关键代码：

	string vsCode  =   "uniform vec4 _color;\varying vec4 outColor;\void main()\{\outColor    =   _color;\gl_TexCoord[0]  =   gl_MultiTexCoord0;\gl_Position =   gl_ModelViewProjectionMatrix * gl_Vertex;\}";string psCode  = "varying vec4 outColor;\uniform     sampler2D   _texture;\void main()\{\vec4 color   =   texture2D(_texture, gl_TexCoord[0].st);\gl_FragColor    =   color;\}";//gl_TexCoord[0]  =   gl_MultiTexCoord0;; 表示接收opengl传过来的纹理坐标//gl_TexCoord是输出，输出到ps里 ，在ps中不可直接使用 gl_MultiTexCoord0  当前版本的opengl每个顶点有八组纹理坐标 gl_TexCoord[0~7] gl_MultiTexCoord0~7//uniform  sampler2D  _texture;  sampler2D变量 只能在PS里 不能放到vs中，可以理解为二维图片，或者叫二维纹理//texture2D() 内置函数，用于根据纹理及坐标获取纹理颜色

代码例子：

main.cpp

/*
*
* 该实例演示访问纹理坐标数据
*
*/#define GLEW_STATIC
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <iostream>#include <GL/glew.h>
#include <GLFW/glfw3.h>#include <glm/vec3.hpp> // glm::vec3
#include <glm/vec4.hpp> // glm::vec4
#include <glm/mat4x4.hpp> // glm::mat4
#include <glm/ext/matrix_transform.hpp> // glm::translate, glm::rotate, glm::scale
#include <glm/ext/matrix_clip_space.hpp>#include "FreeImage.h"#include "shader.hpp"#pragma comment(linker, "/subsystem:\"windows\" /entry:\"mainCRTStartup\"" )  //这行是取消显示控制台char szTitle[64] = "opengl view";//glm::vec4 vec(1.0f, 0.0f, 0.0f, 1.0f);//创建一个点
//glm::mat4 trans = glm::mat4(1.0f);//创建单位矩阵
//Window dimensions    
const GLuint WIDTH = 800, HEIGHT = 600;GLfloat ratio = 1.f;
GLfloat xpos, ypos;glm::vec3 _eye(0, 0, 10);
glm::vec3 _lookAt(0, 0, 0);
glm::vec3 _up(0, 1, 0);glm::mat4 _matProj = glm::mat4(1.0f);//创建单位矩阵
glm::mat4 _matView = glm::mat4(1.0f);//创建单位矩阵float size = 100.0f;//顶点数据
struct Vertex {float x, y, z;float u, v;
};Vertex g_cubeVertices[] =
{{ -1.0f, -1.0f, 1.0f, 0.0f, 0.0f },{ 1.0f, -1.0f, 1.0f, 1.0f, 0.0f },{ 1.0f, 1.0f, 1.0f, 1.0f, 1.0f },{ -1.0f, 1.0f, 1.0f, 0.0f, 1.0f },{ -1.0f, -1.0f, -1.0f, 1.0f, 0.0f },{ -1.0f, 1.0f, -1.0f, 1.0f, 1.0f },{ 1.0f, 1.0f, -1.0f, 0.0f, 1.0f },{ 1.0f, -1.0f, -1.0f, 0.0f, 0.0f },{ -1.0f, 1.0f, -1.0f, 0.0f, 1.0f },{ -1.0f, 1.0f, 1.0f, 0.0f, 0.0f },{ 1.0f, 1.0f, 1.0f, 1.0f, 0.0f },{ 1.0f, 1.0f, -1.0f, 1.0f, 1.0f },{ -1.0f, -1.0f, -1.0f, 1.0f, 1.0f },{ 1.0f, -1.0f, -1.0f, 0.0f, 1.0f },{ 1.0f, -1.0f, 1.0f, 0.0f, 0.0f },{ -1.0f, -1.0f, 1.0f, 1.0f, 0.0f },{ 1.0f, -1.0f, -1.0f, 1.0f, 0.0f },{ 1.0f, 1.0f, -1.0f, 1.0f, 1.0f },{ 1.0f, 1.0f, 1.0f, 0.0f, 1.0f },{ 1.0f, -1.0f, 1.0f, 0.0f, 0.0f },{ -1.0f, -1.0f, -1.0f, 0.0f, 0.0f },{ -1.0f, -1.0f, 1.0f, 1.0f, 0.0f },{ -1.0f, 1.0f, 1.0f, 1.0f, 1.0f },{ -1.0f, 1.0f, -1.0f, 0.0f, 1.0f },// 地面数据{ -size, -1.0f, -size, 0.0f, 0.0f },{ -size, -1.0f, size, 100.0f, 0.0f },{ size, -1.0f, size, 100.0f, 100.0f },{ size, 0.0f, -size, 0.0f, 100.0f }
};//纹理ID
GLuint  _texture;
GLuint  _vbo;//地面纹理
GLuint  _texGround;Shader* _shader = nullptr;static void error_callback(int error, const char* description) {fputs(description, stderr);
