OpenGL笔记二十一之几何类设计

—— 2024-09-16 下午

bilibili赵新政老师的教程看后笔记

code review!

1.运行

1.1.立方体运行

1.2.球体运行

2.几何类搭建

1.立方体分析

将0.5替换成halfSize就可以了。

2.球体分析

3.图片资源文件

goku.jpg

earth.png

4.关键实现

4.1.geometry.h

代码

#pragma once

#include "core.h"

class Geometry {
public:
	Geometry();
	~Geometry();

	static Geometry* createBox(float size);
	static Geometry* createSphere(float radius);

	GLuint getVao()const { return mVao; }
	uint32_t getIndicesCount()const { return mIndicesCount; }

private:
	GLuint mVao{ 0 };
	GLuint mPosVbo{ 0 };
	GLuint mUvVbo{ 0 };
	GLuint mEbo{ 0 };

	uint32_t mIndicesCount{ 0 };
};

4.2.geometry.cpp

代码

#include "geometry.h"
#include <vector>

Geometry::Geometry() {

}

Geometry::~Geometry() {
	if (mVao != 0) {
		glDeleteVertexArrays(1, &mVao);
	}
	if (mPosVbo != 0) {
		glDeleteBuffers(1, &mPosVbo);
	}
	if (mUvVbo != 0) {
		glDeleteBuffers(1, &mUvVbo);
	}
	if (mEbo != 0) {
		glDeleteBuffers(1, &mEbo);
	}
}

Geometry* Geometry::createBox(float size) {
	Geometry* geometry = new Geometry();
	geometry->mIndicesCount = 36;

	float halfSize = size / 2.0f;

	float positions[] = {
		// Front face
		-halfSize, -halfSize, halfSize, halfSize, -halfSize, halfSize, halfSize, halfSize, halfSize, -halfSize, halfSize, halfSize,
		// Back face
		-halfSize, -halfSize, -halfSize, -halfSize, halfSize, -halfSize, halfSize, halfSize, -halfSize, halfSize, -halfSize, -halfSize,
		// Top face
		-halfSize, halfSize, halfSize, halfSize, halfSize, halfSize, halfSize, halfSize, -halfSize, -halfSize, halfSize, -halfSize,
		// Bottom face
		-halfSize, -halfSize, -halfSize, halfSize, -halfSize, -halfSize, halfSize, -halfSize, halfSize, -halfSize, -halfSize, halfSize,
		// Right face
		halfSize, -halfSize, halfSize, halfSize, -halfSize, -halfSize, halfSize, halfSize, -halfSize, halfSize, halfSize, halfSize,
		// Left face
		-halfSize, -halfSize, -halfSize, -halfSize, -halfSize, halfSize, -halfSize, halfSize, halfSize, -halfSize, halfSize, -halfSize
	};

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

	unsigned int indices[] = {
		0, 1, 2, 2, 3, 0,   // Front face
		4, 5, 6, 6, 7, 4,   // Back face
		8, 9, 10, 10, 11, 8,  // Top face
		12, 13, 14, 14, 15, 12, // Bottom face
		16, 17, 18, 18, 19, 16, // Right face
		20, 21, 22, 22, 23, 20  // Left face
	};

	//2 VBO创建
	GLuint& posVbo = geometry->mPosVbo, uvVbo = geometry->mUvVbo;
	glGenBuffers(1, &posVbo);
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, 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
	glGenBuffers(1, &geometry->mEbo);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, geometry->mEbo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

	//4 VAO创建
	glGenVertexArrays(1, &geometry->mVao);
	glBindVertexArray(geometry->mVao);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 3, (void*)0);

	glBindBuffer(GL_ARRAY_BUFFER, uvVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 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, geometry->mEbo);

	glBindVertexArray(0);

	return geometry;
}

Geometry* Geometry::createSphere(float radius) {
	Geometry* geometry = new Geometry();

	//目标：1 位置 2 uv 3 索引
	//1 主要变量声明
	std::vector<GLfloat> positions{};
	std::vector<GLfloat> uvs{};
	std::vector<GLuint> indices{};

	//声明纬线与经线的数量
	int numLatLines = 60;//纬线
	int numLongLines = 60;//经线

	//2 通过两层循环（纬线在外，经线在内）->位置、uv
	for (int i = 0; i <= numLatLines; i++) {
		for (int j = 0; j <= numLongLines; j++) {
			float phi = i * glm::pi<float>() / numLatLines;
			float theta = j * 2 * glm::pi<float>() / numLongLines;

			float y = radius * cos(phi);
			float x = radius * sin(phi) * cos(theta);
			float z = radius * sin(phi) * sin(theta);

			positions.push_back(x);
			positions.push_back(y);
			positions.push_back(z);

			float u = 1.0 - (float)j / (float)numLongLines;
			float v = 1.0 - (float)i / (float)numLatLines;

			uvs.push_back(u);
			uvs.push_back(v);
		}
	}


	//3 通过两层循环（这里没有=号）->顶点索引
	for (int i = 0; i < numLatLines; i++) {
		for (int j = 0; j < numLongLines; j++) {
			int p1 = i * (numLongLines + 1) + j;
			int p2 = p1 + numLongLines + 1;
			int p3 = p1 + 1;
			int p4 = p2 + 1;

			indices.push_back(p1);
			indices.push_back(p2);
			indices.push_back(p3);

			indices.push_back(p3);
			indices.push_back(p2);
			indices.push_back(p4);
		}
	}


