= How to |> use caustics =

Caustics are formed when [light|/light/] refracts through a transparent surface, producing patterns of focused light on the surface behind it. You can render caustics using photon maps and the [physically based rendering|/rendering/pbr] algorithm in mantra.

Additionally, using any of the glass materials ([glass|/gallery/shop/material/glass], [bumpy glass|/gallery/shop/material/bumpy_glass], [frosted glass|/gallery/shop/material/frosted_glass], or [ice cube|/gallery/shop/material/ice_cube]) will provided you with faux caustics by default. For better quality caustics, you can turn off the __Do Faux Caustics__ checkbox on the __Blur.Density.Shadow__ tab which will make the shadow completely black, then use photon maps. For more information, see [Rendering caustics with PBR|/rendering/pbr].

[Image:/images/render/caustics_and_light.jpg]