Tag Archives: attributes

Setting the DataArray2D attribute in scripting

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Last time I tried this, I gave up on JScript (it seemed impossible) and got something to work in Python.

In JScript, I kept getting errors like “# WARNING : 3392 – Invalid offset specified while extracting data from this attributeÈ.

si = Application
from win32com.client import constants as C            # win32com.client.constants

oObj = si.Selection(0)
oICEAttrMats = oObj.ActivePrimitive.AddICEAttribute("MyString", C.siICENodeDataString, C.siICENodeStructureArray, C.siICENodeContextSingleton)
oICEAttrMats.DataArray2D = [["a", "b", "c", "d"]]

x = oICEAttrMats.DataArray2D
print x
print len(x)
print len(x[0])
print len(x[0][0])

for d in x[0][0]:
    print d


# (((u'a', u'b', u'c', u'd'),),)
# 1
# 1
# 4
# a
# b
# c
# d

See also this Getting DataArray2D attribute values post.

Finding degenerate polygons by area

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Degenerate polygons are usually zero-area polygons.

Here’s a script that uses the ICE attribute PolygonArea to find polygons with area less than a specified epsilon:

si = Application
epsilon = 0.00001

# Get PolygonArea DataArray (which is a tuple)
attr = si.Selection(0).ActivePrimitive.GetICEAttributeFromName( "PolygonArea" )
areaData = attr.DataArray

#
# Find the indices of the bad polys
#
bad = [ x for x,y in enumerate( areaData ) if y < epsilon]

# Select the degenerates with a string like 'cube.poly[112,114,155]'
si.SelectGeometryComponents( 'cube.poly[%s]' % ','.join(str(i) for i in bad) )


### OR ###

#
# Get the actual Polygon objects
#
polys = si.Selection(0).ActivePrimitive.Geometry.Polygons
bad = []
for i in range( len(areaData) ):
	if areaData[i] < epsilon:
		bad.append( polys(i) )

si.SelectObj( polys )

Getting the DataArray2D for the Materials ICE attribute

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Here’s the Python way:

Application.SelectObj("Pedestrian_Mesh.Actor_Copies", None, None);
o = Application.Selection(0)

a = o.ActivePrimitive.Geometry.GetICEAttributeFromName("Materials")
print len(a.DataArray2D)
print len(a.DataArray2D[0] )
print a.DataArray2D[0][0]
for s in a.DataArray2D[0][0]:
    print s

# 1
# 1
# (u'', u'Sources.Materials.PedestrianLib.Shoes', u'Sources.Materials.PedestrianLib.Hair', u'Sources.Materials.PedestrianLib.Legs', u'Sources.Materials.PedestrianLib.Skin', u'Sources.Materials.PedestrianLib.Shirt')
# Sources.Materials.PedestrianLib.Shoes
# Sources.Materials.PedestrianLib.Hair
# Sources.Materials.PedestrianLib.Legs
# Sources.Materials.PedestrianLib.Skin
# Sources.Materials.PedestrianLib.Shirt

And here’s how to do it in JScript:

o = Selection(0);

a = o.ActivePrimitive.Geometry.GetICEAttributeFromName("Materials");

x = new VBArray( a.DataArray2D ).toArray();
y = new VBArray( x[0] ).toArray();
for ( var i = 0; i < y.length; i++ )
{
    LogMessage( y[i] )
}

Saturday Snippet: Getting data from a DataArray2D ICE attribute

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I wanted to do this JScript, but I had to do it in Python first, to establish that it was actually possible (with JScript, you’ve got to mess around with VBarrays and such).

# Using one of the CrowdFX sample scenes:
Application.SelectObj("Pedestrian_Mesh.Actor_Copies", None, None);
o = Application.Selection(0)

a = o.ActivePrimitive.Geometry.GetICEAttributeFromName("Materials")
print len(a.DataArray2D)
print len(a.DataArray2D[0] )
print a.DataArray2D[0][0]
for s in a.DataArray2D[0][0]:
    print s

