LPXO Posted June 8, 2005 Share Posted June 8, 2005 Hey, This question's a bit out there. I'm using the inflate SOP to create a stretchy membrane material because it doesn't "stick" like using collision behaviour with a POP network. I was just wondering if anyone knows the mechanics behind it. I'm writing a report on my implementation and I'm talking about the use of springs for elastic materials..... but I don't think the inflate SOP uses springs. Does anyone know the basic mechanical theory behind it? Cheers, LPXO Quote Link to comment Share on other sites More sharing options...
edward Posted June 8, 2005 Share Posted June 8, 2005 Nope, no springs. It does exactly what it is named. It inflates the first input using the shape of the "tool" geometry. The help card gives more detailed description. Quote Link to comment Share on other sites More sharing options...
LPXO Posted June 8, 2005 Author Share Posted June 8, 2005 Nope, no springs. It does exactly what it is named. It inflates the first input using the shape of the "tool" geometry. The help card gives more detailed description. 18632[/snapback] Thanks Edward. So by my undertanding the inflate tool simply moves a surface point in the direction of the surface normal of the point of geomoetry it collides with (relative to the magnitude of the velocity vector of the geometry point it collides with)? This seems like a far simpler approach than springs when one is calculating a soft body that is not subject to aerodynamic forces and gravity. But I get the feeling this wasn't the reason for the inflate tool being created. I guess I'm thinking out loud here. Anyways, it works perfectly for what I need to do which is what counts! Quote Link to comment Share on other sites More sharing options...
edward Posted June 8, 2005 Share Posted June 8, 2005 Er ... something like that ... no "velocity" per se though but i don't think that's what you really mean anyways. Quote Link to comment Share on other sites More sharing options...
bmcgee21 Posted April 17, 2006 Share Posted April 17, 2006 What exactly is the inflate tool? I was trying to experiment with this node and I can't figure out what is connected to each input, the help card didn't help me much. Any ideas? Quote Link to comment Share on other sites More sharing options...
edward Posted April 18, 2006 Share Posted April 18, 2006 There's a very simply and contrived tutorial in the online help. You'll have to follow the instructions to see the final result though: hdox://houdini/content/base/tutorials/fm_07_guide_character_1023673.xml Quote Link to comment Share on other sites More sharing options...
stu Posted April 18, 2006 Share Posted April 18, 2006 What exactly is the inflate tool? I was trying to experiment with this node and I can't figure out what is connected to each input, the help card didn't help me much. Any ideas? 26576[/snapback] Imagine blowing up a balloon under a blanket so that the blanket gets displaced by the balloon's volume - that's what the inflate SOP does. Quote Link to comment Share on other sites More sharing options...
exel Posted April 18, 2006 Share Posted April 18, 2006 Thanks Edward. So by my undertanding the inflate tool simply moves a surface point in the direction of the surface normal of the point of geomoetry it collides with (relative to the magnitude of the velocity vector of the geometry point it collides with)? 18634[/snapback] --That's partially right, but one important thing to note is that the surface point does not get moved according to the normals on the tool geometry (the collision geometry). Instead, the inflate SOP uses a group of points called the "center group" to determine what direction to send the collided geometry. The "center" geometry should lie somewhere inside / behind your tool (collision) geometry, and the SOP will take each point on your incoming geometry and find the closest point on the center group (not the collision group), and use that to determine what direction to send the inflated geometry. If you've got a muscle shape, say maybe an elongated sphere, try making a line running down the center of the sphere and using that as your center group. Make sure the line has plenty of points on it for the inflate SOP to sample. I've attached a pic to try and over-stuplify what the inflate SOP does, hope this helps a little! -JS- Quote Link to comment Share on other sites More sharing options...
AdamJ Posted April 18, 2006 Share Posted April 18, 2006 ahhh.. those red arrows bring back memories Quote Link to comment Share on other sites More sharing options...
exel Posted April 18, 2006 Share Posted April 18, 2006 ahhh.. those red arrows bring back memories 26632[/snapback] Hah right on Adam... now trim those "spikies" and tone down the bungee Quote Link to comment Share on other sites More sharing options...
thekenny Posted April 18, 2006 Share Posted April 18, 2006 Oh you guys... I'm getting all misty eyed now... you big lugs :cry2: now, get to work. -k Quote Link to comment Share on other sites More sharing options...
bmcgee21 Posted April 21, 2006 Share Posted April 21, 2006 I've attached a pic to try and over-stuplify what the inflate SOP does, hope this helps a little! 26623[/snapback] haha, but thanks, i appreciate the diagram and showing me the tutorial. i couldn't find a tutorial but i think school's help files are corrupted. thanks for explaining guys. was thinking of things to use to make a whale slowly inflate then pop. Quote Link to comment Share on other sites More sharing options...
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