Embeded alpha as knockout?

[chuzzlewit]

A fairly simple problem but I need to sort it out ASAP. I'm generating a store fly through and I have a thousand shelves or so to place products on, ketchup bottles, baby food etc (so I'm looking for the most economical way to solve this problem). I've already generated photoshop files with embeded alpha channels, saved them as tifs and was going to map each of them onto a single rectangular polygon. Using the alpha channel I was going to knock out the remaining part of the polygon that doesn't need to be seen so you just have product. However I can't find a way of using the embeded alpha channel to knock the surplus polygon out and have to generate a separate alpha channel file and use that. Is there a way to use a single file with embeded alpha and knock out the background or do I have to generate separate alpha files for the whole project (thats a thousnad extra files to handle and a day to do it in...)

[brett anderson]

how about using the clip map to knock out the background?

[chuzzlewit]

Finally found the clip map option as you say (I'm used to another package where the clip map is defined in the surface style). Do I have to make a seperate alpha channel or is there some way to utilise the one I've generated with the image map?

[brett anderson]

hi there
sorry for misunderstanding your question

by using clip map, you need to load extra alpha images

and for your question, if your images have alpha embedded,
you can open the image editior (crtl+F4) and load your images, under the source tab, select enable for the alpha channel,
finally, apply the images as texture map as usual
then you can knock out the backgound

hope this help

[Lightwolf]

chuzzlewit:
Load your image with embedded alpha
Go to the image editor and clone the image twice
on the first clone, disable alpha
on the second clone, show alpha only

Now use the first clone to map your poly, the second clone as your clip map / transparency map.
If you use a transparency map, to speed up rendering you might want to apply a clip map too (one that is slightly larger than the transparency map). This way LW won't attempt to render the transparent parts of your plane that are clipped out.
You might need to retouch the images a bit so that the semi-transparent edges have full colours, otherwise you'll end up with white/black edges.

Cheers,
Mike

[chuzzlewit]

Cheers Buddy, I have to agree that looks like the most efficient method (duplicate within the programme). I only hope that clip maps en mass don't have disasterous consequencies on the rendering times.

I'm off to do some virtual shelf stacking...anyone seen my pricegun?

[Lightwolf]

Originally posted by chuzzlewit
Cheers Buddy, I have to agree that looks like the most efficient method (duplicate within the programme).
Anytime.

Keep us updated on your progress, just look at my avatar, I'm nosey :D

Cheers,
Mike