Try using barycentric coordinates. If you have a triangle with points A, B and C, then you can define a point P on the surface as: A*w+B*u+C*v=P where w+u+v=1 So what you do is set two random numbers for two of the variables u,v or w and set the third variable so they all add up to 1. Then add them ...

Also, even if your random numbers should start from the beginning, they would have to start at the same position as the first ray. So if the first ray was from the camera into the scene and your ray with a repeating random number is somewhere in the middle of the scene (for example from a wall), the...

You could just reduce the max num consec reject. The lower it is the more biased the image gets too.

The reason we have reflector Telescopes is because they are waaay easier to produce that lens telescopes. It would be so hard to produce a lens with several meters in Diameter.
btw I remember lens being hyperbolic.

Whats the problem with the Null?
A real semi reflecting Mirror reflects photons either to the right or to the left. The Null thing splits the ray in two rays with each having half of the former energy.

actually your right, but I didn't notice earlier just how large my mirror is. Will going to adjust it.

now you lost me
I'm updating
edit: its slow

Lol I'm in the hall of fame because I'm 1 of just 11 users

My second test is made with a paraboloid.

Here a picture showing it:

I just built a parabol by hand and its much easer to get it in focus now! Was actually quite easy thanks to the spin tool.
edit:I put in the IES, its very simple, just look at it in texteditor

Nice, how do you do the parable?
I tried it with an special IES and an squashed halfsphere as mirror, but I can't get it parallel, its always diverging a bit.
The IES is a light which sends out max between zero and one degrees and null above that.

I had a pdf of different Displacmentmapping algorithms on my PC. It is ment for GPU, but it should applie to a CPU as well.

Reliefmapping, conemapping or steep parallax mapping would be cool. The problem of it being 2D when seen from the side should be solveable if you map the texture to a cube rather than a plane. (hope you understand what I mean)

How do you get that out? Could you maybe convert image to bmp and back and see what changes?

Cool now you can write your own angle-based dust shader!