OpenGL笔记十四之GLM数学库的配置与使用

—— 2024-07-20 中午

bilibili赵新政老师的教程看后笔记

code review!

文章目录

OpenGL笔记十四之GLM数学库的配置与使用
- 1.旋转变换运行效果
- 2.平移变换运行效果
- 3.缩放变换运行效果
- 4.复合变换：先旋转再平移运行效果
- 5.复合变换：先平移后旋转运行效果
- 6.每一帧都旋转运行效果
- 7.关键代码
- - 7.1.vs
  - 7.2.fs
  - 7.3.main.cpp关键片段
  - 7.4.shader.h关键片段
  - 7.5.shader.cpp关键片段
  - 7.6.core.h中要把代码包含进来

把GLM文件夹拷贝thirdParty/include文件夹下

1.旋转变换运行效果

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2.平移变换运行效果

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3.缩放变换运行效果

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4.复合变换：先旋转再平移运行效果

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5.复合变换：先平移后旋转运行效果

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6.每一帧都旋转运行效果

注意：每一帧都是从起始位姿旋转而至
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7.关键代码

7.1.vs

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代码

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout (location = 2) in vec2 aUV;out vec3 color;
out vec2 uv;uniform mat4 transform;//aPos作为attribute（属性）传入shader
//不允许更改的
void main()
{vec4 position = vec4(aPos, 1.0);position = transform * position;gl_Position = position;color = aColor;uv = aUV;
}

7.2.fs

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代码

#version 330 core
out vec4 FragColor;in vec3 color;
in vec2 uv;uniform sampler2D sampler;void main()
{FragColor = texture(sampler, uv);
}

7.3.main.cpp关键片段

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main.cpp完整代码

#include <iostream>#include "glframework/core.h"
#include "glframework/shader.h"
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"
#include "glframework/texture.h"/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 初步学习GLM库的平移/旋转/缩放
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*					-1 引入GLM的头文件
*					-2 更改vertexShader，加入uniform变量mat4 transform
*					-3 使用传入的transform给我们的顶点坐标进行变换
*					-4 为shader类增加uniform矩阵传输的功能
*					-5 使用矩阵做复合变换
*					-6 连续转动三角形（动画）
*└────────────────────────────────────────────────┘
*/GLuint vao;
Shader* shader = nullptr;
Texture* texture = nullptr;
glm::mat4 transform(1.0f);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 doRotationTransform() {//构建一个旋转矩阵，绕着z轴旋转45度角//rotate函数：用于生成旋转矩阵//bug1:rotate必须得到一个float类型的角度，c++的template//bug2:rotate函数接受的不是角度（degree），接收的弧度（radians）//注意点：radians函数也是模板函数，切记要传入float类型数据，加f后缀transform = glm::rotate(glm::mat4(1.0f),glm::radians(90.0f), glm::vec3(0.0, 0.0, 1.0));
}//平移变换
void doTranslationTransform() {transform = glm::translate(glm::mat4(1.0f), glm::vec3(0.5f, 0.0f, 0.0f));
}//缩放变换
void doScaleTransform() {transform = glm::scale(glm::mat4(1.0f), glm::vec3(0.1f, 0.5f, 1.0f));
}//复合变换
void doTransform() {glm::mat4 rotateMat = glm::rotate(glm::mat4(1.0f), glm::radians(90.0f), glm::vec3(0.0, 0.0, 1.0));glm::mat4 translateMat = glm::translate(glm::mat4(1.0f), glm::vec3(0.5f, 0.0f, 0.0f));//先旋转 再平移// transform = translateMat * rotateMat;//先平移 后旋转transform = rotateMat * translateMat;
}float angle = 0.0f;
void doRotation() {angle += 2.0f;//每一帧都会“重新”构建一个旋转矩阵transform = glm::rotate(glm::mat4(1.0f), glm::radians(angle), glm::vec3(0.0, 0.0, 1.0));
}void prepareVAO() {//1 准备positions colorsfloat 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,};float uvs[] = {0.0f, 0.0f,1.0f, 0.0f,0.5f, 1.0f,};unsigned int indices[] = {0, 1, 2,};//2 VBO创建GLuint posVbo, colorVbo, uvVbo;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);glGenBuffers(1, &uvVbo);glBindBuffer(GL_ARRAY_BUFFER, uvVbo);glBufferData(GL_ARRAY_BUFFER, sizeof(uvs), uvs, 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uv属性描述数据glBindBuffer(GL_ARRAY_BUFFER, uvVbo);glEnableVertexAttribArray(2);glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, (void*)0);//5.4 加入ebo到当前的vaoglBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);glBindVertexArray(0);
}void prepareShader() {shader = new Shader("assets/shaders/vertex.glsl","assets/shaders/fragment.glsl");
}void prepareTexture() {texture = new Texture("assets/textures/goku.jpg", 0);
}void render() {//执行opengl画布清理操作GL_CALL(glClear(GL_COLOR_BUFFER_BIT));//绑定当前的programshader->begin();shader->setInt("sampler", 0);shader->setMatrix4x4("transform", transform);//绑定当前的vaoGL_CALL(glBindVertexArray(vao));//发出绘制指令GL_CALL(glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0));GL_CALL(glBindVertexArray(0));shader->end();
}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();prepareTexture();// doRotationTransform();// doTranslationTransform();// doScaleTransform();doTransform();while (app->update()) {// doRotation();render();}app->destroy();return 0;
}

