hatrick Posted July 16, 2009 Share Posted July 16, 2009 (edited) Hey do you have some common tips for that very often seen effect of dissolving objects ore images with particles? ... in this case i try to setup a scene with a flat image ... a part of that image is rebuild with particles by cop info and "delete by alpha setup" $BBX,$BBZ,D_CA a.s.o. problem is that i need a giant number of particles to get the needed part of the image look opace over the background and that brings me to an unacceptable simulation time for color ore alpha transfer from cop-image to my particles. a simplified setup with less particles and some animated masks in comp neither seem to be the way to go... thx Edited July 16, 2009 by hatrick Quote Link to comment Share on other sites More sharing options...
geo Posted July 16, 2009 Share Posted July 16, 2009 Hi, maybe my tutorial could be of some help ... ? http://www.sidefx.com/index.php?option=com...&Itemid=132 Cheers Quote Link to comment Share on other sites More sharing options...
hatrick Posted July 16, 2009 Author Share Posted July 16, 2009 thx i know that one some further information would be great i ve found that one in youtube ... made with houdini... it's much more complex than my scene.how did the artist got the texture on particles without waiting years ? are there other methods as the pic ore tex function ? is an animated alpha ore opacitymap used for such things....? thx Quote Link to comment Share on other sites More sharing options...
michael Posted July 16, 2009 Share Posted July 16, 2009 projected from the camera? Quote Link to comment Share on other sites More sharing options...
anim Posted July 16, 2009 Share Posted July 16, 2009 ...are there other methods as the pic ore tex function ? ... you can use VOPs they are much faster than expressions there is Color Map VOP which can get you color or alpha information from any pixel (through u,v) of the image Quote Link to comment Share on other sites More sharing options...
sam.h Posted July 16, 2009 Share Posted July 16, 2009 (edited) Attached a hip file which might help you speed it up. Just the alpha of an image (or madrils red channel ) copied onto the points of a grid, points scattered onto the grid and then points deleted based on the alpha. This is so that you don't have to get a value from the texture millions of times... won't work too well if you have a lot of detail in your alpha. The colour of the particles is done in the shader to speed things up as well. You could also use the alpha in the shader. In this case it would be better to delete point with an alpha of 0 (instead of < 0.5 which i have done in the file.) Hope this helps! image_particles.hipnc Edited July 16, 2009 by sam.h Quote Link to comment Share on other sites More sharing options...
hatrick Posted July 16, 2009 Author Share Posted July 16, 2009 (edited) so how such a workflow could look like ? is my projected imageinformation saved onto every particle after writing it out to disk ? @michael ... thx guys that was fast :! Edited July 16, 2009 by hatrick Quote Link to comment Share on other sites More sharing options...
Magnus Pettersson Posted July 16, 2009 Share Posted July 16, 2009 Hey! If you do it like in the sideFX tutorial that geo done with pic (or tex) command but rather than having a point sop after the popnet, use the point sop before the popnet instead. that will speed things up for you very very much.. i did a test with a 100x100 grid and 1 million particles and the only time it takes is to simulate the particles ohh plus the time it takes to cook the point sop initially when u lay it down and enter the pic commands to color the grid which takes a while but thats just once. To keep it that way you could just write out your geo with your point color to disk and read it in as a file node again. /Magnus Quote Link to comment Share on other sites More sharing options...
hatrick Posted July 17, 2009 Author Share Posted July 17, 2009 nice!! Quote Link to comment Share on other sites More sharing options...
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