LearnOpenGL --- 你好三角形

你好，三角形的课后练习题

---

---

一、创建相同的两个三角形，但对它们的数据使用不同的VAO和VBO

#include <glad/glad.h>
#include <GLFW/glfw3.h>#include <iostream>void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;const char* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos; \n"
"void main()\n"
"{\n"
"	gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"}\n";const char* fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main()\n"
"{\n"
"	FragColor = vec4(1.0, 0.5f, 0.2f, 1.0f);\n"
"}\n";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(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);if (window == NULL){std::cout << "创建窗口失败" << std::endl;glfwTerminate();return -1;}glfwMakeContextCurrent(window);glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "GLAD初始化失败" << std::endl;return -1;}int success;char infoLog[512];unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);glCompileShader(vertexShader);glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);if (!success){glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);std::cout << infoLog << std::endl;}unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);glCompileShader(fragmentShader);glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);if (!success){glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);std::cout << infoLog << std::endl;}unsigned int shaderProgram = glCreateProgram();glAttachShader(shaderProgram, vertexShader);glAttachShader(shaderProgram, fragmentShader);glLinkProgram(shaderProgram);glGetShaderiv(shaderProgram, GL_COMPILE_STATUS, &success);if (!success){glGetShaderInfoLog(shaderProgram, 512, NULL, infoLog);std::cout << infoLog << std::endl;}glDeleteShader(vertexShader);glDeleteShader(fragmentShader);float vertices0[] = {-0.9f, -0.5f, 0.0f,  // left -0.0f, -0.5f, 0.0f,  // right-0.45f, 0.5f, 0.0f,  // top };float vertices1[] = {0.9f, 0.5f, 0.0f,  // left 0.0f, 0.5f, 0.0f,  // right0.45f, -0.5f, 0.0f,  // top };unsigned int VBOs[2], VAOs[2];glGenBuffers(2, VBOs);glGenVertexArrays(2, VAOs);glBindVertexArray(VAOs[0]);//复制顶点数组到缓冲中供OpenGL使用glBindBuffer(GL_ARRAY_BUFFER, VBOs[0]);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices0), vertices0, GL_STATIC_DRAW);//如何解析顶点数据glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);glBindVertexArray(VAOs[1]);glBindBuffer(GL_ARRAY_BUFFER, VBOs[1]);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices1), vertices1, GL_STATIC_DRAW);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);glEnableVertexAttribArray(0);//不知道这两段代码的作用glBindBuffer(GL_ARRAY_BUFFER, 0);glBindVertexArray(0);while (!glfwWindowShouldClose(window)){processInput(window);glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);glUseProgram(shaderProgram);glBindVertexArray(VAOs[0]);glDrawArrays(GL_TRIANGLES, 0, 3);glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);glBindVertexArray(VAOs[1]);glDrawArrays(GL_TRIANGLES, 0, 3);glfwSwapBuffers(window);glfwPollEvents();}glDeleteVertexArrays(2, VAOs);glDeleteBuffers(2, VBOs);glDeleteProgram(shaderProgram);glfwTerminate();return 0;
}void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{glViewport(0, 0, width, height);
}void processInput(GLFWwindow* window)
{if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)glfwSetWindowShouldClose(window, true);
}

二、创建两个着色器程序，第二个程序使用一个不同的片段着色器，输出黄色；再次绘制这两个三角形，让其中一个输出为黄色

#include <glad/glad.h>
#include <GLFW/glfw3.h>#include <iostream>void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;const char* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos; \n"
"void main()\n"
"{\n"
"	gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"}\n";const char* fragmentShader1Source = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main()\n"
"{\n"
"	FragColor = vec4(1.0, 0.5f, 0.2f, 1.0f);\n"
"}\n\0";const char* fragmentShader2Source = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main()\n"
"{\n"
"	FragColor = vec4(1.0, 1.0f, 1.0f, 1.0f);\n"
"}\n\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(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);if (window == NULL){std::cout << "创建窗口失败" << std::endl;glfwTerminate();return -1;}glfwMakeContextCurrent(window);glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "GLAD初始化失败" << std::endl;return -1;}unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);glCompileShader(vertexShader);unsigned int fragmentShaderOrange = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragmentShaderOrange, 1, &fragmentShader1Source, NULL);glCompileShader(fragmentShaderOrange);unsigned int shaderProgramOrange = glCreateProgram();glAttachShader(shaderProgramOrange, vertexShader);glAttachShader(shaderProgramOrange, fragmentShaderOrange);glLinkProgram(shaderProgramOrange);unsigned int fragmentShaderYellow = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragmentShaderYellow, 1, &fragmentShader2Source, NULL);glCompileShader(fragmentShaderYellow);unsigned int shaderProgramYellow = glCreateProgram();glAttachShader(shaderProgramYellow, vertexShader);glAttachShader(shaderProgramYellow, fragmentShaderYellow);glLinkProgram(shaderProgramYellow);float firstTriangle[] = {-0.9f, -0.5f, 0.0f,  // left -0.0f, -0.5f, 0.0f,  // right-0.45f, 0.5f, 0.0f,  // top };float secondTriangle[] = {0.0f, -0.5f, 0.0f,  // left0.9f, -0.5f, 0.0f,  // right0.45f, 0.5f, 0.0f   // top };unsigned int VBOs[2], VAOs[2];glGenVertexArrays(2, VAOs);glGenBuffers(2, VBOs);glBindVertexArray(VAOs[0]);//复制顶点数组到缓冲中供OpenGL使用glBindBuffer(GL_ARRAY_BUFFER, VBOs[0]);glBufferData(GL_ARRAY_BUFFER, sizeof(firstTriangle), firstTriangle, GL_STATIC_DRAW);//如何解析顶点数据glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);glBindVertexArray(VAOs[1]);glBindBuffer(GL_ARRAY_BUFFER, VBOs[1]);glBufferData(GL_ARRAY_BUFFER, sizeof(secondTriangle), secondTriangle, GL_STATIC_DRAW);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);glEnableVertexAttribArray(0);//不知道这两段代码的作用glBindBuffer(GL_ARRAY_BUFFER, 0);glBindVertexArray(0);while (!glfwWindowShouldClose(window)){processInput(window);glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);glUseProgram(shaderProgramOrange);glBindVertexArray(VAOs[0]);glDrawArrays(GL_TRIANGLES, 0, 3);glUseProgram(shaderProgramYellow);glBindVertexArray(VAOs[1]);glDrawArrays(GL_TRIANGLES, 0, 3);glfwSwapBuffers(window);glfwPollEvents();}glDeleteVertexArrays(2, VAOs);glDeleteBuffers(2, VBOs);glDeleteProgram(shaderProgramOrange);glDeleteProgram(shaderProgramYellow);glfwTerminate();return 0;
}void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{glViewport(0, 0, width, height);
}void processInput(GLFWwindow* window)
{if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)glfwSetWindowShouldClose(window, true);
}