Sorry your browser is not supported!

sync on
sync rate 0
make matrix 1,1,1,1,1
do
   lx=x
   ly=y
   x=x+(rightkey()-leftkey())
   y=y+(downkey()-upkey())


   print LucasEngine_Physics_CollideDotToLine( x , y , 100 , 300 , 300 , 100 )
   line 100 , 300 , 300 , 100


   ink rgb(0,255,0),0
   box x-20,y-20,x+20,y+20
sync
loop


Function LucasEngine_Physics_CollideDotToLine( Dot_X , Dot_Y , Line_X1 , Line_Y1 , Line_X2 , Line_Y2 )
   `Local Data
   Local Vector_Address        As DWORD
   Local Vector_Dot            As Integer
   Local Vector_Line           As Integer
   Local Vector_LineNormal     As Integer
   Local Line_Normal           As Integer
   Local Collision_DotProduct1 As Integer
   Local Collision_DotProduct2 As Integer
   Local Collision_State       As Boolean

   `Initialize Variable
   Vector_Dot         = 1
   Vector_Line        = 2
   Vector_LineNormal  = 3
   Vector_ToDotNormal = 4
   Collision_State    = 0

   `Create Vector
   Vector_Address = Make Vector2( Vector_Dot         )
   Vector_Address = Make Vector2( Vector_Line        )
   Vector_Address = Make Vector2( Vector_LineNormal  )

   `Set Vector
   Set Vector2 Vector_Dot        , Dot_X                 , Dot_Y
   Set Vector2 Vector_Line       , ( Line_X2 - Line_X1 ) , ( Line_Y2 - Line_Y1 )

   `Calculate Normal Vector From Line
   Line_Normal  = ( 1 / Sqrt( X Vector2( Vector_Line ) ) ^ 2 + ( Y Vector2( Vector_Line ) ) ^ 2 )

   `Set Normal Vector
   `Set Vector2 Vector_LineNormal , ( Y Vector2( Vector_Line ) ) * Line_Normal , -( X Vector2( Vector_Line ) ) * Line_Normal
   Set Vector2 Vector_LineNormal , -( Y Vector2( Vector_Line ) ) * Line_Normal , ( X Vector2( Vector_Line ) ) * Line_Normal

   `Dot Product Vector
   Collision_DotProduct1 = Dot Product Vector2( Vector_LineNormal , Vector_Dot  )
   Collision_DotProduct2 = Dot Product Vector2( Vector_LineNormal , Vector_Line )

   `Eliminate Vector
   Vector_Address = Delete Vector2( Vector_Dot        )
   Vector_Address = Delete Vector2( Vector_Line       )
   Vector_Address = Delete Vector2( Vector_LineNormal )

   `Check If Dot And Line Is Collided
   `If ( Collision_DotProduct1 >= Collision_DotProduct2 ) Then Collision_State = 1
   If ( Collision_DotProduct1 <= Collision_DotProduct2 ) Then Collision_State = 1
EndFunction Collision_State

rem make a random line
ax = rnd(640) : ay = rnd(480)
bx = rnd(640) : by = rnd(480)

hide mouse

do
	cls
	
	rem mouse position
	mx = mousex()
	my = mousey()
	
	rem draw a new random line
	if spacekey()
		ax = rnd(640)
		ay = rnd(480)
		bx = rnd(640)
		by = rnd(480)
	endif


	rem if point is within 10 pixels of the line, make it green.
	rem remember this function returns the squared distance, so
	rem if comparing within 10 units, square it first to equal 100.
	if DistanceFromLine(ax, ay, bx, by, mx, my, 10) <= 100
		ink rgb(0, 255, 0), 0
	else
		ink rgb(255,0,0), 0
	endif
	
	rem draw the line
	line ax, ay, bx, by

	rem show mouse's position
	ink rgb(255,255,255), 0
	circle mx, my, 2
	
loop





function DistanceFromLine(ax, ay, bx, by, px, py, distance)
	x = bx - ax
	y = by - ay
	n = (px - ax)*x + (py-ay)*y
	d# = x^2 + y^2
	u# = n / d#
	
	rem These two lines are required if checking
	rem a line segment. If checking an infinite
	rem line, then remove them.
	if u# > 1 then u# = 1
	if u# < 0 then u# = 0

	rem point of intersection
	ix = ax + (bx-ax)*u#
	iy = ay + (by-ay)*u#
	
	rem this is the squared distance of the point from the line
	rem if you need the actual distance, use sqrt around it, 
	rem otherwise this is faster when 'comparing' distances.
	d2# = (px - ix)^2 + (py - iy)^2
	
endfunction d2#