opengl - UV mapping for a dome? -

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i trying understand how can change uv mapping of dome, need different texture map projection 1 coded below:

    protected final void createdome(final float radius) {     int lats=16;      int longs=16;      gl11.glenable(gl11.gl_texture_2d);     gl11.glbindtexture(gl11.gl_texture_2d, textures2x4[0].gettextureid());      int i, j;     int halflats = lats / 2;      for(i = 0; <= halflats; i++)     {         double lat0     = mathutils.pi * (-0.5 + (double) (i - 1) / lats);         double z0       = math.sin(lat0)* radius;         double zr0      = math.cos(lat0)* radius;          double lat1     = mathutils.pi * (-0.5 + (double) / lats);         double z1       = math.sin(lat1)* radius;         double zr1      = math.cos(lat1)* radius;          gl11.glbegin(gl11.gl_quad_strip);         for(j = 0; j <= longs; j++)        {             double lng = 2 * mathutils.pi * (double) (j - 1) / longs;             double x    = math.cos(lng);             double y    = math.sin(lng);              double s1, s2, t;             s1      = ((double) i) / halflats;             s2      = ((double) + 1) / halflats;             t       = ((double) j) / longs;              // here: don't know how calculate uv mapping             gl11.gltexcoord2d(s1, t);             gl11.glnormal3d(x * zr0, y * zr0, z0);             gl11.glvertex3d(x * zr0, y * zr0, z0);              gl11.gltexcoord2d(s2, t);             gl11.glnormal3d(x * zr1, y * zr1, z1);             gl11.glvertex3d(x * zr1, y * zr1, z1);        }         gl11.glend();     }  }

i linked output image , original map. pratically need uv mapping places artic @ zenith/top of dome, , antartic streched on bottom side of dome... artic/antartic map used figure out mean, need it's not fit globe emisphere

output image http://img831.imageshack.us/img831/3481/lwjgl.png

source map http://img203.imageshack.us/img203/4930/earthc.png

take @ function calls (disclaimer: untested - haven't used lwjgl, concept should identical):

gl11.glmatrixmode(gl11.gl_texture); gl11.glrotate(90, 0, 0, 1);    // (1) here transform texture space gl11.glmatrixmode(gl11.gl_modelview); // , on

basically, need rotate texture on object. , that's way - transform texture projection matrix. line (1) rotates texture 90 degrees along z axis (perpendicular texture plane). it's z axis, because last argument 1. last 3 arguments denote x, y , z respectively (i'll leave whole explanation later if you're interested).

the best can grasp basic stuff (projection, texture space, normal vectors, triangulation, continuity, particle systems , lot more) download trial version of 3d package , play it. learned lot out of playing 3d studio max (trial version available, , many more free). if have free time , learn new advise it. in end, if you're interested in 3d graphics you'll end using 1 way - 3d package or game engine level editor.

edit: after more reading recognized own code... swap of coordinates reflect symmetrically along diagonal. might end upside down, can fixed additional tweaking (or transforming view axis). here untested guess:

// tweaked pole right s1 = ((double) j) / longs; s2 = ((double) j + 1) / longs; t  = ((double) i) / halflats;

try swapping s1 s2 if it's not right.


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