How simply check if mouse cursor is over specific point[i] and over of any ofpoints ?

[JC_]

There is a better solution to this simple problem? In array of points i will check if is mouse over one specific point[i] and if is on any of points.

after a long time.. i found this:

Type
  TPoint2D = record
    X, Y : Single; // position
    mouseover : boolean; // mouse over specific point
    Rect : TRect; // mouse vs point
  end;  

Var
  Point : array of TPoint2D;
  Count : integer;

  selectedPointID : integer;
  TrueCount, FalseCount : integer; 

  moveWithPoint : boolean; 
 ..

Begin

 trueCount := 0;
 falseCount := 0; 

 for i := 0 to Count-1 do begin   

 // mouse over one specific point
  if col2d_PointInRect( mousecur.x, mousecur.y, point[i].PointRect ) then
   point[i].mouseover := true else point[i].mouseover := false; 

 // Mouseover
 if Point[i].mouseover then begin
   inc(trueCount);
   if not moveWithPoint then selectedPointID := i + 1; // i can select only one point
  end else
   inc(falseCount);

   // is any point selected ?
   if falseCount = shape.count then
     begin
       selectedPointID := 0; // none
       ..
     end;   

  // mouse button interaction, move with point
  if mouse_Down( 0 ) and (selectedPointID > 0) then begin
   moveWithPoint := true;
   point[selectedPointID - 1].x := mousecur.x;
   point[selectedPointID - 1].y := mousecur.y;
   point[selectedPointID - 1].Rect.x := mousecur.x - 5;
   point[selectedPointID - 1].Rect.y := mousecur.y - 5;
  end;

  if not mouse_Down( 0 ) then moveWithPoint := false;

[User137]

Point is a point, not rectangle Every point usually has same size, it is only necessary to save X and Y.

I'm usually using my one and only solution to point picking, that is distance comparison. Think of a situation where 3 points are within eachothers "hitbox" or radius. With normal box focusing, 1 point will overlap the other 2, and they are harder to select. I'll try adapt it to your code, optimizing it without use of sqrt too. And since you can only focus 1 point at the time, i rid of some variables:

Type
  TPoint2D = record
    x, y : integer;
  end;    

 Var 
  Point : array of TPoint2D;
  Count: integer;
  // focusedPoint is -1 if nothing is focused, else it's focused point index
  focusedPoint: integer;
...
var dist, nearest, xx, yy: single;
begin
  nearest:=8*8; // Point radius 8 in power of 2
  focusedPoint:=-1;
  for i := 0 to Count-1 do begin
    // Get X and Y distance from cursor to point
    xx:=mousecur.x-point[i].x;
    yy:=mousecur.y-point[i].y;
    dist:=xx*xx+yy*yy;
    // Think of pythagoras distance formula
    // a^2 + b^2 = c^2
    // If both sides of comparison are in power of 2, we don't need sqrt()
    if dist<nearest then begin
      // Current point is closer to cursor than previous best match.
      // Set it as the new best match.
      nearest:=dist;
      focusedPoint:=i;
    end;
  end;
end;

[JC_]

Ups.. of course TPoint2D have X,Y.. Rectangle is only "collision checker"

i update code above to actual (is possible select only one point and move with him) but i think your code looks better, mathematics is clearer than booleans.. thanks