learnOpenGL-coordinate system

MVP transformation

#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "shader.h"
#include "stb_image.h"
#include <glm.hpp>
#include <gtc/matrix_transform.hpp>
#include <gtc/type_ptr.hpp>

//GLfloat vertices[] = {
    
    
     ---- 位置 ----       ---- 颜色 ----     - 纹理坐标 -
//	0.5f,  0.5f, 0.0f,   1.0f, 0.0f, 0.0f,   1.0f, 1.0f,   // 右上
//	0.5f, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,   1.0f, 0.0f,   // 右下
//	-0.5f, -0.5f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f,   // 左下
//	-0.5f,  0.5f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f    // 左上
//};

GLfloat vertices[] = {
    
    
	-0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
	 0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	-0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 0.0f,

	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	 0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
	-0.5f,  0.5f,  0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,

	-0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	-0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	-0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f, -0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,

	-0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	-0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
	-0.5f,  0.5f, -0.5f,  0.0f, 1.0f
};

GLuint indices[] = {
    
    
	0, 1, 3,
	1, 2, 3
};

GLfloat mixAlpha = 0.2;

//十个立方体的位置向量
glm::vec3 cubePositions[] = {
    
    
  glm::vec3(0.0f,  0.0f,  0.0f),
  glm::vec3(2.0f,  5.0f, -15.0f),
  glm::vec3(-1.5f, -2.2f, -2.5f),
  glm::vec3(-3.8f, -2.0f, -12.3f),
  glm::vec3(2.4f, -0.4f, -3.5f),
  glm::vec3(-1.7f,  3.0f, -7.5f),
  glm::vec3(1.3f, -2.0f, -2.5f),
  glm::vec3(1.5f,  2.0f, -2.5f),
  glm::vec3(1.5f,  0.2f, -1.5f),
  glm::vec3(-1.3f,  1.0f, -1.5f)
};

void processInput(GLFWwindow* window) {
    
    
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);
	if (glfwGetKey(window, GLFW_KEY_UP) == GLFW_PRESS) {
    
    
		mixAlpha += 0.1;
		if (mixAlpha > 1.0) mixAlpha = 1.0;
	}
	if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS)
		mixAlpha -= 0.1;
		if (mixAlpha < 0.0) mixAlpha = 0.0;
}

int main()
{
    
    
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);

	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	GLFWwindow* window = glfwCreateWindow(800, 600, "test", nullptr, nullptr);
	if (window == nullptr)
	{
    
    
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);

	glewExperimental = GL_TRUE;
	if (glewInit() != GLEW_OK)
	{
    
    
		std::cout << "Failed to initialize GLEW" << std::endl;
		glfwTerminate();
		return -1;
	}

	glViewport(0, 0, 800, 600);

	GLuint VAO;
	glGenVertexArrays(1, &VAO);
	glBindVertexArray(VAO);

	GLuint VBO;
	glGenBuffers(1, &VBO);
	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

	GLuint EBO;
	glGenBuffers(1, &EBO);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
	glEnableVertexAttribArray(1);

	glBindVertexArray(0);

	GLuint texture;
	glGenTextures(1, &texture);
	glBindTexture(GL_TEXTURE_2D, texture);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

	int width, height;
	unsigned char* image = stbi_load("container.jpg", &width, &height, 0, 0);

	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);

	glGenerateMipmap(GL_TEXTURE_2D);

	stbi_image_free(image);

	glBindTexture(GL_TEXTURE_2D, 0);

	GLuint texture1;
	glGenTextures(1, &texture1);
	glBindTexture(GL_TEXTURE_2D, texture1); 
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	int width1, height1;
	unsigned char* image1 = stbi_load("awesomeface.png", &width1, &height1, 0, 0);
	if (image1) {
    
    
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width1, height1, 0, GL_RGBA, GL_UNSIGNED_BYTE, image1);
		glGenerateMipmap(GL_TEXTURE_2D);
	}
	else {
    
    
		std::cout << "Failed to load texture" << std::endl;
	}
	stbi_image_free(image1);
	

	Shader* testShader = new Shader("test.vert", "test.frag");

