How to find a pixel after translate and rotation?

djevazi

For example I have a pixel with coordinates (0,0), and I translate it to (mouseX,mouseY), and rotate it to "rotAngle = atan2(mouseY - pmouseY, mouseX - pmouseX)".... So many transformations. How to find an actual coordinates of this pixel?

TfGuy44

Use screenX() and screenY().

djevazi

I'll try this, thanx

djevazi

The problem is that I use Push/Pop Matrix, and the program thinks that my pixel is in the (0,0) coordinates, but after tranlsate and rotate it is not in the (0,0) coordinates. I want to compare my pixel color with another pixel color on the screen, and can't do this because I can't find the actual position of my pixel. "screenX" gives me the same unwanted result.

TfGuy44

void setup() {
  size(200, 200);
  stroke(255, 0, 0);
}

void draw() {
  background(0);
  pushMatrix();
  translate(100, 100);
  rotate(radians(mouseX));
  translate(40, 0);
  rotate(-radians(mouseY));
  translate(0, 20);
  float x = screenX(0, 0);
  float y = screenY(0, 0);
  ellipse(0, 0, 20, 20);
  popMatrix();
  line(0, 0, x, y);
}

djevazi

thanks