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变色三角形

Dettan
2021-04-10 / 0 评论 / 0 点赞 / 108 阅读 / 4,924 字
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#include <iostream>
#include <cmath>

// GLEW
#define GLEW_STATIC
#include <GL/glew.h>

// GLFW
#include <GLFW/glfw3.h>

// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);

// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;

// Shaders
//顶点着色器
const GLchar* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 position;\n"
"layout (location = 1) in vec3 color;\n"
"out vec3 ourColor;\n"
"void main()\n"
"{\n"
"gl_Position = vec4(position, 1.0);\n"
"ourColor = color;\n"
"}\0";
//片段着色器,有一个全局变量 ourColor.
const GLchar* fragmentShaderSource = "#version 330 core\n"
"out vec4 color;\n"
"uniform vec4 ourColor;\n"
"void main()\n"
"{\n"
"color = ourColor;\n"
"}\n\0";

// The MAIN function, from here we start the application and run the game loop
int main()
{
// Init GLFW,glfw是openGl的一个扩展,启动窗口用的.
glfwInit();
// Set all the required options for GLFW,版本号为3.3
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

// Create a GLFWwindow object that we can use for GLFW's functions
GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, &quot;LearnOpenGL&quot;, nullptr, nullptr);
	//激活创建的窗口
glfwMakeContextCurrent(window);

// Set the required callback functions
glfwSetKeyCallback(window, key_callback);

// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
glewExperimental = GL_TRUE;
// Initialize GLEW to setup the OpenGL Function pointers
glewInit();

// Define the viewport dimensions
glViewport(0, 0, WIDTH, HEIGHT);


// Build and compile our shader program
// Vertex shader
GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
// Check for compile time errors
GLint success;
GLchar infoLog[512];
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if (!success)
{
    glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
    std::cout &lt;&lt; &quot;ERROR::SHADER::VERTEX::COMPILATION_FAILED\n&quot; &lt;&lt; infoLog &lt;&lt; std::endl;
}
// Fragment shader
GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
// Check for compile time errors
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
if (!success)
{
    glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
    std::cout &lt;&lt; &quot;ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n&quot; &lt;&lt; infoLog &lt;&lt; std::endl;
}
// Link shaders
GLuint shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
// Check for linking errors
glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
if (!success) {
    glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
    std::cout &lt;&lt; &quot;ERROR::SHADER::PROGRAM::LINKING_FAILED\n&quot; &lt;&lt; infoLog &lt;&lt; std::endl;
}
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);


// Set up vertex data (and buffer(s)) and attribute pointers
GLfloat vertices[] = {
    // Positions        
     0.5f, -0.5f, 0.0f,  // Bottom Right
    -0.5f, -0.5f, 0.0f,  // Bottom Left
     0.0f,  0.5f, 0.0f   // Top 
};
GLuint VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
// Bind the Vertex Array Object first, then bind and set vertex buffer(s) and attribute pointer(s).
glBindVertexArray(VAO);
	//指定缓冲对象的类型,这里是顶点缓冲对象
glBindBuffer(GL_ARRAY_BUFFER, VBO);
	//将数据复制到缓冲对象中.
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

// Position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);

glBindVertexArray(0); // Unbind VAO


// Game loop
while (!glfwWindowShouldClose(window))
{
    // Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
    glfwPollEvents();

    // Render
    // Clear the colorbuffer
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Be sure to activate the shader
    glUseProgram(shaderProgram);

    // Update the uniform color
    GLfloat timeValue = glfwGetTime();
    GLfloat greenValue = (sin(timeValue) / 2) + 0.5;
    GLint vertexColorLocation = glGetUniformLocation(shaderProgram, &quot;ourColor&quot;);
    glUniform4f(vertexColorLocation, 0.0f, greenValue, 0.0f, 1.0f);

    // Draw the triangle
    glBindVertexArray(VAO);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    glBindVertexArray(0);

    // Swap the screen buffers
    glfwSwapBuffers(window);
}
// Properly de-allocate all resources once they've outlived their purpose
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
// Terminate GLFW, clearing any resources allocated by GLFW.
glfwTerminate();
return 0;

}

// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
}

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