OpenGL: multiple views and coordinates

_vk

Based on this thread

http://forum.processing.org/one/topic/set-3-viewports-from-3-camera-s-pointing-the-same-object.html

I was trying to understand the code by @amnon making 4 viewports. My real goal are 6, with specific sizes.

Questions:

1 - When using viewports are the coordinates inverted? Beginning from lower left corner?

2- Why this code (below) do not work as expected? Although the coordinates are right (either coord system) One of the viewports is always in the wrong place behind another? They seams to kind of interact. If you try with one the result is different than when you make more of them... Does any one know what is going on?

3- Is this using direct openGl commands? I think not, because the viewport() command is in PGL javadoc... But glViewport seams to de pure openGL... So... where am I? Where to go for the API?

Thanks a lot.

ps: the code linked above need this updates to run, as far as I could find out: PGL gl; and in setup: PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;

PGL gl;//
float rot;

void setup() {
  size(900, 900, OPENGL); //<>//
  PGraphicsOpenGL pgl = (PGraphicsOpenGL) g; 
  gl = pgl.beginPGL(); 
  colorMode(RGB, 1);
  stroke(1, 1, 1);
  strokeWeight(2.5);
}

void draw() {
  background(1, 1, 1);
  rot+=0.005;



  // - -
  // 0 -
  gl.viewport (0, 0, 450, 450);
  perspective(PI/6, (float) width/height, 1, 10000);
  camera(-400, 200, -700, 0, 0, 0, 0, 1, 0);
  renderGeometry();

  //- 0
  //- -
  gl.viewport (450, 450, 450, 450);
  perspective(PI/6, (float) width/height, 1, 10000);
  camera(-400, 200, 1710, 0, 0, 0, 0, 1, 0);
  renderGeometry();

  // if alone will be the upper left, but
  // it is behind the next, lower right???__________<<<<<<< !!
  //0 -
  //- -
  gl.viewport (0, 450, 450, 450);
  perspective(PI/6, (float) width/height, 1, 10000);
  camera(200, -400, 2000, 0, 0, 0, 0, 1, 0);
  renderGeometry();


  // - -
  // - 0
  gl.viewport (450, 0, 450, 450);
  perspective(PI/6, (float) width/height, 1, 10000);
  camera(300, 300, 200, 0, 0, 0, 0, 1, 0);
  renderGeometry();
}


void renderGeometry() {
  pushMatrix();
  scale(60);
  rotateX(rot);
  rotateY(rot);
  beginShape(QUADS);

  fill(0, 1, 1, 0.6); 
  vertex(-1, 1, 1);
  fill(1, 1, 1, 0.6); 
  vertex( 1, 1, 1);
  fill(1, 0, 1, 0.6); 
  vertex( 1, -1, 1);
  fill(0, 0, 1, 0.6); 
  vertex(-1, -1, 1);

  fill(1, 1, 1, 0.6); 
  vertex( 1, 1, 1);
  fill(1, 1, 0, 0.6); 
  vertex( 1, 1, -1);
  fill(1, 0, 0, 0.6); 
  vertex( 1, -1, -1);
  fill(1, 0, 1, 0.6); 
  vertex( 1, -1, 1);

  fill(1, 1, 0, 0.6); 
  vertex( 1, 1, -1);
  fill(0, 1, 0, 0.6); 
  vertex(-1, 1, -1);
  fill(0, 0, 0, 0.6); 
  vertex(-1, -1, -1);
  fill(1, 0, 0, 0.6); 
  vertex( 1, -1, -1);

  fill(0, 1, 0, 0.6); 
  vertex(-1, 1, -1);
  fill(0, 1, 1, 0.6); 
  vertex(-1, 1, 1);
  fill(0, 0, 1, 0.6); 
  vertex(-1, -1, 1);
  fill(0, 0, 0, 0.6); 
  vertex(-1, -1, -1);

  fill(0, 1, 0, 0.6); 
  vertex(-1, 1, -1);
  fill(1, 1, 0, 0.6); 
  vertex( 1, 1, -1);
  fill(1, 1, 1, 0.6); 
  vertex( 1, 1, 1);
  fill(0, 1, 1, 0.6); 
  vertex(-1, 1, 1, 0.6);

  fill(0, 0, 0); 
  vertex(-1, -1, -1, 0.6);
  fill(1, 0, 0); 
  vertex( 1, -1, -1, 0.6);
  fill(1, 0, 1); 
  vertex( 1, -1, 1, 0.6);
  fill(0, 0, 1); 
  vertex(-1, -1, 1, 0.6);

  endShape();
  popMatrix();
}

_vk

Bumping! Where are you GL experts??? [-O< ^:)^

MenteCode

I can't say I'm sure why this happened, but in your case, you now have to place the gl.viewport() call for every shape after the renderGeometry() call of every shape. That would explain why you see 2 shapes in one of the viewports.

