Incomplete shapes and "blobs" (extra solid shapes)

bballdave025 · June 4, 2011, 2:33am

Hey. I’m new to OpenGL, though I’m a decently experienced programmer. I’m coding what’s basically a particle physics simulator. I’m building wiredrawing 3D shapes to represent the detector. I’ve drawn two concentric cylinders and some boxes. The problem is that, when the graphics window comes up, some of the edges aren’t displayed, and there are some “extra” solid-filled shapes on the edges. I’ve posted images, since I’m not sure exactly how to describe this problem. I have searched all over, but haven’t been able to find a solutions to this problem, or even anyone with the same problem. The problem can get better or worse when I rotate the 3D shapes (that’s visible in the images I’ve posted.) I’ve also attached code.
Like I said, I’m a beginning OpenGL user, though a decently advanced programmer. I’ve borrowed a lot of this code, so I’m not sure where to start in looking for a solution to the problem. Any help would be appreciated. For your information, I’m developing on Fedora 15 Linux running on a VirtualBox VM (Windows 7 host). I actually didn’t have all the same problems (I had some) when I was running it on a previous version of Fedora.

Okay, I’ve tried to attach the pictures, but it keeps telling me that the file size is bigger than 400-something KB, even though it’s a 53 KB GIF file. Here’s a link to somewhere I have the images.
http://www.scribd.com/doc/57071144/Polygon-Problems
I’ll put my code in a reply to this post.

bballdave025 · June 4, 2011, 2:35am

/*
Subroutine: abc_drw.c

  This subroutine (adapted from pp2d.f [Choptuik]), draws ABC objects

and particle trajectories. Entering the routine generates the ABC
Simulator display window. <ESC> returns to the command line in abc_com.
Command options from the active display window are described below in
drw_hlp.
*/

#include “abc.h”
#include <GL/glut.h>

int atag=1,htag=1,ltag=0,mtag=0,ntag=1,ptag=0,utag=0;
int itag=0,inum=0;
int xres,yres;
double ipos[99][5];
double xwin=430.0,xmin,ymin,xsmn,ysmn,
ywin=430.0,xmax,ymax,xsmx,ysmx,
dwin=1.1,dscl=1.1,dtrn=0.05,ddis=1.1,drot=5.0,hscl=0.01;
double vrta=0.0,vrtb=0.0,vrtc=0.0,vdis,vsra,vsrb,vsrc,vsds;

void abc_drw(int argc,char **argv)
{
int i;

vdis = 10.0objdim[0][6];
xmin = dscl(objdim[0][1]-0.5objdim[0][4]); xsmn = xmin; vsra = vrta;
ymin = dscl(objdim[0][2]-0.5objdim[0][5]); ysmn = ymin; vsrb = vrtb;
xmax = dscl(objdim[0][1]+0.5objdim[0][4]); xsmx = xmax; vsrc = vrtc;
ymax = dscl(objdim[0][2]+0.5*objdim[0][5]); ysmx = ymax; vsds = vdis;

drwcol[0][0] = 1.0;
if(mtag) for(i=1;i<=3;i++) drwcol[0][i] = 0.0;
else for(i=1;i<=3;i++) drwcol[0][i] = 1.0;

glutInit(&argc,argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGB);
glutInitWindowPosition(0,0);
glutInitWindowSize(xwin,ywin);
glutCreateWindow(“ABC Simulator”);

glutDisplayFunc(drw_dis);
glutIdleFunc(drw_idl);
glutKeyboardFunc(drw_key);
glutMouseFunc(drw_mou);
glutReshapeFunc(drw_res);
glutSpecialFunc(drw_spe);

