xcode中直接导入framework（下载地址）；2）编译glew源代码进行安装（参考“Installing GLEW in Mac OS X (Leopard)”）；3）通过MacPorts进行安装。

实测了三种方式，均可成功安装glew库，但前两种方式在Xcode中链接不成功，本文通过MacPorts进行安装（参考“GLEW: Apple Mach-O Linker (Id) Error”）。

终端输入

$ sudo port install glew

进行安装，安装成功后显示：

--->  Installing glew @1.10.0_0
--->  Activating glew @1.10.0_0
--->  Cleaning glew
--->  Updating database of binaries: 100.0%
--->  Scanning binaries for linking errors: 100.0%
--->  No broken files found.

安装过程中遇到其它问题请戳

cannot link glew under xcode4, macosx lion

3 Xcode中GLSL的配置

Mac系统中已内置openGL、GLUT和GLSL，无需安装。

启动Xcode，新建Cocoa Application工程，删除“TriangleAppDelegate.*”文件、“*main.m”文件和“MainMenu.xib”文件。右键单击"Supporting Files"添加新文件，选择"C++ File"。添加后，删除对应的头文件。右键单击"Frameworks"，添加"OpenGL.framework"和"GLUT.framework"（参考“MAC OS X And Win7 vs2010 搭建OpenGL”，参考“在Xcode中使用GLUT开发OpenGL应用程序”）。

下面是添加对GLEW库的链接，在build setting中添加如下参数即可：

other linker flags: -lGLEW
header search paths: /opt/local/include/
library search paths: /opt/local/lib/

4 Hello World

在supporting files下添加basic.vert：

void main(){
    gl_Position = ftransform();
}

在supporting files下添加basic.frag：

void main() {
    gl_FragColor = vec4(0.4,0.4,0.8,1.0);
}

在supporting files下添加textfile.h：

#ifndef macGL_textfile_h
#define macGL_textfile_h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char *textFileRead(const char *fn);
int textFileWrite(char *fn, char *s);
unsigned char *readDataFromFile(char *fn);
#endif

 在supporting files下添加textfile.cpp：

#include "textfile.h"

unsigned char * readDataFromFile(char *fn){
    FILE *fp;
    unsigned char *content = NULL;
    int count=0;

    if (fn != NULL) {
        fp = fopen(fn,"rb");
        if (fp != NULL) {
            fseek(fp, 0, SEEK_END);
            count = ftell(fp);
            rewind(fp);
            if (count > 0) {
                content = (unsigned char *)malloc(sizeof(unsigned char) * (count+1));
                count = fread(content,sizeof(unsigned char),count,fp);
                content[count] = '';
            }
            fclose(fp);
        }
    }

    return content;
}


char *textFileRead(const char *fn) {
    FILE *fp;
    char *content = NULL;
    int count=0;

    if (fn != NULL) {
            fp = fopen(fn,"rt");
            if (fp != NULL) {
                fseek(fp, 0, SEEK_END);
                count = ftell(fp);
                rewind(fp);
                if (count > 0) {
                    content = (char *)malloc(sizeof(char) * (count+1));
                    count = fread(content,sizeof(char),count,fp);
                    content[count] = '';
                }
                fclose(fp);
            }
        }
    return content;
}


int textFileWrite(char *fn, char *s) {
    FILE *fp;
    int status  = 0;
    if (fn != NULL){
        fp = fopen(fn,"w");
        if (fp != NULL) {
            if (fwrite(s,sizeof(char),strlen(s),fp) == strlen(s))
                status = 1;
            fclose(fp);
        }
    }
    return(status);
}

在supporting files下添加GLSLTest.cpp。其中display函数中的glutWireTeapot()是glut内置的画茶壶的函数。注意MAC下特有的glBindVertexArrayAPPLE，glBindVertexArrayAPPLE，glGenVertexArraysAPPLE：

//#pragma comment(lib,"libGLEW.a")

#include <GL/glew.h>

#include "textfile.h"

#include <glut/glut.h>
#include <iostream>
using namespace std;

