All four of these sprites are at position (0,0), but their costumes are shifted so they do not overlap at all. Sprite 1 covers the pixels above/right the center plus sign, sprite 2 covers the pixels above/left, etc. The one that is touching the mouse (according to the "touching mouse pointer" block) shows in red. Get the mouse to location (0,0), and you can see that it touches sprite 2. All of the sprites are at location (0,0), but only sprite 2 covers the pixel where the mouse is.
This project tries to answer the question: if the mouse position and the sprite position are equal (say both are at position (45,75)), which pixel in the costume is the mouse actually touching, according to the "touching mouse pointer" block? This matters if the costume leaves some pixels empty - the mouse only counts as "touching" if it hits a pixel that this costume has colored. If you leave a gap in the middle and that's where the mouse is, it is not touching. It turns out that the mouse would be touching the pixel just above and to the left of the plus sign center mark in the costume editor. It does not touch the pixels to the right or below that center mark. (And that plus sign does not mark the center of a pixel. If it did, then when the mouse was at (0,0) all four of these would be touching it, because they all come very VERY close to that center plus sign, much closer than the size of one pixel.) #coding #technical #pixels #touchingmousepointer
