View Full Version : 9.3: I think I found a nasty alpha channel bug

09-09-2007, 12:52 AM
try the following:

1. Load an object or two.. such as a plane and a sphere.. Doesn't matter what it is.

2. Make a particle emitter. To a calc with it.. use collisions if you like so some particles go in front of and behind the sphere / whatever.

3. Save the PFX data (important)

4. Add quickie hypervoxels to your particles; volume mode.

5. Set your loaded models to matte (black) and tell the alpha channel to render "Constant Black"

Essentially what you're doing is setting up a seperate render pass for just your particles. But you will notice, if it's doing the same thing it is here... That your objects you matted black are rendering SOLID WHITE to the alpha channel.

Now... Kill your particle emitter. Add a PARTIGON emitter, and load the same PFX motion data into it. Render.

The alpha channels of your objects should render to black just as they should.

Does your experiment deviate from my results?

09-09-2007, 01:46 AM
Try this...add LW_Hypervoxel to the Pixel Filter Plugin panel.

This generates an error message, just ignore it.

Now the alpha should be right.

I had the same problem while in production...that trick solved the alpha bug.

09-09-2007, 09:59 AM
Wow thanks! That did the trick! They really should fix that, however.

09-09-2007, 12:14 PM
Has been a pleasure....and...yes...it should be fixed as soon as possible.

09-09-2007, 03:54 PM
Did you know about this? If you set a partigon's particle size to -1, it can accept shadows! Just found this out.

09-09-2007, 10:44 PM
what is a partigon, anyway? is it a one point polygon?

09-10-2007, 05:07 AM
what is a partigon, anyway? is it a one point polygon?

Yeah.. the big difference between a HV-emitter and Partigon-emitter is that HVs can only render HVs, while Partigons are treated as polygons, but can still be used as HV-emitter.