not sure if you are currently doing something similar, but when i programmed my own ray tracer, i found that this simple optimisation really spead up the tracing.

-split your film into 4x4 blocks
-for a given block raytrace each of the 4 corners taking note which object was the first object hit.
- if all four rays hit the same object then assume that the remaining 12 pixels in the block hit the same object and so for these 12 pixels start the ray trace from the intesection with the assumed first object.

I never got around to extending this idea to include the whole order of objects at each intersection. I believe further speed reduction can occur if you do take into account all the objects that the ray (inital and secondary) rays hit by each of the four corner pixel rays. i.e. assume that all the 12 pixel rays hit the same objects (primary and secondary rays) until the point where all four corner pixel rays' object intersection order nolonger are identical.

UPDATED !

fps is now 140 at low res on my pc (and 40 fps at mid res).

There was a very big hidden bottleneck : graphics.draw() took 2/3 of the frame rate due to scaling. I have replaced it by a programmatic scaling.
Another big improvement is the borders collision testing algorithm (thanks moogie !)

10.5 fps on my PIII-800 (still too low...)

It's time to try it again :-)

Lilian

Thank you jbanes !

I think I should try to put them back, but it's going to be hard... the byte codes deleted have been filled with optimizing algorithms ;-)

Come back in an hour or so...

Lilian

Very impressive!  32 FPS on medium rez with an AMD 2600

21fps on normal game

all 4k games are ugly