How to make a permanent foreground object

jomizzy · February 2016

If I am doing something which has an object moving, and therefore the background being redrawn each frame, is there any way to keep another object on the screen? I cannot figure out how to do it without redrawing that object every single frame, which is difficult when the origin is moving due to translate().

quark · February 2016

You will have to redraw the background every time but you can isolate translations (also rotation and scale transformations) with pushMatrix(0 and popMatrix() like this

PVector obj0, obj1;

void setup() {
  size(800, 300, P2D);
  obj0 = new PVector(100, 100);
  obj1 = new  PVector(100, 200);
}

void draw() {
  background(0);
  pushMatrix();
  translate(obj0.x, obj0.y);
  fill(255, 255, 0);
  ellipse(0, 0, 20, 20);
  popMatrix();
  pushMatrix();
  translate(obj1.x, obj1.y);
  fill(255, 0, 255);
  ellipse(0, 0, 20, 20);
  popMatrix();
  obj0.x = (obj0.x + 2.5) % width;
  obj1.x = (obj1.x + 1.9) % width;
}

Chrisir · February 2016

in 3D you can also use HUD - see Wikipedia

ask if you need one of those please

Eeyorelife · February 2016

You don't have to use translate() to move one object? You could just change it's coordinates.

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