[snippet] Get Units in Line

/******************************************************************

*                     GROUP UNITS IN LINE v1.0                    *

*                           By moyack                             *

*                              2012                               *

*              ===================================                *

*              Exclusive resource from wc3jass.com                *

*              ===================================                *

******************************************************************/

library GetUnitsInLine requires GeometryLibBase

/* This library catch all the units in a line. This line however,

can be defined in several ways, each one will offer a function for

that purpose:

 * Between 2 points:  GetUnitsInLine_byPoints()

 * Between 2 widgets: GetUnitsInLine_byWidgets()

 The first function takes as arguments a group variable and 4 reals

 which are the X/Y coordinates of the first and second point.

 The second function takes as arguments a group variable and 2 widgets,

 these widgets can be any combination of units, items and destructables.

 The group variable for both functions will store the units catched in

 the line defined by points or widgets, so it's advisable that this group 

 should be empty.

*/

globals

    private constant real SPREAD = 30. // this value defines how wide is the line of units selected

    private group G = CreateGroup()

endglobals

public function byPoints takes group g, real x1, real y1, real x2, real y2 returns nothing

    local unit u

    local real a

    local real b

    local real x = 0.5 * (x1 + x2)

    local real y = 0.5 * (y1 + y2)

    if g == null then

        return

    endif

    call GroupEnumUnitsInRange(G, x, y, GetDistance(x, y, x1, y1) + SPREAD, null)

    for u in G

        if x2 - x1 == 0. then // manages vertical lines

            set x = x1

            set y = GetUnitY(u)

        else

            set x = GetUnitX(u)

            set a = (y2 - y1) / (x2 - x1)

            set b = -a * x1 + y1

            set y = a * x + b

        endif

        if IsUnitInRangeXY(u, x, y, SPREAD) then

            call GroupAddUnit(g, u)

        endif

    endfor

endfunction

public function byWidgets takes group g, widget A, widget B returns nothing

    call byPoints(g, GetWidgetX(A), GetWidgetY(A), GetWidgetX(B), GetWidgetY(B))

endfunction

endlibrary