OpenGL之——assimp加载模型

主要代码：

main.cpp

// Std. Includes
#include 
#include 
// GLEW
#define GLEW_STATIC
#include 

// GLFW
#include 

// GL includes
#include "Shader.h"
#include "Camera.h"
#include "Mesh.h"
#include "Model.h"

// GLM Mathemtics
#include 
#include 
#include 

#include 
// Other Libs
#include 

#pragma comment(lib,"glew32s.lib")
#pragma comment(lib,"glfw3.lib")
#pragma comment(lib,"SOIL.lib")
// Properties
GLuint screenWidth = 800, screenHeight = 600;

// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void Do_Movement();

// Camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
bool keys[1024];
GLfloat lastX = 400, lastY = 300;
bool firstMouse = true;

GLfloat deltaTime = 0.0f;
GLfloat lastFrame = 0.0f;

// The MAIN function, from here we start our application and run our Game loop
int main()
{
	// Init GLFW
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

	GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
	glfwMakeContextCurrent(window);

	// Set the required callback functions
	glfwSetKeyCallback(window, key_callback);
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);

	// Options
	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	// Initialize GLEW to setup the OpenGL Function pointers
	glewExperimental = GL_TRUE;
	glewInit();

	// Define the viewport dimensions
	glViewport(0, 0, screenWidth, screenHeight);

	// Setup some OpenGL options
	glEnable(GL_DEPTH_TEST);

	// Setup and compile our shaders
	Shader shader("load_model.vs", "load_model.frag");

	// Load models
	Model ourModel((GLchar*)("nanosuit/nanosuit.obj"));

	// Draw in wireframe
	//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

	// Game loop
	while (!glfwWindowShouldClose(window))
	{
		// Set frame time
		GLfloat currentFrame = glfwGetTime();
		deltaTime = currentFrame - lastFrame;
		lastFrame = currentFrame;

		// Check and call events
		glfwPollEvents();
		Do_Movement();

		// Clear the colorbuffer
		glClearColor(0.05f, 0.05f, 0.05f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		shader.Use();   // <-- Don't forget this one!
		// Transformation matrices
		glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth / (float)screenHeight, 0.1f, 100.0f);
		glm::mat4 view = camera.GetViewMatrix();
		glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
		glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));

		// Draw the loaded model
		glm::mat4 model;
		model = glm::translate(model, glm::vec3(0.0f, -1.75f, 0.0f)); // Translate it down a bit 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
		glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
		ourModel.Draw(shader);

		// Swap the buffers
		glfwSwapBuffers(window);
	}

	glfwTerminate();
	return 0;
}

#pragma region "User input"

// Moves/alters the camera positions based on user input
void Do_Movement()
{
	// Camera controls
	if (keys[GLFW_KEY_W])
		camera.ProcessKeyboard(FORWARD, deltaTime);
	if (keys[GLFW_KEY_S])
		camera.ProcessKeyboard(BACKWARD, deltaTime);
	if (keys[GLFW_KEY_A])
		camera.ProcessKeyboard(LEFT, deltaTime);
	if (keys[GLFW_KEY_D])
		camera.ProcessKeyboard(RIGHT, deltaTime);
}

// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
		glfwSetWindowShouldClose(window, GL_TRUE);

	if (action == GLFW_PRESS)
		keys[key] = true;
	else if (action == GLFW_RELEASE)
		keys[key] = false;
}

