问题
I writing small program in OpenGL, and I have problem ( textures are skew, and I dont know why, this model work in another obj viewer) What I have: http://img696.imageshack.us/i/obrazo.png/ What I want http://img88.imageshack.us/i/obraz2d.jpg/ Code of project (I use devil for images):
#pragma once
#include <windows.h>
#define GLUT_DISABLE_ATEXIT_HACK
#include <glut.h>
#include <GL/glu.h>
#include <GL/gl.h>
#include <GL/GLEXT.h>
#include <iostream>
#include <cmath>
#include <IL/il.h>
#include <vector>
#include <fstream>
#include <string>
#include <cstdlib>
#include <sstream>
#include <clocale>
class TextureManager
{
struct TextureInfo{
std::string name;
GLuint image;
};
private:
std::vector<TextureInfo> textures;
public:
TextureManager(void);
~TextureManager(void);
bool AddTexture(std::string name, std::string fileName);
int GetTexture(std::string name);
};
TextureManager::TextureManager(void)
{
ilInit();
}
TextureManager::~TextureManager(void)
{
}
bool TextureManager::AddTexture(std::string name, std::string fileName)
{
bool success;
ILuint texId;
GLuint image;
ilGenImages(1, &texId);
ilBindImage(texId);
success = ilLoadImage((WCHAR*)fileName.c_str());
if(success)
{
success = ilConvertImage(IL_RGB, IL_UNSIGNED_BYTE);
if(!success)
{
return false;
}
}
else
{
return false;
}
glGenTextures(1, &image);
glBindTexture(GL_TEXTURE_2D, image);
glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_NEAREST_MIPMAP_LINEAR);
gluBuild2DMipmaps( GL_TEXTURE_2D, 3, ilGetInteger(IL_IMAGE_WIDTH), ilGetInteger(IL_IMAGE_HEIGHT),GL_RGB, GL_UNSIGNED_BYTE, ilGetData());
ilDeleteImages(1, &texId);
TextureInfo ti;
ti.name = name;
ti.image = image;
textures.push_back(ti);
return true;
}
int TextureManager::GetTexture(std::string name)
{
int size = textures.size();
for(int i=0;i<size;i++)
{
if(textures.at(i).name.compare(name) == 0)
{
return textures.at(i).image;
}
}
return -1;
}
using namespace std;
TextureManager tm;
struct Point
{
double x,y,z;
};
struct Normal
{
double x,y,z;
};
struct Triangle
{
int a,b,c;
int at,bt,ct;
int an,bn,cn;
};
struct TexCord
{
float x,y;
};
vector<Point> points;
vector<Normal> normals;
vector<Triangle> triangles;
vector<TexCord> texcords;
int w,h;
double j = 0.0;
double k = 0.0;
int mode = 1;
bool showNormals = false;
void setCamera(double eyex,double eyey, double eyez, double centerx, double centery, double centerz)
{
gluLookAt(eyex,eyey,eyez,centerx,centery,centerz,0,1,0);
}
void DrawPoint(TexCord tc,Point p,Normal n)
{
glTexCoord2f(tc.x,tc.y);
glNormal3f(n.x,n.y,n.z);
glVertex3f(p.x,p.y,p.z);
}
void DrawNormal(Point p,Normal n)
{
glPushMatrix();
glTranslated(p.x,p.y,p.z);
glBegin(GL_LINES);
glVertex3f(0,0,0);
glVertex3f(n.x*2,n.y*2,n.z*2);
glEnd();
glPopMatrix();
}
void processNormalKeys(unsigned char key, int x, int y) {
if (key == 27)
exit(0);
if (key == 'q')
{
mode = 0;
}
if (key == 'w')
{
mode = 1;
}
if (key == 'a')
{
k -= 0.1;
}
if (key == 's')
{
k += 0.1;
}
if (key == 'z')
{
j -= 0.1;
}
if (key == 'x')
{
j += 0.1;
}
if (key == 'n')
{
if(showNormals == true)
{
showNormals = false;
}
else
{
showNormals = true;
}
}
glutPostRedisplay();
}
void renderScene(void) {
//j+=0.0005;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60, (GLfloat)w / (GLfloat)h, 1.0, 100.0);
setCamera(15*sin(j),15*cos(k),15*cos(j)*sin(k),0,0,0);
glMatrixMode(GL_MODELVIEW);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
//glEnable(GL_LIGHT0);
float ambient[]={ 1.0, 1.0, 1.0, 0.0};
float diffuse[]={1.0, 1.0, 1.0, 1.0};
