Direction from angle

BlitzMax Forums/BlitzMax Programming/Direction from angle

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Robert
 #1
Sin(angle) returns the "x portion" of a movement in direction <angle> of length 1. Cos(angle) returns the "y portion" of a movement in direction <angle> of length 1. If you are moving by a different distance, multiply the result by the distance.

Eg, to move 45 degrees for 5 units:
x=5*sin(45)

Small example to demonstrate:

Type Vector
Field x
Field y
End Type

Graphics 800,600,0

Local q:Vector=New Vector
q.x=100
q.y=100

Local p:Vector=q

Local direction:Float=0

While Not KeyHit(KEY_ESCAPE)

DrawLine q.x,q.y,p.x,p.y,True

q=p
p=move(p,direction,5)


If KeyDown(KEY_SPACE) direction :+ 5

Delay 20

Flip

End While

Function move:Vector(initialPos:Vector,direction:Float,distance:Float)

Local result:Vector=New Vector

result.x=initialPos.x+(distance*Sin(180-direction))
result.y=initialPos.y+(distance*Cos(180-direction))

Return result

End Function



The above code does what you need. Hold down the SPACE key whilst the line is being plotted to change the direction.