C++读入obj格式模型文件

#ifndef  _LOADOBJ_H_
#define  _LOADOBJ_H_

#include 
#include 
#include 
#include 
#include 

using namespace std;

#define dot(u,v)   ((u).x * (v).x + (u).y * (v).y + (u).z*(v).z)  
#define norm2(v)   dot(v,v)        // norm2 = squared length of vector  
#define norm(v)    sqrt(norm2(v))  // norm = length of vector  
#define d(u,v)     norm(u-v)       // distance = norm of difference  

// Obj loader
struct TriangleFace 
{
	int v[3]; // vertex indices
};

class float3
{
public:	
	float x;
	float y;
	float z;
public:	
	float3(){x=0;y=0;z=0;}
	float3(float mx,float my,float mz){x=mx;y=my;z=mz;}
	~float3(){}

	float3 operator+(float3);
	float3 operator-(float3);
	float3 operator/(float);

	friend float3 operator*(float m,float3 f3)
	{
		return float3(f3.x*m,f3.y*m,f3.z*m);
	}
	friend float3 operator*(float3 f3,float m)
	{
		return float3(f3.x*m,f3.y*m,f3.z*m);
	}

	float3 operator=(float3);

	float3& operator += (float3);
	
};

float3 float3::operator +(float3 m)
{
	float3 result;
	result.x = x+m.x;
	result.y = y+m.y;
	result.z = z+m.z;
	return result;
}

float3 float3::operator - (float3 m)
{
	float3 result;
	result.x = x-m.x;
	result.y = y-m.y;
	result.z = z-m.z;
	return result;
}

float3 float3::operator /(float m)
{
	if(m==0){
		printf("error /");
		return float3(x,y,z);
	}
	else
		return float3(x/m,y/m,z/m);
}

float3 float3::operator =(float3 f3)
{
	x = f3.x;
	y = f3.y;
	z = f3.z;
	return float3(x,y,z);
}

struct TriangleMesh
{
	vector verts;
	vector faces;
	//模型的包围盒
	float3 bounding_box[2];
	//模型的包围球参数
	float3 bounding_sphere_c;
	float bounding_sphere_r;
};

TriangleMesh mesh;

int total_number_of_triangles = 0;

// Scene bounding box 
float3 scene_aabbox_min;
float3 scene_aabbox_max;

void loadObj(const std::string filename, TriangleMesh &mesh);

void loadObj( const std::string filename, TriangleMesh &mesh )
{
	std::ifstream in(filename.c_str());

	if(!in.good())
	{
		cout  << "ERROR: loading obj:(" << filename << ") file is not good" << "\n";
		exit(0);
	}

	char buffer[256], str[255];
	float f1,f2,f3;
	
	while(!in.getline(buffer,255).eof())
	{
		buffer[255]='\0';

		sscanf_s(buffer,"%s",str,255);

		// reading a vertex
		if (buffer[0]=='v' && (buffer[1]==' '  || buffer[1]==32) )
		{
			if ( sscanf(buffer,"v %f %f %f",&f1,&f2,&f3)==3)
			{
				mesh.verts.push_back(float3(f1,f2,f3));
			}
			else
			{
				cout << "ERROR: vertex not in wanted format in OBJLoader" << "\n";
				exit(-1);
			}
		}
		// reading FaceMtls 
		else if (buffer[0]=='f' && (buffer[1]==' ' || buffer[1]==32) )
		{
			TriangleFace f;
			int nt = sscanf(buffer,"f %d %d %d",&f.v[0],&f.v[1],&f.v[2]);
			if( nt!=3 )
			{
				cout << "ERROR: I don't know the format of that FaceMtl" << "\n";
				exit(-1);
			}

			mesh.faces.push_back(f);
		}
	}
	
	float xmin,ymin,zmin,xmax,ymax,zmax;
	int Pxmin,Pxmax,Pymin,Pymax,Pzmin,Pzmax;
	
