2018/8/19--OpenGL学习笔记（八）Mesh/Model

开篇的话：··········很久没有更新笔记了，因为这段时间忙于改简历和投简历还有面试，往后有看了几个章节，但是没有时间来回顾总结下，所以今天来把之前的补上

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Assimp

（模型加载需要我们用到这个库，教程上让我们用Cmake来编译，因为第一章的时候，我Cmake就各种问题，索性我就网上找了别人编译好的包，直接来使用了。）

Mesh

#ifndef MESH_H
#define MESH_H

#include  

#include 
#include 

#include "Shader.h"

#include 
#include 
#include 
#include 
#include 
using namespace std;

//定义一个顶点
struct Vertex {
	glm::vec3 Position;
	glm::vec3 Normal;
	glm::vec2 TexCoords;
	glm::vec3 Tangent;
	glm::vec3 Bitangent;
};

//将纹理数据整理到一个Texture结构体
struct Texture {
	unsigned int id;
	string type;
	string path; //储存纹理的路径用于与其它纹理进行比较
};

class Mesh {
public:
	/* 网格数据 */
	vector vertices;
	vector indices;
	vector textures;
	unsigned int VAO;

	/*  函数  */
	// 构造函数
	Mesh(vector vertices, vector indices, vector textures)
	{
		this->vertices = vertices;
		this->indices = indices;
		this->textures = textures;

		setupMesh();
	}

	// 渲染mesh
	void Draw(Shader shader)
	{
		// 绑定适当的纹理
		unsigned int diffuseNr = 1;
		unsigned int specularNr = 1;
		unsigned int normalNr = 1;
		unsigned int heightNr = 1;
		for (unsigned int i = 0; i < textures.size(); i++)
		{
			glActiveTexture(GL_TEXTURE0 + i); // 在绑定之前激活相应的纹理单元
			// 获取纹理序号（diffuse_textureN 中的 N）
			string number;
			string name = textures[i].type;
			if (name == "texture_diffuse")
				number = std::to_string(diffuseNr++);
			else if (name == "texture_specular")
				number = std::to_string(specularNr++); // transfer unsigned int to stream
			else if (name == "texture_normal")
				number = std::to_string(normalNr++); // transfer unsigned int to stream
			else if (name == "texture_height")
				number = std::to_string(heightNr++); // transfer unsigned int to stream

			// 设置贴图
			shader.setInt(((name + number).c_str()), i);
			// 绑定纹理
			glBindTexture(GL_TEXTURE_2D, textures[i].id);
		}

		// draw mesh
		glBindVertexArray(VAO);
		glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, 0);
		glBindVertexArray(0);

		// 将配置文件设置为默认
		glActiveTexture(GL_TEXTURE0);
	}

private:
	/*  渲染数据  */
	unsigned int VBO, EBO;

	/*  函数   */
	// 初始化缓冲
	void setupMesh()
	{
		// create buffers/arrays
		glGenVertexArrays(1, &VAO);
		glGenBuffers(1, &VBO);
		glGenBuffers(1, &EBO);

		glBindVertexArray(VAO);
		// load data into vertex buffers
		glBindBuffer(GL_ARRAY_BUFFER, VBO);

		glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(Vertex), &vertices[0], GL_STATIC_DRAW);

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
		glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned int), &indices[0], GL_STATIC_DRAW);

		// vertex Positions
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0);
		// vertex normals
		glEnableVertexAttribArray(1);
		glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Normal));
		// vertex texture coords
		glEnableVertexAttribArray(2);
		glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, TexCoords));
		// vertex tangent
		glEnableVertexAttribArray(3);
		glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Tangent));
		// vertex bitangent
		glEnableVertexAttribArray(4);
		glVertexAttribPointer(4, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Bitangent));

		glBindVertexArray(0);
	}
};
#endif

Model

#ifndef MODEL_H
#define MODEL_H

#include 
#include 	

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

#include 
#include 
#include 

#include "Shader.h"
#include "mesh.h"

#include 
#include 
#include 
#include 
#include 

此时我们已经写好了mesh.h和model.h，接下在主函数：

#include 
#include 
#include 
#include 
#include 
#include "Shader.h"
#include "camera.h"
#include "model.h"
#include 

