Painted shader on water - objects become invisible.

[David]

Hi, Is it possible to use the painted shader around objects that are immersed in water? The image below shows oars in water that I need to paint ripples around. I have no trouble painting the water on it's own but I can't obtain a view that shows the oar objects in the same frame as the 'active' water. The lower image shows the water ready for painting but the oars invisible. Any ideas much appreciated.

[Hetzen]

I'm fairly sure you can get the oar objects and water to be in the same preview. Have you frozen the preview before you start painting?

[David]

Thanks Herzen, I presume you mean, have I 'paused' the preview, yes. I imagine it must be possible but as far as I can see, painting seems only to work on terrain, water and sky. Hope I'm wrong because I can't think of a workaround.

[Hetzen]

Can't say I've ever tried painting on another layer. If you position your camera top down and paint on the land, then save that as a mask, then re-project that as a mask for your water layer that should work?

[Dune]

Painting can be done on the water plane/sphere, afaik, as I've done that once in a while. It can't be done on objects (like oars). It's best to set objects to smooth shaded, and perhaps replace reflective by a plain color on the water layer for ease of work. And pause the preview indeed. Should work.
The way I did my Roman oars foam mask was to make a topdown image from Lightwave, and paint the mask in PS. But that was for a still.

[Matt]

If I understand you correctly, you want to paint on the water and you just need to be able to see the objects at the same time. To show objects in non-RTP mode, use the cube-shaped icon to show the object display mode menu.

[David]

Thanks Guys,
This is a first look-see at the model with splashes and a wake, hence the delay in replying. Working from top-down finally worked for me but I used painted image maps rather than mask painting. I've just tried Matt's suggestion and yes, that works extremely well, so will try that too. I created a local displacement map for the wake which works pretty well and an image map for the foamy bits which works less well. This last might be improved now that I know I can paint on the water. The splashes are geometry, decimated down to 6k polys - the least I could get away with - made in PS, Zbrush and Lightwave. I've given them a tiny bit of motion blur in final render. First pic shows painted wake well but gets obscured in the wake of the lower angle of the second pic - need to fix that. I'd rather like to experiment with some subtle spray but not sure how - is that your department Ulco? By the way I was looking for your Roman ship - is it still on your website? I love your work by the way! In case you are wondering why all the rowers are upright instead of leaning forward or back, apparently space in triremes was very limited and they didn't have sliding seats, so their arms had to do most of the work! Final message to WAS, in the end I opted to use just the glass shader for the splashes but with plenty of roughness as you suggested. Boy this is slow work!
Thanks again guys

[WAS]

If you render a ortho of just the oars (for quick rendering) you can easily paint a spot at the center of each end of the oars, and use that to populate all your splashes quickly. You can lower the rotation to keep them more in line with direction. If you do, keep in mind when you ortho, you want to import at those scales. So a 1000m x 1000m ortho should be a 1000m x 1000m image map when imported back. Keep in mind camera location for the map as well. The spots can be fairly small, and when you populate you want the spacing to be just about as wide as the spot (you can just play with spacing) so only one appears at each position.

[Dune]

It's looking very good so far. Interesting to hear they had to stand and row!

I wouldn't add spray, actually, as it's hard to get the shapes right. Though it's nice to experiment of course. You'd need to add a low (~1m) v2. cloud layer and mask areas for the spray, perhaps slightly elongated patches the way Was describes, or from painted shader on the water plane. Very small scales for the cloud fractal, and quite some density. With low quality settings, the particles could look like water drops.
Another way would be to use that painted/ortho mask and an additional (warped) PF for variation of density to make a population of the internal rocks. Tiny sizes, very small spacing, glass shader if needed, though I'd say a default shader with reflection and translucency would work just as well on a bit of distance. I've done waterfalls like that.

Another way of doing all the splashes would be to make vector displacement maps (one with al splashes or more for each splash), which would displace the actual water plane into splashes. But that's quite some  work too, and I've only managed to do that in Mudbox.

My Roman boat is still on the site, under 3D renders,  a bit down. And thanks for the compliment

[WAS]

Just another thought on those splashes, if you do the ortho route, you could do the dots in RGB (red, green and blue) and randomize the colours used, and then in TG you could use 3 populations, and mesh warp each one uniquely. That way, coupled with size variation, you should have a mix and possibly not draw eyes with repetition of shapes.

[WAS]

Have a play with this for a spray base if you want, as well.

[David]

Thanks again guys, You've given me plenty to play with here! Thanks WAS for taking the time to post the spray test scene - I've learned a lot from just studying the node trees. I can see that this technique would work very well for smoke from, say, a campfire. I will try your idea about populating the splashes. 
Ulco, I presume that you have a similar setup for the smoke rising from some of your houses? I looked at doing the splashes with VDM's but I think you are right  - they look like a lot of work and are probably above my 'pay-grade' anyway.

[Dune]

I haven't looked at WAS' setup, but the smoke from my houses is post. Too much work to get that done in TG. Furthermore, smoke and haze works better on a larger scale, IMO. Less prone to grain too.

[WAS]

Furthermore, smoke and haze works better on a larger scale, IMO. Less prone to grain too.

Yeah if you're too close you gotta lower jitter, and up quality by a lot if you have small scales. My campfire flames for example are clean, but slow.