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

	GLfloat xoffset = xpos - lastX;
	GLfloat yoffset = lastY - ypos;

	lastX = xpos;
	lastY = ypos;

	camera.ProcessMouseMovement(xoffset, yoffset);
}

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

#pragma endregion

Shader.h

#ifndef SHADER_H
#define SHADER_H

#include 
#include 
#include 
#include 

#include 

class Shader
{
public:
	GLuint Program;
	// Constructor generates the shader on the fly
	Shader(const GLchar* vertexPath, const GLchar* fragmentPath)
	{
		// 1. Retrieve the vertex/fragment source code from filePath
		std::string vertexCode;
		std::string fragmentCode;
		std::ifstream vShaderFile;
		std::ifstream fShaderFile;
		// ensures ifstream objects can throw exceptions:
		vShaderFile.exceptions(std::ifstream::badbit);
		fShaderFile.exceptions(std::ifstream::badbit);
		try
		{
			// Open files
			vShaderFile.open(vertexPath);
			fShaderFile.open(fragmentPath);
			std::stringstream vShaderStream, fShaderStream;
			// Read file's buffer contents into streams
			vShaderStream << vShaderFile.rdbuf();
			fShaderStream << fShaderFile.rdbuf();
			// close file handlers
			vShaderFile.close();
			fShaderFile.close();
			// Convert stream into string
			vertexCode = vShaderStream.str();
			fragmentCode = fShaderStream.str();
		}
		catch (std::ifstream::failure e)
		{
			std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
		}
		const GLchar* vShaderCode = vertexCode.c_str();
		const GLchar * fShaderCode = fragmentCode.c_str();
		// 2. Compile shaders
		GLuint vertex, fragment;
		GLint success;
		GLchar infoLog[512];
		// Vertex Shader
		vertex = glCreateShader(GL_VERTEX_SHADER);
		glShaderSource(vertex, 1, &vShaderCode, NULL);
		glCompileShader(vertex);
		// Print compile errors if any
		glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(vertex, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
		}
		// Fragment Shader
		fragment = glCreateShader(GL_FRAGMENT_SHADER);
		glShaderSource(fragment, 1, &fShaderCode, NULL);
		glCompileShader(fragment);
		// Print compile errors if any
		glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(fragment, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED1\n" << infoLog << std::endl;
		}
		// Shader Program
		this->Program = glCreateProgram();
		glAttachShader(this->Program, vertex);
		glAttachShader(this->Program, fragment);
		glLinkProgram(this->Program);
		// Print linking errors if any
		glGetProgramiv(this->Program, GL_LINK_STATUS, &success);
		if (!success)
		{
			glGetProgramInfoLog(this->Program, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
		}
		// Delete the shaders as they're linked into our program now and no longer necessery
		glDeleteShader(vertex);
		glDeleteShader(fragment);

	}
	// Uses the current shader
	void Use()
	{
		glUseProgram(this->Program);
	}
};

#endif

Camera.h

#pragma once

// Std. Includes
#include 

// GL Includes
#include 
#include 
#include 



// Defines several possible options for camera movement. Used as abstraction to stay away from window-system specific input methods
enum Camera_Movement {
	FORWARD,
	BACKWARD,
	LEFT,
	RIGHT
};

// Default camera values
const GLfloat YAW = -90.0f;
const GLfloat PITCH = 0.0f;
const GLfloat SPEED = 3.0f;
const GLfloat SENSITIVTY = 0.25f;
const GLfloat ZOOM = 45.0f;


// An abstract camera class that processes input and calculates the corresponding Eular Angles, Vectors and Matrices for use in OpenGL
class Camera
{
public:
	// Camera Attributes
	glm::vec3 Position;
	glm::vec3 Front;
	glm::vec3 Up;
	glm::vec3 Right;
	glm::vec3 WorldUp;
	// Eular Angles
	GLfloat Yaw;
	GLfloat Pitch;
	// Camera options
	GLfloat MovementSpeed;
	GLfloat MouseSensitivity;
	GLfloat Zoom;

