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

#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);
}

#version 150 core

out vec4 outColor;
in vec3 Color;

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

#include<Windows.h>
#include"freeglut.h"
#include<gl\GL.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;
}