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);

const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = SCR_WIDTH / 2.0f;
float lastY = SCR_HEIGHT / 2.0f;
bool firstMouse = true;

float deltaTime = 0.0f;
float lastFrame = 0.0f;

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, "mesh_load", NULL, NULL);
	if (window == NULL)
	{
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
}

	glfwMakeContextCurrent(window);

	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}

	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);

	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	
	glEnable(GL_DEPTH_TEST);

	// build and compile shaders
	// -------------------------
	Shader ourShader("shader/mesh_vertexshader.vs", "shader/mesh_fragmentshader.vs");


	Model ourModel("nanosuit/nanosuit.obj");


	while (!glfwWindowShouldClose(window))
	{
		// per-frame time logic
		// --------------------
		float currentFrame = glfwGetTime();
		deltaTime = currentFrame - lastFrame;
		lastFrame = currentFrame;

		// input
		// -----
		processInput(window);

		// render
		// ------
		glClearColor(0.05f, 0.05f, 0.05f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		// don't forget to enable shader before setting uniforms
		ourShader.use();
		ourShader.setVec3("viewPos", camera.Position);
		ourShader.setFloat("material.shininess", 32.0f);

		// directional light
		ourShader.setVec3("dirLight.direction", -0.2f, -1.0f, -0.3f);
		ourShader.setVec3("dirLight.ambient", 0.05f, 0.05f, 0.05f);
		ourShader.setVec3("dirLight.diffuse", 0.4f, 0.4f, 0.4f);
		ourShader.setVec3("dirLight.specular", 0.5f, 0.5f, 0.5f);

		// spotLight
		ourShader.setVec3("spotLight.position", camera.Position);
		ourShader.setVec3("spotLight.direction", camera.Front);
		ourShader.setVec3("spotLight.ambient", 0.0f, 0.0f, 0.0f);
		ourShader.setVec3("spotLight.diffuse", 1.0f, 1.0f, 1.0f);
		ourShader.setVec3("spotLight.specular", 1.0f, 1.0f, 1.0f);
		ourShader.setFloat("spotLight.constant", 1.0f);
		ourShader.setFloat("spotLight.linear", 0.09);
		ourShader.setFloat("spotLight.quadratic", 0.032);
		ourShader.setFloat("spotLight.cutOff", glm::cos(glm::radians(12.5f)));
		ourShader.setFloat("spotLight.outerCutOff", glm::cos(glm::radians(15.0f)));

		// view/projection transformations
		glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
		glm::mat4 view = camera.GetViewMatrix();
		ourShader.setMat4("projection", projection);
		ourShader.setMat4("view", view);

		// render the loaded model
		glm::mat4 model;
		model = glm::translate(model, glm::vec3(0.0f, -1.75f, 0.0f)); // translate it down so it's at the center of the scene
		model = glm::scale(model, glm::vec3(0.2f, 0.2f, 0.2f));	// it's a bit too big for our scene, so scale it down
		ourShader.setMat4("model", model);

		ourModel.Draw(ourShader);



		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glfwTerminate();
	return 0;
}

//回调函数
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
	//glViewport函数前两个参数控制窗口左下角的位置。第三个和第四个参数控制渲染窗口的宽度和高度（像素）
	glViewport(0, 0, width, height);
}

void processInput(GLFWwindow* window)
{
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);

	if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
		camera.ProcessKeyboard(FORWARD, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
		camera.ProcessKeyboard(BACKWARD, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
		camera.ProcessKeyboard(LEFT, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
		camera.ProcessKeyboard(RIGHT, deltaTime);

}

void mouse_callback(GLFWwindow*window, double xpos, double ypos)
{
	if (firstMouse)
	{
		lastX = xpos;
		lastY = ypos;
		firstMouse = false;
	}

	float xoffset = xpos - lastX;
	float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top

	lastX = xpos;
	lastY = ypos;

	camera.ProcessMouseMovement(xoffset, yoffset);
}

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
	camera.ProcessMouseScroll(yoffset);
}

unsigned int loadTexture(char const * path)
{
	unsigned int textureID;
	glGenTextures(1, &textureID);

	int width, height, nrComponents;
	unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
	if (data)
	{
		GLenum format;
		if (nrComponents == 1)
			format = GL_RED;
		else if (nrComponents == 3)
			format = GL_RGB;
		else if (nrComponents == 4)
			format = GL_RGBA;

		glBindTexture(GL_TEXTURE_2D, textureID);
		glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
		glGenerateMipmap(GL_TEXTURE_2D);

