C++ OpenGL实现旋转立方体的绘制
目录
1、Z-缓冲
2、GLM库函数
3、PVM矩阵
4、PVM矩阵的使用
5、工程文件结构
shader.h
shader.cpp
main.cpp
1、Z-缓冲
//开启深度测试
glEnable(GL_DEPTH_TEST);
2、GLM库函数
我们需要引入GLM函数库的头文件：
#include<glm/glm.hpp>
#include<glm/gtc/matrix_transform.hpp>
#include<glm/gtc/type_ptr.hpp>
设置vew矩阵的相关参数：
//相机参数
glm::vec3 camera_position = glm::vec3(0.0f, 0.0f, 3.0f); //摄像机位置
glm::vec3 camera_front = glm::vec3(0.0f, 0.0f, -1.0f); //摄像机方向
glm::vec3 camera_up = glm::vec3(0.0f, 1.0f, 0.0f); //摄像机上向量
设置project矩阵视野fov：
float fov = 45.0f;
// Transform坐标变换矩阵
glm::mat4 model(1);//model矩阵，局部坐标变换至世界坐标
model = glm::translate(model, glm::vec3(0.0,0.0,0.0));
model = glm::rotate(model, (float)glfwGetTime(), glm::vec3(0.5f, 1.0f, 0.0f));
model = glm::scale(model, glm::vec3(1.0f,1.0f,1.0f));
glm::mat4 view(1);//view矩阵，世界坐标变换至观察坐标系
view = glm::lookAt(camera_position, camera_position + camera_front, camera_up);
glm::mat4 projection(1);//projection矩阵，投影矩阵
projection = glm::perspective(glm::radians(fov), (float)screen_width / screen_height, 0.1f, 100.0f);
int model_location = glGetUniformLocation(shader.ID, "model"); //获取着色器内某个参数的位置
glUniformMatrix4fv(model_location, 1, GL_FALSE, glm::value_ptr(model));//写入参数值
gl_Position=projection*view*model*vec4(aPos,1.0);
5、工程文件结构
#ifndef __SHADER_H__
#define __SHADER_H__
#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "string"
class Shader
{
public:
unsigned int ID;
Shader(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path);
~Shader();
void Use();
void SetBool(const std::string &name, bool value) const;
void SetInt(const std::string &name, int value) const;
void SetFloat(const std::string &name, float value) const;
void SetVec2(const std::string &name, const glm::vec2 &value) const;
void SetVec2(const std::string &name, float x, float y) const;
void SetVec3(const std::string &name, const glm::vec3 &value) const;
void SetVec3(const std::string &name, float x, float y, float z) const;
void SetVec4(const std::string &name, const glm::vec4 &value) const;
void SetVec4(const std::string &name, float x, float y, float z, float w) const;
void SetMat2(const std::string &name, const glm::mat2 &value) const;
void SetMat3(const std::string &name, const glm::mat3 &value) const;
void SetMat4(const std::string &name, const glm::mat4 &value) const;
private:
int GetShaderFromFile(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path,
std::string *vertex_shader_code, std::string *fragment_shader_code);
int LinkShader(const char* vertex_shader_code, const char* fragment_shader_code);
int GetUniform(const std::string &name) const;
void CheckCompileErrors(GLuint shader, std::string type);
};
#endif // !__SHADER_H__
#ifndef __SHADER_H__
#define __SHADER_H__
#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "string"
class Shader
{
public:
unsigned int ID;
Shader(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path);
~Shader();
void Use();
void SetBool(const std::string &name, bool value) const;
void SetInt(const std::string &name, int value) const;
void SetFloat(const std::string &name, float value) const;
void SetVec2(const std::string &name, const glm::vec2 &value) const;
void SetVec2(const std::string &name, float x, float y) const;
void SetVec3(const std::string &name, const glm::vec3 &value) const;
void SetVec3(const std::string &name, float x, float y, float z) const;
void SetVec4(const std::string &name, const glm::vec4 &value) const;
void SetVec4(const std::string &name, float x, float y, float z, float w) const;
void SetMat2(const std::string &name, const glm::mat2 &value) const;
void SetMat3(const std::string &name, const glm::mat3 &value) const;