}static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {std::cout << "key " << key << std::endl;switch(key) {case GLFW_KEY_ESCAPE:glfwSetWindowShouldClose(window, GL_TRUE);break;case GLFW_KEY_UP:_eye.z  -=  0.1f;   //这里修改摄像机参数break;case GLFW_KEY_DOWN:_eye.z  +=  0.1f;break;case GLFW_KEY_RIGHT:_eye.x  -=  1.0f;break;case GLFW_KEY_LEFT:_eye.x  +=  1.0f;break;default:break;}
}static void mouse_button_callback(GLFWwindow* window, int button, int action, int mods) {if(action != GLFW_PRESS)return;switch(button) {case GLFW_MOUSE_BUTTON_LEFT:std::cout << "Mosue left button clicked!" << std::endl;break;case GLFW_MOUSE_BUTTON_MIDDLE:std::cout << "Mosue middle button clicked!" << std::endl;break;case GLFW_MOUSE_BUTTON_RIGHT:std::cout << "Mosue right button clicked!" << std::endl;break;default:return;}return;
}static void cursor_position_callback(GLFWwindow* window, double x, double y) {//std::cout << "Mouse position move to X: " << x << " Y: " << y << std::endl;xpos = float((x - WIDTH / 2) / WIDTH) * 2;ypos = float(0 - (y - HEIGHT / 2) / HEIGHT) * 2;return;
}static void scroll_callback(GLFWwindow* window, double x, double y) {return;
}static unsigned createTexture(int w, int h, const void* data, GLenum type) {unsigned    texId;glGenTextures(1, &texId);glBindTexture(GL_TEXTURE_2D, texId);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexImage2D(GL_TEXTURE_2D, 0, type, w, h, 0, type, GL_UNSIGNED_BYTE, data);return  texId;
}
/**
*   使用FreeImage加载图片
*/
static unsigned createTextureFromImage(const char* fileName) {//1 获取图片格式FREE_IMAGE_FORMAT fifmt = FreeImage_GetFileType(fileName, 0);if(fifmt == FIF_UNKNOWN) {return  0;}//2 加载图片FIBITMAP    *dib = FreeImage_Load(fifmt, fileName, 0);FREE_IMAGE_COLOR_TYPE type = FreeImage_GetColorType(dib);//3 获取数据指针FIBITMAP*   temp = dib;dib = FreeImage_ConvertTo32Bits(dib);FreeImage_Unload(temp);BYTE*   pixels = (BYTE*)FreeImage_GetBits(dib);int     width = FreeImage_GetWidth(dib);int     height = FreeImage_GetHeight(dib);for(int i = 0; i < width * height * 4; i += 4) {BYTE temp = pixels[i];pixels[i] = pixels[i + 2];pixels[i + 2] = temp;}unsigned    res = createTexture(width, height, pixels, GL_RGBA);FreeImage_Unload(dib);return      res;
}static GLint _colorID;
static GLint _textureID;static void onInit() {_texture    =   createTextureFromImage("../res/1.jpg");_texGround  =   createTextureFromImage("../res/dimian.jpg");glGenBuffers(1, &_vbo);glBindBuffer(GL_ARRAY_BUFFER, _vbo);glBufferData(GL_ARRAY_BUFFER, sizeof(g_cubeVertices), g_cubeVertices, GL_STATIC_DRAW);glBindBuffer(GL_ARRAY_BUFFER, 0);string vsCode  =   "uniform vec4 _color;\varying vec4 outColor;\void main()\{\outColor    =   _color;\gl_TexCoord[0]  =   gl_MultiTexCoord0;\gl_Position =   gl_ModelViewProjectionMatrix * gl_Vertex;\}";string psCode  = "varying vec4 outColor;\uniform     sampler2D   _texture;\void main()\{\vec4 color   =   texture2D(_texture, gl_TexCoord[0].st);\gl_FragColor    =   color;\}";//gl_TexCoord[0]  =   gl_MultiTexCoord0;; 表示接收opengl传过来的纹理坐标//gl_TexCoord是输出，输出到ps里 ，在ps中不可直接使用 gl_MultiTexCoord0  当前版本的opengl每个顶点有八组纹理坐标 gl_TexCoord[0~7] gl_MultiTexCoord0~7//uniform  sampler2D  _texture;  sampler2D变量 只能在PS里 不能放到vs中，可以理解为二维图片，或者叫二维纹理//texture2D() 内置函数，用于根据纹理及坐标获取纹理颜色//_shader = new Shader("../res/shader/vertShader1.vert", "../res/shader/fragShader1.frag");_shader = new Shader(vsCode, psCode, true);//获取shader中的uniform vec4 _color 地址，即建立shader中的变量和程序中变量关联_colorID  =   _shader->getUniformLocation("_color");//获取shader中的uniform sampler2D _texture 地址，即建立shader中的变量和程序中变量关联_textureID = _shader->getUniformLocation("_texture");
