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Igurg
01-30-2011, 11:23 AM
Hey, I am having problems with displaying a 3D Sierpinski Gasket within my program and I'm not overly sure why it isn't displaying. I think it has something to do with my pre-compiled objects in my program that are getting displayed before I call onto the method that draws the Gasket. Or it may be a buffer issue, I'm quite confused.

ZbuffeR
01-30-2011, 04:11 PM
Sorry, my crystal ball is not working :)
Try to do a very small example that works, to isolate the problem(s).
Put printf traces to verify execution order of your code.
Use a debugger, verify runtime values of your 'buffer' (which buffer by the way ?)

Igurg
01-30-2011, 05:48 PM
I believe it may be my depth buffer, though I could be completely wrong. The code itself compiles and runs fine, no errors. I have a menu button of where a user picks an object to render to the screen, it starts off with a pre-compiled Torus and for the rest of the objects it calls from a display list. Since the Gasket is not a prebuilt function I had to make my own method and when the method is called upon the torus it still being display, it doesn't render the Gasket. Even when I call upon the Gasket first it doesn't render. Would it be an animation issue since my objects rotate through the idle function?

mobeen
01-30-2011, 06:50 PM
I believe it may be my depth buffer, though I could be completely wrong. The code itself compiles and runs fine, no errors. I have a menu button of where a user picks an object to render to the screen, it starts off with a pre-compiled Torus and for the rest of the objects it calls from a display list. Since the Gasket is not a prebuilt function I had to make my own method and when the method is called upon the torus it still being display, it doesn't render the Gasket. Even when I call upon the Gasket first it doesn't render. Would it be an animation issue since my objects rotate through the idle function?
Its really hard for us 2 see unless u show us how u r doing it now.

Igurg
01-30-2011, 06:57 PM
Its quite a bit of lengthy code




#include <stdlib.h>
#include <GL/glut.h>

//Windows Definitions and Variables
int winIdMain; /* Main Window handle */
int menIdMain; /* Main menu handle */
int menIdSub; /* Sub-menu handle */
int menIdSubMain;
int value;
int n=3;

//Animation and scene definitions and variables
#define SMALL_ANGLE 1.0 /* Small rotation angle */
static double rotation_angle = 0.0; /* Current angle increment */
static double spin = 0.0; /* Current Spin Angle */

#define GL_TORUS 1 /* Call List Objects */
#define SOLID_CUBE 2
#define TEA_POT 3
#define GL_SPHERE 4
#define GL_GASKET 5
static int object = GL_TORUS; /* Object to use in scene */
GLfloat light_diffuse[]={1.0,1.0,1.0,1.0};
GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 };
GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
GLfloat mat_shininess[] = { 50.0 };
GLfloat v[4][3]={{0.0, 0.0, 1.0}, {0.0, 0.942809, -0.33333},
{-0.816497, -0.471405, -0.333333}, {0.816497, -0.471405, -0.333333}};

void triangle(GLfloat *va, GLfloat *vb, GLfloat *vc){
glVertex3fv(va);
glVertex3fv(vb);
glVertex3fv(vc);
}

void tetra(GLfloat *a, GLfloat *b, GLfloat *c, GLfloat *d){

triangle(a, b, c);
triangle(a, c, d);
triangle(a, d, b);
triangle(b, d, c);
}

void divide_tetra(GLfloat *a, GLfloat *b, GLfloat *c, GLfloat *d, int m){
GLfloat mid[6][3];
int j;
if(m>0){

/* compute six midpoints */
for(j=0; j<3; j++) mid[0][j]=(a[j]+b[j])/2;
for(j=0; j<3; j++) mid[1][j]=(a[j]+c[j])/2;
for(j=0; j<3; j++) mid[2][j]=(a[j]+d[j])/2;
for(j=0; j<3; j++) mid[3][j]=(b[j]+c[j])/2;
for(j=0; j<3; j++) mid[4][j]=(c[j]+d[j])/2;
for(j=0; j<3; j++) mid[5][j]=(b[j]+d[j])/2;