void SetMat4(const std::string &name, const glm::mat4 &value) const;
private:
int GetShaderFromFile(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path,
std::string *vertex_shader_code, std::string *fragment_shader_code);
int LinkShader(const char* vertex_shader_code, const char* fragment_shader_code);
int GetUniform(const std::string &name) const;
void CheckCompileErrors(GLuint shader, std::string type);
};
#endif // !__SHADER_H__
#ifndef __SHADER_H__
#define __SHADER_H__
#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "string"
class Shader
{
public:
unsigned int ID;
Shader(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path);
~Shader();
void Use();
void SetBool(const std::string &name, bool value) const;
void SetInt(const std::string &name, int value) const;
void SetFloat(const std::string &name, float value) const;
void SetVec2(const std::string &name, const glm::vec2 &value) const;
void SetVec2(const std::string &name, float x, float y) const;
void SetVec3(const std::string &name, const glm::vec3 &value) const;
void SetVec3(const std::string &name, float x, float y, float z) const;
void SetVec4(const std::string &name, const glm::vec4 &value) const;
void SetVec4(const std::string &name, float x, float y, float z, float w) const;
void SetMat2(const std::string &name, const glm::mat2 &value) const;
void SetMat3(const std::string &name, const glm::mat3 &value) const;
void SetMat4(const std::string &name, const glm::mat4 &value) const;
private:
int GetShaderFromFile(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path,
std::string *vertex_shader_code, std::string *fragment_shader_code);
int LinkShader(const char* vertex_shader_code, const char* fragment_shader_code);
int GetUniform(const std::string &name) const;
void CheckCompileErrors(GLuint shader, std::string type);
};
#endif // !__SHADER_H__
shader.cpp
#include "Shader.h"
#include "fstream"
#include "sstream"
#include "iostream"
Shader::Shader(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path)
{
std::string vertex_shader_code;
std::string fragment_shader_code;
if (GetShaderFromFile(vertex_shader_path, fragment_shader_path, &vertex_shader_code, &fragment_shader_code))
{
return;
}
if (LinkShader(vertex_shader_code.c_str(), fragment_shader_code.c_str()))
{
return;
}
}
Shader::~Shader()
{
}
void Shader::Use()
{
glUseProgram(ID);
}
void Shader::SetBool(const std::string &name, bool value) const
{
SetInt(name, (int)value);
}
void Shader::SetInt(const std::string &name, int value) const
{
glUniform1i(GetUniform(name), value);
}
void Shader::SetFloat(const std::string &name, float value) const
{
glUniform1f(GetUniform(name), value);
}
void Shader::SetVec2(const std::string &name, float x, float y) const
{
glUniform2f(GetUniform(name), x, y);
}
void Shader::SetVec2(const std::string &name, const glm::vec2 &value) const
{
SetVec2(name, value.x, value.y);
}
void Shader::SetVec3(const std::string &name, float x, float y, float z) const
{
glUniform3f(GetUniform(name), x, y, z);
}
void Shader::SetVec3(const std::string &name, const glm::vec3 &value) const
{
SetVec3(name, value.x, value.y, value.z);
}
void Shader::SetVec4(const std::string &name, float x, float y, float z, float w) const
{
glUniform4f(GetUniform(name), x, y, z, w);
}
void Shader::SetVec4(const std::string &name, const glm::vec4 &value) const
{
SetVec4(name, value.x, value.y, value.z, value.w);
}
void Shader::SetMat2(const std::string &name, const glm::mat2 &value) const
{
glUniformMatrix2fv(GetUniform(name), 1, GL_FALSE, &value[0][0]);
}
void Shader::SetMat3(const std::string &name, const glm::mat3 &value) const
{
glUniformMatrix3fv(GetUniform(name), 1, GL_FALSE, &value[0][0]);
