前言  

      前面的文章中有讲过assimp加载obj三维文档格式，如果想要加入纹理还得配合对应的mtl格式和png格式才能加入纹理，今天来说下使用assimp加载fbx格式的三维模型。

先看下运行效果

使用fbx模型

1.  assimp库下载以及配置

2. 在openGL中使用assimp库

3. 加载fbx三维模型代码

   （1）AssimpLoadFbxModel.cpp

// AssimpLoadFbxModel.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//

//#include "stdafx.h"
#include "glew/glew.h"
#include "GLFW/glfw3.h"

#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"
#include "glm/gtc/type_ptr.hpp"

#include "filesystem.h"
#include "shader.h"
#include "camera.h"
#include "model.h"

#include <iostream>

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);

// settings
const unsigned int SCR_WIDTH = 1920;
const unsigned int SCR_HEIGHT = 1080;

// camera
Camera camera(glm::vec3(0.0f, -8.0f, 30.0f));
//Camera camera(glm::vec3(0.0f, 0.0f, 10.0f));
float lastX = SCR_WIDTH / 2.0f;
float lastY = SCR_HEIGHT / 2.0f;
bool firstMouse = true;

// timing
float deltaTime = 0.0f;
float lastFrame = 0.0f;

int main()
{
	// glfw: initialize and configure
	// ------------------------------
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef __APPLE__
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
#endif

														 // glfw window creation
														 // --------------------
	GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
	if (window == NULL)
	{
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);
	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);

	// tell GLFW to capture our mouse
	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	// glad: load all OpenGL function pointers
	// ---------------------------------------
	/*if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}*/

	GLenum glewErr = glewInit();   //ctrl+k, ctrl+f代码对齐
	if (GLEW_OK != glewErr)
	{
		cout << "GLEW initialization failed!" << endl;
		return -1;
	}


	// configure global opengl state
	// -----------------------------
	glEnable(GL_DEPTH_TEST);

	// build and compile shaders
	// -------------------------
	Shader ourShader("1.model_loading.vs", "1.model_loading.fs");

	// load models
	// -----------
	//Model ourModel(FileSystem::getPath("resources/objects/nanosuit/nanosuit.obj"));   //tank01.obj
	Model ourModel(FileSystem::getPath("resources/changChengCar/girl/export/skin.fbx"));   //tank01.obj
	//Model ourModel(FileSystem::getPath("resources/objects/nanosuit/dui_xing_zhu_ti.FBX"));


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

	// render loop
	// -----------
	while (!glfwWindowShouldClose(window))
	{
		// per-frame time logic
		// --------------------
		float currentFrame = glfwGetTime();
		deltaTime = (currentFrame - lastFrame) * 10;
		lastFrame = currentFrame;

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

		// render
		// ------
		glClearColor((GLfloat)148.0f / (GLfloat)255.0f, (GLfloat)0.0f / (GLfloat)255.0f, (GLfloat)211.0f / (GLfloat)255.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		// don't forget to enable shader before setting uniforms
		ourShader.use();

		// view/projection transformations
		glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.01f, 100000.0f);
		glm::mat4 view = camera.GetViewMatrix();
		ourShader.setMat4("projection", projection);
		ourShader.setMat4("view", view);

		// render the loaded model
		glm::mat4 model = glm::mat4(1.0f);
		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);


		// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
		// -------------------------------------------------------------------------------
		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	// glfw: terminate, clearing all previously allocated GLFW resources.
	// ------------------------------------------------------------------
	glfwTerminate();
	return 0;
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
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);
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
	// make sure the viewport matches the new window dimensions; note that width and 
	// height will be significantly larger than specified on retina displays.
	glViewport(0, 0, width, height);
}

// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
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);
}

// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
	camera.ProcessMouseScroll(yoffset);
}

（2）shader文件顶点着色器：model_loading.vs

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

out vec2 TexCoords;

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

void main()
{
    TexCoords = aTexCoords;    
    gl_Position = projection * view * model * vec4(aPos, 1.0);
}

（3）shader文件片元着色器：1.model_loading.fs

#version 330 core
out vec4 FragColor;

in vec2 TexCoords;

uniform sampler2D texture_diffuse1;

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

源码下载：