	//创建模型矩阵
	glm::mat4 model;
	//model = glm::rotate(model, glm::radians(-55.0f) , glm::vec3(1.0f, 0.0f, 0.0f));

	glm::mat4 view;
	// 将矩阵向我们要进行移动场景的反向移动。
	view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));

	//投影矩阵
	glm::mat4 projection;
	projection = glm::perspective(glm::radians(45.0f), 800.0f / 600.0f, 0.1f, 100.0f);
	//透视投影矩阵。参数：1.fov，表示的是视野，通常为45，2.宽高比，3.平截头体近平面，通常为0.1，4.平截头体远平面通常为100.0
	//glm::ortho(0.0f, 800.0f, 0.0f, 600.0f, 0.1f, 100.0f);
	//正交投影矩阵。参数：1.2.3.4分别为平截头体的左右底顶。5.6分别为近平面，远平面距离。

	//深度信息存储在Z缓冲区。输出片段颜色时，OpenGL会对比其与z缓冲区的深度值，若当前片段在其他片段之后，则被丢弃并重写
	glEnable(GL_DEPTH_TEST);//开启深度测试，默认关闭。
	//glDisable(GL_DEPTH_TEST);

	testShader->Use();
	//给shader传值前，先激活要使用的program
	glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "view"), 1, GL_FALSE, glm::value_ptr(view));
	glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "projection"), 1, GL_FALSE, glm::value_ptr(projection));

	while (!glfwWindowShouldClose(window))
	{
    
    
		processInput(window);
		glfwPollEvents();

		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT);//清除前一帧的深度信息


		//model = glm::rotate(model, (GLfloat)glfwGetTime() * glm::radians(0.1f), glm::vec3(0.5f, 1.0f, 0.0f));


		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, texture); 
		glUniform1i(glGetUniformLocation(testShader->getProgram(), "ourTexture"), 0); 

		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, texture1);
		glUniform1i(glGetUniformLocation(testShader->getProgram(), "ourTexture1"), 1);

		glUniform1f(glGetUniformLocation(testShader->getProgram(), "mixAlpha"), mixAlpha);

		glBindVertexArray(VAO);
		//glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
		for (GLuint i = 0; i < 10; i++)
		{
    
    
			glm::mat4 model;
			model = glm::translate(model, cubePositions[i]);
			GLfloat angle = 20.0f * i;
			model = glm::rotate(model, angle, glm::vec3(1.0f, 0.3f, 0.5f));
			glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "model"), 1, GL_FALSE, glm::value_ptr(model));

			glDrawArrays(GL_TRIANGLES, 0, 36);
		}

		glBindVertexArray(0);

		glfwSwapBuffers(window);
	}


	glfwTerminate();
	return 0;
}

vertex shader

#version 330 core
layout (location = 0) in vec3 position; // position变量的属性位置值为0
layout (location = 1) in vec2 textCoord; // textCoord变量的属性位置值为2

out vec2 TextCoord;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main() //每个着色器的入口点都是main函数
{
    
    
    gl_Position = projection * view * model * vec4(position, 1.0);
    
    TextCoord = vec2(textCoord.x, textCoord.y);
}

fragment shader

#version 330 core
in vec2 TextCoord;

out vec4 color; // 片段着色器输出的变量名可以任意命名，类型必须是vec4

uniform sampler2D ourTexture;
//uniform采样器，不用glUniform赋值。使用glUniform1i，给纹理采样器分配一个位置值，在一个FS中设置多个纹理。
//一个纹理位置值称为一个纹理单元。默认激活的为0。
//纹理单元使着色器可以使用多个纹理。赋值一个纹理单元到采样器，可以绑定多个纹理。
uniform sampler2D ourTexture1;

uniform float mixAlpha;

void main()
{
    
    
    //FragColor = texture(texture1, texcoord);
    color = mix(texture(ourTexture, TextCoord), texture(ourTexture1, vec2(1.0-TextCoord.x,TextCoord.y)), mixAlpha);
    //输出两个纹理的结合。根据第三个参数进行线性插值，0则返回第一个输入，1则返回第二个
}