shading points with transparency changing with distance from the camer

[Guest ravin]

I am attaching a file with spheres copied to particles, and I am applying a color to the spheres. Now I want to control the transparency of the spheres with the distance from the camera. So if a point is far it is less opaque than the ones in the front. How can I achieve this?

Basically I am trying to achieve a dusty volumetric look.

thanks,

dustRendering.hip

[Macha]

Hi Ravin.

Here is an example with colors instead of opacity. It fits your distance values automatically into 0-1 range.

dist.hipnc

Edited August 8, 2010 by Macha

[Macha]

BTW, with millions of particles this may be very slow to render. I don't know you exact intentions but from previous posts it seems you want to render lots of points? Perhaps I would be tempted to write out a Pz or opacity or alpha variable and doing something with it in compositing.

Edited August 8, 2010 by Macha

[Guest ravin]

BTW, with millions of particles this may be very slow to render. I don't know you exact intentions but from previous posts it seems you want to render lots of points? Perhaps I would be tempted to write out a Pz or opacity or alpha variable and doing something with it in compositing.

I will try this technique with opacity coz i really need this for opacity. And yes you are right I am intending to render lots of particles. How do you write out the Pz or opacity variable in houdini and use it in compositing? I have no experience with this technique.

thanks,

[Macha]

Check out deep rasters.

Also, it is probably better to write or rewire a shader using the technique in my above file, rather than using per point values.

[anim]

it's much easier to do this in shader

here is the simple example, you just need to set min and max distance parameters and you can tweak the opacity in this range by opacity ramp

camera_dist_opacity.hipnc