@DrDoom9It is not as easy as you would think. You need to perform a projection of the original image onto whatever surface the shadow is to fall, turn it into a partially transparent silhouette, blur it and, in some cases, trim it if it reaches the edge of the surface it falls on.
To get a realistic shadow on a horizontal floor you need to do the following
1. Recoloured a version of the image to grey and partially transparent.
2. Invert it
3. Reposition it under the original
4. Rescale it vertically
5. Apply a shear transform to offset the head end horizontally
6. Apply a taper transform
7. Blur the edges
8. Optionally trim it
(Actually this list applies to shadows on any flat surface, though item 2 may then not be needed).
Of this list only items 1 to 4 can be done in a straightforward way using just the facilities provide by the scene description language used in the .scn file and you could do 8 in a less straightforward manner. Items 5, 6, and 7 can only be done using a shader. Fortunately Totem have provided a couple of blur filters in used in a few of their scenes and one of these, or slightly tweaked versions, are used in the majority of scenes that go beyond simple hard edged shadows.
But Totem have not provided shear or taper transform shaders so if we want to apply these distortions, which when combined with rescaling and repositioning. create a full projective transform then we have to do it ourselves. We could use separate shear and taper shaders, or a combined shear and taper shader, but it is more efficient to combine all the shaders, including that for blurring, into a single shader.
I have done this and you can get a copy by downloading http://www.theemusnest.eu/scenes/Zips/TheEmuLib/0000%20-%20Basics.zip
where, after unzipping, you will find two such shaders in the folder
TheEmuLib = Library/Shaders/TheEmuLib.Misc
with examples of how to use them in the TheEmuLib = Library folder itself. These examples include showing how to create shadows that fall partly on the floor and partly on a wall behind the performers.
Unfortunately they are rather awkward to use as I find that after adjusting one parameter I frequently need to then readjust others so that getting things to look right turns into an iterative procedure gradually improving the outcome each time. One of these days I may get round to improving this to make it more user friendly.
There are examples of my using them in
http://www.theemusnest.eu/scenes/Zips/TheEmu%20=%20Misc.zip
where they are used in the Hotel Lobby and Music Room Scenes
and in
http://www.theemusnest.eu/scenes/Zips/TheEmu%20=%20Club%20Callipyg.zip
where one is used in the TheEmu = Club Callipyg - A2 - 3 acts.scn scene.
Warning, the Emulib zip file is 62 MB in size and the Misc scene zip is even larger at 110 MB, but the Club Callipyg zip is only 4.8 MB.
If you do decide to use them then a tip is to initially set up the scene using a poledance clip as then you have a fixed point, the bottom of the pole, to use when you are tweaking the parameters to get everything looking right. You can then change to using other clip types once you have position the shadow using pole clips. (this of course will not work if you want to use table clips or swing clips).