float position[]={25.0,25.0, 25.0, 1.0};
glLightfv(GL_LIGHT0, GL_AMBIENT, diffuse);
glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
glLightfv(GL_LIGHT0, GL_POSITION, position);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, tm.GetTexture("tex"));
if(mode == 0 )
{
glBegin(GL_TRIANGLES);
}
else
{
glBegin(GL_LINES);
}
for(int i=0;i<triangles.size();i++)
{
//double r = rand()/(double)RAND_MAX;
//glColor3f(r,r,r);
DrawPoint(texcords[triangles[i].ct-1],points[triangles[i].c-1],normals[triangles[i].cn-1]);
DrawPoint(texcords[triangles[i].bt-1],points[triangles[i].b-1],normals[triangles[i].bn-1]);
DrawPoint(texcords[triangles[i].at-1],points[triangles[i].a-1],normals[triangles[i].an-1]);
}
glEnd();
glDisable(GL_TEXTURE_2D);
if(showNormals == true)
{
glDisable(GL_LIGHTING);
glDisable(GL_LIGHT0);
glColor3f(1,0.5f,0.25f);
for(int i = 0;i<points.size();i++)
{
DrawNormal(points[i],normals[i]);
}
}
glFlush();
glutSwapBuffers();
}
void reshape (int width, int height) {
w = width; h = height;
glViewport(0, 0, (GLsizei)width, (GLsizei)height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60, (GLfloat)width / (GLfloat)height, 1.0, 100.0);
glMatrixMode(GL_MODELVIEW);
}
void update(int value) {
j += 0.1f;
glutPostRedisplay(); //Tell GLUT that the scene has changed
//Tell GLUT to call update again in 25 milliseconds
// glutTimerFunc(100, update, 0);
}
int main(int argc, char **argv) {
vector<Normal> *nn = &normals;
vector<Point> *pp = &points;
vector<Triangle> *tt = &triangles;
vector<TexCord> *ttcc = &texcords;
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowPosition(100,100);
glutInitWindowSize(320,320);
glutCreateWindow("Model view");
glutKeyboardFunc(processNormalKeys);
glutDisplayFunc(renderScene);
//glutIdleFunc(renderScene);
glutReshapeFunc(reshape);
ifstream f;
string cmd;
f.open ("model.obj");
if (f.is_open())
{
while(!f.eof())
{
f>>cmd;
if(cmd=="v")
{
Point p;
f>>p.x;
f>>p.y;
f>>p.z;
points.push_back(p);
}
if(cmd=="vn")
{
Normal n;
f>>n.x;
f>>n.y;
f>>n.z;
normals.push_back(n);
}
if(cmd=="vt")
{
TexCord tc;
f>>tc.x;
f>>tc.y;
texcords.push_back(tc);
}
if(cmd=="f")
{
Triangle t;
string str;
string pointStr,normalStr,cordStr;
string delimeter("/");
int pos,pos2;
stringstream ss (stringstream::in | stringstream::out);
f>>str;
pos = str.find(delimeter);
pointStr = str.substr(0,pos);
cordStr = str.substr(pos+delimeter.length());
pos2 = cordStr.find(delimeter);
normalStr = cordStr.substr(pos2+delimeter.length());
cordStr = cordStr.substr(0,pos2);
ss<<pointStr;
ss>>t.a;
ss.clear();
ss<<normalStr;
ss>>t.an;
ss.clear();
ss<<cordStr;
ss>>t.at;
ss.clear();
f>>str;
pos = str.find(delimeter);
pointStr = str.substr(0,pos);
cordStr = str.substr(pos+delimeter.length());
pos2 = cordStr.find(delimeter);
normalStr = cordStr.substr(pos2+delimeter.length());
cordStr = cordStr.substr(0,pos2);
ss<<pointStr;
ss>>t.b;
ss.clear();
ss<<normalStr;
ss>>t.bn;
ss.clear();
ss<<cordStr;
ss>>t.bt;
ss.clear();
f>>str;
pos = str.find(delimeter);
pointStr = str.substr(0,pos);
cordStr = str.substr(pos+delimeter.length());
pos2 = cordStr.find(delimeter);
normalStr = cordStr.substr(pos2+delimeter.length());
cordStr = cordStr.substr(0,pos2);
ss<<pointStr;
ss>>t.c;
ss.clear();
ss<<normalStr;
ss>>t.cn;
ss.clear();
ss<<cordStr;
ss>>t.ct;
ss.clear();
triangles.push_back(t);
}
cmd = "";
}
f.close(); }
tm.AddTexture("tex","texture.png");
//glutTimerFunc(100, update, 0);
glutMainLoop();
}
回答1:
