Development Journal of a Raytracer

I have worked on the refraction definition today. What I had was nearly uncontrollable. I think it is a bit better now, but I still have to check something.

The refraction code has the ability to filter the light based on thickness of the material. It is only the first order solution, so I am only using an exponential function. Before I used a color in the UI which was abused so that the color components directly defined the constants in the filter. That made it hard to control. The UI always showed the inverse color of the filter (so if I wanted the filter to be green, I would turn green to a very low value and red and blue to a high one, the color shown would then be magenta). Also the density was not controllable at all. And finally the domain was limited to 0 to 1 (which is not sufficient).

Now I do it a bit differently, I define the color of the filter depending on a specified depth. I think that should work better. But I also have one issue, the resulting color looks too light for me, it is as if the density was not correct. I will have to check the code again, but it could also be the result of tone mapping.

I managed to finally model a bit. I haven't rendered a new picture, but I seem to make some progress. The paw now has some toes and the overall outline seems to slowly get into the right shape. I had to change some things, I noticed too late that the reference images I had used was showing the leg a bit twisted to the outside. The reference should mainly show the skeleton of a cat and to show that of the paw the leg was shown twisted so the bones of the five toes can be clearly seen.

But for modeling that is not a good way to do it. I want to give the model a skeleton and there it is hard enough to get it right without watching for even more details. I also noticed that some of my lines didn't fit and would result in problems later when animating the cat. So I fixed those.

The last problem I saw was, that the overall form of the paw is not right when seen from behind. I hope to fix that tomorrow and then I will have to do some more detail work. I hope it ends in a nice paw and if it does I will render a new picture of the model.