GLuint vShader,fShader;//顶点着色器对象

//顶点位置数组
float positionData[] = {
    -0.8f, -0.8f, 0.0f,
    0.8f, -0.8f, 0.0f,
    0.0f,  0.8f, 0.0f };
//颜色数组
float colorData[] = {
    1.0f, 0.0f, 0.0f,
    0.0f, 1.0f, 0.0f,
    0.0f, 0.0f, 1.0f };

GLuint vaoHandle;//vertex array object

void initShader(const char *VShaderFile,const char *FShaderFile)
{
    //1、查看GLSL和OpenGL的版本
    const GLubyte *renderer = glGetString( GL_RENDERER );
    const GLubyte *vendor = glGetString( GL_VENDOR );
    const GLubyte *version = glGetString( GL_VERSION );
    const GLubyte *glslVersion =
    glGetString( GL_SHADING_LANGUAGE_VERSION );
    GLint major, minor;
    glGetIntegerv(GL_MAJOR_VERSION, &major);
    glGetIntegerv(GL_MINOR_VERSION, &minor);
    cout << "GL Vendor    :" << vendor << endl;
    cout << "GL Renderer  : " << renderer << endl;
    cout << "GL Version (string)  : " << version << endl;
    cout << "GL Version (integer) : " << major << "." << minor << endl;
    cout << "GLSL Version : " << glslVersion << endl;
    
    //2、编译着色器
    //创建着色器对象：顶点着色器
    vShader = glCreateShader(GL_VERTEX_SHADER);
    //错误检测
    if (0 == vShader)
    {
        cerr << "ERROR : Create vertex shader failed" << endl;
        exit(1);
    }
    
    //把着色器源代码和着色器对象相关联
    const GLchar *vShaderCode = textFileRead(VShaderFile);
    const GLchar *vCodeArray[1] = {vShaderCode};
    glShaderSource(vShader,1,vCodeArray,NULL);
    
    //编译着色器对象
    glCompileShader(vShader);
    
    
    //检查编译是否成功
    GLint compileResult;
    glGetShaderiv(vShader,GL_COMPILE_STATUS,&compileResult);
    if (GL_FALSE == compileResult)
    {
        GLint logLen;
        //得到编译日志长度
        glGetShaderiv(vShader,GL_INFO_LOG_LENGTH,&logLen);
        if (logLen > 0)
        {
            char *log = (char *)malloc(logLen);
            GLsizei written;
            //得到日志信息并输出
            glGetShaderInfoLog(vShader,logLen,&written,log);
            cerr << "vertex shader compile log : " << endl;
            cerr << log << endl;
            free(log);//释放空间
        }
    }
    
    //创建着色器对象：片断着色器
    fShader = glCreateShader(GL_FRAGMENT_SHADER);
    //错误检测
    if (0 == fShader)
    {
        cerr << "ERROR : Create fragment shader failed" << endl;
        exit(1);
    }
    
    //把着色器源代码和着色器对象相关联
    const GLchar *fShaderCode = textFileRead(FShaderFile);
    const GLchar *fCodeArray[1] = {fShaderCode};
    glShaderSource(fShader,1,fCodeArray,NULL);
    
    //编译着色器对象
    glCompileShader(fShader);
    
    //检查编译是否成功
    glGetShaderiv(fShader,GL_COMPILE_STATUS,&compileResult);
    if (GL_FALSE == compileResult)
    {
        GLint logLen;
        //得到编译日志长度
        glGetShaderiv(fShader,GL_INFO_LOG_LENGTH,&logLen);
        if (logLen > 0)
        {
            char *log = (char *)malloc(logLen);
            GLsizei written;
            //得到日志信息并输出
            glGetShaderInfoLog(fShader,logLen,&written,log);
            cerr << "fragment shader compile log : " << endl;
            cerr << log << endl;
            free(log);//释放空间
        }
    }
    