	// Constructor with vectors
	Camera(glm::vec3 position = glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f), GLfloat yaw = YAW, GLfloat pitch = PITCH) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVTY), Zoom(ZOOM)
	{
		this->Position = position;
		this->WorldUp = up;
		this->Yaw = yaw;
		this->Pitch = pitch;
		this->updateCameraVectors();
	}
	// Constructor with scalar values
	Camera(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat upY, GLfloat upZ, GLfloat yaw, GLfloat pitch) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVTY), Zoom(ZOOM)
	{
		this->Position = glm::vec3(posX, posY, posZ);
		this->WorldUp = glm::vec3(upX, upY, upZ);
		this->Yaw = yaw;
		this->Pitch = pitch;
		this->updateCameraVectors();
	}

	// Returns the view matrix calculated using Eular Angles and the LookAt Matrix
	glm::mat4 GetViewMatrix()
	{
		return glm::lookAt(this->Position, this->Position + this->Front, this->Up);
	}

	// Processes input received from any keyboard-like input system. Accepts input parameter in the form of camera defined ENUM (to abstract it from windowing systems)
	void ProcessKeyboard(Camera_Movement direction, GLfloat deltaTime)
	{
		GLfloat velocity = this->MovementSpeed * deltaTime;
		if (direction == FORWARD)
			this->Position += this->Front * velocity;
		if (direction == BACKWARD)
			this->Position -= this->Front * velocity;
		if (direction == LEFT)
			this->Position -= this->Right * velocity;
		if (direction == RIGHT)
			this->Position += this->Right * velocity;
	}

	// Processes input received from a mouse input system. Expects the offset value in both the x and y direction.
	void ProcessMouseMovement(GLfloat xoffset, GLfloat yoffset, GLboolean constrainPitch = true)
	{
		xoffset *= this->MouseSensitivity;
		yoffset *= this->MouseSensitivity;

		this->Yaw += xoffset;
		this->Pitch += yoffset;

		// Make sure that when pitch is out of bounds, screen doesn't get flipped
		if (constrainPitch)
		{
			if (this->Pitch > 89.0f)
				this->Pitch = 89.0f;
			if (this->Pitch < -89.0f)
				this->Pitch = -89.0f;
		}

		// Update Front, Right and Up Vectors using the updated Eular angles
		this->updateCameraVectors();
	}

	// Processes input received from a mouse scroll-wheel event. Only requires input on the vertical wheel-axis
	void ProcessMouseScroll(GLfloat yoffset)
	{
		if (this->Zoom >= 1.0f && this->Zoom <= 45.0f)
			this->Zoom -= yoffset;
		if (this->Zoom <= 1.0f)
			this->Zoom = 1.0f;
		if (this->Zoom >= 45.0f)
			this->Zoom = 45.0f;
	}

private:
	// Calculates the front vector from the Camera's (updated) Eular Angles
	void updateCameraVectors()
	{
		// Calculate the new Front vector
		glm::vec3 front;
		front.x = cos(glm::radians(this->Yaw)) * cos(glm::radians(this->Pitch));
		front.y = sin(glm::radians(this->Pitch));
		front.z = sin(glm::radians(this->Yaw)) * cos(glm::radians(this->Pitch));
		this->Front = glm::normalize(front);
		// Also re-calculate the Right and Up vector
		this->Right = glm::normalize(glm::cross(this->Front, this->WorldUp));  // Normalize the vectors, because their length gets closer to 0 the more you look up or down which results in slower movement.
		this->Up = glm::normalize(glm::cross(this->Right, this->Front));
	}
};

Model.h

#pragma once
// Std. Includes
#include 
#include 
#include 
#include 
#include 

Mesh.h

#pragma once
// Std. Includes
#include "Shader.h"
#include 
#include 
#include 
#include 
#include 
using namespace std;
// GL Includes
#include  // Contains all the necessery OpenGL includes
#include 
#include 

struct Vertex {
	// Position
	glm::vec3 Position;
	// Normal
	glm::vec3 Normal;
	// TexCoords
	glm::vec2 TexCoords;
};

struct Texture {
	GLuint id;
	string type;
	string path;
};

class Mesh {
public:
	/*  Mesh Data  */
	vector vertices;
	vector indices;
	vector textures;

