creating separate objects

how do you render your objects?

// first object
glBegin..
glEnd..

// second object
glBegin..
glEnd...

and maybe you should try GL_TRIANGLES.

I'm very new to opengl so it may be easier for you to cast your eyes over the code.

http://developer.apple.com/samplecode/GLUTBasics/index.html

the following is from the above which creates and draws one object. It works perfectly for what I need except I need it for a number of objects which are created on the fly. I think I need to know how to rewrite the *polyList = glGenLists (1) routine to draw more than one object. I realize that a complete rewrite of the whole procedure may be necessary.

at the moment what I'm doing is putting my data into vertexPos[index]. Using GL_TRIANGLES won't allow individual object selection which is what I eventually want.

// delete existing list
if (*polyList)
glDeleteLists (*polyList, 1);
if (*lineList)
glDeleteLists (*lineList, 1);
if (*pointList)
glDeleteLists (*pointList, 1);
*polyList = *lineList = *pointList = 0;

if (surface == kCube) // build the standard color cube (disregard color, subdivisions, and xyRatio)
BuildCube (polyList, lineList, pointList, colorScheme);
else {
// build buffers
vertexPos = (recVec*) malloc ((maxI) * (maxJ) * sizeof (recVec));
if (vertexNormal)
free (vertexNormal);
vertexNormal = (recVec*) malloc ((maxI) * (maxJ) * sizeof (recVec));
if (vertexColor)
free (vertexColor);
vertexColor = (recColor*) malloc ((maxI) * (maxJ) * sizeof (recColor));
if (vertexTexCoord)
free (vertexTexCoord);
vertexTexCoord = (recTexCoord*) malloc ((maxI) * (maxJ) * sizeof (recTexCoord));
if (!vertexPos || !vertexNormal || !vertexColor || !vertexTexCoord)
return;

// build surface
for (i = 0; i < maxI; i++) {
for (j = 0; j < maxJ; j++) {
index = i * maxJ + j;
u = -PI + (i % maxI) * TWOPI / maxI;
v = -PI + (j % maxJ) * TWOPI / maxJ;
vertexPos[index] = Eval(u,v, surface);
p1 = Eval(u + delta, v, surface);
p2 = Eval(u, v + delta, surface);
vertexNormal[index] = CalcNormal(vertexPos[index],p1,p2);
vertexColor[index] = getColor(u, -PI, PI, colorScheme);
vertexTexCoord[index].s = (float) i * 5.0f / (float) maxI;
vertexTexCoord[index].t = (float) j * 1.0f/ (float) maxJ;
}
}

*polyList = glGenLists (1);
glNewList(*polyList, GL_COMPILE);
for (i=0; i< maxI; i++) {
glBegin(GL_TRIANGLE_STRIP);
for (j = 0; j <= maxJ; j++) {
index = (i % maxI) * maxJ + (j % maxJ);
glColor3fv (&vertexColor[index].r);
glNormal3fv (&vertexNormal[index].x);
glTexCoord2fv (&vertexTexCoord[index].s);
glVertex3fv (&vertexPos[index].x);

index = ((i + 1) % maxI) * maxJ + (j % maxJ);
glColor3fv (&vertexColor[index].r);
glNormal3fv (&vertexNormal[index].x);
glTexCoord2fv (&vertexTexCoord[index].s);
glVertex3fv (&vertexPos[index].x);
// index = ((i - 1) % maxI) * maxJ + (j % maxJ);
}
glEnd ();
}
glEndList ();

everything you put inside a displaylist will be drawn when you call this list.

I'd simply do this:

Setup displaylist
new list
draw first object
end list
setup display list
new list
draw second object
end list.

then either create another displaylist which calls the other lists, or call them separatly.

If you created the first program, I'm pretty sure that this would be a walk in the park - unless the triangles in VRML is a trianglesoup?

I didn't create it, I'm certainly not that familiar with opengl

Thanks I shall try your suggestions and will no doubt get back to you when I get stuck.

u say on the fly
display lists are for things that are static eg the ground, a static tree etc.
if u wanna change something every frame dont use a list
also that code uses a lot of mem allocations whiich aint optimal
anyways ignore what i just said

// easy method
in a preprocessing phase setup the objects in identity space calc the verts + save them in a displaylist

during runtime use
glPushMatrix();
glMultMatrix( orientation );
glCallList(..);
glPopMatrix();

easy + fast

thanks I'll let you know how I get on