Improperly rendering broken fragment

i am currently using lib3ds library loading a vehicle model from 3ds file after i draw in on the screen it appears that there r a lot of broken fragment and cannot be rendered properly.it seems that there r some far points draw onto a nearer surface but ive no idea what s the problem really any answer would be appreciated.
attached is my code.


#include <windows.h>
#include <gl/gl.h>
#include <gl/glu.h>
#include <gl/glut.h>
#include <lib3ds.h>
#include <iostream>

typedef float Lib3dsVector[3];
typedef float Lib3dsTexel[2];
using namespace std;

Lib3dsFile* model;
Lib3dsMesh** mesh;
Lib3dsCamera** camera;
Lib3dsFace* face;
Lib3dsLight** light;
Lib3dsMaterial** material;

unsigned long total_face;

void lightup()
{
	glShadeModel(GL_SMOOTH);
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_CULL_FACE);
	glFrontFace(GL_CCW);
	glCullFace(GL_BACK);
	float gambient[]={0.2,0.2,0.2,1.0};
	float lightpos[]={1.0,1.0,1.0,0.0};
	float lambient[]={0.8,0.8,0.8,1.0};
	float ldiffuse[]={1.0,1.0,1.0,1.0};
	float lspecular[]={0.3,0.3,0.3,1.0};

	glClearColor(0.0,0.0,0.0,0.0);
	
	glLightfv(GL_LIGHT0,GL_DIFFUSE,ldiffuse);
	glLightfv(GL_LIGHT0,GL_AMBIENT,lambient);
	glLightfv(GL_LIGHT0,GL_SPECULAR,lspecular);
	glLightfv(GL_LIGHT0,GL_POSITION,lightpos);
	glLightModelfv(GL_LIGHT_MODEL_AMBIENT,gambient);
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
}
void display()
{
	glEnable(GL_DEPTH_TEST);
	glClearDepth(1.0);
	glDepthFunc(GL_LEQUAL);
	
	glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
	glLoadIdentity(); 
	gluLookAt(camera[0]->position[0]+1000,camera[0]->position[1],camera[0]->position[2],camera[0]->target[0],camera[0]->target[1],camera[0]->target[2],0.0,0.0,1.0);
	
	glColor3f(1.0,0.0,0.0);
	glPushMatrix();
	lightup();
	glTranslatef(0.0,0.0,-1000.0);
	long meshcount;
	for(meshcount=0;meshcount<model->nmeshes;meshcount++)
	{
		face=mesh[meshcount]->faces;
		Lib3dsVector* vertex_normal=new Lib3dsVector[mesh[meshcount]->nfaces*3];
		Lib3dsVector* face_normal=new Lib3dsVector[mesh[meshcount]->nfaces];
		lib3ds_mesh_calculate_vertex_normals(mesh[meshcount],vertex_normal);
		lib3ds_mesh_calculate_face_normals(mesh[meshcount],face_normal);
		for(long i=0;i<mesh[meshcount]->nfaces;i++)
		{			
			glMaterialfv(GL_FRONT,GL_DIFFUSE,material[face[i].material]->diffuse);
			glMaterialfv(GL_FRONT,GL_AMBIENT,material[face[i].material]->ambient);
			glMaterialfv(GL_FRONT,GL_SPECULAR,material[face[i].material]->specular);
			glBegin(GL_TRIANGLES);
			
			glNormal3fv(face_normal[i]);
			glNormal3fv(vertex_normal[i*3]);
			glVertex3fv(mesh[meshcount]->vertices[face[i].index[0]]);
			glNormal3fv(vertex_normal[i*3+1]);
			glVertex3fv(mesh[meshcount]->vertices[face[i].index[1]]);
			glNormal3fv(vertex_normal[i*3+2]);
			glVertex3fv(mesh[meshcount]->vertices[face[i].index[2]]);
			glEnd();
		}
	}
	
	glPopMatrix();
/*
	glPushMatrix();
	glTranslatef(0.0,0.0,-2000.0);
	glColor3f(1.0,1.0,1.0);
	glBegin(GL_QUADS);
	glVertex3f(-10000.0f,-10000.0f,0.0f);
	glVertex3f(10000.0f,-10000.0f,0.0f);
	glVertex3f(10000.0f,10000.0f,0.0f);
	glVertex3f(-10000.0f,10000.0f,0.0f);
	glEnd();
	glPopMatrix();
*/
	
	glutSwapBuffers();
}

void keypress(unsigned char key,int x,int y)
{
	switch(key)
	{
	case 27:
		exit(0);
		break;
	}
}
void reshape(int w,int h)
{
	if(h==0) h=1;
	glViewport(0,0,w,h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(45.0,w/h,0.0,5.0);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}
int main(int argc,char* argv[])
{
	
	glutInit(&argc,argv);
	model=lib3ds_file_open("vehicle.3DS");
	if(model==NULL) cout<<"Error"<<endl; else cout<<model->nmaterials<<endl;
	mesh=model->meshes;
	material=model->materials;
	camera=model->cameras;
	light=model->lights;
	cout<<"Light Num:"<<model->nlights<<endl;
	glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BITS);

	glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH);
	glutInitWindowSize(800,800);
	glutInitWindowPosition(100,100);
	glutCreateWindow("VC 2008 Glut");
	//glutFullScreen();
	glShadeModel(GL_FLAT);
	glutKeyboardFunc(keypress);
	glutDisplayFunc(display);
	glutReshapeFunc(reshape);
	glutMainLoop();
	return 0;
}

It looks a bit like the model’s back faces are being rendered, rather than the front faces. Does it appear any better if you use:

glFrontFace(GL_CW);

thank you very much.after change it into

glFrontFace(GL_CW);

the model turned dark.after relocate the light there r still some deeper points drawn onto the nearer faces.

This topic was automatically closed 183 days after the last reply. New replies are no longer allowed.