Hi,
it seems that i'll need to dither the Shadows outside the ground-plates in my current Blender project.
I guess that most people do it in some sort of Imaging programm. I was planning to do it in gimp also.
The questions are:
1. how exactly do you do it? Just painting single transparent pixels into rendered image or with some sort of alpha-mask or something like that? I'm really no expert, usually just cutting/pasting and doing other pretty basic stuff.
2. Is there a way to dither those Shadows directly in Blender? It seems to be doable with Composite Nodes(shadow pass?), but I couldn't get it to work yet.
Was planning to ask about Implementation of Alpha-Channel into Makeobj/Simutrans, but already found an old thread about it.
Since there is no alpha in Simutrans, shadows are effectively "Emental" black - pattern of black and transparent pixels. With Gimp you could create a pattern, select the area you want and fill it...
I haven't it test it but seems that using ColorRamp in Composite mode you should be able to extract the shadow. I got the info from this tutorial (http://blendrunderground.com/2008/04/10/introduction-to-composite-nodes-part-2/). The resulting shadow seems to be plain with no alpha, so you just have to cut and paste.
(http://img210.imageshack.us/img210/7615/shadowalpha.th.jpg) (http://img210.imageshack.us/i/shadowalpha.jpg/)
I've been trying to follow the advices of the tutorial mentioned above, and I must conclude it's possible to "render" the shadow in another image/layer and get a good result.
In fact, it's really simple. You need to use composite nodes with this config (all the details are in the tutorial)
us (site down, do not visit) ]/image/show/pmCDEBCS3k/shadow.png](http:///thumbstore/be/pmCDEBCS3k.shadow_thumb.png) (http://files.[%20simutrans%20[dot)
Note: I used an extra node to output the result into a file. the Add node is a Math type node.
and from this scene..
us (site down, do not visit) ]/image/show/g92xq3Gsll/original.png](http:///thumbstore/7e/g92xq3Gsll.original_thumb.png) (http://files.[%20simutrans%20[dot)
you should get these shadows....
us (site down, do not visit) ]/image/show/XsxHvUKUvh/prueba-sombra0010.png](http:///thumbstore/f8/XsxHvUKUvh.prueba_sombra0010_thumb.png) (http://files.[%20simutrans%20[dot)
There's no possible overlaping between the original and shadow images, thus it's just a matter of copy and paste.. :)
us (site down, do not visit) ]/image/show/oUmwmIY4wf/result-shadow.png](http:///thumbstore/f5/oUmwmIY4wf.result_shadow_thumb.png) (http://files.[%20simutrans%20[dot)
Note: I've modified the shadow's color using GIMP to make it more visible.