7.4.shader.h关键片段

void setMatrix4x4(const std::string& name, glm::mat4 value);

shader.h完整代码

#pragma once#include "core.h"
#include<string>class Shader {
public:Shader(const char* vertexPath, const char* fragmentPath);~Shader();void begin();//开始使用当前Shadervoid end();//结束使用当前Shadervoid setFloat(const std::string& name, float value);void setVector3(const std::string& name, float x, float y, float z);void setVector3(const std::string& name, const float* values);void setInt(const std::string& name, int value);void setMatrix4x4(const std::string& name, glm::mat4 value);
private://shader program//type:COMPILE LINKvoid checkShaderErrors(GLuint target,std::string type);private:GLuint mProgram{ 0 };
};

7.5.shader.cpp关键片段

void Shader::setMatrix4x4(const std::string& name, glm::mat4 value) {//1 通过名称拿到Uniform变量的位置LocationGLint location = GL_CALL(glGetUniformLocation(mProgram, name.c_str()));//2 通过Location更新Uniform变量的值//transpose参数：表示是否对传输进去的矩阵数据进行转置glUniformMatrix4fv(location, 1, GL_FALSE, glm::value_ptr(value));
}

shader.cpp完整代码

#include"shader.h"
#include"../wrapper/checkError.h"#include<string>
#include<fstream>
#include<sstream>
#include<iostream>Shader::Shader(const char* vertexPath, const char* fragmentPath) {//声明装入shader代码字符串的两个stringstd::string vertexCode;std::string fragmentCode;//声明用于读取vs跟fs文件的inFileStreamstd::ifstream vShaderFile;std::ifstream fShaderFile;//保证ifstream遇到问题的时候可以抛出异常vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);try {//1 打开文件vShaderFile.open(vertexPath);fShaderFile.open(fragmentPath);//2 将文件输入流当中的字符串输入到stringStream里面std::stringstream vShaderStream, fShaderStream;vShaderStream << vShaderFile.rdbuf();fShaderStream << fShaderFile.rdbuf();//3 关闭文件vShaderFile.close();fShaderFile.close();//4 将字符串从stringStream当中读取出来，转化到code String当中vertexCode = vShaderStream.str();fragmentCode = fShaderStream.str();}catch (std::ifstream::failure& e) {std::cout << "ERROR: Shader File Error: " << e.what() << std::endl;}const char* vertexShaderSource = vertexCode.c_str();const char* fragmentShaderSource = fragmentCode.c_str();//1 创建Shader程序（vs、fs）GLuint vertex, fragment;vertex = glCreateShader(GL_VERTEX_SHADER);fragment = glCreateShader(GL_FRAGMENT_SHADER);//2 为shader程序输入shader代码glShaderSource(vertex, 1, &vertexShaderSource, NULL);glShaderSource(fragment, 1, &fragmentShaderSource, NULL);//3 执行shader代码编译 glCompileShader(vertex);//检查vertex编译结果checkShaderErrors(vertex, "COMPILE");glCompileShader(fragment);//检查fragment编译结果checkShaderErrors(fragment, "COMPILE");//4 创建一个Program壳子mProgram = glCreateProgram();//6 将vs与fs编译好的结果放到program这个壳子里glAttachShader(mProgram, vertex);glAttachShader(mProgram, fragment);//7 执行program的链接操作，形成最终可执行shader程序glLinkProgram(mProgram);//检查链接错误checkShaderErrors(mProgram, "LINK");//清理glDeleteShader(vertex);glDeleteShader(fragment);
