fischertechnik community forum

program

uses pure2d, keyset

procedure Swap(byref a :integer, byref b :integer)
var
c :integer
begin
c := a
a := b
b := c
end

var
x, x0, x1, delta_x, step_x :integer
y, y0, y1, delta_y, step_y :integer
z, z0, z1, delta_z, step_z :integer
swap_xy, swap_xz :boolean
drift_xy, drift_xz :integer
cx, cy, cz :integer

begin

//start and end points (change these values)
x0 := 0 x1 := -2
y0 := 0 y1 := 5
z0 := 0 z1 := -10

//'steep' xy Line, make longest delta x plane
swap_xy := Abs(y1 - y0) > Abs(x1 - x0)
if swap_xy
Swap(x0, y0)
Swap(x1, y1)
endif

//do same for xz
swap_xz := Abs(z1 - z0) > Abs(x1 - x0)
if swap_xz
Swap(x0, z0)
Swap(x1, z1)
endif

//delta is Length in each plane
delta_x := Abs(x1 - x0)
delta_y := Abs(y1 - y0)
delta_z := Abs(z1 - z0)

//drift controls when to step in 'shallow' planes
//starting value keeps Line centred
drift_xy := (delta_x / 2)
drift_xz := (delta_x / 2)

//direction of line
step_x := 1; if (x0 > x1) then step_x := -1
step_y := 1; if (y0 > y1) then step_y := -1
step_z := 1; if (z0 > z1) then step_z := -1

//starting point
y := y0
z := z0

//step through longest delta (which we have swapped to x)
for x = x0 to x1 step step_x

//copy position
cx := x; cy := y; cz := z

//unswap (in reverse)
if swap_xz then Swap(cx, cz)
if swap_xy then Swap(cx, cy)

//passes through this point
debugmsg(":" + cx + ", " + cy + ", " + cz)

//update progress in other planes
drift_xy = drift_xy - delta_y
drift_xz = drift_xz - delta_z

//step in y plane
if drift_xy < 0
y = y + step_y
drift_xy = drift_xy + delta_x
endif

//same in z
if drift_xz < 0
z = z + step_z
drift_xz = drift_xz + delta_x
endif
next

end