OpenGL笔记二十之深度检测概念

—— 2024-08-25 晚上

bilibili赵新政老师的教程看后笔记

code review!

1.课程PPT截图

2.运行

3.代码

关键部分

main.cpp

#include <iostream>

#include "glframework/core.h"
#include "glframework/shader.h"
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"
#include "glframework/texture.h"

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 学习使用深度测试功能
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*				-1 演示为什么需要深度检测
				-2 演示OpenGL深度检测的使用	
					2.1 glEnable深度检测
					2.2 glDepthFunc设置深度检测的算法
					2.3 在glClear里面清理深度缓存的数据
* 
*└────────────────────────────────────────────────┘
*/

GLuint vao;
Shader* shader = nullptr;

glm::mat4 transformGoku(1.0f);
glm::mat4 transformLuffy(1.0f);

Texture* textureGoku = nullptr;
Texture* textureLuffy = nullptr;


glm::mat4 viewMatrix(1.0f);
glm::mat4 perspectiveMatrix(1.0f);

void OnResize(int width, int height) {
	GL_CALL(glViewport(0, 0, width, height));
	std::cout << "OnResize" << std::endl;
}

void OnKey(int key, int action, int mods) {
	std::cout << key << std::endl;
}

void prepareVAO() {
	float positions[] = {
		-1.0f, 0.0f, 0.0f,
		1.0f, 0.0f, 0.0f,
		0.0f,  1.0f, 0.0f,
	};


	float colors[] = {
		1.0f, 0.0f,0.0f,
		0.0f, 1.0f,0.0f,
		0.0f, 0.0f,1.0f,
	};

	float uvs[] = {
		0.0f, 0.0f,
		1.0f, 0.0f,
		0.5f, 1.0f,
	};

	unsigned int indices[] = {
		0, 1, 2,
	};

	//2 VBO创建
	GLuint posVbo, colorVbo, uvVbo;
	glGenBuffers(1, &posVbo);
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	glGenBuffers(1, &colorVbo);
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);

	glGenBuffers(1, &uvVbo);
	glBindBuffer(GL_ARRAY_BUFFER, uvVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(uvs), uvs, GL_STATIC_DRAW);

	//3 EBO创建
	GLuint ebo;
	glGenBuffers(1, &ebo);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

	//4 VAO创建
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//5 绑定vbo ebo 加入属性描述信息
	//5.1 加入位置属性描述信息
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 3, (void*)0);

	//5.2 加入颜色属性描述数据
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 3, (void*)0);

	//5.3 加入uv属性描述数据
	glBindBuffer(GL_ARRAY_BUFFER, uvVbo);
	glEnableVertexAttribArray(2);
	glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, (void*)0);

	//5.4 加入ebo到当前的vao
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);

	glBindVertexArray(0);
}

void prepareShader() {
	shader = new Shader("assets/shaders/vertex.glsl","assets/shaders/fragment.glsl");
}

void prepareTexture() {
	textureGoku = new Texture("assets/textures/goku.jpg", 0);
	textureLuffy = new Texture("assets/textures/luffy.jpg", 0);
}

void prepareCamera() {
	//lookat:生成一个viewMatrix
	//eye:当前摄像机所在的位置
	//center:当前摄像机看向的那个点
	//up:穹顶向量
	viewMatrix = glm::lookAt(glm::vec3(0.0f,0.0f,3.0f),glm::vec3(0.0f,0.0f,0.0f),glm::vec3(0.0f,1.0f,0.0f));
}

void preparePerspective() {
	//fovy:y轴方向的视张角,弧度单位
	//aspect：近平面的横纵百分比
	//near:近平面距离
	//far：远平面距离
	perspectiveMatrix = glm::perspective(glm::radians(60.0f), (float)app->getWidth() / (float)app->getHeight(), 0.1f, 1000.0f);
}

void prepareState() {
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LESS);
//	glClearDepth(0.0f);
}

void render() {
	//执行opengl画布清理操作
	GL_CALL(glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT));

	//绑定当前的program
	shader->begin();
	shader->setInt("sampler", 0);
	shader->setMatrix4x4("transform", transformGoku);
	shader->setMatrix4x4("viewMatrix", viewMatrix);
	shader->setMatrix4x4("projectionMatrix", perspectiveMatrix);
	
	textureGoku->bind();
	//绑定当前的vao
	GL_CALL(glBindVertexArray(vao));

	//第一次绘制
	GL_CALL(glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0));

	//第二次绘制
	textureLuffy->bind();
	transformLuffy = glm::translate(glm::mat4(1.0f), glm::vec3(0.8f, 0.0f, -1.0f));
	shader->setMatrix4x4("transform", transformLuffy);
	GL_CALL(glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0));

	GL_CALL(glBindVertexArray(0));

	shader->end();
}


int main() {
	if (!app->init(800, 600)) {
		return -1;
	}

	app->setResizeCallback(OnResize);
	app->setKeyBoardCallback(OnKey);

	//设置opengl视口以及清理颜色
	GL_CALL(glViewport(0, 0, 800, 600));
	GL_CALL(glClearColor(0.2f, 0.3f, 0.3f, 1.0f));

	prepareShader();
	prepareVAO();
	prepareTexture();
	prepareCamera();
	preparePerspective();
	prepareState();

	while (app->update()) {
		render();
	}

	app->destroy();

	return 0;
}