我现在使用 glut 之类的任务，我从 3ds max 的 obj 文件中导入所有顶点我现在使用的是立方体，但它呈现出所有奇怪的东西，很难解释，但它没有呈现为立方体我看起来更像一个三角形:
#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include "glut.h"
#include <istream>
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>
using namespace std;
// structs for arrays
struct point3D
{
float x;
float y;
float z;
};
//camera structs
struct camera
{
point3D pos;
point3D lookAt;
point3D up;
};
//global variables
camera cam = {0, 0, 5, 0, 0, 0, 0, 1, 0};
int mousex = 0;
int mousey = 0;
bool mouseDown=false;
point3D v[8] = {};
point3D vn[6] = {};
point3D vt[4] = {};
point3D f[12][3] = {};
void init()
{
glClearColor(0.5, 0.7, 0.0, 1.0);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-1.0, 1.0, -1.0, 1.0, 1.0, 1000);
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT );
glMatrixMode(GL_MODELVIEW);
glLoadIdentity(); // reset the matrix
gluLookAt(cam.pos.x, cam.pos.y, cam.pos.z,
cam.lookAt.x, cam.lookAt.y, cam.lookAt.z,
cam.up.x, cam.up.y, cam.up.z); // sets camera position.
glColor3f(1.0, 0.0, 0.0);
glTranslatef(0.0f, 0.0f, -15.0f);
for(int i = 0; i < 8; i++)//reads coords for verts from global arrays.
{
glBegin(GL_TRIANGLES);
int one = f[i][0].x;
int two = f[i][1].x;
int three = f[i][2].x;
glVertex3fv(&(v[one].x));
glVertex3fv(&(v[two].x));
glVertex3fv(&(v[three].x));
glEnd();
}
glFlush();
}
void drawAxes() {
glBegin(GL_LINES);
glVertex3f(0, 0, 0);
glVertex3f(10, 0, 0);
glVertex3f(0, 0, 0);
glVertex3f(0, 10, 0);
glVertex3f(0, 0, 0);
glVertex3f(0, 0, 10);
glEnd();// draws a axis to show scene
}
void passiveMouseFunc(int x, int y )
{
if (mouseDown == true)
{
if (x > mousex)
cam.lookAt.x+= 0.5;
if (x < mousex)
cam.lookAt.x-= 0.5;
if (y > mousey)
cam.lookAt.y-= 0.5;
if (y < mousey)
cam.lookAt.y+= 0.5;
mousex = x;
mousey = y;
glutPostRedisplay();
}
else
{
if (x > mousex)
cam.lookAt.x+= 0.0;
if (x < mousex)
cam.lookAt.x-= 0.0;
if (y > mousey)
cam.lookAt.y-= 0.0;
if (y < mousey)
cam.lookAt.y+= 0.0;
mousex = x;
mousey = y;
glutPostRedisplay(); //redraws scene
}
}
void glutMouseFunc(int button, int state, int x, int y)
{
switch (button)
{
case GLUT_LEFT_BUTTON: //makes it so i have to click to move cam
mouseDown = true;
break;
case GLUT_RIGHT_BUTTON:
mouseDown = false;
break;
}
}
void specialKeyboard(int key, int x, int y) // methods used for moving cam
{
switch (key)
{
case GLUT_KEY_RIGHT:
cam.pos.x+=0.2;
break;
case GLUT_KEY_LEFT:
cam.pos.x-=0.2;
break;
case GLUT_KEY_UP:
cam.pos.y+=0.2;
break;
case GLUT_KEY_DOWN:
cam.pos.y-=0.2;
break;
case GLUT_KEY_PAGE_UP:
cam.pos.z+=0.2;
break;
case GLUT_KEY_PAGE_DOWN:
cam.pos.z-=0.2;
break;
}
glutPostRedisplay();
}
void ObjloaderSpaceship () // loads a cube from .obj file
{
int numVert = 0;
int numNormals= 0;
int numcoords = 0;
int numFaces = 0;
int ammount = 0;
string test;
ifstream inputFile;
inputFile.open("cube.obj");
if (!inputFile.good())
cout << "Problem with Input File";
else
{
while(!inputFile.eof())
{
inputFile >> test;
if (test == "v")
{
inputFile >> v[numVert].x;
