Hi All,

I was trying to use Unity3d directional light and use it to transform a mesh of 6 vertices(two quads) which is projected on a floor, this mesh is used as a shadow for a 3D Object.

Someone suggested to project the light vector onto that plane and use that vector to translate the vertices. I wish I visualize that concept, because I can't get it all, how come a vector will be projected onto that plane and use it to translate the vertices left or right and shear them?

I have watched Khan Academy projecting a line onto a line and I got it totally.

Hi,

As a 3D modeler, I know that objects have characteristics which are usually adjustable in a 3D modeling software, such as color in the materials or ambient lighting in a diffuse applied surface. I have actually adjusted the light literally thru the 3D or 2D object by making changes which are available in the modeling software. When the modeler makes the setting, then the changes are recorded in a file included with the model in the model folder. Some game engines allow the modeler to also change type and amount of shadow by using the modeling software and/or an SDK included with the game engine. The most common thing that I have seen is some kind of configuration file which the game engine writes (such as xml or a conf.ini file) that can be manipulated directly, with 3D modeling software, by the game engine SDK, or all of these options may be available. This can be for shadow, as well.

Unity3D is fairly well documented. I am sure that there is a module in the coding which you may customize for this sort of thing. Perhaps you need to write an exception so the game engine knows when it should apply your coding to the scene. Not to be mean, but it can't read your mind, if you know what I am saying. I am sure that there is a prescribed way in Unity 3D for coding your own shadow and lighting effects. It might not be exactly by industry standards if they wrote their own library for it.

Hi All,

Someone suggested to project the light vector onto that plane and use that vector to translate the vertices. I wish I visualize that concept, because I can't get it all, how come a vector will be projected onto that plane and use it to translate the vertices left or right and shear them?

I have watched Khan Academy projecting a line onto a line and I got it totally.

Without having heard the conversation - I think this is the gist of it:

Any space of n dimensions can be projected onto a 'surface' or into a 'space' of n-1 dimensions. Ultimately, this is how the "3D" world of a game gets displayed on the flat surface of a monitor or the 3D of the 'real world' displays on a TV.

What was suggested to you is to treat the floor like the surface of your monitor. Make all the projections from 3D space onto that flat surface. Once you've done that, you can translate that surface wherever you want to - everything will seem to shift relative to that surface.