	//calculate the bounding sphere
	xmin = xmax = mesh.verts[0].x;
	ymin = ymax = mesh.verts[0].y;
	zmin = zmax = mesh.verts[0].z;
	Pxmin = Pxmax = Pymin = Pymax = Pzmin = Pzmax = 0;

	//calculate the bounding box
	mesh.bounding_box[0] = float3(mesh.verts[0].x,mesh.verts[0].y,mesh.verts[0].z);
	mesh.bounding_box[1] = float3(mesh.verts[0].x,mesh.verts[0].y,mesh.verts[0].z);

	for(unsigned int i = 1; i < mesh.verts.size(); i++)
	{
		//update min value
		mesh.bounding_box[0].x = min(mesh.verts[i].x,mesh.bounding_box[0].x);
		mesh.bounding_box[0].y = min(mesh.verts[i].y,mesh.bounding_box[0].y);
		mesh.bounding_box[0].z = min(mesh.verts[i].z,mesh.bounding_box[0].z);

		//update max value
		mesh.bounding_box[1].x = max(mesh.verts[i].x,mesh.bounding_box[1].x);
		mesh.bounding_box[1].y = max(mesh.verts[i].y,mesh.bounding_box[1].y);
		mesh.bounding_box[1].z = max(mesh.verts[i].z,mesh.bounding_box[1].z);

		//update the  x min and max
		if (mesh.verts[i].x < xmin){
			xmin = mesh.verts[i].x;
			Pxmin = i;
		}
		else if(mesh.verts[i].x > xmax){
			xmax = mesh.verts[i].x;
			Pxmax = i;
		}
		//update the y min and max
		if (mesh.verts[i].y < ymin){
			ymin = mesh.verts[i].y;
			Pymin = i;
		}
		else if(mesh.verts[i].y > ymax){
			ymax = mesh.verts[i].y;
			Pymax = i;
		}
		//update the z min and max
		if(mesh.verts[i].z < zmin){
			zmin = mesh.verts[i].z;
			Pzmin = i;
		}
		else if(mesh.verts[i].z > zmax){
			zmax = mesh.verts[i].z;
			Pzmax = i;
		}
	}
	
	//calculate the bounding sphere
	float3 dVx = mesh.verts[Pxmax] - mesh.verts[Pxmin];
	float3 dVy = mesh.verts[Pymax] - mesh.verts[Pymin];
	float3 dVz = mesh.verts[Pzmax] - mesh.verts[Pzmin];
	float dx2 = norm2(dVx);
	float dy2 = norm2(dVy);
	float dz2 = norm2(dVz);

	float3 center;
	float  radius2;
	float  radius;

	if (dx2 >= dy2 && dx2>=dz2) {					// x direction is largest extent  
		center = mesh.verts[Pxmin] + (dVx / 2.0);	// Center = midpoint of extremes  
		radius2 = norm2(mesh.verts[Pxmax] - center);// radius squared  
	}  
	else if (dy2 >= dx2  && dy2>=dz2){				// y direction is largest extent  
		center = mesh.verts[Pymin] + (dVy / 2.0);	// Center = midpoint of extremes  
		radius2 = norm2(mesh.verts[Pymax] - center);// radius squared  
	} 
	else{
		center = mesh.verts[Pzmin] + (dVz / 2.0);	// Center = midpoint of extremes  
		radius2 = norm2(mesh.verts[Pzmax] - center);// radius squared  	
	}

	radius = sqrt(radius2);  

	// now check that all points V[i] are in the ball  
	// and if not, expand the ball just enough to include them  
	float3 dV;
	float dist2,dist;
	for (unsigned int i=0;i

用法：

#include "LoadObj.h"

void main()
{
	std::string filename = "E:\\codeLab\\cube.obj";
	
	TriangleMesh mesh;

	loadObj(filename, mesh);
}

注意：请使用英文目录。