drawing text in front in 3d

nikolaj

My latest sketch is a 3D figure, that you can move around, and some text on the screen, the text is drawn at (-width,-height,0). and it works fine, as long as the figures z value is lower than the text's. But if i move closer to the figure, so that it's z value is greater than the text's, the figure is drawn in front of the text, so that you cant read it.

here are some pictures of it:

When the figure is far away the text is in front.

Now the text is behind the figure (it shouldn't be)

I do know why this happens, when the text has a lower z value than the figure, it is drawn behind it. But i want a way to draw the text, as though it was drawn on the camera.

TfGuy44

Can you draw the text without a z position? text("Test",20,20); Other possibilities: Draw the text in a separate PGraphics with a transparent background, then draw it as a 2D image. Disable and enable the depth test before drawing your text.

nikolaj

i do not use a z position, and the computer do therefor asumes that i wants to draw it at z = 0.

I am thinking about doing something like your second sugestion, but i don't know how

nikolaj

Using different PGraphichs turned out to be much easier than i thought it would. But drawing the text on a 2D PGraphic and then displaying it as an image, do still require a z coordinate, and the figure would still sometimes be displayed in front of the text.

Instead i tried to draw all 3D figures on a separate 3 dimemsional PGraphichs and then display that, as an image, and then draw the text on that. And it worked:

Thanks

nikolaj

on the downside, that just made the framerate jump from 40 FPS in average before, to 30 FPS in average after.

quark

Try using push and pop matrix e.g.

void draw(){
  pushMatrix();
  // draw 3D
  popMatrix();
  // draw text
}

Chrisir

here

void setup() {
  size(800, 800, OPENGL);
}

void draw() {
  background(0);
  lights();

  // reset some stuff that was set differently by the HUD
  // maybe you need to set the camera
  // hint(ENABLE_DEPTH_TEST);
  textSize(32);


  // main program


  // display a text in the corner 
  fill(255);
  textSize(12);
  showTextInHUD("Test ");
} 



// HUD funcs  ----------------------
// Head-up-Display 
// see http://de.wikipedia.org/wiki/Head-up-Display

void showTextInHUD(String str1) {
  // A small 2D HUD for text in the
  // upper left corner. 
  // This func may only be called a the very end of draw() afaik.
  camera();
  hint(DISABLE_DEPTH_TEST);
  noLights();
  textMode(MODEL);
  if (str1!=null)
    text(str1, 20, 20);
  hint(ENABLE_DEPTH_TEST);
} // func 

void showTextInHUD(String str1, float x, float y) {
  // A small 2D HUD for text at
  // free pos.
  // This func may only be called a the very end of draw() afaik.
  camera();
  hint(DISABLE_DEPTH_TEST);
  noLights();
  textMode(MODEL);
  if (str1!=null)
    text(str1, x, y);
  hint(ENABLE_DEPTH_TEST);
} // func 

nikolaj

Pop and Pushmatrix doesn't change that the text is drawn behind the figure

nikolaj

Oh, i did not know about disabeling and enabeling the debth test. Turns out i don't need to use different PGraphics at all. The text is now working perfectly, and the framerate is the same as without text.

Chrisir

yeah, common problem, should be FAQ

;-)

nikolaj

By the way, the project i was working on is finished and uploaded now: 3D human figure