glEnable(GL_POINT_SMOOTH);
glutMainLoop();
}

void drw_idl(void)
{
return;
}

void drw_key(unsigned char key,int x, int y)
{
double xavg,yavg,xdel,ydel;
int ig;
if(itag) return;
if(key >= ‘0’ && key <= ‘9’)
{
ig = key - ‘0’; if(ig == 0) ig = 10; abc_gen(ig);
drw_res(xres,yres);
return;
}
switch(key)
{
case ‘A’:
vrta += drot; drw_res(xres,yres);
break;
case ‘a’:
vrta -= drot; drw_res(xres,yres);
break;
case ‘B’:
vrtb += drot; drw_res(xres,yres);
break;
case ‘b’:
vrtb -= drot; drw_res(xres,yres);
break;
case ‘C’:
vrtc += drot; drw_res(xres,yres);
break;
case ‘c’:
vrtc -= drot; drw_res(xres,yres);
break;
case ‘D’:
vdis = ddis; drw_res(xres,yres);
break;
case ‘d’:
vdis /= ddis; drw_res(xres,yres);
break;
case ‘S’:
xavg = 0.5(xmin+xmax); yavg = 0.5*(ymin+ymax);
xdel = 0.5*(xmax-xmin); ydel = 0.5*(ymax-ymin);
xmin = xavg - xdel/dscl; xmax = xavg + xdel/dscl;
ymin = yavg - ydel/dscl; ymax = yavg + ydel/dscl;
drw_res(xres,yres);
break;
case ‘s’:
xavg = 0.5*(xmin+xmax); yavg = 0.5*(ymin+ymax);
xdel = 0.5*(xmax-xmin); ydel = 0.5*(ymax-ymin);
xmin = xavg - xdeldscl; xmax = xavg + xdeldscl;
ymin = yavg - ydeldscl; ymax = yavg + ydeldscl;
drw_res(xres,yres);
break;
case ‘W’:
xwin *= dwin; ywin *= dwin;
glutReshapeWindow(xwin,ywin);
glutPostRedisplay();
break;
case ‘w’:
xwin /= dwin; ywin /= dwin;
glutReshapeWindow(xwin,ywin);
glutPostRedisplay();
break;
case ‘r’:
xmin = xsmn; ymin = ysmn; xmax = xsmx; ymax = ysmx; inum = 0;
vrta = vsra; vrtb = vsrb; vrtc = vsrc; vdis = vsds;
drw_res(xres,yres);
break;
case ‘v’:
vrta = 46.0; vrtb = 45.0; vrtc = 90.0;
drw_res(xres,yres);
break;
case ‘x’:
vrta = 180.0; vrtb = -90.0; vrtc = -90.0;
drw_res(xres,yres);
break;
case ‘y’:
vrta = 90.0; vrtb = 90.0; vrtc = 180.0;
drw_res(xres,yres);
break;
case ‘z’:
vrta = 0.0; vrtb = 0.0; vrtc = 0.0;
drw_res(xres,yres);
break;
case ‘i’:
if(inum < 99)
{
if(inum == 0)
{
ipos[inum][1] = xmin; ipos[inum][2] = ymin;
ipos[inum][3] = xmax; ipos[inum][4] = ymax;
}
inum++; itag = 1;
}
break;
case ‘o’:
if(inum > 0)
{
inum–;
xmin = ipos[inum][1]; ymin = ipos[inum][2];
xmax = ipos[inum][3]; ymax = ipos[inum][4];
drw_res(xres,yres);
}
break;
case ‘h’:
htag = !htag; drw_res(xres,yres);
break;
case ‘j’:
atag = !atag; drw_res(xres,yres);
break;
case ‘l’:
ltag = !ltag; drw_res(xres,yres);
break;
case ‘m’:
mtag = !mtag; drw_res(xres,yres);
break;
case ‘n’:
ntag = !ntag; drw_res(xres,yres);
break;
case ‘p’:
ptag = !ptag; drw_res(xres,yres);
break;
case ‘t’:
trknum = 0; hitnum = 0; drw_res(xres,yres);
break;
case ‘u’:
utag = !utag; drw_res(xres,yres);
break;
case 27:
abc_com(); drw_res(xres,yres);
break;
case ‘q’:
fprintf(stderr,"
"); exit(0);
case ‘?’:
drw_hlp();
break;
default:
break;
}
}

void drw_mou(int button,int state,int x,int y)
{
double xmou,ymou,xdel,ydel;
if(!itag) return;
switch(state)
{
case GLUT_DOWN:
ipos[inum][1] = xmin + (x/xwin)(xmax-xmin);
ipos[inum][4] = ymax - (y/ywin)(ymax-ymin);
break;
case GLUT_UP:
ipos[inum][2] = ymax - (y/ywin)(ymax-ymin);
ipos[inum][3] = xmin + (x/xwin)(xmax-xmin);
itag = 0;
xmin = ipos[inum][1]; ymin = ipos[inum][2];
xmax = ipos[inum][3]; ymax = ipos[inum][4];
drw_res(xres,yres);
break;
default:
break;
}
}

