particle's transparency based on distance to camera

[itriix]

Hello everyone,

i'm disintegrating a 3d world, which has a camera projection of the shot applied to it. a noisey shape grows over time and is used as a bounding box for grouping the points in the city that are going to be emitting while in the group. I would like the particles to fade as they age and ALSO fade as they approach the camera location because i don't want them in the calculation for motion blur. plus it'll look a bit cleaner.

please let me know if you have any thoughts

[storyteller]

Hi,

you can use a Colour Node in you POP Network and set the Alpha expression to something like

(1-$LIFE) * clamp(0.03*distance($TX,$TY,$TZ,origin("","/obj/cam1","TX"),origin("","/obj/cam1","TY"),origin("","/obj/cam1","TZ")),0,1)

.

You can see the effect in the "Details View", having the Colour Node selected.

particle_alpha.hipnc

Edited March 18, 2009 by storyteller

[itriix]

Hi,

you can use a Colour Node in you POP Network and set the Alpha expression to something like

(1-$LIFE) * clamp(0.03*distance($TX,$TY,$TZ,origin("","/obj/cam1","TX"),origin("","/obj/cam1","TY"),origin("","/obj/cam1","TZ")),0,1)

.

You can see the effect in the "Details View", having the Colour Node selected.

Thanks Storyteller,

Your example works but i have a couple questions. first off, is there anything different about using this inside my popnet and using a point node in the geo level, with the same equation in the Add Alpha Tab..? How can i make it so that everything is "full alpha" based on $LIFE only, all the way up to a "distance" from the "camera" as soon as it reaches that distance, it "falls off fairly rapidly before getting to the camera completely".