Intro:
Shadows are an extremely useful visual clue of depth, size, and relationships
between objects. A lot of people have expressed disatisfaction that
Director 8.5 does not have support for shadows. Shadows, however, are
extremely computationally slow or place a huge burden on the graphics
card, which makes them impractical for current projects on current hardware.
All is not lost however! It is easy enough to mimic simple shadows,
and so below is one fairly flexible (I hope!) solution.
Method:
Basically I do create another copy of the model to be shadowed, and
squash it flat!.
To make it look right, there are obviously a few gotchas, but they introduce
some interesting facts about Director 8.5.
Firstly, I create a shadow shader. This gets applied to the shadow object
(what I call my copy of your model). It contains no texture, it's merely
a colour (which you can set). It accepts no lighting from lights in
the scene (after all, shadows are not actually something for light to
reflect off of.
Secondly to make the shadow object look correct from the point of view
of the light, I also skew my model. This involves directly manipulating
the shadow object's transforms, which as well as achieving the desired
effect also breaks Director's standard transform functions. Because
of this I create several groups and nest them, with the shadow object
at the bottom. This allows me to perform certain operations on certain
groups. EG one of the groups is purely for skewing, and another for
scaling. This allows me to carry on rotating and positioning the other
groups happily without breaking anything.
All this can be played with if you wish, but the main aim of this code
is to allow people to use shadows as simply as possible, therefore I
won't be explictly detailing my shadows commands, just the two lines
of code you need to make it work :)
One final point - you can move the object 'through' the shadow plane.
Since this would equate to the model going through solid ground, it'll
look wrong. That'll teach you.
In Practice:
To succesfully use the shadows you only need write 2 lines of code::
Creating the
shadow object script.
For this you create a new instance of the "[P]
Shadows" script, with one of the following lines of code:
where tWorld is the name of the 3D member you wish to create the shadow
object in.
tObj is the name of the model or node you wish to create a shadow
object of. It must exist in member tWorld. Why do I say node as well
as model? Because you can pass the routine (for example) a group that
contains a collection of models, and all models in the hierarchy will
be shadowed correctly. This makes life easier - you can group a set
of objects together and just use one shadow script for the lot.
tLight can be an integer, a string or a vector. If it is an integer
then the light direction vector is calculated from the direction of
member(tWorld).light[tLight].
A string is almost identical, but it refers to the explicit name of
the light, IE member(tWorld).light(tLight).
tFloorHeight is the height in world units along the Y axis, of the
floor plane the shadows are cast onto. This can be any value, positive
or negative.
tShadowColour specifies the colour of the shadow shader and hence
the shadows. It is supplied in rgb(red, green, blue) colour object
format. If this is omitted, then it defaults to rgb(0, 0, 0) - black.
Updating the
shadow object.
If the model changes or the lighting changes, the shadows need to
be recalculated. This is done by calling the following object handler:
tShadowObj.UpdateShadow()
where tShadowObj is the object reference returned when you created
the shadow script instance.
It should be noted that if the light is shining upwards (IE from underneath
the shadow plane) then no shadow is cast - the shadow object is removed
from the world, and added back again if or when the light shines downwards.
Note that lighting directions are only recalculated if you supplied
a reference to a proper Director 8.5 light (see tLight parameter above).
When you call UpdateShadow() the code looks at what the current direction
of the light is and uses that for the new shadows.
Download the source here. 
