Honestly I have never had luck with these, ever, not once. At least not on my own accord. There will be need for them in this, I think, unless we can fake light beams which I think would be more of possibility than using volume shaders. I am trying to use the smoke.sl shader in a shader test scene so I can test out various ideas and so far I have had no luck. Anyone want to run a quick tutorial my way so I can use it with Mosaic? I have been able to run some test RIBs and I do have Adv. RenderMan book but for some reason volume shaders just never work with me and I have no idea why or how… sniff sniff lol….
If it helps you can experiment with noisysmoke.sl as a starting point, I know these settings work with Pixie:
vs_noisysmoke
Atmosphere "noisysmoke"
"uniform float density" [ 0.05 ]
"uniform float integstart" [ 0 ]
"uniform float integend" [ 21 ]
"uniform float stepsize" [ 1 ]
"uniform float debug" [ 0 ]
"uniform float use_lighting" [ 1 ]
"uniform float use_noise" [ 0 ]
"uniform color scatter" [ 1 1 1 ]
"uniform float octaves" [ 3 ]
"uniform float freq" [ 3 ]
"uniform float smokevary" [ 1 ]
"uniform float lightscale" [ 15 ]
One of the keys is to start with adjusting density down before enabling noise ;-)
It seems Aqsis won't compile this shader, after making the changes to correct this (simply a variable name change from "incident" to "incidentI") Aqsis still won't render with this correctly. If you could work on some other part of project widow MOSAIC's shaders will eventually have this. Currently I'm rewriting the light shader, then the atmosphere shader, and finally the image shader. The light and surface shaders interacts with the atmosphere shader which is why I'm doing them first. Once I get to the atmosphere shader I can either figure out whats incompatible with the logic/syntax or post a bug if it's something wrong with Aqsis.
Eric
I've uploaded a blender test file, so you can play with parameters to see the results.
Look in the tmp directory (smoke.blend)
Re uploaded, I haven't saved the final version ;)
Works great for me (looks cool too), thanks Cedric =)
Not sure why noisysmoke.sl is giving Aqsis so much trouble but I'll use smoke.sl for reference in MOSAIC's atmosphere shader instead. Hope it works for you too Ted.
Yes I see where I have not "got it" before, renders very well.
If I remember correctly about noisysmoke.sl is that it has some raytrace functions in it? I could be wrong? I remember back a few years ago when I offered a test case scene to Aqsis, the one with the spiky object and all forms of shader types in it that noisysmoke.sl was not compiling. So a variant was made. That whole RIB and shader collection came from Saty (Rendering for Beginners) and as far as I know it was made for PRMan. Either way…
Yes this is much better idea of what to do here, I believe that I just wasn't sure what parameters controlled what. Good test scene Cerdic! Thanks :)
Hey guys,
I downloaded a version of noisysmoke.sl from
http://www.renderman.org/RMR/Shaders/BMRTShaders/noisysmoke.sl
and you're correct - it fails to compile with aqsis. The reason is the odd way that the aqsis shader compiler treats the word "incident" as a keyword rather than a builtin function name… keywords don't have any scoping rules in contrast to function names. I'll add a bug report, but it's easy to work around by renaming the variable so I'll set the priority to low.
Regarding rendering artefacts when using the hacked noisysmoke.sl - is the test case in dropbox or on the ftp server? I've finally got around to setting up dropbox at home, but apparently can't access the project widow files yet.
~Chris.