Indigo Renderer Forum

How do I use pos for bump mapping ?

Can't do eval(vec3 pos) real.

Hi CTZn,
I'll add a posWS() function soon that will return the world space position when available.

You seem to imply that I could use posOS() already, wich makes sense for wooden objects. I'll have to try this, thanks !

CTZn wrote:You seem to imply [...]

Ah no you didn't

Is it possible to compute the maximum range returned by a fbm ? At iteration 1 it is ~ [-0.83 : 0.83], at it8 absolute is above 1.1. It's not easy to get everything into the 0:1 range since min and max are variant, depending (mostly) on the iterations. I guess I need to know a (simplified) ratio that adds to intensity with iterations.

Could I also have a working example for the print statement ? I thought I would print the fbm values as they go evaluated but couldn't figure it out. Thanks.

Practically I'd need a fbm within the 0:1 range to apply curves on it.

Hi CTZn,
Base Perlin noise returns values in the range [-1, 1].
FBM with one octave is just perlin noise.
FBM with infinite octaves should lie in the range [-2, 2], but most values will be near the zero than near the extreme values I guess.

Printing should work, the only problem is that it prints to stdout. Try running the console indigo

The problem with extreme values is when they produce clipping, my concern is vertical

I'll play more with the normalise functions eventually, maybe that's just what I want.

Thank you for the tip Sir !

If I may add a question to this thread, is it possible to emulate normal map functionnality through ISL?

Perhaps someone like galinette could make use of a normal map data while dealing with bump mapping, but otherwise I think emulation would require the writing of certain parameters that are not exposed in Indigo despite a request (would allow NPR shading).

I am not sure on that topic though, I may be mixing facts... for the matter I am bumping your question

It is mathematically possible do derivate the normal map from a height map, by calculating the gradient vector of the height map. That's actually what renderers do.

However, it's not possible to compute a height map from a normal map in general : arbitrary normal map has a non-zero rotational vector, which means it cannot be derivated from a height map by a gradient.

If the normal map has a uniform zero rotational vector, it's theoretically possible to compute a height map, but this require numerical integration which would be a non-local calculation... not possible in a simple shading language, and always computationally intensive.

If your normal map is a texture (not a shader), there are maybe tools that could compute a height map from it (provided the fact that they will need to remove the rotational component of it if non-zero, thus modifying the appearance of the material)

Try this : http://www.crazybump.com/

Etienne

Thanks I'll try that