}
void Shader::SetMat4(const std::string &name, const glm::mat4 &value) const
{
glUniformMatrix4fv(GetUniform(name), 1, GL_FALSE, &value[0][0]);
}
int Shader::GetShaderFromFile(const GLchar* vertex_shader_path, const GLchar* fragment_shader_path, std::string *vertex_shader_code, std::string *fragment_shader_code)
{
std::ifstream vertex_shader_file;
std::ifstream fragment_shader_file;
vertex_shader_file.exceptions(std::ifstream::badbit | std::ifstream::failbit);
fragment_shader_file.exceptions(std::ifstream::badbit | std::ifstream::failbit);
try
{
vertex_shader_file.open(vertex_shader_path);
fragment_shader_file.open(fragment_shader_path);
std::stringstream vertex_shader_stream, fragment_shader_stream;
vertex_shader_stream << vertex_shader_file.rdbuf();
fragment_shader_stream << fragment_shader_file.rdbuf();
vertex_shader_file.close();
fragment_shader_file.close();
*vertex_shader_code = vertex_shader_stream.str();
*fragment_shader_code = fragment_shader_stream.str();
}
catch (std::ifstream::failure e)
{
std::cout << "Load Shader File Error!" << std::endl;
return -1;
}
return 0;
}
int Shader::LinkShader(const char* vertex_shader_code, const char* fragment_shader_code)
{
int vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &vertex_shader_code, NULL);
glCompileShader(vertex_shader);
CheckCompileErrors(vertex_shader, "VERTEX");
int fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader, 1, &fragment_shader_code, NULL);
glCompileShader(fragment_shader);
CheckCompileErrors(fragment_shader, "FRAGMENT");
this->ID = glCreateProgram();
glAttachShader(ID, vertex_shader);
glAttachShader(ID, fragment_shader);
glLinkProgram(ID);
CheckCompileErrors(ID, "PROGRAM");
glDeleteShader(vertex_shader);
glDeleteShader(fragment_shader);
return 0;
}
int Shader::GetUniform(const std::string &name) const
{
int position = glGetUniformLocation(ID, name.c_str());
if (position == -1)
{
std::cout << "uniform " << name << " set failed!" << std::endl;
}
return position;
}
void Shader::CheckCompileErrors(GLuint shader, std::string type)
{
GLint success;
GLchar infoLog[512];
if (type == "PROGRAM")
{
glGetProgramiv(shader, GL_LINK_STATUS, &success);
if (!success)
{
glGetProgramInfoLog(shader, 512, NULL, infoLog);
std::cout << "ERROR::PROGRAM_LINKING_ERROR!\n" << infoLog << std::endl;
}
}
else
{
glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(shader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::" << type << "::COMPILATION_FAILED\n" << infoLog << std::endl;
}
}
}
main.cpp
//总体流程
//1. 初始化并创建窗口
//2. 加载立方体顶点VAOVBO以及着色器并开启深度测试
//3. 进入主循环清除缓冲
//4. 使用立方体着色器，构造并传入pvm矩阵，绘制
//5. 循环结束，释放VAOVBO
#include <iostream>
#include "glad/glad.h"
#include "GLFW/glfw3.h"
#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"
#include "glm/gtc/type_ptr.hpp"
#include "shader.h"
const float vertices[] = { //立方体数组
-0.5f, -0.5f, -0.5f, 1.0f,0.0f,0.0f,
0.5f, -0.5f, -0.5f, 1.0f,0.0f,0.0f,
0.5f, 0.5f, -0.5f, 1.0f,0.0f,0.0f,
0.5f, 0.5f, -0.5f, 1.0f,0.0f,0.0f,
-0.5f, 0.5f, -0.5f, 1.0f,0.0f,0.0f,
-0.5f, -0.5f, -0.5f, 1.0f,0.0f,0.0f,
-0.5f, -0.5f, 0.5f, 0.0f,1.0f,0.0f,
0.5f, -0.5f, 0.5f, 0.0f,1.0f,0.0f,
0.5f, 0.5f, 0.5f, 0.0f,1.0f,0.0f,
0.5f, 0.5f, 0.5f, 0.0f,1.0f,0.0f,
-0.5f, 0.5f, 0.5f, 0.0f,1.0f,0.0f,
-0.5f, -0.5f, 0.5f, 0.0f,1.0f,0.0f,
-0.5f, 0.5f, 0.5f, 0.0f,0.0f,1.0f,
-0.5f, 0.5f, -0.5f, 0.0f,0.0f,1.0f,
-0.5f, -0.5f, -0.5f, 0.0f,0.0f,1.0f,
-0.5f, -0.5f, -0.5f, 0.0f,0.0f,1.0f,
-0.5f, -0.5f, 0.5f, 0.0f,0.0f,1.0f,
-0.5f, 0.5f, 0.5f, 0.0f,0.0f,1.0f,
0.5f, 0.5f, 0.5f, 0.5f,0.0f,0.0f,
0.5f, 0.5f, -0.5f, 0.5f,0.0f,0.0f,
0.5f, -0.5f, -0.5f, 0.5f,0.0f,0.0f,
0.5f, -0.5f, -0.5f, 0.5f,0.0f,0.0f,