/* create 4 tetrahedrons by subdivision */
divide_tetra(a, mid[0], mid[1], mid[2], m-1);
divide_tetra(mid[0], b, mid[3], mid[5], m-1);
divide_tetra(mid[1], mid[3], c, mid[4], m-1);
divide_tetra(mid[2], mid[4], d, mid[5], m-1);
}

else(tetra(a,b,c,d)); /* draw tetrahedron at end of recursion */
}

//Commands to listen for the up and down arrow keys
void SpecialKeys(int key, int x, int y) {

switch (key){
case GLUT_KEY_UP:{
n++;
break;
}
case GLUT_KEY_DOWN:{
n--;
break;
case GLUT_KEY_RIGHT:{
//
break;
}
case GLUT_KEY_LEFT:{
//
break;
}
}

}
}


/* function that processes keyboard events */
void keyboard (unsigned char key, int x, int y){
static int is_rotation = 0;
switch (key){

case 'q':
case 'Q':
case 27 :
exit (0);
break;


case 32 :

if(is_rotation) {
rotation_angle = 0.0;
is_rotation = 0;

}
else {
rotation_angle = SMALL_ANGLE;
is_rotation = 1;
};
break;
};
};

//Event Handling
void mainMenu(int value){

switch(value){

case 1:{
object = GL_TORUS;
break;
}
case 2:{
object = SOLID_CUBE;
break;
}
case 3:{
object = TEA_POT;
break;
}
case 4:{
object =GL_SPHERE;
break;
}
case 5:{
divide_tetra(v[0], v[1], v[2], v[3], n);

break;
}
case 6:{
exit(0);
break;
}
};
};

//List of cases from the submenu
void subMenu(int value){

switch(value){

case 1:{
// Change the colour of the object to Red
light_diffuse[0]=1.0;
light_diffuse[1]=0.0;
light_diffuse[2]=0.0;
break;
}
case 2:{
// Change the colour of the object to Green
light_diffuse[0]=0.0;
light_diffuse[1]=1.0;
light_diffuse[2]=0.0;
break;
}
case 3:{
// Change the colour of the object to Blue
light_diffuse[0]=0.0;
light_diffuse[1]=0.0;
light_diffuse[2]=1.0;
break;
}
case 4:{
// Change the colour of the object to Yellow
light_diffuse[0]=1.0;
light_diffuse[1]=1.0;
light_diffuse[2]=0.0;
break;
}
case 5:{
//Change the colour of the object to Purple
light_diffuse[0]=1.0;
light_diffuse[1]=0.0;
light_diffuse[2]=1.0;
break;
}
case 6:{
//Change the colour of the object to Cyan
light_diffuse[0]=0.0;
light_diffuse[1]=1.0;
light_diffuse[2]=1.0;
break;
}
};
};

/* There can be only one idle() callback function. In an
animation, this idle() function must update not only the
main window but also all derived subwindows */
void idle (void){
spin += rotation_angle;
/* Update main */
glutSetWindow (winIdMain);
glutPostRedisplay();
};

void reshape(int w, int h){
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION); /* switch matrix mode */
glLoadIdentity();
if (w <= h)
gluOrtho2D(-2.0, 2.0, -2.0 * (GLfloat) h / (GLfloat) w,
2.0 * (GLfloat) h / (GLfloat) w);
else gluOrtho2D(-2.0 * (GLfloat) w / (GLfloat) h, 2.0 *
(GLfloat) w / (GLfloat) h, -2.0, 2.0);
glMatrixMode(GL_MODELVIEW); /* return to modelview mode */
}

void init(){
glEnable(GL_LIGHTING);

glEnable(GL_DEPTH_TEST);

/* set clear color to black */
glShadeModel (GL_SMOOTH);
glClearColor (0.0, 0.0, 0.0, 0.0);
/* set fill color to white */
glColor3f(1.0, 1.0, 1.0);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrtho(-2.0, 2.0, -2.0, 2.0, 1.0, 50.0);
}

//Windows updating callback functions
void mainDisplay (void){

/* Clean drawing board */
glutSetWindow (winIdMain);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity ();

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
glColorMaterial(GL_FRONT_AND_BACK,GL_AMBIENT_AND_D IFFUSE ) ;
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_LIGHT0);

/* Draw rotating Objects*/
glPushMatrix ();
glRotatef (spin, 0.0, 0.0, 1.0);
glCallList(object);
glPopMatrix ();

glutSwapBuffers ();
};

