Does anyone know how (or if it is possible) to sense the light intensity on a particular surface? My goal is to have an expression that reacts to the amount of light that is hitting the surface (or point on the surface). TIA!
You can use a surface luminance node to tell you how bright an object is, but it only acts within the render of a frame. You might be able to have the luminance node set a global variable and use that to trigger some expression on subsequent frames. It makes more sense to base the expression conditional on the light's intensity.
/*In theory there is no difference between theory and practice
In practice they are very different*/