I.e, this:

gl.viewport (450, 0, 450, 450);
perspective(PI/6, (float) width/height, 1, 10000);
camera(300, 300, 200, 0, 0, 0, 0, 1, 0);
renderGeometry();

V.S. this:

perspective(PI/6, (float) width/height, 1, 10000);
camera(-400, 200, -700, 0, 0, 0, 0, 1, 0);
renderGeometry();
gl.viewport (0, 0, 450, 450);

_vk

Genius!! Thanks very much!!! ^:)^

For the records, here the updated, working code:

PGL gl;//
float rot;

void setup() {
  size(900, 900, OPENGL); //<>//
  PGraphicsOpenGL pgl = (PGraphicsOpenGL) g; 
  gl = pgl.beginPGL(); 
  colorMode(RGB, 1);
  stroke(1, 1, 1);
  strokeWeight(2.5);
}

void draw() {
  background(1, 1, 1);
  rot+=0.005;



  // - -
  // 0 -

  perspective(PI/6, (float) width/height, 1, 10000);
  camera(-400, 200, -700, 0, 0, 0, 0, 1, 0);
  renderGeometry();
  gl.viewport (0, 0, 450, 450);

  //- 0
  //- -

  perspective(PI/6, (float) width/height, 1, 10000);
  camera(-400, 200, 1710, 0, 0, 0, 0, 1, 0);
  renderGeometry();
   gl.viewport (450, 450, 450, 450);

  // if alone will be the upper left, but
  // it is behind the next, lower right???__________<<<<<<< !!
  //0 -
  //- -

  perspective(PI/6, (float) width/height, 1, 10000);
  camera(200, -400, 2000, 0, 0, 0, 0, 1, 0);
  renderGeometry();
  gl.viewport (0, 450, 450, 450);


  // - -
  // - 0

  perspective(PI/6, (float) width/height, 1, 10000);
  camera(300, 300, 200, 0, 0, 0, 0, 1, 0);
  renderGeometry();
  gl.viewport (450, 0, 450, 450);
}


void renderGeometry() {
  pushMatrix();
  scale(60);
  rotateX(rot);
  rotateY(rot);
  beginShape(QUADS);

  fill(0, 1, 1, 0.6); 
  vertex(-1, 1, 1);
  fill(1, 1, 1, 0.6); 
  vertex( 1, 1, 1);
  fill(1, 0, 1, 0.6); 
  vertex( 1, -1, 1);
  fill(0, 0, 1, 0.6); 
  vertex(-1, -1, 1);

  fill(1, 1, 1, 0.6); 
  vertex( 1, 1, 1);
  fill(1, 1, 0, 0.6); 
  vertex( 1, 1, -1);
  fill(1, 0, 0, 0.6); 
  vertex( 1, -1, -1);
  fill(1, 0, 1, 0.6); 
  vertex( 1, -1, 1);

  fill(1, 1, 0, 0.6); 
  vertex( 1, 1, -1);
  fill(0, 1, 0, 0.6); 
  vertex(-1, 1, -1);
  fill(0, 0, 0, 0.6); 
  vertex(-1, -1, -1);
  fill(1, 0, 0, 0.6); 
  vertex( 1, -1, -1);

  fill(0, 1, 0, 0.6); 
  vertex(-1, 1, -1);
  fill(0, 1, 1, 0.6); 
  vertex(-1, 1, 1);
  fill(0, 0, 1, 0.6); 
  vertex(-1, -1, 1);
  fill(0, 0, 0, 0.6); 
  vertex(-1, -1, -1);

  fill(0, 1, 0, 0.6); 
  vertex(-1, 1, -1);
  fill(1, 1, 0, 0.6); 
  vertex( 1, 1, -1);
  fill(1, 1, 1, 0.6); 
  vertex( 1, 1, 1);
  fill(0, 1, 1, 0.6); 
  vertex(-1, 1, 1, 0.6);

  fill(0, 0, 0); 
  vertex(-1, -1, -1, 0.6);
  fill(1, 0, 0); 
  vertex( 1, -1, -1, 0.6);
  fill(1, 0, 1); 
  vertex( 1, -1, 1, 0.6);
  fill(0, 0, 1); 
  vertex(-1, -1, 1, 0.6);

  endShape();
  popMatrix();
}

_vk

Have I said thank you? Thank you!

:)