// Initializes GLUT machine, opens frames, windows and menus and runs GLUT's main loop
int main (int argc, char *argv[]){

/* Glut initializations */
glutInit (&amp;argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
glutInitWindowPosition (5, 5);
glutInitWindowSize (600, 600);

/* Main window creation and setup */
winIdMain = glutCreateWindow ("Test");
glutDisplayFunc (mainDisplay);
glutReshapeFunc(reshape);
glutKeyboardFunc (keyboard);
glutSpecialFunc(SpecialKeys);
glutIdleFunc (idle);
init();

/* Create submenu */
menIdSub = glutCreateMenu(subMenu);
glutAddMenuEntry("Red", 1);
glutAddMenuEntry("Green",2);
glutAddMenuEntry("Blue", 3);
glutAddMenuEntry("Yellow", 4);
glutAddMenuEntry("Purple", 5);
glutAddMenuEntry("Cyan",6);

/* Create main menu */
menIdMain = glutCreateMenu(mainMenu);
glutAddMenuEntry("Torus", 1);
glutAddMenuEntry("Cube",2);
glutAddMenuEntry("Teapot",3);
glutAddMenuEntry("Sphere",4);
glutAddMenuEntry("3D Gasket",5);
glutAddSubMenu("Colours", menIdSub);
glutAddMenuEntry("Quit", 6);
glutAttachMenu(GLUT_LEFT_BUTTON);

/* Create call list elements */
glNewList(GL_TORUS, GL_COMPILE);
glColor3f(1.0,1.0,1.0);
glPushMatrix();
glRotatef(45,1,1,0);
glutSolidTorus(0.25,0.5,25,25);
glPopMatrix();
glEndList();

glNewList(SOLID_CUBE, GL_COMPILE);
glPushMatrix();
glRotatef(25,1,1,0);
glutSolidCube(1.0);
glPopMatrix();
glEndList();

glNewList(TEA_POT, GL_COMPILE);
glPushMatrix();
glRotatef(45,1,1,0);
glutSolidTeapot(0.5);
glPopMatrix();
glEndList();

glNewList(GL_SPHERE, GL_COMPILE);
glPushMatrix();
glutSolidSphere(0.5,25,25);
glPopMatrix();
glEndList();

glNewList(GL_GASKET, GL_COMPILE);
glPushMatrix();
divide_tetra(v[0], v[1], v[2], v[3], n);
glPopMatrix();
glEndList();

glutMainLoop ();
return 0;
};

Please excuse any "newb" errors you see =(

mobeen
01-30-2011, 08:04 PM
Hi do two things
1) Wrao glBegin(GL_TRIANGLES); and glEnd() around your divide tetra function when u create the display list in main func. as follows,


glNewList(GL_GASKET, GL_COMPILE);
glPushMatrix();
glBegin(GL_TRIANGLES);
divide_tetra(v[0], v[1], v[2], v[3], n);
glEnd();
glPopMatrix();
glEndList();

And assign object=GL_GASKET in the switch case


case 5:{
object=GL_GASKET;
divide_tetra(v[0], v[1], v[2], v[3], n);
break;

That should do it. Here is the complete code


#include <stdlib.h>
#include <GL/glut.h>

//Windows Definitions and Variables
int winIdMain; /* Main Window handle */
int menIdMain; /* Main menu handle */
int menIdSub; /* Sub-menu handle */
int menIdSubMain;
int value;
int n=3;

//Animation and scene definitions and variables
#define SMALL_ANGLE 1.0 /* Small rotation angle */
static double rotation_angle = 0.0; /* Current angle increment */
static double spin = 0.0; /* Current Spin Angle */

