OpenGL（二十四） VAO、VBO和着色器使用示例

1. 新建一个工程，新建一个头文件Shader.h，内容如下：

#ifndef _SHADER_H_  #define _SHADER_H_#include <vector>#include <string>#include <cstring>#include <GL/glew.h>class Shader{public:static GLuint createShader(GLenum eShaderType, const std::string &strShaderFile);static GLuint createShader(GLenum eShaderType, const char* fileName);static GLuint createProgram(const std::vector<GLuint> &shaderList);};#endif

2. 相应的新建一个源文件Shader.h，内容如下：

#include <fstream>  #include <sstream>#include "shader.h"//从字符串流构造着色器对象  GLuint Shader::createShader(GLenum eShaderType, const std::string &strShaderFile){GLuint shader = glCreateShader(eShaderType);//根据类型创建shader  const char * strFileData = strShaderFile.c_str();glShaderSource(shader, 1, &strFileData, NULL);//绑定shader字符串  glCompileShader(shader);//编译shader  //检查shader状态  GLint status;glGetShaderiv(shader, GL_COMPILE_STATUS, &status);if (status == GL_FALSE){GLint infoLogLength;glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLogLength);GLchar *strInfoLog = new GLchar[infoLogLength + 1];glGetShaderInfoLog(shader, infoLogLength, NULL, strInfoLog);const char * strShaderType = NULL;switch (eShaderType){case GL_VERTEX_SHADER: strShaderType = "vertex"; break;case GL_GEOMETRY_SHADER: strShaderType = "geometry"; break;case GL_FRAGMENT_SHADER: strShaderType = "fragment"; break;}fprintf(stderr, "Compile failure in %s shader:\n%s\n", strShaderType, strInfoLog);delete[] strInfoLog;}return shader;}//从文件构造着色器对象  GLuint Shader::createShader(GLenum eShaderType, const char* fileName){std::ifstream infile(fileName);if (!infile){fprintf(stderr, "Could not open file : %s for reading.", fileName);return 0;}std::stringstream  buffer;buffer << infile.rdbuf();infile.close();return Shader::createShader(eShaderType, buffer.str());}//构造着色器程序对象  GLuint Shader::createProgram(const std::vector<GLuint> &shaderList){GLuint programId = glCreateProgram();//创建program  for (std::vector<GLuint>::size_type iLoop = 0; iLoop < shaderList.size(); iLoop++)glAttachShader(programId, shaderList[iLoop]);//绑定shader  glLinkProgram(programId);//链接shader   //检查program状态  GLint status;glGetProgramiv(programId, GL_LINK_STATUS, &status);if (status == GL_FALSE){GLint infoLogLength;glGetProgramiv(programId, GL_INFO_LOG_LENGTH, &infoLogLength);GLchar *strInfoLog = new GLchar[infoLogLength + 1];glGetProgramInfoLog(programId, infoLogLength, NULL, strInfoLog);fprintf(stderr, "Linker failure: %s\n", strInfoLog);delete[] strInfoLog;}for (size_t iLoop = 0; iLoop < shaderList.size(); iLoop++)glDetachShader(programId, shaderList[iLoop]);return programId;}

3. Shader.h和Shader.cpp文件主要作用是构建了一个着色器，以下是主要的工程实现代码，新建一个源文件VaoVboTest.cpp，内容如下：

//使用VAO VBO和着色器绘制三角形(现代OpenGL方式)  #include <string>#include <vector>#include <GL/glew.h>#include <GL/freeglut.h>#include "Shader.h"using namespace std;void userInit();void reshape(int w, int h);void display(void);void keyboardAction(unsigned char key, int x, int y);GLuint vboId;//vertex buffer object句柄  GLuint vaoId;//vertext array object句柄  GLuint programId;//shader program 句柄  int main(int argc, char **argv){glutInit(&argc, argv);glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);glutInitWindowPosition(100, 100);glutInitWindowSize(512, 512);glutCreateWindow("Triangle demo");glewInit();userInit();glutReshapeFunc(reshape);glutDisplayFunc(display);glutKeyboardFunc(keyboardAction);glutMainLoop();return 0;}//自定义初始化函数  void userInit(){glClearColor(0.0, 0.0, 0.0, 0.0);//创建顶点数据  const GLfloat vertices[] = {-0.5f,-0.5f,0.0f,1.0f,   0.5f,0.0f,0.0f,1.0f,   0.0f,0.5f,0.0f,1.0f,};//创建vertex array object对象  glGenVertexArrays(1, &vaoId);glBindVertexArray(vaoId);//创建vertex buffer object对象  glGenBuffers(1, &vboId);glBindBuffer(GL_ARRAY_BUFFER, vboId);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);glBindBuffer(GL_ARRAY_BUFFER, 0);//创建着色器  const std::string vertexStr("#version 450\n""layout(location=0) in vec4 position;\n""void main()\n""{gl_Position = position;}\n");const std::string fragmentStr("#version 450\n""out vec4 outputColor;\n""void main()\n""{outputColor = vec4(1.0f,1.0f,0.0f,1.0f);}\n");std::vector<GLuint> idVector;idVector.push_back(Shader::createShader(GL_VERTEX_SHADER, vertexStr));idVector.push_back(Shader::createShader(GL_FRAGMENT_SHADER, fragmentStr));programId = Shader::createProgram(idVector);}//调整窗口大小回调函数  void reshape(int w, int h){glViewport(0, 0, (GLsizei)w, (GLsizei)h);}//绘制回调函数  void display(void){glClear(GL_COLOR_BUFFER_BIT);glUseProgram(programId);glBindBuffer(GL_ARRAY_BUFFER, vboId);glEnableVertexAttribArray(0);glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);glDrawArrays(GL_TRIANGLES, 0, 3);glBindBuffer(GL_ARRAY_BUFFER, 0);glUseProgram(0);glDisableVertexAttribArray(0);glutSwapBuffers();}//键盘按键回调函数  void keyboardAction(unsigned char key, int x, int y){switch (key){case 033:  // Escape key  exit(EXIT_SUCCESS);break;}}

不要忘了在链接器->输入->附加依赖项里添加 “glew32.lib”。完成之后编译生成效果：