void drw_spe(int key, int x, int y )
{
int xdel,ydel,imod=glutGetModifiers();
if(itag) return;
switch(key)
{
case GLUT_KEY_LEFT:
if(imod == GLUT_ACTIVE_SHIFT) vrtb += drot;
else { xdel = xmax - xmin; xmax -= xdeldtrn; xmin -= xdeldtrn; }
drw_res(xres,yres);
break;
case GLUT_KEY_RIGHT:
if(imod == GLUT_ACTIVE_SHIFT) vrtb -= drot;
else { xdel = xmax - xmin; xmax += xdeldtrn; xmin += xdeldtrn; }
drw_res(xres,yres);
break;
case GLUT_KEY_DOWN:
if(imod == GLUT_ACTIVE_SHIFT) vrta += drot;
else { ydel = ymax - ymin; ymax -= ydeldtrn; ymin -= ydeldtrn; }
drw_res(xres,yres);
break;
case GLUT_KEY_UP:
if(imod == GLUT_ACTIVE_SHIFT) vrta -= drot;
else { ydel = ymax - ymin; ymax += ydeldtrn; ymin += ydeldtrn; }
drw_res(xres,yres);
break;
default:
break;
}
}

void drw_dis(void)
{
int i;
double x1,y1,x2,y2,x3,y3,x4,y4;

if(mtag) glClearColor(1.0,1.0,1.0,1.0);
else glClearColor(0.0,0.0,0.0,1.0);
if(mtag) for(i=1;i<=3;i++) drwcol[0][i] = 0.0;
else for(i=1;i<=3;i++) drwcol[0][i] = 1.0;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

if(atag) drw_axe();
for(i=utag;i<maxobj;i++) if(i == 0 || objnum[i] > 0)
{
if(strcmp(objshp[i],“box”) == 0) drw_box(i);
if(strcmp(objshp[i],“BOX”) == 0) drw_box(i);
if(strcmp(objshp[i],“cyl”) == 0) drw_cyl(i);
if(strcmp(objshp[i],“CYL”) == 0) drw_cyl(i);
}
for(i=0;i<trknum;i++) drw_trk(i);
if(htag) for(i=0;i<hitnum;i++) drw_hit(i);
glutSwapBuffers();
}

void drw_res(int nw, int nh)
{
xres = nw;
yres = nh;
glViewport(0,0,xres,yres);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(xmin,xmax,ymin,ymax,-1.0,0.0);
glMatrixMode(GL_MODELVIEW);
glutPostRedisplay();
}

void drw_axe()
{
double x,y,z,ax[4],ay[4],az[4];
int i,nc;
for(i=1;i<4;i++)
{
x = 0.0; y = 0.0; z = 0.0;
if(i == 1) x = objdim[0][1] + 0.5objdim[0][4];
if(i == 2) y = objdim[0][2] + 0.5objdim[0][5];
if(i == 3) z = objdim[0][3] + 0.5*objdim[0][6];
drw_rot(x,y,z,&ax[i],&ay[i],&az[i]);
}
glPointSize(1.0);
nc = 0; if(ntag) nc = 1;
glColor3d(drwcol[nc][1],drwcol[nc][2],drwcol[nc][3]);
glBegin(GL_LINES);
glVertex2d(0.0,0.0); glVertex2d(ax[1],ay[1]);
glEnd();
nc = 0; if(ntag) nc = 2;
glColor3d(drwcol[nc][1],drwcol[nc][2],drwcol[nc][3]);
glBegin(GL_LINES);
glVertex2d(0.0,0.0); glVertex2d(ax[2],ay[2]);
glEnd();
nc = 0; if(ntag) nc = 3;
glColor3d(drwcol[nc][1],drwcol[nc][2],drwcol[nc][3]);
glBegin(GL_LINES);
glVertex2d(0.0,0.0); glVertex2d(ax[3],ay[3]);
glEnd();
}

