// Include standard headers
#include <stdio.h>
#include <stdlib.h>
// Include GLEW
#include <GL/glew.h>
// Include GLFW
#include <GLFW/glfw3.h>
GLFWwindow* window;
// Include GLM
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
using namespace glm;
#include <common/shader.hpp>
int main( void )
{
// 初始化GLFW
if( !glfwInit() )
{
fprintf( stderr, "Failed to initialize GLFW\n" );
getchar();
return -1;
}
glfwWindowHint(GLFW_SAMPLES, 4);//4*抗锯齿
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//使用OpenGL的版本
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // 适配Mac
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); //使用新版本的OpenGl文件
// 创建窗口并命名
window = glfwCreateWindow( 1024, 768, "Tutorial 03 - Matrices", NULL, NULL);
if( window == NULL ){
fprintf( stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n" );
getchar();
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
// 初始化 GLEW
glewExperimental = true; //核心类需要这个
if (glewInit() != GLEW_OK) {
fprintf(stderr, "Failed to initialize GLEW\n");
getchar();
glfwTerminate();
return -1;
}
// 确保能接受esc键
glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);
// 设置背景
glClearColor(0.0f, 0.0f, 0.4f, 0.0f);
GLuint VertexArrayID;
glGenVertexArrays(1, &VertexArrayID);
glBindVertexArray(VertexArrayID);
//使用shader
GLuint programID = LoadShaders( "SimpleTransform.vertexshader", "SingleColor.fragmentshader" );
// Get a handle for our "MVP" uniform
GLuint MatrixID = glGetUniformLocation(programID, "MVP");//用glGetUniformLocation请求uniform ourColor的地址。我们为请求函数提供着色器程序和uniform的名字（这是我们希望获得的地址的来源）。如果glGetUniformLocation返回-1就代表没有找到这个地址。
// 投影矩阵，视角弧度为45，比例为4:3,显示范围为0.1到100
glm::mat4 Projection = glm::perspective(glm::radians(30.0f), 4.0f / 3.0f, 0.1f, 100.0f);
// Or, for an ortho camera :
//glm::mat4 Projection = glm::ortho(-10.0f,10.0f,-10.0f,10.0f,0.0f,100.0f); // In world coordinates
// Camera matrix
glm::mat4 View = glm::lookAt(
glm::vec3(10,3,3), //摄像机在(4,3,3)，世界坐标
glm::vec3(0,0,0), // 摄像机照向的点
glm::vec3(0,1,0) // 向上抬（上下的范围是-1~1）
);
// 模型的矩阵，它在原点
glm::mat4 Model = glm::mat4(1.0f);
// Our ModelViewProjection : multiplication of our 3 matrices
glm::mat4 MVP = Projection * View * Model; // Remember, matrix multiplication is the other way around
static const GLfloat g_vertex_buffer_data[] = {
-1.0f, -1.0f, 0.0f,
1.0f, -1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
};//定义三个点
GLuint vertexbuffer;
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
do{
//清空屏幕
glClear( GL_COLOR_BUFFER_BIT );
// 使用shader
glUseProgram(programID);
// 把我们的转换发送到当前绑定的着色器
// in the "MVP" uniform
glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &MVP[0][0]);
// 第一个属性缓冲区：顶点缓冲区
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glVertexAttribPointer(
0, //要和shader在一个层次.
3, // 几个点
GL_FLOAT, // 类型
GL_FALSE, // 是否标准化
0, // 指定连续顶点属性之间的偏移量。如果为0，那么顶点属性会被理解为：它们是紧密排列在一起的。初始值为0。
(void*)0 // 指定一个指针，指向数组中第一个顶点属性的第一个组件。初始值为0。
);
// 画出三角形
glDrawArrays(GL_TRIANGLES, 0, 3); // 3 indices starting at 0 -> 1 triangle
glDisableVertexAttribArray(0);
//
清除缓存
glfwSwapBuffers(window);
glfwPollEvents();
} // 检查esc是否被按下
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
glfwWindowShouldClose(window) == 0 );
// 清除顶点缓冲对象（Vertex Buffer Objects，VBO）和shader
glDeleteBuffers(1, &vertexbuffer);
glDeleteProgram(programID);
glDeleteVertexArrays(1, &VertexArrayID);
// 关闭窗口停止glfw
glfwTerminate();
return 0;
}
