arbitrary reflections

[Vexator]

if i want e.g. to reflect a scene in water, i scale about (1, -1, 1), setup a clipping plane with a normal vector pointing up and offset the scene.

now i'm trying to figure out how i have to setup the scale matrix and the clipping plane to reflect a scene about an arbitrary plane, for arbitrarily placed and oriented mirrors.

does someone know how to do that? thanks :)

[Budric]

I haven't done this personally, but I'd start with a definition of a reflection matrix here:
http://en.wikipedia.org/wiki/Transformation_matrix

So you wouldn't be using the scale transformation but using something like glMultMatrixd on the GL_MODELVIEW_MATRIX.

If your plane isn't through the origin then you'd have to apply a translation after the reflection.

[V-man]

Look at glhGeneralPlanarMirrorf_1, glhGeneralPlanarMirrorf_2
in the header file.
http://www.geocities.com/vmelkon/glhlibrary.html

It's open source so you can adapt it to your particular way of transforming your mirror to eye space.