[info-performer] pfTex subload problem/question

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From: Gary Quinn (G.Quinn++at++tees.ac.uk)
Date: 03/25/2004 07:24:24

  PfHi !

  I'm trying to grab the frame buffer into a pfTex,
  ultimately for dome distortion, but I'm getting
  strange results...

  When I read the framebuffer, and draw a textured
  GL_QUAD in the top right of the frame I'm getting
  different (and wrong) results on an O2 and a PC.

  On an O2 performer 2.5.3 runtime...
  http://vr.tees.ac.uk/gary/grab_sgi.jpg

  The topleft triangle (of the GL_QUAD) is
  correct, but the bottom right triangle is
  wrong.

  However, on a PC performer 3.0.2
  http://vr.tees.ac.uk/gary/grab_pc.jpg
  the whole GL_QUAD texture is sheared, and
  the amount of shear changes at each frame

  To setup the pfTexture...

      texture = pfNewTex(shared->arena);
      image = (unsigned int *)pfMalloc(sizeof(unsigned
int)*sizeTex*sizeTex, shared->arena);

      pfApplyTEnv( pfNewTEnv( shared->arena ) );

      pfTexLoadMode(texture, PFTEX_LOAD_SOURCE,
PFTEX_SOURCE_FRAMEBUFFER);

      pfTexFormat(texture, PFTEX_EXTERNAL_FORMAT, PFTEX_PACK_8);
//PFTEX_PACK_8
      pfTexFormat(texture, PFTEX_INTERNAL_FORMAT, PFTEX_RGBA);
//PFTEX_RGBA_8
      pfTexFormat(texture, PFTEX_IMAGE_FORMAT, PFTEX_RGBA); //PFTEX_RGBA
     
      pfTexName(texture, "Frame Buffer Texture");
      pfTexImage(texture, image, 4, sizeTex, sizeTex, 1);

      pfTexLoadOrigin(texture, PFTEX_ORIGIN_SOURCE, 0, 0);
      pfTexLoadOrigin(texture, PFTEX_ORIGIN_DEST, 0, 0);
      pfTexLoadSize(texture, sizeTex, sizeTex);
    
      pfTexFormat(texture, PFTEX_SUBLOAD_FORMAT, PF_ON);
      pfTexFilter(texture, PFTEX_MINFILTER, PFTEX_BILINEAR);
      pfTexFilter(texture, PFTEX_MAGFILTER, PFTEX_BILINEAR);

      pfApplyTex(texture);

  Then to use the texture after pfDraw() in the draw callback...

    pfLoadTex(texture);

    glColor3f(1.0f, 1.0f, 1.0f);

    glBegin(GL_QUADS);

      glVertex2f(xsize/2.0f, ysize/2.0f);
      glTexCoord2f(0.0f,0.0f);
      
      glVertex2f(xsize,ysize/2.0f);
      glTexCoord2f(0.0f,1.0f);
      
      glVertex2f(xsize,ysize);
      glTexCoord2f(1.0f,1.0f);
      
      glVertex2f(xsize/2.0f,ysize);
      glTexCoord2f(1.0f,0.0f);

    glEnd();

  In an attempt to narrow down the problem, I
  tried ...

  pfSaveTexFile(texture, filename);
  but that just gives me a blank image in the file.

  Sadly, www.dorbie.com seems to be down :-(

  What am I doing wrong ?

  Cheers,
  Gary. 

-- 

Gary Quinn, VR Centre            Technical Manager 
University of Teesside           SGI Network Admin 
Borough Road, Middlesbrough              Go Player 
Cleveland, TS1 3BA          mailto:Gary++at++tees.ac.uk 
+44 (0)1642 384303 fax 384310 http://vr.tees.ac.uk 

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