Flat Donut | GameDev.net

Original Post

Mar 31, 2004 at 3:04 AM

I''m looking to draw a band between 2 concentric circles (like a flat donut) using only triangles with openGL. Can anyone help? (I know there''s the gluPartialDisk() method, but it doesn''t use separate triangles). Thanx.

szinkopa

Mar 31, 2004 at 8:56 AM

Use trianglestrip like this

int N;//Number Of Triangles

double pi=4*atan(1);
double twopi=2*pi;

double r,R;//the inner and outer radius

glBegin(GL_TRIANGLE_STRIP);
for(i=0;i {
sn=sin(i/N * twopi);
cs=cos(i/N * twopi);
if(i&1) //i odd
{
glVertex(r*cs,r*sn,0);
}
else//i even
{
glVertex(R*cs,R*sn,0);
}
}
glEnd();

It may not work properly, I did not try it, but I would make it this way, with some optimizations.

szinkopa

Mar 31, 2004 at 8:58 AM

...
for(i=0;i...

It has deleted somehow.

szinkopa

Mar 31, 2004 at 8:59 AM

And again

for(i=1;i less than N;i++)

)

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