CODEWITHSUNDEEP
pythonpygamegame-physics
Tobias Laving
Tobias Laving

Reputation: 35

Angular movement in pygame

I've defined a function which allows me to move an object diagonally:

    if(myX > targetX):
        dx = myX - targetX
    else:
        dx = targetX - myX 
    if(myY > targetY):
        dy = myY - targetY
    else:
        dy = targetY - myY

    if(dy == 0):
        dy = 1
    if(dx == 0):
        dx = 1

    #Calc Movement
    if(dx < dy):
        Speedy = dy/dx 
        Speedx = 1
    if(dx > dy):
        Speedy = 1
        Speedx = dx/dy
    elif(dx == dy):
        Speedx = 1
        Speedy = 1

    if(myX < targetX):
        Speedx = Speedx * -1
    if(myY < targetY):
        Speedy = Speedy * -1


    return Speedx,Speedy

The code works, but the problem is that it doesn't do what I want. Right now the object speeds up if I move closer to it, which looks rather odd. I am very aware why it does this, but is there an easy way to fix the speed to be constant, but not the direction?

Upvotes: 0

Views: 1607

Answers (1)

placeybordeaux
placeybordeaux

Reputation: 2216

If you do it this way dx and dy are scalars of a vector that points from your guy to the target. Then you divide by the magnitude of both of them, here it is represented as dz. Now dx and dy represent a unit vector. Once you multiply them by speed you will get your object moving at a constant speed, but varrying direction.

import math

#set speed to how fast you want your guy to move
speed = 1
dx = myX - targetX
dy = myY - targetY

dz = math.sqrt(dx**2 + dy**2)

speedx = dx/dz * speed
speedy = dy/dz * speed

Upvotes: 2

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