I made particles inherit colors form a picture, then I wanted to make them fade into another colour. I use color node in POP, Ramp. set the first point color as this - “point(”../image/null/“, $PT, ”Cd“, 0)” -

it works if I use color node to color a gird instead of a image.

anyone knows why ?

I really dont have the clear concepts of houdini

I'm not certain but I think you might find some help in this tutorial:
http://www.sidefx.com/index.php?option=com_content&task=view&id=1423&Itemid=132 [sidefx.com]

hi thank you, but this cant do the effects I want. I want to change particles color by time, so I use color - ramp Node to do it. however, the particle just cant get the color form grid. does anyone know why ?

The problem seems to be that the parameters for the ramp on the Color POP don't seem to like local variables such as PT, ID, CR, etc which is why you can't use expressions like rand($PT), point(), etc.

I attached a file that does it in SOPs. The ramp has it's first values set to $CR/CG/CB since those are the incoming colors and fades to whatever color using $LIFE.

Thank you , graham!

this is what I want. Do you know why the color node doesn't take local Attr. ? Actually, in the same file, I did another color node (color2) to make the ramp take the color form POP/ color, and it does! that is the part really confuse me. if you can check it, that would be very help!! thank you again !!!!!