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Soft Selection For Groupsop


Jordan

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Hi, guys.

I am running an ocean whitefoam simulation which using the groupSop's bounding box to select

points from an ocean mesh(generated by HOT) when the points reach certain frequency.

To spawn the particles more gradually, i notice i have to apply soft selection to those point's group

which is unavailable in groupSop.(Maybe we are able to do that in groupSOP, it just out of my knowlege.)

You guys have any ideas or an alternate way to do it?

Here is the attached video.

Ocean_whiteCap_rnd.mov

much appreciated,

jordan.

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The concept of a soft selection while being more general than "groups", is less general than the concept of "attributes". So the answer is to use point attributes. Recall that to convert a point group to an attribute, just use the haspoint() expression in an AttribCreate SOP. Note also that it's not clear as to how you want the selection to be "soft" in the first place. There are a near infinite number of ways to do it. So create your attributes the way you want them to behave and combine them in the way you like.

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There are a nearhe concept of a soft selection while being more general than "groups", is less general than the concept of "attributes". So the answer is to use point attributes. Recall that to convert a point group to an attribute, just use the haspoint() expression in an AttribCreate SOP.

Thanks edward, i've worked out a solution b4 your reply but i still prefer to do it in the way that you suggested which is make use of the real houdini's power "attribute".

Note also that it's not clear as to how you want the selection to be "soft" in the first place. There are a near infinite number of ways to do it. So create your attributes the way you want them to behave and combine them in the way you like.

erm... what about we use the soft-radius in editSOP as a standard unit say 0.5.

does the haspoint() experession allow me to apply soft radius with the range of 0.5?

And here is my solution which is a non-solid way of working.

I append a editSOP right after the groupSOP, then i make use of the soft-radius

in editSOP while remain the point's group with certain falloff range which generated by soft-radius.

Then I append a deleteSOP to delete the inverted selection of points.

And i use that to generate particles now.

Thanks.

jordan.

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No, the haspoint() expression gives you a 0 or 1 value for whether the point belongs in the group.

For some reason I keep thinking that when people say "soft selection", they just mean a selection isn't just a 0 or 1 value, but can be any value between 0-1. But maybe you just means a "falloff" from a point position. For that, I've lots of examples before but I can never seem to find them again on the forums. :)

Anyhow, for the "softselection" file attached, move the controller around. For the "dist_blend" file, just hit play to see the effect.

I keep forgetting that Simon Barrick has examples on the Houdini Exchange as well:

http://www.sidefx.com/exchange/info.php?fi...p;versionid=105

http://www.sidefx.com/exchange/info.php?fi...mp;versionid=96

softselection.hipnc

dist_blend.hipnc

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