[Gambas-user] gb3: DrawAlpha

[Kevin Fishburne]

On 07/05/2011 06:34 AM, Benoît Minisini wrote:
>> Since DrawImage just copies the RGBA channels and PaintImage blends the
>> channels using the alpha channel, I'm assuming that DrawAlpha copies
>> (but does not blend) the alpha channel. Is that the case?
>
> Actually DrawAlpha is PaintAlpha. I saw no point of just copying the alpha
> channel.
>
> Blending the alpha channel is just keeping the greater transparency between
> the destination pixel and the source pixel. This is what DrawAlpha does.

Very good. I think I misunderstood how it worked, despite it doing what 
it was supposed to in my program.

> By the way, I have fixed a bug in the alpha blending of PaintImage in revision
> #3926. Tell me if you notice the change.

I'm going to try recompiling again since revision 3910 involved SDL, but 
right now I get the error "The program has returned the value: 127" as 
soon as Client.Initialize() calls Render.Initialize(). The procedure 
call raises the error immediately, not a line inside the 
Render.Initialize() procedure, which is interesting.

I'll let you know the results when I compile again to 3910 or higher, 
and if there's any different in appearance or frame rate since the 
PaintImage bug fix.

-- 
Kevin Fishburne
Eight Virtues
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