void drw_box(int no)
{
double xi,yi,zi,x0,y0,z0,xw,yw,zw,ea,eb,ec,xo,yo,zo,bx[9],by[9],bz[9];
int i,nc=0;
x0 = objdim[no][1]; xw = 0.5objdim[no][4]; ea = objdim[no][7];
y0 = objdim[no][2]; yw = 0.5objdim[no][5]; eb = objdim[no][8];
z0 = objdim[no][3]; zw = 0.5*objdim[no][6]; ec = objdim[no][9];
if(ntag) nc = objcol[no];
for(i=1;i<9;i++)
{
xi = -xw; if(i==2 || i==3 || i==6 || i==7) xi = xw;
yi = -yw; if(i==3 || i==4 || i==7 || i==8) yi = yw;
zi = -zw; if(i > 4) zi = zw;
uti_rot(-1,xi,yi,zi,x0,y0,z0,ea,eb,ec,&xo,&yo,&zo);
drw_rot(xo,yo,zo,&bx[i],&by[i],&bz[i]);
}
glColor3d(drwcol[nc][1],drwcol[nc][2],drwcol[nc][3]);
glPointSize(1.0);
glBegin(GL_LINE_LOOP);
glVertex2d(bx[1],by[1]); glVertex2d(bx[2],by[2]);
glVertex2d(bx[3],by[3]); glVertex2d(bx[4],by[4]);
glEnd();
glBegin(GL_LINE_LOOP);
glVertex2d(bx[5],by[5]); glVertex2d(bx[6],by[6]);
glVertex2d(bx[7],by[7]); glVertex2d(bx[8],by[8]);
glEnd();
glBegin(GL_LINES);
glVertex2d(bx[1],by[1]); glVertex2d(bx[5],by[5]);
glVertex2d(bx[2],by[2]); glVertex2d(bx[6],by[6]);
glVertex2d(bx[3],by[3]); glVertex2d(bx[7],by[7]);
glVertex2d(bx[4],by[4]); glVertex2d(bx[8],by[8]);
glEnd();
}

void drw_cyl(int no)
{
double xi,yi,zi,x0,y0,z0,iw,ow,zw,ea,eb,ec,ei,es,xo,yo,zo,z,w;
double cx[17],cy[17];
int i,j,k,ni,nc=0;
x0 = objdim[no][1]; iw = 0.5objdim[no][4]; ea = objdim[no][7];
y0 = objdim[no][2]; ow = 0.5objdim[no][5]; eb = objdim[no][8];
z0 = objdim[no][3]; zw = 0.5objdim[no][6]; ec = objdim[no][9];
if(ntag) nc = objcol[no]; ni = 4maxinc; ei = 2.0pi/ni;
glColor3d(drwcol[nc][1],drwcol[nc][2],drwcol[nc][3]); glPointSize(1.0);
for(j=1;j<=4;j++)
{
z = -zw; if(j == 2 || j == 4) z = +zw;
w = iw; if(j > 2) w = ow; if(w > 0.0)
{
glBegin(GL_LINE_LOOP);
es = 0.0; for(i=1;i<=ni;i++)
{
es = es + ei; xi = wcos(es); yi = w*sin(es); zi = z;
uti_rot(-1,xi,yi,zi,x0,y0,z0,ea,eb,ec,&xo,&yo,&zo);
drw_rot(xo,yo,zo,&xi,&yi,&zi); glVertex2d(xi,yi);
if(i % maxinc == 0)
{
k = i/maxinc;
if(j > 2) k = k + 4;
if(j == 2 || j == 4) k = k + 8;
cx[k] = xi; cy[k] = yi;
}
}
glEnd();
}
}
glBegin(GL_LINES);
for(i=1;i<=8;i++) if(i > 4 || iw > 0)
{
glVertex2d(cx[i],cy[i]); glVertex2d(cx[i+8],cy[i+8]);
}
glEnd();
}

