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Dark GDK / Solid sprite with alpha control??

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Petr
16
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Joined: 1st May 2008
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Posted: 9th May 2008 09:35
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Hi,

I need some help here.

I need a sprite that is solid and that I can control its alpha (basically I need to fade in/out pictures with black in them) but I am only getting one of the two:

Alpha works but black color is see through:
dbSetSprite(1, 1, 1);
dbSetSpriteAlpha(1, 128);

Black is now solid but alpha does not work:
dbSetSprite(1, 1, 0);
dbSetSpriteAlpha(1, 128);

Thanks.
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Lilith
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Posted: 9th May 2008 18:11
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I'm not sure how you're going about it but can you use dbSetImageColorKey to set the transparency color of your image to something other than black?

Lilith, Night Butterfly
I'm not a programmer but I play one in the office
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jinzai
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Location: USA
Posted: 9th May 2008 19:42 Edited at: 9th May 2008 20:09
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This happened yesterday in the DBPro forum. Let's see if it is the same thing.

Alpha transparency is not the same thing as image transparency. Image transparency is only a single color key, like Lilith said.

Images with alpha channels use a separate channel for the alpha. PNG and TGA are the best for this, but MSPaint does not save an alpha channel, just the RGB.

You need a paint program that uses an alpha channel for that to work.

If you don't have such a program, you can post the image and I can fix it for you.

This image uses the red channel as the source for the alpha, so it really doesn't show a great use of alpha...but, your program should be able to set the transparency of the flag using alpha:

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jason p sage
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Posted: 10th May 2008 02:33
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You can also do what JinZai said programmatically...

1: load image
2: make memblock from image (1st DWORD = width, 2nd DWORD = Height, 3rd DWORD = Bit Depth usually 32 in DarkGDK for me so far) After that, each pixel is a DWORD. Each DWORD has four bytes, one for red, green, blue, and alpha.. I forget the order... but....
4: By manipulating the Alpha channel, you can poke holes, or fade stuff more or less that other parts in same image...

Its cool once you get it going.


http://www.jasonpetersage.com/?PAGE=ironinfantry&SECTION=ironinfantry
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Petr
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Posted: 13th May 2008 08:08
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Thanks for all the answers.
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