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

		stbi_image_free(data);
	}
	else
	{
		std::cout << "Texture failed to load at path: " << path << std::endl;
		stbi_image_free(data);
	}

	return textureID;
}

我们在场景中添加了平行光和手电筒

vertexshader:

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoords;

out vec2 TexCoords;
out vec3 FragPos;
out vec3 Normal;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
    FragPos = vec3(model * vec4(aPos, 1.0));
    Normal = mat3(transpose(inverse(model))) * aNormal;  
    TexCoords = aTexCoords;
    gl_Position = projection * view * vec4(FragPos, 1.0);
}

fragmentshader:

#version 330 core
out vec4 FragColor;

in vec3 FragPos;  
in vec3 Normal;  
in vec2 TexCoords;

struct Material {
    sampler2D texture_diffuse1;
    sampler2D texture_specular1;
    float shininess;
}; 
uniform Material material;

struct DirLight{
    vec3 direction;

    vec3 ambient;
    vec3 diffuse;
    vec3 specular;
};
uniform DirLight dirLight;

struct SpotLight {
    vec3 position;
    vec3 direction;
    float cutOff;
    float outerCutOff;
  
    float constant;
    float linear;
    float quadratic;
  
    vec3 ambient;
    vec3 diffuse;
    vec3 specular;       
};
uniform SpotLight spotLight;

uniform vec3 viewPos;

vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir);
vec3 CalcSpotLight(SpotLight light, vec3 normal, vec3 fragPos, vec3 viewDir);

void main()
{
    // 属性
    vec3 normal = normalize(Normal);
    vec3 viewDir = normalize(viewPos - FragPos);

    // 第一阶段：定向光照
    vec3 result = CalcDirLight(dirLight, normal, viewDir);
 
    // 第三阶段：聚光
    result += CalcSpotLight(spotLight, normal, FragPos, viewDir);    

    FragColor = vec4(result, 1.0);
}

vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir)
{
    vec3 lightDir = normalize(-light.direction);
    // 漫反射着色
    float diff = max(dot(normal, lightDir), 0.0);
    // 镜面光着色
    vec3 reflectDir = reflect(-lightDir, normal);
    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
    // 合并结果
    vec3 ambient  = light.ambient  * vec3(texture(material.texture_diffuse1, TexCoords));
    vec3 diffuse  = light.diffuse  * diff * vec3(texture(material.texture_diffuse1, TexCoords));
    vec3 specular = light.specular * spec * vec3(texture(material.texture_specular1, TexCoords));
    return (ambient + diffuse + specular);
}

vec3 CalcSpotLight(SpotLight light, vec3 normal, vec3 fragPos, vec3 viewDir)
{
    vec3 lightDir = normalize(light.position - fragPos);

    //diffuse
    float diff = max(dot(normal, lightDir), 0.0);

    //specular 
    vec3 reflectDir = reflect(-lightDir, normal);
    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
    
    // spotlight (soft edges)
    float theta = dot(lightDir, normalize(-light.direction)); 
    float epsilon = (light.cutOff - light.outerCutOff);
    float intensity = clamp((theta - light.outerCutOff) / epsilon, 0.0, 1.0);

    vec3 ambient = light.ambient * vec3(texture(material.texture_diffuse1, TexCoords));
    vec3 diffuse = light.diffuse * diff * vec3(texture(material.texture_diffuse1, TexCoords));
    vec3 specular = light.specular * spec * vec3(texture(material.texture_specular1, TexCoords));
    
    float distance = length(light.position - fragPos);
    float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance)); 
    
    ambient *= attenuation * intensity;
    diffuse *= attenuation * intensity;
    specular *= attenuation * intensity;
    return (ambient + diffuse + specular);
}

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这章模型加载，我并没有写很多的东西，很多我也没有看很懂，也不是很想深入了解下，就差不多知道了流程，copy的源码，能够运行出来结果，再自己加上灯光，实现最后的效果。