From: Uwe Woessner COVISE Development (uw_te++at++blubber.de)
Date: 05/30/2001 05:19:33
Hi Hui,
> I have Onyx2 Reality workstation, when rendering a face with alpha texture to
> simulate a shade, I find that at the place where alpha number gradually transfer
> from 255 to 0, I got a stair like result, not smooth at all. it seems that
> the alpha value have very limited choice, are there any configuration in performer
> to correct this?
I have the same problem on my Onyx2 IR2: here is the code that generates
the texture
// create texture object
tex = new pfTexture;
tex->setFilter(PFTEX_MINFILTER, PFTEX_POINT);
tex->setFilter(PFTEX_MAGFILTER, PFTEX_POINT);
tex->setRepeat(PFTEX_WRAP,PFTEX_CLAMP);
tex->setFormat(PFTEX_EXTERNAL_FORMAT,PFTEX_PACK_8);
tex->setFormat(PFTEX_IMAGE_FORMAT,PFTEX_RGBA);
//tex->setFormat(PFTEX_INTERNAL_FORMAT,PFTEX_RGBA_8);
tex->setFormat(PFTEX_INTERNAL_FORMAT,GL_RGBA);
textureData= (unsigned char*) new(2*4*256) pfMemory;
myTransFunc->makeColorBar(256, textureData);
tex->setImage((uint*) textureData, 4, 256, 2, 1);
This is the visual that I am using:
0x6f, RGBA 12/12/12/12, db, stereo, Z 23, S 1, samples 4
What I get is smooth color shades, but 6 steps in the alpha blended
region of the texture.
It has to be somehow related to antialiasing, as if I turn of
antialiasing, it looks correct.
Can anybody explain why this is happening or what I am doing wrong?
Regards,
Uwe
This archive was generated by hypermail 2b29 : Wed May 30 2001 - 05:03:43 PDT