Indigo Renderer Forum

Hi.
Strange things. Only the fbm posOS() seems to work actually.
I´m not able to make it work even with old betas of the serie 3.8 (this is the strange thing).
Can anybody check if fbm noise works correctly for bump or displacement please?

Strange - I successfully used fbm bump for the coating of my carpaint material: http://www.indigorenderer.com/forum/dow ... &mode=view

I used Indigo 3.8.25 for that.

Hi Oscar.
PosOS() works fine and is the one you use for the orange peel of the carpaint (what a beautiful material).
Fbm, fbm01 and fbm3Valued seems don´t work here.
Could you just try it please?
Thanks for the quick reply.

I think this was intended behavior - something about how bump and displacement shaders alter the absolute position of the object surface, which can produce a loop of sorts, and so the shader can't evaluate it properly. it works with posOS(), as you mention, but why that works is above my paygrade.

I have been digging into ISL a lot lately and I still find it confusing which functions are allowed for which channels and shaders. I was trying to do a blend material recently with meanCurvature(), I believe, and while it didn't give me an error, it didn't blend as I expected. there was basically no relationship to the black and white shading you get when using meanCurvature() as an albedo shader.

this stuff is probably clearly defined in the manual, but I have yet to fully grasp it. maybe some simple guidelines of what's allowed or restricted for ISL in certain channels would be a help.

yonosoy wrote:Hi Oscar.
PosOS() works fine and is the one you use for the orange peel of the carpaint (what a beautiful material).
Fbm, fbm01 and fbm3Valued seems don´t work here.
Could you just try it please?
Thanks for the quick reply.

Ah, pardon me. And thanks!

FakeShamus wrote:I think this was intended behavior - something about how bump and displacement shaders alter the absolute position of the object surface, which can produce a loop of sorts, and so the shader can't evaluate it properly. it works with posOS(), as you mention, but why that works is above my paygrade.

I have been digging into ISL a lot lately and I still find it confusing which functions are allowed for which channels and shaders. I was trying to do a blend material recently with meanCurvature(), I believe, and while it didn't give me an error, it didn't blend as I expected. there was basically no relationship to the black and white shading you get when using meanCurvature() as an albedo shader.

this stuff is probably clearly defined in the manual, but I have yet to fully grasp it. maybe some simple guidelines of what's allowed or restricted for ISL in certain channels would be a help.

I have bumped into similar caveheats and this is about polishing once beta features I'm sure.
I happen to have requested the option to have the shading evaluated either before of after displacement, if that allows for pos(). We (I) need (want) pos() allowed everywhere !

I experienced a partially black albedo shader just yesterday, the bottom of the render sphere was showing black (it's not uncommon when developing shaders). I'll take notice of the circumstances next time and report.

edit: actually it's illustrated here. Probably happens when very high pos/tex frequencies are involved.