[Gambas-user] gb.image: image alpha channel accessibility

[kevinfishburne]

Benoît Minisini wrote:
> 
> - There is no rotation in gb.image because I don't have the algorithm at
> the 
> moment. It is a bit complex, because all gb.image color formats should be 
> supported.
> 
Did you mean the SDL component? gb.image does have rotation (although I
don't know if it preserves the alpha channel):

http://gambasdoc.org/help/comp/gb.qt/image/rotate
http://old.nabble.com/gb.image:-how-to-keep-a-rotated-image-centered-td29369608.html

Benoît Minisini wrote:
> 
> - The alpha channel is the highest byte of the 4-bytes pixel color. What
> do 
> you want to do with the alpha channel?
> 
Thanks, that is good to know. Briefly, I'd like to copy the alpha channel
from one image to the alpha channel of another image, preserving the target
RGB channel. It would be like using Image.Draw but being able to specify the
source channel[s] (RGB, Alpha, All) and destination channel[s] (RGB, Alpha,
All).

Specifically, the game I'm writing uses a layered landscape (bedrock, sand,
soil, vegetation, snow) with one large tileable texture for each layer. As
each layer is rendered it needs to be seamlessly blended with the other
layers using smaller alpha channel images. The smaller images used only for
their alpha channel are "interconnective" or "in-between" tiles and create a
smooth transition between, for example, sand and grass tiles.

I could address the pixels individually, but that would be super inefficient
as opposed to using a GAMBAS method with its underlying C code's speed. I'm
probably pushing GAMBAS in a direction it wasn't meant to go, but
nevertheless that would be a damn useful functionality for games and
graphics apps.

Let me know what you think, and here's my web site if you're curious:

http://www.eightvirtues.com/sanctimonia

-----
Kevin Fishburne, Eight Virtues
www:  http://sales.eightvirtues.com http://sales.eightvirtues.com 
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phone: (770) 853-6271
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