I thought that mouseX and mouseY would refer to the current origin and their values would be "sensitive" to translations, but apparently this is not true.
For example, in the code below I was expecting that the circles were drawn in the mouse position. What am I doing wrong?

Code:

void draw() {
  translate(100,100);

  float x = mouseX;
  float y = mouseY;

  fill(200,0,200);
  ellipse(x, y, 3, 3);
}
 

Hi,

To use the translation method is best to wrapped inside the push and pop Matrix like this:
Code:

pushMatrix();
translate(x, y);
//draw here
popMatrix(); 

So in your code try this:
Code:

pushMatrix();
translate(mouseX, mouseY);
fill(color);
ellipse(0, 0, 3, 3);
popMatrix(); 

on the other hand you don't necessarily need to use the translate method to achieve your objective.

Hope that make sense

Cheers
rS

PhiLho  wrote on Apr 14^th, 2010, 4:51am:


OK, this confirms what I was suspecting. Thanks for clarifying it.

I find this a bit annoying, but there must be a good reason for not having the same coordinates for the mouse and for what we draw.

Unless you put in the setup()
If you put it in the draw loop I don't think you are going to get the behavior you expected, nardove is trying to give you a steer.

Its not that I'm really thinking of, I guessed that the translate is probably spurious and unnecessary (especially for each loop). I've been trying to think what he's trying to do, which is I presume to start with an ellipse in the center, that can picked up and moved. In the OO world you would create a nice ellipse object initialized in setup. Which is then controlled by the mouse in draw, with or without redrawn background, depending on whether you wanted a persistent image?
If I'm right in my assumption a solution would be to initialize x and y to the center instead, draw the ellipse, and on a boolean (mouse clicked for example) turn on the mouse tracking (but it is still a bit of mess as it depends where your mouse is). To make it less jumpy you could use a calculated displacement rather than the actual mouse coordinates for the movement.
An even better solution use the mouse dragged function to control the ellipse. To make sure x and y are visible between setup and draw, declare them before draw.
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