Question by DigitalMagic · Dec 11, 2013 at 06:08 AM · shader shadows shadow

How to measure the area of shadow on a GameObject?

Good day everyone.

I have a simple scene: a plane with several cube GameObjects (of varying sizes, with textures on each facet) and a directional light shining at an angle (with hard shadows). The result is that each facet of most of the cubes has a differently-sized shadows cast on it.

Is it possible to read how much shadow is cast (in percentages maybe?) on each facet of a cube?

I was thinking maybe by reading how the color of the texture on each facet of a cube changes by the shadow cast on it, but I do not know how to do it.

Does the color of the texture actually changes?

Do I need to read some light map on a GameObject to determine this?

Could someone provide a sample code on how this could be done?

Thank you!

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fafase · Dec 11, 2013 at 06:10 AM 0

I do not quite get it, if you have the cubes on scene, the shadow is not on them but on any object behind them.

Then you can read on: http://web.cs.wpi.edu/~matt/courses/cs563/talks/shadow/shadow.html

tanoshimi · Dec 11, 2013 at 06:48 AM 0

Also, section 9.4 of the Cg tutorial has a good explanation of the basic technique: http://http.developer.nvidia.com/CgTutorial/cg_tutorial_chapter09.html

DigitalMagic · Dec 11, 2013 at 07:33 AM 0

Of course not all the cubes have shadows. I am asking, how do I access that information in Unity?

I want to know, for each cube that has a shadow cast on it, to be able to calculate how much shadow is cast, without having to implement an outside algorithm to do it.

I mean, the information is right there - the shadow is displayed correctly after all. I am only asking - how do I access that data and read from it?

tanoshimi · Dec 11, 2013 at 07:42 AM 0

You can't. Follow Aras' advice to render it manually from the light's POV using the information already provided.