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Thread: dynamic transparency

  1. #1
    Member Newbie
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    dynamic transparency

    Hi folks,

    i seek some information about the most efficient (fastest) way to dynamically set some texels (random ammount and order)transparent (or opaqu depending on there previous state).
    I first thought about modifying the alpha value of the texels and then recreate the whole texture again. - but i doubt that i can do this in realtime.

    Please let me know how you would solve the problem.
    Thank's in advance.
    Hail to
    ...the fine folks at SGI.

  2. #2
    Senior Member Regular Contributor
    Join Date
    Jul 2001
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    442

    Re: dynamic transparency

    GL_ALPHA texture format - and then use glTexSubImage2D to upload a new texture. You will need to combine the alpha map with any diffuse texture you want to use (with multi-texture).

    I assume you want the alpha test, rather than a blend operation?

  3. #3
    Member Newbie
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    Re: dynamic transparency

    Hi again,

    Robbo, thanks for the hint with glTexSubImage2D.
    Just a few more questions. Can i use glTexSubImage2D to change only the alpha values of an existing rgba texture? Or do i have to create a texture that only contains alpha values? ( but, ahm... how can i combine the alpha texture with the "image texture"?)
    If both would be possible, what would be faster?

    Blending would be a good idea, because i could fade the texels in/out (would certainly look nice) but for now i just like to get it to work - anyway.

    Thank's in advance for any information...
    Hail to
    ...the fine folks at SGI.

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