View Full Version : particle fx question

06-23-2003, 12:18 AM
hi folks..

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?

06-23-2003, 12:49 AM
this is really strange.....

i used a procedural like "fractalnoise" to generate the particles on the object surface. further ive 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. ;(

any ideas?

06-23-2003, 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?

06-23-2003, 07:30 AM
hi howard

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.

06-23-2003, 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....


06-23-2003, 08:06 AM
now i feel completely "stupid"...

am i dreaming ?? 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.

06-23-2003, 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!

06-23-2003, 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
object surface

2.pic a procedural applied to the 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.

06-23-2003, 05:52 PM
ok, finally gotcha...and I remember now when I was doing THIS ( LW is flaky with 2 color image maps...AND YOU MUST hit FXstart to get the image map to work 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 it?

theres a hoaky way around the LW pain though...

06-23-2003, 06:05 PM
Hi Andras,

it works fine here if I set the blending mode of the image layer to "Alpha". And yes, it crashes LW sometimes :-)


06-23-2003, 06:10 PM
the problem is that my object is a human skull 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 ive applied the particles to that animated stripe object.


but i will give your ideas a try.. ;)


06-23-2003, 06:18 PM

06-23-2003, 06:21 PM

MAN...thanks alot!...look that this! a former Cinema4D user knows how it works!...CRAZY world.. ;)

i owe you a beer

06-23-2003, 06:46 PM
i owe you a beer

I'll remember that one, you know! :beer:


06-23-2003, 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 will work the same for your skull, no bones required.

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