Scale + noFill not working ?

marc_nostromo

I'm trying to use scale and I'm puzzle by the result of the following code:

void setup()
{
  size(1000, 600);
  noLoop();
}

void draw()
{
  scale(width/2, height/4);
  noFill();
  rect(0,0,1,1);
}

I'm expecting a unfilled rectange taking half the width and quarter the height but I'm seeing a filled rectange with strange boundaries.

Is there any reason or is this a bug ? The same happens with shapes.

Chrisir

Scale values are specified as decimal percentages. For example, the function call scale(2.0) increases the dimension of a shape by 200%.

marc_nostromo

I understand that, it is exactly why I don't understand what is going on in the above example

GoToLoop

size(1000, 600);
noLoop();
smooth(4);

rectMode(CENTER);
noFill();
stroke(0);

background(0350);
translate(width>>1, height>>1);
scale(width>>1, height>>2);

rect(0, 0, 1, 1);
//point(0, 0);

jeremydouglass

@marc_nostromo --

If you comment out your call to scale() you will see that you have drawn a 1x1 pixel rect -- it has no fill, but the default stroke is black, so the result is a black dot in the upper-left corner of your sketch. You use scale() to zoom in on that black dot with width of x500 and a height of x150. The zoomed in and distorted shape of that single pixel becomes a very big rectangle on the screen.

Here is a simple sketch to show you this happening -- it zooms in x1, x2, x3, x4 etc. as the frameCount increases. When the count becomes higher than x400 (after about seven seconds) that 1 pixel rectangle will 400 pixels wide and will fill the sketch area.

void setup()
{
  size(400, 400);
}

void draw()
{
  background(255);
  scale(frameCount);
  noFill();
  rect(0,0,1,1);
}

To better understand how scale() works and why, check the reference page and read the Processing "Coordinate System and Shapes" tutorial for background:

• https://processing.org/reference/scale_.html
• https://processing.org/tutorials/drawing/

Regarding:

I'm expecting a unfilled rectangle taking half the width and quarter the height

...the easiest way to do this is:

rect(0,0,width/2,height/4);

marc_nostromo

Haa... I get it. So I'm basically stroking with a huge pen. That make sense, thanks