#define GL_TORUS 1 /* Call List Objects */
#define SOLID_CUBE 2
#define TEA_POT 3
#define GL_SPHERE 4
#define GL_GASKET 5
static int object = GL_TORUS; /* Object to use in scene */
GLfloat light_diffuse[]={1.0,1.0,1.0,1.0};
GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 };
GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
GLfloat mat_shininess[] = { 50.0 };
GLfloat v[4][3]={{0.0, 0.0, 1.0}, {0.0, 0.942809, -0.33333},
{-0.816497, -0.471405, -0.333333}, {0.816497, -0.471405, -0.333333}};

void triangle(GLfloat *va, GLfloat *vb, GLfloat *vc){
glVertex3fv(va);
glVertex3fv(vb);
glVertex3fv(vc);
}

void tetra(GLfloat *a, GLfloat *b, GLfloat *c, GLfloat *d){

triangle(a, b, c);
triangle(a, c, d);
triangle(a, d, b);
triangle(b, d, c);
}

void divide_tetra(GLfloat *a, GLfloat *b, GLfloat *c, GLfloat *d, int m){
GLfloat mid[6][3];
int j;
if(m>0){

/* compute six midpoints */
for(j=0; j<3; j++) mid[0][j]=(a[j]+b[j])/2;
for(j=0; j<3; j++) mid[1][j]=(a[j]+c[j])/2;
for(j=0; j<3; j++) mid[2][j]=(a[j]+d[j])/2;
for(j=0; j<3; j++) mid[3][j]=(b[j]+c[j])/2;
for(j=0; j<3; j++) mid[4][j]=(c[j]+d[j])/2;
for(j=0; j<3; j++) mid[5][j]=(b[j]+d[j])/2;

/* create 4 tetrahedrons by subdivision */
divide_tetra(a, mid[0], mid[1], mid[2], m-1);
divide_tetra(mid[0], b, mid[3], mid[5], m-1);
divide_tetra(mid[1], mid[3], c, mid[4], m-1);
divide_tetra(mid[2], mid[4], d, mid[5], m-1);
}

else(tetra(a,b,c,d)); /* draw tetrahedron at end of recursion */
}

//Commands to listen for the up and down arrow keys
void SpecialKeys(int key, int x, int y) {

switch (key){
case GLUT_KEY_UP:{
n++;
break;
}
case GLUT_KEY_DOWN:{
n--;
break;
case GLUT_KEY_RIGHT:{
//
break;
}
case GLUT_KEY_LEFT:{
//
break;
}
}

}
}


/* function that processes keyboard events */
void keyboard (unsigned char key, int x, int y){
static int is_rotation = 0;
switch (key){

case 'q':
case 'Q':
case 27 :
exit (0);
break;


case 32 :

if(is_rotation) {
rotation_angle = 0.0;
is_rotation = 0;

}
else {
rotation_angle = SMALL_ANGLE;
is_rotation = 1;
};
break;
};
};

//Event Handling
void mainMenu(int value){

switch(value){

case 1:{
object = GL_TORUS;
break;
}
case 2:{
object = SOLID_CUBE;
break;
}
case 3:{
object = TEA_POT;
break;
}
case 4:{
object =GL_SPHERE;
break;
}
case 5:{
object=GL_GASKET;
divide_tetra(v[0], v[1], v[2], v[3], n);

break;
}
case 6:{
exit(0);
break;
}
};
};

//List of cases from the submenu
void subMenu(int value){

switch(value){

case 1:{
// Change the colour of the object to Red
light_diffuse[0]=1.0;
light_diffuse[1]=0.0;
light_diffuse[2]=0.0;
break;
}
case 2:{
// Change the colour of the object to Green
light_diffuse[0]=0.0;
light_diffuse[1]=1.0;
light_diffuse[2]=0.0;
break;
}
case 3:{
// Change the colour of the object to Blue
light_diffuse[0]=0.0;
light_diffuse[1]=0.0;
light_diffuse[2]=1.0;
break;
}
case 4:{
// Change the colour of the object to Yellow
light_diffuse[0]=1.0;
light_diffuse[1]=1.0;
light_diffuse[2]=0.0;
break;
}
case 5:{
//Change the colour of the object to Purple
light_diffuse[0]=1.0;
light_diffuse[1]=0.0;
light_diffuse[2]=1.0;
break;
}
case 6:{
//Change the colour of the object to Cyan
light_diffuse[0]=0.0;
light_diffuse[1]=1.0;
light_diffuse[2]=1.0;
break;
}
};
};

