View Full Version : particle fx question
06 June 2003, 12:18 AM
id like to emitt particles on a object but on "white" areas of my texture-image only.
it seems that the birth-rate "t-function" works with procedurales only.
can anybody confirm this limitation?
06 June 2003, 12:49 AM
this is really strange.....
i used a procedural like "fractalnoise" to generate the particles on the object surface. further i´ve add a image-map (layer-type) with the blending mode set to "alpha" with a black texture showing white (bold) line.
so what i get is, that particles are generated on the objects surface and due to the "alpha" mapped image-map, i see the particles only on the white area (the white line) of my image map.
but when i am trying to animate the 2 maps lw crashs. ;(
06 June 2003, 03:18 AM
did you try without the procedural and just the image map?
not exactly sure what youre trying to do, but is the procedural really neccessary?
06 June 2003, 07:30 AM
its just very easy .... make a ball....make a b/w image-map (like white dots on a black background) in photoshop....add particle emitter on the ball in layouter....
enable the "t" button to controll the birth-rate using a procedurale or an image-map (like planar mapping)...
first you will see that "automatic sizing" will not work - which means that scale is set to 1,1,1.
second the particle wont be created on the white or black areas of your image-map that is mapped to that object.
using an lw-procedural like grid, fractal noise etc. will work...that means that particle will be generated at the white respectively on the back eares of your procedural.
06 June 2003, 07:52 AM
i almost forget to mention ...
set the nozzle-type to "object surface" (or whatever except sphere or box).
what you will see is that you cant controll the birth-rate using a procedural map or image-map.
instead when you set the nozzle type to "sphere" or "box" you can controll the birth-rate with a procedural map.
unfortunately my emitter object is not a "perfect" sphere....
06 June 2003, 08:06 AM
now i feel completely "stupid"...
am i dreaming ??...now it works. nozzle type is set to "object surface" and i can controll the birthrate using a procedural.
but it seems that only certain types like fractal noise or grid are working and some like checker arent working.
but i cant animate the procedurals with the envelope nor by an texture-reference object. ;(
okay...i think its better i stop here ...and i will try to find a different way to solve my effect.
06 June 2003, 03:04 PM
Dont forget FXstart!
thats probably your biggest issue! scrubbing just the timeline doesnt work most of the time, especially with birthrates using an imagemap!
06 June 2003, 05:35 PM
i tried fx-start.....all i get is that lw crashs ;(
here are a few images ... just to be sure that everyone understands my problem. ;)
1. pic....shows a simple ball and the nozzle is set to
2.pic ...show a procedural applied to the birth-rate....so particles
are emitted on the white areas of the grid only.
3.pic...shows the ball and nozzle type is set to OBJECT SURFACE
and a simple image map is applied to controll the birth-rate areas.
So i would except that the particles should be emitted either on the black or the white area of my planar or spherical...etc. mapped nozzle object.
BUT NOTHING HAPPENS...even when I do the particle calculation with FX-START.
06 June 2003, 05:52 PM
ok, finally gotcha...and I remember now when I was doing THIS (http://forums.newtek.com/discus/messages/2/37858.html?)...that LW is flaky with 2 color image maps...AND YOU MUST hit FXstart to get the image map to work right...so youve got to solve your crashing problems....also, sometimes you have to tap the <> buttons next to the birthrate to get LW to restart the emitter after tweaking settings...its a bug that really is annoying!
also I think setting the image maps opacity higher than 100% can help...also play with Normal, Additive, etc...
If worse comes to worse, and its just an image map of a line, you could actually use the collision/event trick and move a collision object however you were going to move the line...got it?
theres a hoaky way around the LW bugs...total pain though...
06 June 2003, 06:05 PM
it works fine here if I set the blending mode of the image layer to "Alpha". And yes, it crashes LW sometimes :-)
06 June 2003, 06:10 PM
the problem is that my object is a human skull ...so much more complex than a simple ball. ;)
what i did is, i have modeled a simple stripe (an object) and i moved that object along the skull and I used bones to deform that stripe object, so that it fits the outer shape of the skull....luckly i had to animate 15 frames only. ;) its like simulating the white line of the image that i tried to use.
than i´ve applied the particles to that animated stripe object.
but i will give your ideas a try.. ;)
06 June 2003, 06:18 PM
06 June 2003, 06:21 PM
MAN...thanks alot!...look that this! a former Cinema4D user knows how it works!...CRAZY world.. ;)
i owe you a beer
06 June 2003, 06:46 PM
i owe you a beer
I'll remember that one, you know! :beer:
06 June 2003, 07:38 PM
well like i said, you could use a collision plane instead of an image map, then you can move the plane in 3D in LW manually...it will work the same for your skull, no bones required.
01 January 2006, 12:00 PM
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