The Knockout shader is used to mask elements of the CG render when composited against the video feed in Previzion. This shader cuts a hole in all CG elements that are behind it, NOT in front! The shader shows no remorse in cutting holes in CG elements.
You may download the Knockout Shader from our Download Manager.
How it works…
Any object with the knockoutShader assigned creates a hole in the alpha channel of the rendering of the CG plate. This hole in the alpha allows for the background video plate to be seen. Any part of a standard 3D element which is rendered behind the knockoutObject will be hidden by the knockoutObject. Any part of the standard 3D object NOT occluded by the knockoutObject will be rendered as normal and will occlude the background video plate.
Because the shader is essentially a black hole, an additional wireframe mode has been added. To turn it on, set the value to “1.”
For more information, click here