画一个正方形
其实，画正方形就是画两个三角形，用四个顶点以及使用索引来实现
完整代码在Square项目的Application.cpp里
先贴上窗口初始化代码
void BaseInit()
{
glfwInit();//初始化
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//配置GLFW
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//配置GLFW
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//
glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);
float screenWidth = 800.0f;
float screenHeight = 600.0f;
//创建窗口
glWindow = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr);
if (glWindow == nullptr)
{
cout << "Failed to create GLFW window" << endl;
glfwTerminate();
return;
}
glfwMakeContextCurrent(glWindow);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return;
}
画一个普通的正方形
void NormalSquare()
{
float vertices[] = {
// ---- 位置 ----
0.5f, 0.5f, 0.0f, // 右上
0.5f, -0.5f, 0.0f, // 右下
-0.5f, -0.5f, 0.0f, // 左下
-0.5f, 0.5f, 0.0f, // 左上
};
//索引
unsigned int indices[] = {
0,1,3,
1,2,3
};
//编译着色器
Shader ourShader("vertex_1.vs", "fragment_1.fs");
ourShader.use();//glUseProgram(shaderProgram);
unsigned int VAO;
//顶点数组
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);
//绑定顶点数组缓存
unsigned int VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
//绑定索引缓存
unsigned int EBO;
glGenBuffers(1, &EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// 位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
while (!glfwWindowShouldClose(glWindow))
{
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
//draw
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
glfwPollEvents();
glfwSwapBuffers(glWindow);
}
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
glfwTerminate();
}
最终效果
画一个彩色的正方形
和上一个笔记里画彩色三角形的逻辑一样，在顶点属性后面加上颜色属性，设置数据访问指针的属性，记得顶点着色器要加上颜色的输入(步长和相位)
//彩色正方形
void ColourfulSquare()
{
float vertices[] = {
// ---- 位置 ---- ---- 颜色 ----
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, // 右上
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, // 右下
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, // 左下
-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, // 左上
};
//索引
unsigned int indices[] = {
0,1,3,
1,2,3
};
//编译着色器
Shader ourShader("vertex_4.vs", "fragment_4.fs");
ourShader.use();//glUseProgram(shaderProgram);
unsigned int VAO;
//顶点数组
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);
//绑定顶点数组缓存
unsigned int VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
//绑定索引缓存
unsigned int EBO;
glGenBuffers(1, &EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// 位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// 颜色属性
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))); //最后一个参数是数据的起点
glEnableVertexAttribArray(1);
while (!glfwWindowShouldClose(glWindow))
{
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
//draw
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
glfwPollEvents();
glfwSwapBuffers(glWindow);
}
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
glfwTerminate();
}
最终效果
可以试试线框模式，在while之前加上
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
效果图