	//4 生成vbo与vao
	GLuint& posVbo = geometry->mPosVbo, uvVbo = geometry->mUvVbo;
	glGenBuffers(1, &posVbo);
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, positions.size() * sizeof(float), positions.data(), GL_STATIC_DRAW);

	glGenBuffers(1, &uvVbo);
	glBindBuffer(GL_ARRAY_BUFFER, uvVbo);
	glBufferData(GL_ARRAY_BUFFER, uvs.size() * sizeof(float), uvs.data(), GL_STATIC_DRAW);

	glGenBuffers(1, &geometry->mEbo);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, geometry->mEbo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLuint), indices.data(), GL_STATIC_DRAW);

	glGenVertexArrays(1, &geometry->mVao);
	glBindVertexArray(geometry->mVao);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 3, (void*)0);

	glBindBuffer(GL_ARRAY_BUFFER, uvVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, (void*)0);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, geometry->mEbo);

	glBindVertexArray(0);

	geometry->mIndicesCount = indices.size();


	return geometry;
}

4.3.vertex.glsl

代码

#version 460 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aUV;

out vec2 uv;

uniform mat4 transform;
uniform mat4 viewMatrix;
uniform mat4 projectionMatrix;

//aPos作为attribute（属性）传入shader
//不允许更改的
void main()
{
	vec4 position = vec4(aPos, 1.0);
	position = projectionMatrix * viewMatrix * transform * position;
	gl_Position = position;
	uv = aUV;
}

4.4.fragment.glsl

代码

#version 460 core
out vec4 FragColor;

in vec2 uv;

uniform sampler2D sampler;

void main()
{
  FragColor = texture(sampler, uv);
}

4.5.main.cpp

代码

#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"

//引入相机+控制器
#include "application/camera/perspectiveCamera.h"
#include "application/camera/orthographicCamera.h"
#include "application/camera/trackBallCameraControl.h"
#include "application/camera/gameCameraControl.h"

#include "glframework/geometry.h"

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 设计并实现Geometry系统，用于学习方便
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*			搭建Geometry类框架
*└────────────────────────────────────────────────┘
*/

Geometry* geometry = nullptr;
Shader* shader = nullptr;
Texture* texture = nullptr;
glm::mat4 transform(1.0f);

PerspectiveCamera* camera = nullptr;
TrackBallCameraControl* cameraControl = nullptr;

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) {
	cameraControl->onKey(key, action, mods);
}

//鼠标按下/抬起
void OnMouse(int button, int action, int mods) {
	double x, y;
	app->getCursorPosition(&x, &y);
	cameraControl->onMouse(button, action, x, y);
}

//鼠标移动
void OnCursor(double xpos, double ypos) {
	cameraControl->onCursor(xpos, ypos);
}

//鼠标滚轮
void OnScroll(double offset) {
	cameraControl->onScroll(offset);
}

void prepareVAO() {
	geometry = Geometry::createBox(3.0f);
	// geometry = Geometry::createSphere(3.0f);
}

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

void prepareTexture() {
	texture = new Texture("assets/textures/goku.jpg", 0);
	// texture = new Texture("assets/textures/earth.png", 0);
}

void prepareCamera() {
	float size = 6.0f;
	//camera = new OrthographicCamera(-size, size, size, -size, size, -size);
	camera = new PerspectiveCamera(
		60.0f, 
		(float)app->getWidth() / (float)app->getHeight(),
		0.1f,
		1000.0f
	);

	cameraControl = new TrackBallCameraControl();
	cameraControl->setCamera(camera);
	cameraControl->setSensitivity(0.4f);
}

void prepareState() {
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LESS);
}

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", transform);
	shader->setMatrix4x4("viewMatrix", camera->getViewMatrix());
	shader->setMatrix4x4("projectionMatrix", camera->getProjectionMatrix());
 
	//绑定当前的vao
	GL_CALL(glBindVertexArray(geometry->getVao()));

	//发出绘制指令
	GL_CALL(glDrawElements(GL_TRIANGLES, geometry->getIndicesCount(), 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);
	app->setMouseCallback(OnMouse);
	app->setCursorCallback(OnCursor);
	app->setScrollCallback(OnScroll);

	//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();
	prepareState();

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

	app->destroy();

	return 0;
}