inputFile >> v[numVert].y;
inputFile >> v[numVert].z;
numVert++;
}
else if(test == "vn")
{
inputFile >> vn[numNormals].x;
inputFile >> vn[numNormals].y;
inputFile >> vn[numNormals].z;
numNormals++;
}
else if(test == "vt")
{
inputFile >> vt[numcoords].x;
inputFile >> vt[numcoords].y;
inputFile >> vt[numcoords].z;
numcoords++;
}
else if(test == "f")
{
string temp;
for(int count = 0; count < 3; count++)
{
inputFile >> temp;
stringstream stream(temp);
f[numFaces][count].x -= 1;
getline(stream, temp, '/');
f[numFaces][count].x = atof(temp.c_str());
getline(stream, temp, '/');
f[numFaces][count].y = atof(temp.c_str());
getline(stream, temp, '/');
f[numFaces][count].z = atof(temp.c_str());
}
numFaces++;
}
}
}
}
//void normalKeyboard(unsigned char key, int x, int y) {
// switch (key)
// {
// case 'w' :
// cam.lookAt.y+=0.5;
// break;
// case 'a' :
// cam.lookAt.y-=0.5;
// break;
// case 's' :
// cam.lookAt.x-=0.5;
// break;
// case 'd' :
// cam.lookAt.x+=0.5;
// break;
// }
//
// glutPostRedisplay();
//}
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutCreateWindow("C++ Assignment");
drawAxes();
glutMouseFunc(glutMouseFunc);
glutPassiveMotionFunc(passiveMouseFunc);
ObjloaderSpaceship();
glutDisplayFunc(display);
glutSpecialFunc(specialKeyboard);
// glutKeyboardFunc(normalKeyboard);
init();
glutMainLoop();
}
这是 obj 文件。
# 3ds Max Wavefront OBJ Exporter v0.97b - (c)2007 guruware
# File Created: 23.04.2013 13:50:59
mtllib cube.mtl
#
# object Box001
#
v 2.2289 0.0000 -1.5936
v 2.2289 0.0000 -30.3830
v 31.1072 0.0000 -30.3830
v 31.1072 0.0000 -1.5936
v 2.2289 29.4346 -1.5936
v 31.1072 29.4346 -1.5936
v 31.1072 29.4346 -30.3830
v 2.2289 29.4346 -30.3830
# 8 vertices
vn 0.0000 -1.0000 -0.0000
vn 0.0000 1.0000 -0.0000
vn 0.0000 0.0000 1.0000
vn 1.0000 0.0000 -0.0000
vn 0.0000 0.0000 -1.0000
vn -1.0000 0.0000 -0.0000
# 6 vertex normals
vt 1.0000 0.0000 0.0000
vt 1.0000 1.0000 0.0000
vt 0.0000 1.0000 0.0000
vt 0.0000 0.0000 0.0000
# 4 texture coords
g Box001
usemtl wire_006135006
f 1/1/1 2/2/1 3/3/1
f 3/3/1 4/4/1 1/1/1
f 5/4/2 6/1/2 7/2/2
f 7/2/2 8/3/2 5/4/2
f 1/4/3 4/1/3 6/2/3
f 6/2/3 5/3/3 1/4/3
f 4/4/4 3/1/4 7/2/4
f 7/2/4 6/3/4 4/4/4
f 3/4/5 2/1/5 8/2/5
f 8/2/5 7/3/5 3/4/5
f 2/4/6 1/1/6 5/2/6
f 5/2/6 8/3/6 2/4/6
# 12 faces
最佳答案
这段代码很粗糙，并且有很多基于对输入数据的假设的陷阱。但这是你要解决的问题，而不是问题的一部分。
您可能错过的重要信息是 OBJ 格式指定任何具有基于 1 的索引。但在 C/C++ 中，索引是基于 0 的。您可以在读取例程或渲染例程中修复它。 (我会去阅读，因为这使您能够阅读其他格式而不更改呈现代码。)
所以在第 219 行，您将代码更改为:
else if(test == "f")
{
string temp;
for(int count = 0; count < 3; count++)
{
inputFile >> temp;
stringstream stream(temp);
getline(stream, temp, '/');
f[numFaces][count].x = atoi(temp.c_str()) - 1;
getline(stream, temp, '/');
f[numFaces][count].y = atoi(temp.c_str()) - 1;
getline(stream, temp, '/');
f[numFaces][count].z = atoi(temp.c_str()) - 1;
}
numFaces++;
}
您还肯定希望将您的面部格式更改为整数而不是 float 。我完全可以想象值(value)观会发生变化。
您还需要捕获以下情况:
- 只有一个顶点(1)
- 顶点和纹理线(1/1)
- 顶点和法线(1//1)
- 脸不是三角形(超过3个顶点)
关于c++ - OpenGL 渲染错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16170410/