OpenGL入门（二） 红宝书第一个demo代码

#include <stdio.h>
#include <string>
#include <vector>
#include <iostream>
using namespace std;

//opengl headers!
#include <glew.h>
#include <glut.h>

#pragma comment(lib,"glew32.lib")
#pragma comment(lib,"glut32.lib")

////////////////////////////////////////

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;

GLuint LoadShaders()
{
//generate shader names
GLuint vertShader = glCreateShader(GL_VERTEX_SHADER);
GLuint fragShader = glCreateShader(GL_FRAGMENT_SHADER);

const char* vertShaderSrc ="#version 450 core \n layout (location = 0)  in vec4 vPosition; void main(){gl_Position = vPosition;}";
const char* fragShaderSrc ="#version 450 core \n layout (location = 0)  out vec4 fColor; void main(){fColor =  vec4 (255, 0, 0, 255);}";
GLint result = GL_FALSE;
int logLength;

//compile vertex shader
glShaderSource(vertShader, 1, &vertShaderSrc, NULL);
glCompileShader(vertShader);
glGetShaderiv(vertShader, GL_COMPILE_STATUS, &result);
glGetShaderiv(vertShader, GL_INFO_LOG_LENGTH, &logLength);
vector<char> vertShaderError(logLength+1);
glGetShaderInfoLog(vertShader, logLength, NULL, &vertShaderError[0]);
cout << &vertShaderError[0] << endl;

//compile fragment shader
glShaderSource(fragShader, 1, &fragShaderSrc, NULL);
glCompileShader(fragShader);
glGetShaderiv(fragShader, GL_COMPILE_STATUS, &result);
glGetShaderiv(fragShader, GL_INFO_LOG_LENGTH, &logLength);
vector<char> fragShaderError(logLength+1);
glGetShaderInfoLog(fragShader, logLength, NULL, &fragShaderError[0]);
cout << &fragShaderError[0] << endl;

//link the program
GLuint program = glCreateProgram();
glAttachShader(program, vertShader);
glAttachShader(program, fragShader);
glLinkProgram(program);

glGetProgramiv(program, GL_LINK_STATUS, &result);
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logLength);
vector<char> programError(logLength > 1 ? logLength : 1);
glGetProgramInfoLog(program, logLength, NULL, &programError[0]);
cout << &programError[0] << endl;

glDeleteShader(vertShader);
glDeleteShader(fragShader);

return program;
}

#define BUFFER_OFFSET(a) ((void*)(a))

void Init()
{
static const GLfloat vertices[NumVertices][2] =
{
{ -0.90, -0.90 }, // Triangle 1
{ 0.85, -0.90 },
{ -0.90, 0.85 },
{ 0.90, -0.85 }, // Triangle 2
{ 0.90, 0.90 },
{ -0.85, 0.90 }
};
glCreateBuffers(NumBuffers, Buffers);
glNamedBufferStorage(Buffers[ArrayBuffer]   ,  sizeof(vertices),
vertices, 0);

GLuint program = LoadShaders();
glUseProgram(program);
glGenVertexArrays(NumVAOs, VAOs);
glBindVertexArray(VAOs[Triangles]);
glBindBuffer(GL_ARRAY_BUFFER, Buffers[ArrayBuffer]);
glVertexAttribPointer(vPosition, 2, GL_FLOAT,
GL_FALSE, 0, BUFFER_OFFSET(0));
glEnableVertexAttribArray(vPosition);

}

void display()
{
static const float color[] = { (float)240/255, (float)240/255, (float)240/255,1.0};
glClearBufferfv(GL_COLOR, 0, color);

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

glutSwapBuffers();
}

int _tmain(int argc, char* argv[])
{
glutInit( &argc, argv );                                       //用于初始化GULT库
glutInitDisplayMode ( GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA );  //设置初始显示模式
glutInitWindowPosition (0,0);                                  //确定窗口的位置
glutInitWindowSize  ( 900, 500 );                              //设置窗口大小
glutCreateWindow    ( "OpenGlScreen" );                        //创建一个窗口标题
glewInit();

const GLubyte* name = glGetString(GL_VENDOR); //返回负责当前OpenGL实现厂商的名字
const GLubyte* biaoshifu = glGetString(GL_RENDERER); //返回一个渲染器标识符，通常是个硬件平台
const GLubyte* OpenGLVersion =glGetString(GL_VERSION); //返回当前OpenGL实现的版本号
const GLubyte* gluVersion= gluGetString(GLU_VERSION); //返回当前GLU工具库版本
printf("OpenGL实现厂商的名字：%s\n", name);
printf("渲染器标识符：%s\n", biaoshifu);
printf("OOpenGL实现的版本号：%s\n",OpenGLVersion );
printf("OGLU工具库版本：%s\n", gluVersion);

Init ();
//glutFullScreen      ( );          //Put Into Full Screen
glutDisplayFunc     ( display );    //注册一个绘图函数
glutReshapeFunc     ( nullptr );    //设置投影的函数
glutKeyboardFunc    ( nullptr );    //键盘回调函数
glutSpecialFunc     ( nullptr );    //设置当前窗口的特殊键盘回调。
glutIdleFunc        ( nullptr );    //程序空闲时调用的函数
glutMainLoop        ( );            // 进入GLUT事件处理循环

return 0;
}