Point Position Expression

[Xsiv]

I am now tearing through a cloth curtain. It really blows apart. I want most of the cloth to move, but only to tear at the point of impact.

My thoughts are:

Write an expression on the Tear Threshold based on each point's position from the point of impact.

ImpactPos - $PT = dist. Divide this by the size of the object to normalize and put that in the Stretch/Shear/Bend of the Tear Threshold.

I am not sure how to write this. If I put a dummy object at the point of impact, use its transform?

Suggestions?

Thank you

Chris

SlicedCurtainExpression.hipnc

[anim]

what about just using Paint Tearable shelf tool?

you can paint weak spots on cloth

it will create point attributes (stretchtearthreshold, sheartearthreshold, bendtearthreshold) on source geometry which will be used as multipliers to Stretch/Shear/Bend Tear Threshold parameters

if you really need to do that procedurally, I suppose you can change/create that attributes in SOP Solver, and since you can use SOP nodes inside SOP solver, you can use many ways to make just impact area tearable, attribtransfer or VOPs, or just Point SOP with something like your mentioned expression

Edited July 14, 2011 by anim

[Kevju]

I'm sorry to upping this topic, but where is Paint Tearable Shelf Tool?

I'm in Houdini 12.1 and in my cloth Shelf I'have not this tool :

only Cloth Object, Cloth Body, Attach Cloth, Cloth Follow, Stitch Cloth, Cloth Proxy and Distribute.

[anim]

you are right, it disappeared, puff

houdini obviously does more magic than we might like

you can create new tool in the shelf and put this into script tab

import dopclothtoolutils

dopclothtoolutils.selectAndPaintTearableClothObjects(kwargs)[/CODE]