# 1
# 1
# (u'', u'Sources.Materials.PedestrianLib.Shoes', u'Sources.Materials.PedestrianLib.Hair', u'Sources.Materials.PedestrianLib.Legs', u'Sources.Materials.PedestrianLib.Skin', u'Sources.Materials.PedestrianLib.Shirt')
# Sources.Materials.PedestrianLib.Shoes
# Sources.Materials.PedestrianLib.Hair
# Sources.Materials.PedestrianLib.Legs
# Sources.Materials.PedestrianLib.Skin
# Sources.Materials.PedestrianLib.Shirt

After I had it working in Python, I was able to figure it out in JScript:

// Using one of the CrowdFX sample scenes:
SelectObj("Pedestrian_Mesh.Actor_Copies", null, null);
o = Selection(0);

a = o.ActivePrimitive.Geometry.GetICEAttributeFromName("Materials");

x = new VBArray( a.DataArray2D ).toArray();
y = new VBArray( x[0] ).toArray();
for ( var i = 0; i < y.length; i++ )
{
    LogMessage( y[i] );
}

Finding empty polygon meshes

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Now that there are intrinsic ICE attributes like NbPoints and NbPolygons, there a couple of ways you can check for an empty mesh:

# Assume a polymesh is selected...
o = Application.Selection(0)

# Check the intrinsic ICE attribute
nb =  o.ActivePrimitive.ICEAttributes("NbPoints")
print nb.IsDefined and nb.DataArray[0] <= 0

# Check using the object model
print o.ActivePrimitive.Geometry.Points.Count <= 0

The typical way to package this up for users it to define a filter. Then a user just has to select the filter and press CTRL+A. Here’s the Match callback for a filter that finds empty polygon meshes. Note that I switched to checking the number of polygons. That way, if somehow there was something weird like a mesh with just one point, you’d still find it.

The intrinsic attribute NbPolygons should always exist, but just to be sure I check IsDefined, and if that is False, I fall back to checking Geometry.Polygons.Count.

# Match callback for the EmptyPolygonMesh custom filter.
def EmptyPolygonMesh_Match( in_ctxt ):
	Application.LogMessage("EmptyPolygonMesh_Match called",constants.siVerbose)

	o = in_ctxt.GetAttribute( 'Input' )
	if o.type == 'polymsh':
		nb =  o.ActivePrimitive.ICEAttributes("NbPolygons")
		return (nb.IsDefined and nb.DataArray[0] <= 0) or o.ActivePrimitive.Geometry.Polygons.Count <= 0
	else:
		return False

I packaged the filter as an addon. Get it here.

Copying a polygon attribute to vertices

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This question came up last weekend (on si-community and xsibase): how do I copy a polygon attribute to a point attribute?

As Chris_TC and gray pointed out, a point can be associated with multiple polygons. So you use VertexToPolygons to either build a per-point array of polygon attribute values, or you do something like average the polygon attribute values and store that as a point attribute value.

ICE attributes: user-defined versus built-in

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ICE attributes are categorized as built-in or user-defined, so you would assume you could easily find your own custom attributes by checking the AttributeCategory property. However, try this: create an empty point cloud and run this script:

si = Application
attrs = si.Selection(0).ActivePrimitive.Geometry.ICEAttributes;

# There's also a "unknown" category but I'll ignore that here
for attr in attrs:
	si.LogMessage( "Attribute: %s, IsDefined: %s, AttributeCategory: %s" % (attr.Name, attr.IsDefined, "Built-in" if attr.AttributeCategory == 1 else "User-defined" ) )

You’ll see that while some attributes, like NbPoints, PointPostion, and PointVelocity are “built-in” as you would expect, most of the attributes are in the “user-defined” category.

For example, size and shape are listed as user-defined attributes. Why’s that?

I think it is because those attributes are dynamic attributes added by [factory-default] ICE compounds. Until you plug in those compounds, the compounds don’t exist and aren’t initialized (in other words, they are not defined yet). They’re not really built into the system (and the attribute explorer is hard-coded to show them as a convenience).

Built-in attributes like PointPosition are intrinsic attributes.

Consider this ICE tree on my empty point cloud. The Size attribute is just like my own custom Xxx attribute, whereas the built-in PointPosition attribute resolves nicely.

If you want to distinguish your own attributes, I’d use a prefix for the attribute names. For example, I sometimes use a “ps” (for Product Support) prefix or a “sisupp” prefix.