Blender Git Loki

Point Density texture: colouring

This introduces a few new ways of modifying the intensity and colour output
generated by the Point Density texture. Previously, the texture only output
intensity information, but now you can map it to colours along a gradient
ramp, based on information coming out of a particle system.

This lets you do things like colour a particle system based on the individual
particles' age - the main reason I need it is to fade particles out over time.

The colorband influences both the colour and intensity (using the colorband's
alpha value), which makes it easy to map a single point density texture to
both intensity values in the Map To panel (such as density or emit) and colour
values (such as absorb col or emit col). This is how the below examples are
set up, an example .blend file is available here:

http://mke3.net/blender/devel/rendering/volumetrics/pd_test4.blend

The different modes:

* Constant
No modifications to intensity or colour (pure white)

* Particle Age
Maps the color ramp along the particles' lifetimes:
http://mke3.net/blender/devel/rendering/volumetrics/pd_mod_partage.mov

* Particle Speed
Maps the color ramp to the particles' absolute speed per frame (in Blender
units). There's an additional scale parameter that you can use to bring this
speed into a 0.0 - 1.0 range, if your particles are travelling too faster or
slower than 0-1.
http://mke3.net/blender/devel/rendering/volumetrics/pd_mod_speed.mov

* Velocity -> RGB
Outputs the particle XYZ velocity vector as RGB colours. This may be useful
for comp work, or maybe in the future things like displacement. Again, there's
a scale parameter to control it.
http://mke3.net/blender/devel/rendering/volumetrics/pd_mod_velrgb.mov