前言

变换对于图形图像的显示时至关重要的。本节参考：https://learnopengl-cn.github.io/01%20Getting%20started/07%20Transformations/

代码演示：

#include<glad/glad.h>
#include<GLFW/glfw3.h>
#include"Shader.h"
#include"stb_image.h"
#include<iostream>
#include<glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
using namespace std;

float mixValue = 0.2f;

//视口
void framebuff_size_callback(GLFWwindow*window, int width, int height)
{
	glViewport(0, 0, width, height);
}

//按键响应
void processInput(GLFWwindow* window)
{
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);
	if (glfwGetKey(window, GLFW_KEY_UP) == GLFW_PRESS)
	{
		mixValue += 0.01f;
		if (mixValue >= 1.0f)
			mixValue = 1.0f;
	}
	if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS)
	{
		mixValue -= 0.01f;
		if (mixValue <= 0.0f)
			mixValue = 0.0f;
	}
}

const int SCR_WIDTH = 800;
const int SCR_HEIGHT = 600;



int main()
{
	//初始化
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	//创建窗口
	GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "OpenGLTexture", NULL, NULL);
	if (window == NULL)
	{
		cout << "Failed to create GLFW window" << endl;
		glfwTerminate();
		return -1;
	}

	//上下文
	glfwMakeContextCurrent(window);
	glfwSetFramebufferSizeCallback(window, framebuff_size_callback);

	//glad初始化
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		cout << "Failed to initialize GLAD" << endl;
	}
	//着色程序
	Shader ourshader("3dvshader.txt", "3dfshader.txt");

	float vertes[] =
	{
		//坐标               颜色          纹理坐标
		0.5f,  0.5f,0.0f, 1.0f,0.0f,0.0f, 1.0f,1.0f,
		0.5f, -0.5f,0.0f, 0.0f,1.0f,0.0f, 1.0f,0.0f,
		-0.5f,-0.5f,0.0f, 0.0f,0.0f,1.0f, 0.0f,0.0f,
		-0.5f, 0.5f,0.0f, 1.0f,1.0f,0.0f, 0.0f,1.0f
	};
	//索引
	unsigned int indices[] = {
		0,1,3,
		1,2,3
	};


	//纹理
	//创建纹理对象
	unsigned int texture1, texture2;
	glGenTextures(1, &texture1);
	//绑定对象类型
	glBindTexture(GL_TEXTURE_2D, texture1);

	//为当前绑定的纹理对象设置环绕、过滤方式
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	//装载图片
	int width, height, nrChannels;

	unsigned char *data = stbi_load("container.jpg", &width, &height, &nrChannels, 0);
	if (data)
	{
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
		glGenerateMipmap(GL_TEXTURE_2D);//多级渐进纹理
	}
	else
	{
		cout << "Failed to load texture1" << endl;
	}
	stbi_image_free(data);

	glGenTextures(1, &texture2);

	glBindTexture(GL_TEXTURE_2D, texture2);

	//为当前绑定的纹理对象设置环绕、过滤方式
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	//装载图片
	stbi_set_flip_vertically_on_load(true);//反转图片Y轴
	data = stbi_load("awesomeface.png", &width, &height, &nrChannels, 0);
	if (data)
	{
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
		glGenerateMipmap(GL_TEXTURE_2D);
	}
	else
	{
		cout << "Failed to load texture2" << endl;
	}
	stbi_image_free(data);

	ourshader.use();//设置uniform变量之前激活着色器程序
					glUniform1i(glGetUniformLocation(ourshader.ID, "texturel"), 0);//手动设置
	ourshader.setInt("texture1", 0);
	ourshader.setInt("texture2", 1);//或者使用着色器类设置

									//顶点数组对象
	unsigned int VAO, VBO, EBO;
	glGenVertexArrays(1, &VAO);
	glGenBuffers(1, &VBO);
	glGenBuffers(1, &EBO);
	//绑定对象
	glBindVertexArray(VAO);
	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	//赋值
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertes), vertes, GL_STATIC_DRAW);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

	//位置
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(0);
	//颜色
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
	glEnableVertexAttribArray(1);
	//纹理坐标
	glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
	glEnableVertexAttribArray(2);

	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindVertexArray(0);

	while (!glfwWindowShouldClose(window))
	{
		processInput(window);
		ourshader.setFloat("aMixValue", mixValue);

		//背景颜色
		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
		//清除颜色缓存
		glClear(GL_COLOR_BUFFER_BIT);

		///绑定纹理
		//激活纹理对象
		glActiveTexture(GL_TEXTURE0);
		//绑定纹理对象
		glBindTexture(GL_TEXTURE_2D, texture1);
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, texture2);

		//创建模型、观察、透视矩阵
		glm::mat4 model = glm::mat4(1.0f);
		glm::mat4 view = glm::mat4(1.0f);
		glm::mat4 projection = glm::mat4(1.0f);

		//矩阵赋值
		model = glm::rotate(model, glm::radians(-55.0f), glm::vec3(1.0f, 0.0f, 0.0f));
		view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
		projection = glm::perspective(glm::radians(45.0f),(float) SCR_WIDTH /(float) SCR_HEIGHT, 0.1f, 100.0f);

		//传递
		unsigned int modelLoc = glGetUniformLocation(ourshader.ID, "model");
		glUniformMatrix4fv(modelLoc, 1, GL_FALSE, value_ptr(model));
		unsigned int viewLoc = glGetUniformLocation(ourshader.ID, "view");
		glUniformMatrix4fv(viewLoc, 1, GL_FALSE, &view[0][0]);
		
		ourshader.setMat4("projection",projection);

		glBindVertexArray(VAO);
		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

		//窗口交换缓存
		glfwSwapBuffers(window);
		//事件
		glfwPollEvents();
	}
	glDeleteVertexArrays(1, &VAO);
	glDeleteBuffers(1, &VBO);
	glDeleteBuffers(1, &EBO);

	glfwTerminate();
	system("pause");
	return 0;
}

结果展示