【OpenGL/Assimp】渲染模型、半透明材质与封装光源

渲染成果

Assimp库准备：

从GitHub拉取源码，根据网络教程，借助CMake生成VS工程项目，并用VS将其编译为静态链接库（lib）或动态链接库（dll + lib）。最后将其库文件和工程内的include文件复制到图形工程下。

Mesh类修改：

在抽象Model，Mesh这些类时，我改动LearnOpenGL的最大的类是Mesh类，将其直接使用的GLAPI替换成了封装好的API，类如下。修改的数据结构在Model中修改相应的数据存放方法即可

//Mesh.h#pragma once
#include <GL/glew.h>
#include <GLFW/glfw3.h>#include <glm/glm.hpp>#include <vector>#include "Shader.h"
#include "VertexArray.h"
#include "VertexBuffer.h"
#include "VertexBufferLayout.h"
#include "IndexBuffer.h"
#include "Texture.h"using namespace std;struct Vertex
{glm::vec3 Position;glm::vec3 Normal;glm::vec2 TexCoords;
};struct TextureData
{string name;Texture* texture;
};class Mesh
{
public:vector<Vertex> vertices;vector<GLuint> indices;vector<TextureData> textures;Mesh(vector<Vertex> vertices, vector<GLuint> indices, vector<TextureData> textures);void Draw(Renderer& renderer, Shader& shader);private:VertexArray VAO;VertexBuffer VBO;IndexBuffer EBO;void setupMesh();
};//Mesh.cpp
#include "Mesh.h"Mesh::Mesh(vector<Vertex> vertices, vector<GLuint> indices, vector<TextureData> textures)
{this->vertices = vertices;this->indices = indices;this->textures = textures;this->setupMesh();             
}void Mesh::setupMesh()
{VAO.Bind();VBO.Init(&vertices[0], vertices.size() * sizeof(Vertex));EBO.Init(&indices[0], indices.size());VAO.AddVertexBuffer(VBO);VAO.Unbind();
}void Mesh::Draw(Renderer& renderer, Shader& shader)
{for (int i = 0; i < textures.size(); i++){textures[i].texture->Bind(i);shader.SetUniform1i(textures[i].name, i);}renderer.Draw(VAO, EBO, shader);
}

透明贴图使用：

我所需要绘制的模型有半透明的面部贴图，因此需要使用透明度，这里需要注意的是，如果所有使用数据获取数据的地方都没有出错但仍没有透明效果，可以检查原始数据的问题，如图片本身的透明效果，在工程中加载图片时是否包含透明通道。

//shader
void main()
{vec3 norm = normalize(Normal);vec3 viewDir = normalize(viewPos - FragPos);//透明测试vec4 texColor = texture(texture_diffuse, TexCoords);if(texColor.a < 0.2 && mixFactor == 0)discard;//光照着色color = vec4(CalcPointLight(light, norm, FragPos, viewDir), 1);
}

光源封装：

每次使用光源需要大段的赋值语句，因此对其进行简单封装，目前只封装了点光源

//Light.h#pragma once
#include <iostream>
#include <glm/glm.hpp>#include "Shader.h"using namespace std;class Light
{
public:Light(glm::vec3 position = { 1.2f, 1.0f, 2.0f }, glm::vec3 ambient = { 0.4, 0.4, 0.4 },glm::vec3 diffuse = { 1.2, 1.2, 1.2 },glm::vec3 specular = { 0.1, 0.1, 0.1 },float constant = 1, float linear = 0.09, float quadratic = 0.032);void SetupShader(Shader& shader, string lightName);private:glm::vec3 m_Position;glm::vec3 m_Ambient;glm::vec3 m_Diffuse;glm::vec3 m_Specular;float m_Constant;float m_Linear;float m_Quadratic;
};//Light.cpp
#include "Light.h"Light::Light(glm::vec3 position, glm::vec3 ambient, glm::vec3 diffuse, glm::vec3 specular, float constant, float linear, float quadratic)
{m_Position = position;m_Ambient = ambient;m_Diffuse = diffuse;m_Specular = specular;m_Constant = constant;m_Linear = linear;m_Quadratic = quadratic;
}void Light::SetupShader(Shader& shader, std::string lightName)
{shader.SetUniform3f(lightName + ".position", m_Position.x, m_Position.y, m_Position.z);shader.SetUniform3f(lightName + ".ambient", m_Ambient.x, m_Ambient.y, m_Ambient.z);shader.SetUniform3f(lightName + ".diffuse", m_Diffuse.x, m_Diffuse.y, m_Diffuse.z);shader.SetUniform3f(lightName + ".specular", m_Specular.x, m_Specular.y, m_Specular.z);shader.SetUniform1f(lightName + ".constant", m_Constant);shader.SetUniform1f(lightName + ".linear", m_Linear);shader.SetUniform1f(lightName + ".quadratic", m_Quadratic);
}

使用方式在如下测试环境中：

#pragma once#include "RunBase.h"#include "Model.h"
#include "Light.h"#include <glm/gtc/type_ptr.hpp>class AssimpTest : public RunBase
{
public:Model* body, *blue, *ear, *eye, *mao, *mouth;Shader diffuseShader;Renderer renderer;Light light;AssimpTest() : RunBase(){diffuseShader.Init("res/shaders/AssimpTest.shader");}virtual void Init(GLFWwindow* window, float targetFrameTime) override{/*GLCall(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC1_ALPHA));GLCall(glEnable(GL_BLEND));*/body = new Model("res/models/jixuanyou/body.obj");blue = new Model("res/models/jixuanyou/blue.obj");ear = new Model("res/models/jixuanyou/ear.obj");eye = new Model("res/models/jixuanyou/eye.obj");mao = new Model("res/models/jixuanyou/mao.obj");mouth = new Model("res/models/jixuanyou/mouth.obj");}virtual void RenderLoop(GLFWwindow* window, float targetFrameTime) override{renderer.Clear();//绘制受光物体diffuseShader.Bind();//视图矩阵（透视参数）glm::mat4 view(1), proj(1), model(1);view = camera.GetViewMatrix();proj = glm::perspective<GLfloat>(45, 640 / 480, .1f, 100.f);//赋值透视diffuseShader.SetUniformMat4f("view", glm::value_ptr(view));diffuseShader.SetUniformMat4f("projection", glm::value_ptr(proj));diffuseShader.SetUniformMat4f("model", glm::value_ptr(model));//赋值光照light.SetupShader(diffuseShader, "light");//赋值视图位置diffuseShader.SetUniform3f("viewPos", camera.Position.x, camera.Position.y, camera.Position.z);diffuseShader.SetUniform1f("shininess", 4);// 取消纯色diffuseShader.SetUniform1f("mixFactor", 0);//不透明物件body->Draw(renderer, diffuseShader);ear->Draw(renderer, diffuseShader);eye->Draw(renderer, diffuseShader);mouth->Draw(renderer, diffuseShader);// 使用纯色diffuseShader.SetUniform1f("mixFactor", 1);// 浅蓝色diffuseShader.SetUniform3f("diffuseColor", 0.50, 0.66, 0.81);mao->Draw(renderer, diffuseShader);// 深蓝色diffuseShader.SetUniform3f("light.diffuse", 4, 4, 4);diffuseShader.SetUniform3f("light.specular", 0.5, 0.5, 0.5);diffuseShader.SetUniform3f("diffuseColor", 0.022, 0.06, 0.21);blue->Draw(renderer, diffuseShader);}virtual bool UseCameraControl() override{return true;}
};