	/*  Functions  */
	// Constructor
	Mesh(vector vertices, vector indices, vector textures)
	{
		this->vertices = vertices;
		this->indices = indices;
		this->textures = textures;

		// Now that we have all the required data, set the vertex buffers and its attribute pointers.
		this->setupMesh();
	}

	// Render the mesh
	void Draw(Shader shader)
	{
		// Bind appropriate textures
		GLuint diffuseNr = 1;
		GLuint specularNr = 1;
		for (GLuint i = 0; i < this->textures.size(); i++)
		{
			glActiveTexture(GL_TEXTURE0 + i); // Active proper texture unit before binding
			// Retrieve texture number (the N in diffuse_textureN)
			stringstream ss;
			string number;
			string name = this->textures[i].type;
			if (name == "texture_diffuse")
				ss << diffuseNr++; // Transfer GLuint to stream
			else if (name == "texture_specular")
				ss << specularNr++; // Transfer GLuint to stream
			number = ss.str();
			// Now set the sampler to the correct texture unit
			glUniform1i(glGetUniformLocation(shader.Program, (name + number).c_str()), i);
			// And finally bind the texture
			glBindTexture(GL_TEXTURE_2D, this->textures[i].id);
		}

		// Also set each mesh's shininess property to a default value (if you want you could extend this to another mesh property and possibly change this value)
		glUniform1f(glGetUniformLocation(shader.Program, "material.shininess"), 16.0f);

		// Draw mesh
		glBindVertexArray(this->VAO);
		glDrawElements(GL_TRIANGLES, this->indices.size(), GL_UNSIGNED_INT, 0);
		glBindVertexArray(0);

		// Always good practice to set everything back to defaults once configured.
		for (GLuint i = 0; i < this->textures.size(); i++)
		{
			glActiveTexture(GL_TEXTURE0 + i);
			glBindTexture(GL_TEXTURE_2D, 0);
		}
	}

private:
	/*  Render data  */
	GLuint VAO, VBO, EBO;

	/*  Functions    */
	// Initializes all the buffer objects/arrays
	void setupMesh()
	{
		// Create buffers/arrays
		glGenVertexArrays(1, &this->VAO);
		glGenBuffers(1, &this->VBO);
		glGenBuffers(1, &this->EBO);

		glBindVertexArray(this->VAO);
		// Load data into vertex buffers
		glBindBuffer(GL_ARRAY_BUFFER, this->VBO);
		// A great thing about structs is that their memory layout is sequential for all its items.
		// The effect is that we can simply pass a pointer to the struct and it translates perfectly to a glm::vec3/2 array which
		// again translates to 3/2 floats which translates to a byte array.
		glBufferData(GL_ARRAY_BUFFER, this->vertices.size() * sizeof(Vertex), &this->vertices[0], GL_STATIC_DRAW);

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, this->EBO);
		glBufferData(GL_ELEMENT_ARRAY_BUFFER, this->indices.size() * sizeof(GLuint), &this->indices[0], GL_STATIC_DRAW);

		// Set the vertex attribute pointers
		// Vertex Positions
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)0);
		// Vertex Normals
		glEnableVertexAttribArray(1);
		glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, Normal));
		// Vertex Texture Coords
		glEnableVertexAttribArray(2);
		glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, TexCoords));

		glBindVertexArray(0);
	}
};

load_model.vs

#version 330 core
layout(location = 0) in vec3 position;
layout(location = 1) in vec3 normal;
layout(location = 2) in vec2 texCoords;

out vec2 TexCoords;

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

void main()
{
	gl_Position = projection * view * model * vec4(position, 1.0f);
	TexCoords = texCoords;
}

load_model.frag

#version 330 core

in vec2 TexCoords;

out vec4 color;

uniform sampler2D texture_diffuse1;

void main()
{
	color = vec4(texture(texture_diffuse1, TexCoords));
}

效果：

 obj文件已上传至我的资源，需要的可以下载