    //3、链接着色器对象
    //创建着色器程序
    GLuint programHandle = glCreateProgram();
    if (!programHandle)
    {
        cerr << "ERROR : create program failed" << endl;
        exit(1);
    }
    //将着色器程序链接到所创建的程序中
    glAttachShader(programHandle,vShader);
    glAttachShader(programHandle,fShader);
    //将这些对象链接成一个可执行程序
    glLinkProgram(programHandle);
    //查询链接的结果
    GLint linkStatus;
    glGetProgramiv(programHandle,GL_LINK_STATUS,&linkStatus);
    if (GL_FALSE == linkStatus)
    {
        cerr << "ERROR : link shader program failed" << endl;
        GLint logLen;
        glGetProgramiv(programHandle,GL_INFO_LOG_LENGTH,
                       &logLen);
        if (logLen > 0)
        {
            char *log = (char *)malloc(logLen);
            GLsizei written;
            glGetProgramInfoLog(programHandle,logLen,
                                &written,log);
            cerr << "Program log : " << endl;
            cerr << log << endl;
        }
    }
    else//链接成功，在OpenGL管线中使用渲染程序
    {
        glUseProgram(programHandle);
    }
}

void initVBO()
{
    // Create and populate the buffer objects
    GLuint vboHandles[2];
    glGenBuffers(2, vboHandles);
    GLuint positionBufferHandle = vboHandles[0];
    GLuint colorBufferHandle = vboHandles[1];
    
    //绑定VBO以供使用
    glBindBuffer(GL_ARRAY_BUFFER,positionBufferHandle);
    //加载数据到VBO
    glBufferData(GL_ARRAY_BUFFER,9 * sizeof(float),
                 positionData,GL_STATIC_DRAW);
    
    //绑定VBO以供使用
    glBindBuffer(GL_ARRAY_BUFFER,colorBufferHandle);
    //加载数据到VBO
    glBufferData(GL_ARRAY_BUFFER,9 * sizeof(float),
                 colorData,GL_STATIC_DRAW);
    
    glGenVertexArraysAPPLE(1,&vaoHandle);
    glBindVertexArrayAPPLE(vaoHandle);
    
    glEnableVertexAttribArray(0);//顶点坐标
    glEnableVertexAttribArray(1);//顶点颜色
    
    //调用glVertexAttribPointer之前需要进行绑定操作
    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 );
}

void init()
{
    //初始化glew扩展库
    GLenum err = glewInit();
    if( GLEW_OK != err )
    {
        cout <<"Error initializing GLEW: " << glewGetErrorString(err) << endl;
    }
    
    initShader("basic.vert","basic.frag");
    
    initVBO();
    
    glClearColor(0.0,0.0,0.0,0.0);
    //glShadeModel(GL_SMOOTH);
    
}

void display()
{
    glClear(GL_COLOR_BUFFER_BIT);
    
    ////绘制一个三角形(使用普通方法)
    //glBegin(GL_TRIANGLES);
    //glColor3f(0.0f,1.0f,0.0f);
    //glVertex3f(0.0f,1.0f,0.0f);
    
    //glColor3f(0.0f,1.0f,0.0f);
    //glVertex3f(-1.0f,-1.0f,0.0f);
    
    //glColor3f(0.0f,0.0f,1.0f);
    //glVertex3f(1.0f,-1.0f,0.0f);
    //glEnd();
    
    //使用VAO、VBO绘制
    glBindVertexArrayAPPLE(vaoHandle);
    //glDrawArrays(GL_TRIANGLES,0,3);
    glutWireTeapot(0.5);
    GLint tiz = glGetUniformLocation(vaoHandle, "iz");
    glUniform1iARB(tiz, 20);
    glBindVertexArrayAPPLE(0);
    glutWireTeapot(1.0);
    
    glutSwapBuffers();
}

void keyboard(unsigned char key,int x,int y)
{
    switch(key)
    {
        case 27:
            glDeleteShader(vShader);
            glUseProgram(0);
            break;
    }
}

int main(int argc,char** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(600,600);
    glutInitWindowPosition(100,100);
    glutCreateWindow("GLSL Test : Draw a triangle");
    init();
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    
    glutMainLoop();
    return 0;
}

运行成功后的效果图：

其它参考网址：

【GLSL教程】（四）shder的简单示例

GLSL Tutorial

How to link glew in xcode

【GLSL教程】（二）在OpenGL中使用GLSL

GLSL.Refract & Reflect & Diffraction