DynamicCoordinates Command

DynamicCoordinates[ <Point A>, <Number X>, <Number Y> ]

Creates a point with coords (X, Y). This point is dependent, but can be moved. Whenever you try to move the new point to coordinates (x,y), point A is moved there and coordinates for the new point are calculated. Works best if point A is not visible and dragging is done with the mouse. At least one of X and Y should depend on A.

Example:

• B = DynamicCoordinates[A, round(x(A)), round(y(A))].When you try to move B to (1.3, 2.1) using the Move Tool, point A becomes (1.3, 2.1) and B appears at (1,2).
• B = DynamicCoordinates[A, x(A), min(y(A), sin(x(A))) ] creates a point under sin(x).

Note: PointIn[y<sin(x)] is the easier solution in this case.

• The following examples show other ways to restrain the positions of a point C: let A = Point[xAxis] and B = Point[xAxis]. Now type in the Input Bar:
  DynamicCoordinates[B, Min[x(B), x(A)], 0], and press Enter
  

SetVisibleInView[B, 1, false], and press Enter

SetLayer[C, 1], and press Enter
Now, C cannot be moved to the right of A.

• Define A=(1,2). Now, type in the Input Bar:
  SetVisibleInView[A, 1, false and press Enter
  B = DynamicCoordinates[A, If[x(A) > 3, 3, If[x(A) < -(3), -3, If[x(A)< 0, round(x(A)), x(A)]]], If[x(A) < 0, 0.5, If[y(A) > 2, 2, If[y(A) <0, 0, y(A)]]]], and press Enter,
• This example makes A a sticky point when a point C is dragged near it.
  Define A = (1,2) and B = (2,3). Now, type in the Input Bar:
  SetVisibleInView[B, 1, false] and press Enter
  C = DynamicCoordinates[B, If[Distance[A, B] < 1, x(A), x(B)], If[Distance[A, B] < 1, y(A), y(B)]].