Tiago Posted May 30, 2007 Share Posted May 30, 2007 Hello, Does anyone know what is the expression to change the size of particles throughout their life? I know it has to do with $LIFE, but I can't seam to get any result. What makes it difficult, is that I'm using sprites, so I don't know where I should change the values. On the particles or on the sprites, or on both? Thank you for your help Quote Link to comment Share on other sites More sharing options...
GallenWolf Posted May 30, 2007 Share Posted May 30, 2007 Hi there, welcome to Odforce! Did you try the Sprite POP? There is a scale parameter that will add the spritescale attribute. I tried it with $LIFE and it seems to work. My sprites are Mantra procedural sprites though. HTHs! GW Quote Link to comment Share on other sites More sharing options...
Tiago Posted May 30, 2007 Author Share Posted May 30, 2007 Hi there, welcome to Odforce!Did you try the Sprite POP? There is a scale parameter that will add the spritescale attribute. I tried it with $LIFE and it seems to work. My sprites are Mantra procedural sprites though. HTHs! GW Hi GallenWolf, Thanks for your help. I tried the $LIFE expression on there and it worked great. I now have the scale changing. Another thing however, under the Source POP, on life expectancy, can't we use the rand expression? It seams to always retrieve an error... Once again, thanks Tiago Quote Link to comment Share on other sites More sharing options...
GallenWolf Posted May 31, 2007 Share Posted May 31, 2007 Hi GallenWolf,Thanks for your help. I tried the $LIFE expression on there and it worked great. I now have the scale changing. Another thing however, under the Source POP, on life expectancy, can't we use the rand expression? It seams to always retrieve an error... Once again, thanks Tiago You'll want to use the Life Variance to control that. GW Quote Link to comment Share on other sites More sharing options...
Tiago Posted May 31, 2007 Author Share Posted May 31, 2007 You'll want to use the Life Variance to control that.GW ok, i tried that, but i got to the conclusion than life variance would work throughtout time, in waves, and not throughout life. maybe i got iluded by the slow velocity of the computer... thanks once again tiago Quote Link to comment Share on other sites More sharing options...
GallenWolf Posted May 31, 2007 Share Posted May 31, 2007 Hey man, Life variance will basically add or subtract the variance value from the Life Expectancy to give particles a varied lifespan. Is this the end result you need or are you looking for some other effect? GW ok, i tried that, but i got to the conclusion than life variance would work throughtout time, in waves, and not throughout life. maybe i got iluded by the slow velocity of the computer...thanks once again tiago Quote Link to comment Share on other sites More sharing options...
Tiago Posted May 31, 2007 Author Share Posted May 31, 2007 Hey man,Life variance will basically add or subtract the variance value from the Life Expectancy to give particles a varied lifespan. Is this the end result you need or are you looking for some other effect? GW that's precisely it! thanks Quote Link to comment Share on other sites More sharing options...
SgtSpamBoy Posted June 2, 2007 Share Posted June 2, 2007 For controlling the size of particles at the SOP level, I use a spare channel to control the scale based on the life of each particle. First create a point SOP under your popnet/pop merge, and create a spare channel (float) on the point SOP. On the spare channel, add a keyframe on frames 1, 50, and 100. Give frames 1 and 100 a value of 0 and frame 50 a value of .5 (for now). If you look at the spare channel in the channel editor, the curve it creates will be used as the scale of the particles over life (not time), so frame 1 of the spare is when it's born and frame 100 is death, making the particles scale-in and scale-out over their life. Next, on the "particle" tab of the point sop, change "Scale" to "Add Scale" and use the following expression in the scale field: "chf("spare1", rint($LIFE*100))" (note that "spare1" should match the name of your spare channel). This expression will fit the values in the spare channel tab to the scale of the particles based on their life. Since life is 0-1, we multiply it by 100 to make it 0-100 for some breathing room - anything on your spare channel above frame 100 will not be used. Now add a copy SOP below the point SOP and attach a sphere to the copy SOP to see your particles scale in and out. You can adjust the amount of scaling and overall scale by adjusting the curve in the spare channel and by adjusting the scale of the sphere (or whatever your particle is). Hope this makes sense and is helpful! Quote Link to comment Share on other sites More sharing options...
Tiago Posted June 3, 2007 Author Share Posted June 3, 2007 Thanks for the tip SgtSpamBoy! I'll most definetly try that. Quote Link to comment Share on other sites More sharing options...
stevenong Posted June 21, 2007 Share Posted June 21, 2007 There is a display option to erm... display particles as sprites. Type 'd' in the viewport, go to the Particles tab & change the Display particles as to Sprites. Cheers! steven Quote Link to comment Share on other sites More sharing options...
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