/* There can be only one idle() callback function. In an
animation, this idle() function must update not only the
main window but also all derived subwindows */
void idle (void){
spin += rotation_angle;
/* Update main */
//glutSetWindow (winIdMain);
glutPostRedisplay();
};

void reshape(int w, int h){
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION); /* switch matrix mode */
glLoadIdentity();
if (w <= h)
gluOrtho2D(-2.0, 2.0, -2.0 * (GLfloat) h / (GLfloat) w,
2.0 * (GLfloat) h / (GLfloat) w);
else gluOrtho2D(-2.0 * (GLfloat) w / (GLfloat) h, 2.0 *
(GLfloat) w / (GLfloat) h, -2.0, 2.0);
glMatrixMode(GL_MODELVIEW); /* return to modelview mode */
}

void init(){
glEnable(GL_LIGHTING);

glEnable(GL_DEPTH_TEST);

/* set clear color to black */
glShadeModel (GL_SMOOTH);
glClearColor (0.0, 0.0, 0.0, 0.0);
/* set fill color to white */
glColor3f(1.0, 1.0, 1.0);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrtho(-2.0, 2.0, -2.0, 2.0, 1.0, 50.0);
}

//Windows updating callback functions
void mainDisplay (void){

/* Clean drawing board */
glutSetWindow (winIdMain);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity ();

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
glColorMaterial(GL_FRONT_AND_BACK,GL_AMBIENT_AND_D IFFUSE ) ;
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_LIGHT0);

/* Draw rotating Objects*/
glPushMatrix ();
glRotatef (spin, 0.0, 0.0, 1.0);
glCallList(object);
glPopMatrix ();

glutSwapBuffers ();
};

// Initializes GLUT machine, opens frames, windows and menus and runs GLUT's main loop
int main (int argc, char *argv[]){

/* Glut initializations */
glutInit (&amp;argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
glutInitWindowPosition (5, 5);
glutInitWindowSize (600, 600);

/* Main window creation and setup */
winIdMain = glutCreateWindow ("Test");
glutDisplayFunc (mainDisplay);
glutReshapeFunc(reshape);
glutKeyboardFunc (keyboard);
glutSpecialFunc(SpecialKeys);
glutIdleFunc (idle);
init();

/* Create submenu */
menIdSub = glutCreateMenu(subMenu);
glutAddMenuEntry("Red", 1);
glutAddMenuEntry("Green",2);
glutAddMenuEntry("Blue", 3);
glutAddMenuEntry("Yellow", 4);
glutAddMenuEntry("Purple", 5);
glutAddMenuEntry("Cyan",6);

/* Create main menu */
menIdMain = glutCreateMenu(mainMenu);
glutAddMenuEntry("Torus", 1);
glutAddMenuEntry("Cube",2);
glutAddMenuEntry("Teapot",3);
glutAddMenuEntry("Sphere",4);
glutAddMenuEntry("3D Gasket",5);
glutAddSubMenu("Colours", menIdSub);
glutAddMenuEntry("Quit", 6);
glutAttachMenu(GLUT_LEFT_BUTTON);

/* Create call list elements */
glNewList(GL_TORUS, GL_COMPILE);
glColor3f(1.0,1.0,1.0);
glPushMatrix();
glRotatef(45,1,1,0);
glutSolidTorus(0.25,0.5,25,25);
glPopMatrix();
glEndList();

glNewList(SOLID_CUBE, GL_COMPILE);
glPushMatrix();
glRotatef(25,1,1,0);
glutSolidCube(1.0);
glPopMatrix();
glEndList();

glNewList(TEA_POT, GL_COMPILE);
glPushMatrix();
glRotatef(45,1,1,0);
glutSolidTeapot(0.5);
glPopMatrix();
glEndList();

glNewList(GL_SPHERE, GL_COMPILE);
glPushMatrix();
glutSolidSphere(0.5,25,25);
glPopMatrix();
glEndList();

glNewList(GL_GASKET, GL_COMPILE);
glPushMatrix();
glBegin(GL_TRIANGLES);
divide_tetra(v[0], v[1], v[2], v[3], n);
glEnd();
glPopMatrix();
glEndList();

glutMainLoop ();
return 0;
};


See if this helps,
Mobeen

Igurg
01-30-2011, 08:55 PM
Thanks it worked, I figured it be something minor!