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Alpha Channel Transparency

OpenGL

Started by Pooya65 Jan 21, 2008 at 5:33 AM 4 replies 1.3k views

Original Post

Pooya65

Jan 21, 2008 at 5:33 AM

hi i am using devil with OpenGL and i want to draw images(no texture)whit Transparency(using alpha chanel in the png files) on the screen via using glDrawPixels function, how i can do it?!

Trenki

Jan 21, 2008 at 5:39 AM

I don't think that is even possible with glDrawPixels. AFAIK the use of glDrawPixels should be avoided too, since that is not too fast.

MaR_dev

Jan 21, 2008 at 6:05 AM

Draw a quad (or two triangles) with right tex coordinates and set your image as a texture. In fact its really simple, no need to use glDrawPixels.

Pooya65

Author

Pooya65

Jan 21, 2008 at 8:51 AM

hi
how i can use "Alpha Channel Transparency" ????

i_luv_cplusplus

Jan 21, 2008 at 9:09 AM

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

V-man

163

V-man

Jan 21, 2008 at 10:44 AM

Quote:
Original post by Trenki
I don't think that is even possible with glDrawPixels. AFAIK the use of glDrawPixels should be avoided too, since that is not too fast.

Yes it is possible.
And use a format like GL_BGRA for good performance.

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