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Index › Programming Questions & Help › OpenGL and 3D Libraries › [FIXED] Unexpected texture behaviour
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[FIXED] Unexpected texture behaviour (Read 537 times)
SamH
[FIXED] Unexpected texture behaviour
Dec 5th, 2008, 11:39pm  
Hello,

I was wondering if someone might be able to help me figure out what's going on here.

I'm just making a quad and texturing it - very simple.  Works fine until I rotate the quad then everything goes awry.

Try the following code (just replace the jpg with something else - anything will work but a grid gives you a clearer idea that bad things are happening).  See what happens when you comment out the rotation and then put it back again.

Ideas anyone?

Quote:
float cx, cy, wd, ht;

PGraphics pg;
PImage img;

void setup()
{
  size( 500, 500, P3D );
  pg = createGraphics( width, height, P3D );
  img = loadImage( "uvtemplate001-lg.jpg" );
  
  cx = width/2;
  cy = height/2;
  wd = 120.0f;
  ht = 120.0f;
}

void draw()
{
  pg.beginDraw();
  pg.background( 128, 32 );

  pg.translate( cx, cy, 0.0f );
  pg.rotateX( 45 );
      
  pg.textureMode( NORMALIZED );

  pg.beginShape(QUADS);
    pg.texture( img );
    pg.vertex( - wd, - ht, 0.0f, 0, 0 );
    pg.vertex(   wd, - ht, 0.0f, 1, 0 );
    pg.vertex(   wd,   ht, 0.0f, 1, 1 );
    pg.vertex( - wd,   ht, 0.0f, 0, 1 );
  pg.endShape();
    
  pg.endDraw();

  image( pg, 0, 0 );
}



NOTE: the graphics context makes no difference - if you did this without the pg. it still doesn't work...
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« Last Edit: Dec 7th, 2008, 7:34am by SamH »  
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SamH
Re: Unexpected texture behaviour
Reply #1 - Dec 6th, 2008, 12:56am  
Actually, I'm pretty sure it's a bug in P3D - if I get more certain I'll add it to the bug tracker.  If you change P3D to OpenGL the problem goes away.
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koogy
Re: Unexpected texture behaviour
Reply #2 - Dec 6th, 2008, 5:43pm  
haven't tried your code but this sounds familiar

have you tried adding the hint ENABLE_ACCURATE_TEXTURES as mentioned in http://dev.processing.org/bugs/show_bug.cgi?id=103 ?

it's also visible in the cube rotate example:

http://processing.org/learning/3d/texture1.html
http://processing.org/learning/3d/texturecube.html
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SamH
Re: Unexpected texture behaviour
Reply #3 - Dec 7th, 2008, 7:24am  
Yeah, I saw that bug post - thanks for making me look at it harder.  I tried ENABLE_ACCURATE_TEXTURES, which broke the texturing, then found this:

http://dev.processing.org/bugs/show_bug.cgi?id=985

So ENABLE_ACCURATE_TEXTURES is deprecated, and is now handled by smooth().

Turns out that smooth fixes the bug with the texture rendering, too.

eg:

Quote:
void draw()
{
  pg.beginDraw();
  pg.background( 128, 32 );

  pg.translate( cx, cy, 0.0f );
  pg.rotateX( 45 );
      
  //float rot = (float)(millis() % 3600) / 10.0f;
  //pg.rotateZ( -radians(rot) );
  pg.textureMode( NORMALIZED );
  //pg.smooth();  // uncomment this line to fix the texture mapping

  pg.beginShape(QUADS);
    //pg.hint( ENABLE_ACCURATE_TEXTURES );
    pg.texture( img );
    pg.vertex( - wd, - ht, 0.0f, 0, 0 );
    pg.vertex(   wd, - ht, 0.0f, 1, 0 );
    pg.vertex(   wd,   ht, 0.0f, 1, 1 );
    pg.vertex( - wd,   ht, 0.0f, 0, 1 );
  pg.endShape();
  
  pg.endDraw();

  image( pg, 0, 0 );
}



I'll add a bug to the tracker.
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