PNG alpha channel help

I know this has come up many times before, but for the life of me I can't find any info on it.

Say I have a simple filled circle image, using a drop shadow in photoshop. I save the image as PNG.

How do I place these images in Blitz3D next to each other retaining the alpha channel?

Lol, it's doing my head in. I know I'm missing something really simple here.

On the Photoshop side you probably need to create an additional Layer. after R,G and B this will be Alpha by default. If you save it now, I guess it will save the PNG (if memory serves :) ).

On the blitz side note images cannot use transparency info. all they can utilize is a mask color. It's black by default, but it may be altered to use an other color (MaskImage, IIRC)

Alpha Channels can only be used by textures. You may use a system that positions Sprites or Quads side by side to get the effect of images that are supporting smooth alpha transparency.

Thanks :)

Damnit!!! I thought there was a technique which allowed PNG images to use their alpha channel via drawimage?. Ah well, not to worry, I'll just have to tone down certain areas.

All depends on the software. In PSP you can save the png and (being sure to save as True Colour, not 256 colour) choose "Transparency : use current transparency". No need to setup an alpha channel - WYSIWYG!

Shifty. yes. but, it still wont work with DrawImage ;)

Sorry, wasn't paying attention!

er...

you could load them as sprites or textures though (for a quad for example) and use the flags set to 3 to keep alpha info.

It would be one image not two separate images though.

This would work - try it :

www.smartscreenuk.com/circle.png

(although this is a none filled circle).

IPete2.

Well textures are out because some of the people who'll be using the proggy are still using voodoo III's and I remember correctly those cards don't support above 256kb textures.

My best bet is to skip using any fancy shading and alpha windows for this project.