Generate Lightmaps

*1 Determine the primary axis plane based on the absolute value of the normal for this surface.
- I guess i can just check wich axis is the largest?

Pretty much. Though, i don't honestly see a valid reason to use a cardinal axis. If your surface is made of coplanar triangles, then pick any triangle and its normal is the primary axis.

*2 Get the min and max (2D vertices) along that plane. This means to use only the 2 relevant coordinate components for this particular plane. For example if you're using the XY plane, only x and y at the vertices count for this step.
- I dont really know what this means. is min a vector at "0,0" corner and max "1,1" corner if the polygon would start at 0,0 and be 1 wide and high?

Once you have a plane, compute a tangent and bi-tangent for it (perpendicular vectors that run along that plane). The reason people use a cardinal axis as their primary in #1 is so these vectors can just be the other 2 cardinal axis vectors without needing to generate them.
Use those vectors to project a 2d vector (basically, a signed distance from plane, using those directions and the origin. the actual origin doesnt really matter, its just to create a planar projection)

*3 Determine the texture plane origin (p) from the min. This, and the previous step can be done very simply by getting the 3D points based on your 2D (projected) min/max using the equation of the plane. You have only 1 unknown (the missing vertex component), so solving for it is trivial.
- Texture plane origin?

*4 Determine the u and v lengths (max-min)
- If i just had the min and max hmm?

The answer to these came from the 2D projections from #2

*5 And finally, determine lightmap coordinates:
(for each vertex) ltu=((pu - minu) / ulen) and ltv=((pv - minv) / vlen)
where pu and pv are the x and y in PLANE space (not world space).
- ?? Texture coordinates??

The projected coordinate from #2 gets scaled and biased in #4 to give you your texture coordinate.

Thx for the tips, but i'm still having problems.

What's texture plane origin(p) supposed to be?
And pu, pv from *5?

The top plane looks fairly nice but for some reason it gets a bright line at the edges and the coordinates i get from *5 does not match the 2 planes, please help.

Does anyone know of any example code for generating lightmaps?

Thanks!

Does anyone know of any example code for generating lightmaps?

Thanks!

IIRC there's a fairly complete example in Core Techniques and Algorithms in Game Programming.

Hi Surp, I'm having the same issue here creating lightmap, Have you found any new ressources , book, or example you were able to use ? .