void drw_trk(int no)
{
double xi,yi,zi,xo,yo,zo;
int i,nc=0;
if(ntag) nc = prtcol[trkprt[no]];
glColor3d(drwcol[nc][1],drwcol[nc][2],drwcol[nc][3]);
if(ltag)
{
glPointSize(1.0);
glBegin(GL_LINE_STRIP);
for(i=0;i<trkpnt[no];i++)
{
xi = trkxpo[no][i]; yi = trkypo[no][i]; zi = trkzpo[no][i];
drw_rot(xi,yi,zi,&xo,&yo,&zo);
glVertex2d(xo,yo);
}
glEnd();
}
else
{
glPointSize(2.0);
glBegin(GL_POINTS);
for(i=0;i<trkpnt[no];i++)
{
xi = trkxpo[no][i]; yi = trkypo[no][i]; zi = trkzpo[no][i];
drw_rot(xi,yi,zi,&xo,&yo,&zo);
glVertex2d(xo,yo);
}
glEnd();
}
}

void drw_hit(int no)
{
double xi,yi,zi,xo,yo,zo,x1,y1,x2,y2,dx,dy,dh;
int nc=0;
if(ntag) nc = prtcol[hitprt[no]];
glColor3d(drwcol[nc][1],drwcol[nc][2],drwcol[nc][3]); glPointSize(1.0);

dx = hscl*(xmax-xmin); dy = hscl*(ymax-ymin);
dh = hscldx; if(dy < dx) dh = hscldy;
xi = hitxpo[no]; yi = hitypo[no]; zi = hitzpo[no];
drw_rot(xi,yi,zi,&xo,&yo,&zo);
x1 = xo - dx; y1 = yo - dy;
x2 = xo + dx; y2 = yo + dy;
glBegin(GL_LINES);
glVertex2d(x1,y1); glVertex2d(x2,y2);
glVertex2d(x1,y2); glVertex2d(x2,y1);
glEnd();
}

void drw_rot(xi,yi,zi,xo,yo,zo)
double xi,yi,zi,*xo,yo,zo;
{
double xr,yr,zr;
uti_rot(+1,xi,yi,zi,0.0,0.0,0.0,vrta,vrtb,vrtc,&xr,&yr,&zr);
if(ptag && (vdis-zr) > 0)
{
xr = xr(vdis/(vdis-zr));
yr = yr(vdis/(vdis-zr));
}
*xo = xr; *yo = yr; *zo = zr;
}

void drw_hlp()
{
fprintf(stderr,"
“);
fprintf(stderr,” Commands:");
fprintf(stderr," (type ‘?’ for help, ‘q’ to quit, <ESC> for prompt)
“);
fprintf(stderr,”
“);
fprintf(stderr,” # - generate particle # (‘0’=10)
“);
fprintf(stderr,” i,o - zoom in with mouse (down on UL corner, ");
fprintf(stderr, "up on LR), zoom out
“);
fprintf(stderr,” l,t - toggle tracks (lines/points), ");
fprintf(stderr, "clear tracks/hits
“);
fprintf(stderr,” m,n - toggle background (B/W), color
“);
fprintf(stderr,” u,j,h,p - toggle universe,axes,hits,perspective
“);
fprintf(stderr,” v,x,y,z - view from angle,x-,y-,z-axis
“);
fprintf(stderr,” r - reset view
“);
fprintf(stderr,”
“);
fprintf(stderr,” a/A,b/B,c/C - dec/inc view angle a,b,c
“);
fprintf(stderr,” d/D,s/S,w/W - dec/inc view distance,scale,window
“);
fprintf(stderr,”
“);
fprintf(stderr,” <arrow> - move view left/right/up/down
“);
fprintf(stderr,” <SHIFT><arrow> - rotate x-y view angle
“);
fprintf(stderr,”
");
}

bballdave025 · July 12, 2011, 5:19pm

Anyone have any ideas for this problem? I have another copy of my code that’s more nicely color-coded. I hope I didn’t scare people off with my code reply–it’s pretty big. Here’s the link to the “nicer” version of code: http://www.scribd.com/doc/59895636/abc-drw

mobeen · July 12, 2011, 6:55pm

Hi,
Please use the [ code ][/ code ] tags when posting code snippets.

You need to enable the depth test by issuing a call to


glEnable(GL_DEPTH_TEST);

somewhere at the initialization probably after glEnable(GL_POINT_SMOOTH);

See if this helps.

MaxH · July 12, 2011, 10:54pm

Hey. I might be able to help if you do the [ code ] and [/ code ] tags as mentioned above. Also, what is abc.h? I’m going to need that too. (Posting your code on Facebook is useless to me.)