}static void onDestory() {glDeleteTextures(1, &_texture);glDeleteTextures(1, &_texGround);glDeleteBuffers(1, &_vbo);   //删除VBO 显存中释放VBO内存
}// 绘制
static void render(GLFWwindow * window) {glClearColor(0, 0, 0, 1);glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glEnable(GL_DEPTH_TEST);glEnable(GL_TEXTURE_2D);glMatrixMode(GL_MODELVIEW);_matView = glm::lookAt(_eye, _lookAt, _up); //使用glm数学库 根据公式计算得到视图矩阵  这公式可以推倒出来//摄像机围绕目标旋转static float angle = 0; //旋转角度float r = 10;           //旋转半径_eye.x = cos(angle * glm::pi<double>() / 180) * r;_eye.z = sin(angle * glm::pi<double>() / 180) * r;angle += 1;  //角度每帧加一glm::mat4 matVP = _matProj * _matView;glLoadMatrixf(&matVP[0][0]);glBindTexture(GL_TEXTURE_2D, _texture); //该函数表示把纹理放到第0个纹理单元glEnableClientState(GL_VERTEX_ARRAY);glEnableClientState(GL_TEXTURE_COORD_ARRAY);//开始使用ID为 _vbo  的buffer 接下来的操作针对这个VBOglBindBuffer(GL_ARRAY_BUFFER, _vbo);float* addrVertex = (float*)0;float* uvAddress = (float*)12;glVertexPointer(3, GL_FLOAT, sizeof(Vertex), addrVertex);glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), uvAddress);// 绘制 立方体_shader->begin(); //使用 shader 对绘制立方体起作用//先begin 使用这个shader 然后才能修改glUniform4f(_colorID, 0, 1, 1, 1); //通过_colorID 改变对应的shader中 _color 的值glUniform1i(_textureID, 0); //该函数表示shader程序纹理数据从第0个纹理单元取， opengl 当前版本一个顶点有八个纹理单元， glBindTexture(GL_TEXTURE_2D, _texture);//该函数设置了第0个纹理单元纹理数据glDrawArrays(GL_QUADS, 0, 24);   //shader 只在针对 glDrawArrays 这类绘制函数其作用，顶点处理阶段调用顶点shader 光栅化处理阶段调用片元shader_shader->end();   //结束  如果不掉用这个函数 glUseProgram设置为0，这个shader程序会对后面的绘制产生影响//绘制地面//glLoadIdentity(); //这里打开 地面就不会跟着旋转 说明摄像机操作的是模型矩阵glBindTexture(GL_TEXTURE_2D, _texGround);glDrawArrays(GL_QUADS, 24, 4);glDisableClientState(GL_VERTEX_ARRAY);glDisableClientState(GL_TEXTURE_COORD_ARRAY);glBindTexture(GL_TEXTURE_2D, 0);glfwSwapBuffers(window);glfwPollEvents();
}int main(void) {GLFWwindow * window;glfwSetErrorCallback(error_callback);if(!glfwInit())return -1;window = glfwCreateWindow(WIDTH, HEIGHT, szTitle, NULL, NULL);if(!window) {glfwTerminate();exit(EXIT_FAILURE);}glfwSetKeyCallback(window, key_callback);glfwSetMouseButtonCallback(window, mouse_button_callback);glfwSetCursorPosCallback(window, cursor_position_callback);glfwSetScrollCallback(window, scroll_callback);glfwMakeContextCurrent(window);glewExperimental = GL_TRUE;glewInit();onInit();glViewport(0, 0, WIDTH, HEIGHT); //设置opengl视口 即看到的显示区域_matProj = glm::perspective(glm::radians(60.0f), float(WIDTH) / float(HEIGHT), 0.1f, 1000.0f);//使用glm数学库 根据公式计算得到投影矩阵  这公式可以推倒出来while(!glfwWindowShouldClose(window)) {render(window);}onDestory();glfwDestroyWindow(window);glfwTerminate();return 0;
}

运行结果：