}
Shader::~Shader() {}void Shader::begin() {GL_CALL(glUseProgram(mProgram));
}void Shader::end() {GL_CALL(glUseProgram(0));
}void Shader::setFloat(const std::string& name, float value) {//1 通过名称拿到Uniform变量的位置LocationGLint location = GL_CALL(glGetUniformLocation(mProgram, name.c_str()));//2 通过Location更新Uniform变量的值GL_CALL(glUniform1f(location, value));
}void Shader::setVector3(const std::string& name, float x, float y, float z) {//1 通过名称拿到Uniform变量的位置LocationGLint location = GL_CALL(glGetUniformLocation(mProgram, name.c_str()));//2 通过Location更新Uniform变量的值GL_CALL(glUniform3f(location, x, y, z));
}//重载 overload
void Shader::setVector3(const std::string& name, const float* values) {//1 通过名称拿到Uniform变量的位置LocationGLint location = GL_CALL(glGetUniformLocation(mProgram, name.c_str()));//2 通过Location更新Uniform变量的值//第二个参数：你当前要更新的uniform变量如果是数组，数组里面包括多少个向量vec3GL_CALL(glUniform3fv(location, 1, values));
}void Shader::setInt(const std::string& name, int value) {//1 通过名称拿到Uniform变量的位置LocationGLint location = GL_CALL(glGetUniformLocation(mProgram, name.c_str()));//2 通过Location更新Uniform变量的值glUniform1i(location, value);
}void Shader::setMatrix4x4(const std::string& name, glm::mat4 value) {//1 通过名称拿到Uniform变量的位置LocationGLint location = GL_CALL(glGetUniformLocation(mProgram, name.c_str()));//2 通过Location更新Uniform变量的值//transpose参数：表示是否对传输进去的矩阵数据进行转置glUniformMatrix4fv(location, 1, GL_FALSE, glm::value_ptr(value));
}void Shader::checkShaderErrors(GLuint target, std::string type) {int success = 0;char infoLog[1024];if (type == "COMPILE") {glGetShaderiv(target, GL_COMPILE_STATUS, &success);if (!success) {glGetShaderInfoLog(target, 1024, NULL, infoLog);std::cout << "Error: SHADER COMPILE ERROR" << "\n" << infoLog << std::endl;}}else if (type == "LINK") {glGetProgramiv(target, GL_LINK_STATUS, &success);if (!success) {glGetProgramInfoLog(target, 1024, NULL, infoLog);std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;}}else {std::cout << "Error: Check shader errors Type is wrong" << std::endl;}
}

7.6.core.h中要把代码包含进来

core.h

#pragma once//注意：glad头文件必须在glfw引用之前引用
#include <glad/glad.h>
#include <GLFW/glfw3.h>//GLM
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>#define GLM_ENABLE_EXPERIMENTAL
#include <glm/gtx/string_cast.hpp>