OpenGL笔记九之彩色三角形与重心插值算法
------ 2024-07-07 晚上
总结自bilibili赵新政老师的教程
code review!
文章目录
1.运行
3.main.cpp
代码
cpp
#include <iostream>
#define DEBUG
//注意:glad头文件必须在glfw引用之前引用
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"
/*
*┌────────────────────────────────────────────────┐
*│ 目 标: 学习彩色三角形绘制
*│ 讲 师: 赵新政(Carma Zhao)
*│ 拆分目标:
*│ vs:
*│ 1 在vs当中获取layout为1的属性-color
* 2 在vs当中声明out类型变量,向后传递颜色数据
* 3 给out类型变量赋值
* fs:
* 1 在fs当中声明in类型变量,接收前方阶段传递的颜色数据
* 2 将获取的in类型颜色数据,赋值给fragColor
*└────────────────────────────────────────────────┘
*/
GLuint vao, program;
void OnResize(int width, int height) {
GL_CALL(glViewport(0, 0, width, height));
std::cout << "OnResize" << std::endl;
}
void OnKey(int key, int action, int mods) {
std::cout << key << std::endl;
}
void prepareVAO() {
//1 准备positions colors
float positions[] = {
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
0.0f, 0.5f, 0.0f,
};
float colors[] = {
1.0f, 0.0f,0.0f,
0.0f, 1.0f,0.0f,
0.0f, 0.0f,1.0f
};
unsigned int indices[] = {
0, 1, 2
};
//2 VBO创建
GLuint posVbo, colorVbo;
glGenBuffers(1, &posVbo);
glBindBuffer(GL_ARRAY_BUFFER, posVbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);
glGenBuffers(1, &colorVbo);
glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);
//3 EBO创建
GLuint ebo;
glGenBuffers(1, &ebo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
//4 VAO创建
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
//5 绑定vbo ebo 加入属性描述信息
//5.1 加入位置属性描述信息
glBindBuffer(GL_ARRAY_BUFFER, posVbo);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 3, (void*)0);
//5.2 加入颜色属性描述数据
glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 3, (void*)0);
//5.3 加入ebo到当前的vao
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
glBindVertexArray(0);
}
void prepareShader() {
//1 完成vs与fs的源代码,并且装入字符串
const char* vertexShaderSource =
"#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"layout (location = 1) in vec3 aColor;\n"
"out vec3 color;\n"
"void main()\n"
"{\n"
" gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
" color = aColor;\n"
"}\0";
const char* fragmentShaderSource =
"#version 330 core\n"
"out vec4 FragColor;\n"
"in vec3 color;\n"
"void main()\n"
"{\n"
" FragColor = vec4(color, 1.0f);\n"
"}\n\0";
//2 创建Shader程序(vs、fs)
GLuint vertex, fragment;
vertex = glCreateShader(GL_VERTEX_SHADER);
fragment = glCreateShader(GL_FRAGMENT_SHADER);
//3 为shader程序输入shader代码
glShaderSource(vertex, 1, &vertexShaderSource, NULL);
glShaderSource(fragment, 1, &fragmentShaderSource, NULL);
int success = 0;
char infoLog[1024];
//4 执行shader代码编译
glCompileShader(vertex);
//检查vertex编译结果
glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
if (!success) {
glGetShaderInfoLog(vertex, 1024, NULL, infoLog);
std::cout << "Error: SHADER COMPILE ERROR --VERTEX" << "\n" << infoLog << std::endl;
}
glCompileShader(fragment);
//检查fragment编译结果
glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
if (!success) {
glGetShaderInfoLog(fragment, 1024, NULL, infoLog);
std::cout << "Error: SHADER COMPILE ERROR --FRAGMENT" << "\n" << infoLog << std::endl;
}
//5 创建一个Program壳子
program = glCreateProgram();
//6 将vs与fs编译好的结果放到program这个壳子里
glAttachShader(program, vertex);
glAttachShader(program, fragment);
//7 执行program的链接操作,形成最终可执行shader程序
glLinkProgram(program);
//检查链接错误
glGetProgramiv(program, GL_LINK_STATUS, &success);
if (!success) {
glGetProgramInfoLog(program, 1024, NULL, infoLog);
std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;
}
//清理
glDeleteShader(vertex);
glDeleteShader(fragment);
}
void render() {
//执行opengl画布清理操作
GL_CALL(glClear(GL_COLOR_BUFFER_BIT));
//1 绑定当前的program
GL_CALL(glUseProgram(program));
//2 绑定当前的vao
GL_CALL(glBindVertexArray(vao));
//3 发出绘制指令
// glDrawArrays(GL_LINE_STRIP, 0, 6);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
}
int main() {
if (!app->init(800, 600)) {
return -1;
}
app->setResizeCallback(OnResize);
app->setKeyBoardCallback(OnKey);
//设置opengl视口以及清理颜色
GL_CALL(glViewport(0, 0, 800, 600));
GL_CALL(glClearColor(0.2f, 0.3f, 0.3f, 1.0f));
prepareShader();
prepareVAO();
while (app->update()) {
render();
}
app->destroy();
return 0;
}