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RiotGODD
02-01-2001, 07:17 AM
I've just added lightmapping to my engine but
lightmaps does not look perfect because I cant get my lumel lighting equation to work.Can anyone help?(I have position of lumel in worldspace, it's normal, distance to pointlight and light's radiur).

Cem UZUNLAR
02-02-2001, 12:47 AM
Can you give more details about "not perfect"?

RiotGODD
02-02-2001, 11:11 AM
Well, faces with lightmaps look nice but some of them are black even if distance to the light source is shorter than light radius. I use this equation:
Brightness = (1 - 1 / LightRadius * Distance ) * (cosAngle-0.5).

Ysaneya
02-02-2001, 12:18 PM
Here is mine:

Brightness=MIN (cos Angle*2.5 , 1 - 1.3 * Distance / Radius )

I'm also searching a better one :)

Y.

02-02-2001, 01:26 PM
Isn't the light intensity just the dot of
the face normal and the normalized direction
to the light, divided by the square of the
distance to the light? At least, I believe
that's how physics works in general.

Then you apply the light function (i e
color, specular, etc).

I e if the point is P and the light is L and
the point normal is N, you'd get brightness
like this:

B = fL( N . Norm( L - P ) / ( | L - P | ** 2) )

(B = brightness, fL == light function).

Note that fL should probably return the
ambient value for negative arguments (i e
things facing away from the light).

Oh, and this argument to fL simplifies
reasonably well when you start writing it out
as coordinate operations. Especially the
| L - P | ** 2 part :-)

Humus
02-02-2001, 03:38 PM
Just copy the OpenGL lighting model and it'll look good.
brightness = (1 / (c + d * length + e * length^2)) * dot(norm(L-P),Vertex_Normal);

where c,d,e are arbitrary constants.