Controlling cloud placement with the painter shader / "Fit to blendshader to thi

[PG]

Hmm. na, I tried -5e+007, -2e+007 and -1e+007 but it didn't work. But you're right, it is an inside-out sphere.

Edity: Here's what it looks like at a size of -40 from the outside I painted inside it and it created a cloud inside without affecting the outside world. Works after all. woo

[FrankB]

I've got an image that you can see below where I would like to mask out all the clouds below the red line, I only want to see the clouds above the red line.

If you still want to mask away clouds below the red line, here's a really simple method that just works:
Create a distance shader and use it as a blend shader for your cloud fractal, set the near color to white, the far color to black, and adjust the distance value so that it fits your scene. Near distance would be 0 and far distance - well you'll have to try but start with ..10k

If you still want to mask away clouds with the painted shader, why not set your camera to an ortographic view and paint onto the ground of the planet (paint where you want the clouds to appear), THEN use it as a blendshader for the cloud fractal. Shoud work, too, but is more complicated than the other solution with the distance shader. Also renders slower.

Frank

[reck]

Hi Frank, in the end I decided to use a distance shader. I didn't quite do it as you describe though, it sounds your method is best and next time i'm going to try it your way. Sounds like a simple, fast solution which is what I was trying to get with the painter shader.

[PG]

I just asked oshyan and he says the fit to blendshader tries to "fit" the blend shader to the scale of the shader in question.
So if you use an image map in the shape of an "S" but you don't configure the mask to the same scale as the thing you're trying to mask then this option will estimate that work for you. It's preferable to work out the proper scale and translation to use on the mask as it provides higher accuracy.

[reck]

I didn't think I was going to get anyone come back to me with a response regarding the "Fit blendshader to this" option. I never know if I should tick it or not. PG thanks a lot for asking and making the effort to post the information here, really appreciate it.

Well that's another option I can tick off my "what the hell does this option do" list.  

Cheers PG

[PG]

Got any more?