Transparent stuff

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11 comments, last by SKSlayer 23 years, 6 months ago
I know this is not directly ogl related, but, lets ask anyway ... I am making a configurator utlity for a gl project, I want it to look HI TECH, and not square. How do I have a partially transparent window, like, based on a BlacknWhite image ? Les''t say I want a complex shape, with curves and stuff which is not possible to delimitate all points (that''s why I want it based on an image) ?
(you can find me on IRC : #opengl on undernet)
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alpha blending.
glEnable(GL_BLEND);//or something like that, don''t really remember
glColor4f(r,g,b,a);


JoeMont001@aol.com www.polarisoft.n3.net
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That''s not the question
I of course know how to blend gl stuff,
Blending in gl is only about the window content, not the window itself

Let''s reask the question

Of course, as my configurator is up to setup the renderer, it does not uses gl itself, but pure win32 api
(you can find me on IRC : #opengl on undernet)
Although I''m really no expert at Window$ programming, I think you should use some kind of build in Window$ functions, although I don''t know if you would still be able to render in that window with OpenGL (if that''s what you want to do anyway).
Prosser: But the plans were on display.Arthur Dent: On display? I eventually had to go down to the cellar.Prosser: That's the display department.Arthur Dent: With a torch.Prosser: The lights had probably gone.Arthur Dent: So had the stairs.Prosser: But you did see the notice, didn't you?Arthur Dent: Oh, yes. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign outside the door saying "Beware of the Leopard." Ever thought of going into advertising?
MMmh, but which function ???(and no, I don''t want gl render in it)
(you can find me on IRC : #opengl on undernet)
Hey SK,

Check out the functions TransparentBlt(...) and AlphaBlend(...) ...I haven''t used them myself (I just looked them up on MSDN), but I can tell you that the first is for colour-keying, and the second is for images with an alpha channel.

Hope that helps

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like u say this has got nothing to do with gl, your best bet would be looking in msdn or one of the windows sdk''s, information about creating a transparent window

http://members.xoom.com/myBollux
SK, there has been an article about this in
(german) PCMAGAZIN 2/00. If you''re interested,
i''d could mail you the sources for 2 programs
(vc6, projects&exe, full compilable), size
is 120k...

arno@hangelar.de
you want to use regions. I think the API calls are something like
CreateRectRgn
CombineRgn
SelectObject

and there are other Create*Rgn for createing round regions, polygonal regions, etc. CombineRgn allows you to take 2 regions and combine them using logical operations (and, or, xor, etc.). SelectObject allows you to apply a constructed region to a window.
There''s a way you can specify a shape that isn''t made from rectangles - look at the mp3 player sonique...

don''t ask me how it''s done tho, i only do opengl!

been doing more win32 stuff lately though - not that bad really when you start getting into it.

- peter
peter@digital-animations.com

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