0.5f, -0.5f, 0.5f, 0.5f,0.0f,0.0f,
0.5f, 0.5f, 0.5f, 0.5f,0.0f,0.0f,
-0.5f, -0.5f, -0.5f, 0.0f,0.5f,0.0f,
0.5f, -0.5f, -0.5f, 0.0f,0.5f,0.0f,
0.5f, -0.5f, 0.5f, 0.0f,0.5f,0.0f,
0.5f, -0.5f, 0.5f, 0.0f,0.5f,0.0f,
-0.5f, -0.5f, 0.5f, 0.0f,0.5f,0.0f,
-0.5f, -0.5f, -0.5f, 0.0f,0.5f,0.0f,
-0.5f, 0.5f, -0.5f, 0.0f,0.0f,0.5f,
0.5f, 0.5f, -0.5f, 0.0f,0.0f,0.5f,
0.5f, 0.5f, 0.5f, 0.0f,0.0f,0.5f,
0.5f, 0.5f, 0.5f, 0.0f,0.0f,0.5f,
-0.5f, 0.5f, 0.5f, 0.0f,0.0f,0.5f,
-0.5f, 0.5f, -0.5f, 0.0f,0.0f,0.5f
};
float screen_width = 1280.0f; //窗口宽度
float screen_height = 720.0f; //窗口高度
//相机参数
glm::vec3 camera_position = glm::vec3(0.0f, 0.0f, 3.0f); //摄像机位置
glm::vec3 camera_front = glm::vec3(0.0f, 0.0f, -1.0f); //摄像机方向
glm::vec3 camera_up = glm::vec3(0.0f, 1.0f, 0.0f); //摄像机上向量
//视野
float fov = 45.0f;
int main() {
// 初始化GLFW
glfwInit(); // 初始化GLFW
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // OpenGL版本为3.3，主次版本号均设为3
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 使用核心模式(无需向后兼容性)
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // 如果使用的是Mac OS X系统，需加上这行
glfwWindowHint(GLFW_RESIZABLE, FALSE); // 不可改变窗口大小
// 创建窗口(宽、高、窗口名称)
auto window = glfwCreateWindow(screen_width, screen_height, "Cube", nullptr, nullptr);
if (window == nullptr) { // 如果窗口创建失败，输出Failed to Create OpenGL Context
std::cout << "Failed to Create OpenGL Context" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window); // 将窗口的上下文设置为当前线程的主上下文
// 初始化GLAD，加载OpenGL函数指针地址的函数
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
// 指定当前视口尺寸(前两个参数为左下角位置，后两个参数是渲染窗口宽、高)
glViewport(0, 0, screen_width, screen_height);
Shader shader("res/shader/task-cube.vs", "res/shader/task-cube.fs");//加载着色器
// 生成并绑定VAO和VBO
GLuint vertex_array_object; // == VAO
glGenVertexArrays(1, &vertex_array_object);
glBindVertexArray(vertex_array_object);
GLuint vertex_buffer_object; // == VBO
glGenBuffers(1, &vertex_buffer_object);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object);
// 将顶点数据绑定至当前默认的缓冲中
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
// 设置顶点属性指针
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
glEnable(GL_DEPTH_TEST);
// Render loop主循环
while (!glfwWindowShouldClose(window)) {
//进入主循环，清理颜色缓冲深度缓冲
glClearColor(0.0f, 0.34f, 0.57f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//清理颜色缓冲和深度缓冲
shader.Use();
// Transform坐标变换矩阵
glm::mat4 model(1);//model矩阵，局部坐标变换至世界坐标
model = glm::translate(model, glm::vec3(0.0,0.0,0.0));
model = glm::rotate(model, (float)glfwGetTime(), glm::vec3(0.5f, 1.0f, 0.0f));
model = glm::scale(model, glm::vec3(1.0f,1.0f,1.0f));
glm::mat4 view(1);//view矩阵，世界坐标变换至观察坐标系
view = glm::lookAt(camera_position, camera_position + camera_front, camera_up);
glm::mat4 projection(1);//projection矩阵，投影矩阵
projection = glm::perspective(glm::radians(fov), (float)screen_width / screen_height, 0.1f, 100.0f);
// 向着色器中传入参数
int model_location = glGetUniformLocation(shader.ID, "model"); //获取着色器内某个参数的位置
glUniformMatrix4fv(model_location, 1, GL_FALSE, glm::value_ptr(model));//写入参数值
int view_location = glGetUniformLocation(shader.ID, "view");
glUniformMatrix4fv(view_location, 1, GL_FALSE, glm::value_ptr(view));
int projection_location = glGetUniformLocation(shader.ID, "projection");
glUniformMatrix4fv(projection_location, 1, GL_FALSE, glm::value_ptr(projection));
//绘制
glBindVertexArray(vertex_array_object);
glDrawArrays(GL_TRIANGLES, 0, 36);
glBindVertexArray(0);
glfwSwapBuffers(window);
glfwPollEvents();
}
//释放VAOVBO
glDeleteVertexArrays(1, &vertex_array_object);
glDeleteBuffers(1, &vertex_buffer_object);
// 清理所有的资源并正确退出程序
glfwTerminate();
return 0;
}
输出结果：
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