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Texture vs Blending?

Started by July 22, 2005 11:47 AM
0 comments, last by Krohm 19 years, 4 months ago
hi all, it's quite simple thing i am doing here; i read some texture (not mapped to anything yet), and left GL_TEXTURE_2D enabled; then i try to draw some simpel points providing glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA); but the points just won't show up; until i found that if i disable GL_TEXTURE_2D before drawing the blended points.... what's the reason behind this situation? thx all... plus: i am using jogl
Well, I am just speculating because I'm not sure of what are you doing. There's too less information however, here are my suppositions.

You said you have used TEXTURE_2D. I understand you possibly just called TexImage and thus, bound the texture target to the object.
The fact you didn't draw textured things really does not matter. When you do
glEnable(GL_TEXTURE_2D);

you're telling the hardware that "when something will be drawn, texture it with the current texture (object)".

Now, as far as I can remember, the default texture coordinate is (0,0). It does not really matter the exact value anyway.
My speculation is that maybe you're using a RGBA texture and fetching a texture color which is (?,?,?,0). Since default texture env function is MODULATE, you end up with all transparent fragments.
Another idea may be to fetch (0,0,0,?) on a black background so they don't show up anyway.

Maybe provide some additional information.

PS: please check your private messages.

Previously "Krohm"

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