Vector Question (using vector class from boards)

Monkey Forums/Monkey Programming/Vector Question (using vector class from boards)

xzess

(Posted 2011) [#1]

Hi,

im using the vector class, posted in the boards.

I have 2 Vectors, Postion and Movement

I set the Movement and the Position will smoothmove to it by dividing the distance.

My question is:
How can i move to a destination without changing the length/speed?
Or how can i get the direction to the movement and then apply a x=1 force so it will move to the direction of the destination with a 1.0 speed

Thanks in advice!

Jesse

(Posted 2011) [#2]

you need to figure out the unit movement:
vx -> is the component x for movement
vy -> is the component y for movement
dx -> unit movement for x (x normalized)
dy -> unit movement for y (y normalized)

length:float = sqrt(vx*vx+vy*vy)
dx = vx/length
dy = vy/length

dx and dy will produce a 1 unit movement if added to the position.

note that if length is zero you will get a division by zero error(NAN).

there should be something that do that in one of the functions.

Tibit

(Posted 2011) [#3]

If you want to have something move from A to B over certain time, without considering the distance. It will always take the same time, then what you probably want is to interpolate:

Function Main()
	
	Local a:Float = 10
	Local b:Float = 100
	Print "From "+a+" To "+b
	Print "0%: "+Interpolate(a,b,0)
	
	Print Interpolate(a,b,0.2)
	Print Interpolate(a,b,0.4) 
	Print Interpolate(a,b,0.6) 
	Print Interpolate(a,b,0.8) 
	Print Interpolate(a,b,1.0) 
	
	Print "More than 100%..."
	Print "150%: "+Interpolate(a,b,1.5) 	
	Print "200%: "+Interpolate(a,b,2.0) 
	Print "1000%: "+Interpolate(a,b,10.0) 
	Print "10000%: "+Interpolate(a,b,100.0) 
			
	Print "Less than 0%..."				
	Print Interpolate(a,b,-0.2)
	Print Interpolate(a,b,-0.4) 
	Print Interpolate(a,b,-0.6)	
	
	
End

Function Interpolate:Float(a:Float,b:Float,percent:Float) 
      Return (a+( (b-a)*percent) )
End

You input StartPosition and EndPosition, then you pick a speed, let us say 10% of this distance over time, meaning you will reach the end (100%) in 10sec then.

If that was not what you meant, what Jesse said (above) in Vector Math is:
Velocity.Normalize()
Note: It will not crash on zero (assuming you are using my Vector class), instead if you attempt to normalize a Vector with a length of 0, nothing will happen.

This will give you a Velocity of 100 for example:
Velocity.Normalize().Multiply( 100 )

You can then use Delta-Time to add Velocity to Position:
Velocity.Multiply( DeltaTime ) 'Use pixels/sec instead of pixels/fps
Position.Add( Velocity )

xzess

(Posted 2011) [#4]

Thank you both very much and thanks for sharing!