"https://open.gl/"教程之Drawing Polygons源码(freeglut版)

VERTEX_SHADER

#version 150 core

in vec2 position;
in vec3 color;

out vec3 Color;
void main(){
    Color=color;
    gl_Position=vec4(position.x,-position.y,0,1);
}

FRAGMENT_SHADER

#version 150 core

out vec4 outColor;
in vec3 Color;

uniform vec3 triangleColor;
void main(){
    //outColor=vec4(triangleColor,1.0);
    outColor=vec4(Color,1.0);
}

源文件：#include"glew.h"

#include<Windows.h>
#include"freeglut.h"
#include<glGL.h>
#include<random>
#include"LoadShaders.h"　　　　　　//使用红宝书8版工具
GLuint vao;
GLuint vbo;
GLuint ebo;
GLuint uniColor;
GLfloat rColor=1.f;
void Init(){
    GLfloat vertices[] = {
        0.0,0.5,    1.f,0.f,0.f,
        0.5,-0.5,    0.f,1.f,0.f,
        -0.5,-0.5,    0.f,0.f,1.f
    };

    GLuint elements[] = { 0, 1, 2 };
    ShaderInfo shaders[] = {
        {GL_VERTEX_SHADER,"vertexShader.txt"},
        {GL_FRAGMENT_SHADER,"fragementShader.txt"},
        {GL_NONE,NULL}
    };
    GLuint shaderProgram = LoadShaders(shaders);
    //**VAO开始记录
    glGenVertexArrays(1, &vao);
    glBindVertexArray(vao);
    //*VBO
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    //*EBO
    glGenBuffers(1, &ebo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW);
    //*数据配接
    glUseProgram(shaderProgram);

    GLuint posAttri = glGetAttribLocation(shaderProgram, "position");
    glVertexAttribPointer(posAttri, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GL_FLOAT), 0);
    glEnableVertexAttribArray(posAttri);
    GLuint colorAttri = glGetAttribLocation(shaderProgram, "color");
    glVertexAttribPointer(colorAttri, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GL_FLOAT), (void*)(2 * sizeof(GL_FLOAT)));
    glEnableVertexAttribArray(colorAttri);
    uniColor = glGetUniformLocation(shaderProgram, "triangleColor");
    glUniform3f(uniColor, 1.f, 0.f, 0.f);

    glClearColor(0, 0, 0, 1);
}
void Display(){
    glClear(GL_COLOR_BUFFER_BIT);
    glBindVertexArray(vao);
    glUniform3f(uniColor, rColor, 0.f, 0.f);
    //glDrawArrays(GL_TRIANGLES, 0, 3);
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0);
    glFlush();
}

//作者使用定时改变颜色，这里利用键盘、随机数改变颜色
void KeyboardFunc(unsigned char key,int x,int y){
    static std::default_random_engine dre;
    static std::uniform_int_distribution<int> di(1, 100);
    switch (key)
    {
    case 'c':
        rColor = std::abs(std::sin((double)di(dre)));
        glutPostRedisplay();
        break;
    default:
        break;
    }
}
int main(int argc,char** argv){
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGBA);
    glutInitWindowSize(512, 512);
    glutInitWindowPosition(100, 200);
    glutInitContextVersion(3, 2);
    glutInitContextProfile(GLUT_CORE_PROFILE);
    glutCreateWindow(argv[0]);
    glewExperimental = true;
    glewInit();
    Init();
    glutDisplayFunc(Display);
    glutKeyboardFunc(KeyboardFunc);
    glutMainLoop();
    return 0;
}