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Caustics - new in Project Dogwaffle's "Puppy Ray GPU", with Howler 11.1
The Summer Splash update 11.1 for PD Howler has brought a bunch of new features for better renderingof indirect light, Skylight, bump texturesfar away and ground fog as well as other features related to better rendering of water. You may have learned already about the dispersion (scattering) for the look of murky waters. You may have seen the attenuation or absorption due to the depth of the water, causing the color of the ocean floor to loose the red channel, then green and finally blue channel when it goes deep.
But, you haven't seen it all, yet.
We also have added caustics. The Sun light may hit the water plane from above at some angle. The waves are causing reflections and refractions. They also bend the sun's rays into areas that are focused brighter on the ocean floor, especially when close to the beach. The more shallow the water, i.e. the closer the ocean floor is to the surface of the water, the more likely it has a chance not to be completely absorbed, and thus remain visible. And it appears as an animated, dancing light show of caustics curves, as mentioned, unless it hits the floor too deep and is absorbed into oblivion on the way down or when coming back up from down deep.
Caustics have two natural enemies: absorbtion, and scattering. The absorbtion (or attenuation, as we also call it), makes light from the deep parts disappear. First the red channel, then the green and eventually even the blue is gone. Scattering will diffuse the colors coming from the ground and add a milky, murky appearance, whose color you can set too, and which can also mask the faint details of caustics.
To learn more about caustics in Puppy Ray GPU, look for details here: the Summer Splash 11.1 update
Here are examples where caustics are used:
Crashing waves appear to have foam - from far away. It is 'just' caustics.
Here's another example with caustics used to simulate foam on the water coming from crashing waves. This is a composition with the two panels showing, so you can explore the values used for caustics, attenuation, wave height, etc...
and finally, this one is focused on another visual effect: using Real Fresnel angle caalculation to determine whether to reflect the view above or to refract the view below, in which case caustics may appear too. Since it is very shallow, you will easily see some places with bright spots, possibly due to caustics. If caustics were not enabled, you might see a slightly darker overall appearance of the parts of the water that refract and show the rocks below. We also have a little bit of specular highlights going on here, which adds to the wet look.
Here's an animation with a number of renderings, some with mild caustics:
And next time you see a cool image, ask yourself, with a Southern accent: Is it Real, or is it Puppy Rayl ?
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