I think I'd just push a dummy point on the beginning of your points vector, and leave the point references 1-based. I'd also get rid of the while (!in.eof()), which will normally read the last line twice. Finally, I'd use a few overloads of operator>> to read most of the data, giving a result that looked something like this:
#include <locale>
#include <vector>
#include <sstream>
#include <string>
#include <fstream>
/* change to "#if 0" for normal compilation: */
#if 1
struct Triangle { float a, an, atc, b, bn, btc, c, cn, ctc; };
struct Vector2d { float x, y; };
struct Vector3d { float x, y, z; };
std::vector<Triangle> triangles;
std::vector<Vector3d> points, normals;
std::vector<Vector2d> texcords;
#endif
namespace {
struct slashsep: std::ctype<char> {
slashsep(): std::ctype<char>(get_table()) {}
static std::ctype_base::mask const* get_table() {
static std::vector<std::ctype_base::mask>
rc(std::ctype<char>::table_size,std::ctype_base::mask());
rc['/'] = std::ctype_base::space; // Treat '/' as a separator between numbers.
rc[' '] = std::ctype_base::space;
rc['\n'] = std::ctype_base::space;
rc['\t'] = std::ctype_base::space;
return &rc[0];
}
};
std::istream &operator>>(std::istream &in, Triangle &triangle) {
std::string str;
std::getline(in, str);
std::istringstream temp(str);
slashsep loc;
temp.imbue(std::locale(std::locale(), &loc));
temp >> triangle.a >> triangle.an >> triangle.atc;
temp >> triangle.b >> triangle.bn >> triangle.btc;
temp >> triangle.c >> triangle.cn >> triangle.ctc;
return in;
}
std::istream &operator>>(std::istream &in, Vector3d &v) {
return in >> v.x >> v.y >> v.z;
}
std::istream &operator>>(std::istream &in, Vector2d &v) {
return in >> v.x >> v.y;
}
}
bool read_obj(std::string const &fileName) {
points.clear();
points.push_back(Vector3d());
triangles.clear();
std::ifstream in(fileName.c_str());
std::string cmd;
if (!in.is_open())
return false;
while(in>>cmd) {
if(cmd=="v") {
Vector3d vector;
in >> vector;
points.push_back(vector);
}
if(cmd=="vt") {
Vector2d texcord;
in >> texcord;
texcords.push_back(texcord);
}
if(cmd=="vn"){
Vector3d normal;
in >> normal;
normals.push_back(normal);
}
if(cmd=="f") {
Triangle triangle;
in >> triangle;
triangles.push_back(triangle);
}
}
return true;
}
One minor point: while using the locale to treat '/' as a separator between numbers works for the specific variant of OBJ that you're looking at, it will not work for files that contain lines like:
f a//b c//d e//f
Nonetheless, the general idea (most reading with operator>>) will be fine when/if you decide to enhance it to handle this variant of the format.
Edit: I think I just realized part of the problem. The code to read a face should be like this:
temp >> triangle.a >> triangle.atc >> triangle.an;
temp >> triangle.b >> triangle.btc >> triangle.bn;
temp >> triangle.c >> triangle.ctc >> triangle.cn;
I.e., in the file, it's arranged as vertex/texcoord/normal, but your code and my previous version above tried to read it as vertex/normal/texcoord). Once the code was arranged this way, checking against a reference made the problem fairly obvious.
回答2:
Ok i fix all :D:D What I do: change
glTexCoord2f(tc.x,tc.y);
to
glTexCoord2f(tc.x,1-tc.y);
and the most important thing I change image resolution to 1024x1024 ( I useing mipmaping so I think correct image resolution is important) Now: Can sameone explain me why lTexCoord2f(tc.x,1-tc.y); work ? and is it important to make every image 2^x resolution ?
来源：https://stackoverflow.com/questions/2908854/opengl-problem-with-texture-in-model-from-obj