Filter Forge - Underwater-caustics from normalmap?

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Tim2501 Posts: 26 Filters: 63	Hi, everyone! I have a little puzzle for you I never could quite solve: I'm trying to create underwater-caustics for a game I'm working on. I baked a cycle of water-normalmaps I want to create the caustics from, but nothing I try will produce nice looking caustics. Any ideas if/ how it can be done in FF? Here's some informative article about it: GPU-Gems: Water caustics I've also attached one of my normalmaps you can play around with...
	Posted: June 7, 2014 7:56 pm	Details E-Mail
Skybase 2D/3D Generalist Posts: 4025 Filters: 76	The math's kinda crazy haha. I don't know if that can be thrown into FF. But I'm pretty certain it can be faked (accuracy aside). Just in my head I'd first convert the normal map to a bump map and the rest would be tinkering with some values and fudging looks and feelings. I know it's not the best of answers but that's just what I'd do. Pretty crazy though haha.
	Posted: June 8, 2014 3:22 am	Details E-Mail
Rachel Duim So Called Tortured Artist Posts: 2498 Filters: 188	Here's something I tried with a snippet of code I threw together. If it's useful, let me know and I will post it here. Rickster Math meets art meets psychedelia.
	Posted: June 8, 2014 12:43 pm	Details E-Mail
Rachel Duim So Called Tortured Artist Posts: 2498 Filters: 188	Here's another one, a little more subtle. Math meets art meets psychedelia.
	Posted: June 8, 2014 6:13 pm	Details E-Mail
Skybase 2D/3D Generalist Posts: 4025 Filters: 76	Rick, I think Tim means he wants to use the already-exported normal map to generate caustics applicable to other images/textures.
	Posted: June 9, 2014 1:06 am	Details E-Mail
Rachel Duim So Called Tortured Artist Posts: 2498 Filters: 188	True, the image is a height map. My thought was this, in FF it's probably easier to use the refraction tool and the edge detection tool on an existing image (as opposed to trying to create a normal based on the crazy math ). My reasoning, the refraction in water or glass varies based on the peaks (eges) and valleys in the image. However, this method only really works well on gradients... Math meets art meets psychedelia.
	Posted: June 9, 2014 8:59 am	Details E-Mail
Rachel Duim So Called Tortured Artist Posts: 2498 Filters: 188	Might be helpful: Fast Real-time Caustics from Height Fields. Math meets art meets psychedelia.
	Posted: June 10, 2014 9:04 am	Details E-Mail
ThreeDee Lost in Space Posts: 1672 Filters: 112	Simplified (not real) caustics from normal map with Loop:
	Posted: June 13, 2014 7:52 am	Details E-Mail
ThreeDee Lost in Space Posts: 1672 Filters: 112	Even More simplified without a Loop:
	Posted: June 13, 2014 8:00 am	Details E-Mail
ThreeDee Lost in Space Posts: 1672 Filters: 112	Alternate method.
	Posted: June 13, 2014 8:13 am	Details E-Mail
Rachel Duim So Called Tortured Artist Posts: 2498 Filters: 188	Those look really good! How did you do these? Math meets art meets psychedelia.
	Posted: June 13, 2014 9:24 am	Details E-Mail
ThreeDee Lost in Space Posts: 1672 Filters: 112	Here's the simplest method that the second image was done with. Needs your normal map as the source image. (I actually did it first much more complicated before I realized the Lookup component does it in one go...) Simple Caustics from Normal Map V0.5.ffxml
	Posted: June 13, 2014 1:18 pm	Details E-Mail
Rachel Duim So Called Tortured Artist Posts: 2498 Filters: 188	Thanks. I'm going to take a look at this. I've already done some experimenting with the Lookup component. Powerful, takes a bit of thought to wrap your mind around the function. I've already used it for tiling, boring compared to this Math meets art meets psychedelia.
	Posted: June 13, 2014 5:15 pm	Details E-Mail
ThreeDee Lost in Space Posts: 1672 Filters: 112	It is essentially a single-ray caustic: you shoot one ray directly up and use the normal map to check where in the sky the ray will hit. The circular gradient acts as the sky with the sun directly overhead. You can move the sun around in the sky and get it looking different. Real caustics require multiple rays, but like your references show, the math gets more involved. It is probably not all that difficult to script, but doing the refraction math without scripting can be tricky, as the outgoing rays are not perpendicular to the surface.
	Posted: June 14, 2014 3:15 am	Details E-Mail
Rachel Duim So Called Tortured Artist Posts: 2498 Filters: 188	Good stuff. I am going back to school, so to speak. Gotta get my trigonometry skills back up to speed. Haven't used trig or calculus much since college. Caustics are a future challenge, again, thanks for the snippet. Math meets art meets psychedelia.
	Posted: June 14, 2014 10:47 am	Details E-Mail
Tim2501 Posts: 26 Filters: 63	First of all, thank you for all your suggestions I have tried some stuff with the lookup-component myself and came up with a nice solution, which, though not physically correct, looks quite nice. I have attached the snippet, which also contains some of my earlier attempts. CausticsFromNormals.ffxml
	Posted: June 20, 2014 8:57 am	Details E-Mail
SpaceRay SpaceRay Posts: 12302 Filters: 35	This looks very good and interesting, although I do not have time to test it
	Posted: June 23, 2014 11:14 am	Details E-Mail