Hello, I just wondered if someone knows of an algorithm to create a hemisphere? And if anyone knows a place with some nice sky textures? Guess what I''m coding... Greets Tobias

Generating the coords for a hemisphere should be quite simple..

Use the XY axis to strike one arc, from 3o''clock to 12o''clock (anti-clockwise), say, every 10 degrees.. Use the resulting X as a new radius..

With this new radius, find all the points around the XZ for a full circle (again pick an angle..)

Hey presto you''ll have X,Y & Z coords for a hemisphere.

You''ll still have to work on the normals, and apply spherical texture mapping though (that I''m afraid I can''t help you with - I''m still learning too!)

If you really need to see a code example of the coord generation routines, just say so..

Cheers

Matt


Check out my project at: www.btinternet.com/~Matthew.Bennett

Thanks 3dModelMan,

I stole this routine from Paul Bourke (I think), and
it works fine.


#define PI 3.141592654f
#define TWOPI 6.283185308f

void SphereMap( vec_t x, vec_t y, vec_t z, vec_t radius, vec_t *u, vec_t *v )
{
*v = (vec_t)acos(z/radius) / PI;
if (y >= 0.0f)
*u = (vec_t)acos(x/(radius * (vec_t)sin(PI*(*v)))) / TWOPI;
else
*u = (PI + (vec_t)acos(x/(radius * (vec_t)sin(PI*(*v))))) / (TWOPI*2.0f);
}

Greets Tobias

Edited by - Tobias on 4/10/00 1:10:40 PM