Monthly Archives: February 2013

Splitting an edge into equal-length new edges

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Here’s the basic idea of how to split an edge into N equal-length new edges. Notice how I work backwards (in the sense that my split ratio decreases). That way I don’t know have to know (or care) about the new edges. I just keep splitting the same edge, whose EdgeIndex I already know.

SplitEdge0

SplitEdge1

SplitEdge2

SplitEdge3

Based on that observation, here’s a rough draft of an ICE tree that takes an edge of length N, and splits it into N equal-length edges.

SplitEdges

Saturday snippet – ShaderDef attributes

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Getting shaderdef attributes. 

si = Application
#sdef = si.GetShaderDef( "Softimage.BA_particle_density3.1.0" )

sdefs = si.ShaderDefinitions
print sdefs.Count # 1390

for sdef in si.ShaderDefinitions:
	print sdef
	for n,v in map( None, sdef.Attributes.Names,sdef.Attributes.Values ):
		print "   %s=%s" % (n,v)

For most shaderdefs, the only attributes are “shaderlocation” and “thumbnail”.
Softimage.BA_particle_density is one of the few that has anything more interesting. If a Softimage.BA_particle_density shader exists in the scene, you’ll get this:

# Softimage.BA_particle_density3.1.0
#    shaderlocation=3
#    thumbnail=particle.bmp
#    {C535FA4D-E44A-45EB-AEE0-9F9AAEA91745}=None
#    {20ECB4F8-A4A1-44FE-956A-0F6E98D541A8}=Color,Id,PointVelocity,Orientation,Size,PointPosition,Age,AgeLimit,StrandPosition,StrandVelocity,StrandSize,StrandOrientation,StrandColor

If you look at the BA_particle_density3 spdl, you’ll see that that last attribute corresponds to the “ICEattribute” entry for the output parameter. That ICEattribute tells Softimage to pull date from the ICE tree during rendering.

SPDL
Version = "2.0.0.0";
Reference = "{047CA80F-9EED-4507-9F83-4BB77C01DFC1}";
PropertySet "BA_particle_density3_params"
{
	Parameter "out" output
	{
		title = "BA_particle_density3 output parameter";
		guid = "{0B955B1D-CCBA-4B68-9CD3-ABE9467D665D}";
		ICEattribute = "Color,Id,PointVelocity,Orientation,Size,PointPosition,Age,AgeLimit,StrandPosition,StrandVelocity,StrandSize,StrandOrientation,StrandColor";