Wednesday, January 28, 2009

I Can See (Through) You

Blitz Plus doesn't support alpha channels or .PNG transparency. That's going to be a problem.

I've discovered a solution - I can fake it.

The technique is something that I'll refer to as "micro-texturing." It works like this : Blitz can remove a single "mask" color from a drawn image, usually flat black but more likely to be green or magenta in the future. So, the idea is to overlay "transparent" objects (see the previous post) with a grid or texture of the mask color. The amount of transparency can then be controlled on a fine level using PhotoShop. When "transparent" items overlap, there will be some look though due to the tiny mask color grid and so they will appear to average out at large scales.

For example, in my test I placed a big red X over a blue field and used PhotoShop to mask out the whole thing. When I added my grid micro-texture to the mask level the big red X appeared to be purple. The amount was adjustable by using different textures.

When I did the same with a Green Stripe and Red stripe over blue, the Green and Red averaged to a kind of yellow (when zoomed out) and a dirty brown when over a blue field.

In the Engine, if a micro grid was applied to the images that we want to be transparent (instead of trying to add it later like in the test) then they would be see through during gameplay. I'll do an in game test when my work computer works again.

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