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Index › Programming Questions & Help › Programs › texture perspective

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texture perspective (Read 1444 times)

anachronik

texture perspective
Jun 1^st, 2010, 6:25am

Hi,

I'm actuallly learning how 2D textures works within P3D.
I've tried something really simple, create a texture and map over a square. The result is kinda weird, got some perspective distortion.

After read a bit of opengl tutorials, this doesn't seems to be that weird.
I think i've to use glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST) in opengl to get ride of it but what for P3D ?

Does Processing have any core functions to handle that ?

Here's the source code:
Quote:

PGraphics b;
int l = 24;

void setup()
{
  size(200, 200, P3D);
  b = createGraphics(l*2, l*2, P3D);
  textureMode(NORMALIZED);
}

void draw()
{
  //generate the texture
  b.beginDraw();
  b.noStroke();
  b.fill(0);
  b.rect(0, 0, l, l);
  b.rect(l, l, l, l);
  b.fill(255);
  b.rect(l, 0, l, l);
  b.rect(0, l, l, l);
  b.endDraw();

  //basic tranformations
  pushMatrix();
  translate(width/2, height/2);
  rotateX(-PI/4);
  rotateY(-PI/4);

  beginShape(QUADS);
  texture(b);
  vertex(l, -l, -l, 0, 0);
  vertex(-l, -l, -l, 0, 1);
  vertex(-l, -l, l, 1, 1);
  vertex(l, -l, l, 1, 0);
  endShape();

  popMatrix();
  image(b, 0 ,0);
}

koogy God Member Offline Posts: 788	Re: texture perspective Reply #1 - Jun 1^st, 2010, 2:57pm did you see the texture examples? it mentions the problem there. the way around it is to split the quad up into smaller pieces, that way the distortion is minimised. it's barely noticeable on the third example. http://processing.org/learning/3d/texture3.html

Cedric

Re: texture perspective
Reply #2 - Jun 1^st, 2010, 4:06pm

its the same with lightning. you can see the difference by changing the mousepos. you get much better results when you subdivide the shape

Code:

 

void setup(){
size(500, 500, P3D);
background(255);
noStroke();
sphereDetail(35);
}

void draw(){

//lights();
pointLight(151, 202, 226, 235, 440,   80);
pointLight(251, 22, 226, 205, 240,   80);
pointLight( 151, 222,  6,  305,  140,   80);

fill(215,220,210 );
translate(100,100);
int res = 1+mouseX/50;
 
for(int i = 0; i<res; i++){
 beginShape(QUAD_STRIP);
for(int j = 0; j<=res; j++){

vertex(i*300/res,j*300/res);
vertex((i+1)*300/res,(j)*300/res);

}endShape();
}}

twitter.com/CedricKiefer

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