关于运动的2D精灵物理

Question

I'm trying to implement 2D physics into an asteroids type game. I have collision boundaries set up at the window borders.

However, when I collide my ship sprite into a boundary (and reverse the proper velocity for either the x or y axis), I occasionally get a glitch when I go to move. The ship will jump temporarily, but if I hold the move key long enough it will usually fix itself.

The problem is that this glitch is noticeable.

Relevant code sections:

#update velocity
def velocity(self, speed):
    self.vx += math.sin(math.radians(self.angle)) * speed
    self.vy += math.cos(math.radians(self.angle)) * speed

    magnitude = math.sqrt(self.vx*self.vx + self.vy*self.vy)
    if magnitude > self.maxvel:
        self.vx *= 4/magnitude
        self.vy *= 4/magnitude
    if self.speed >= self.maxvel:
        self.speed = self.maxvel
    if self.speed <= -self.maxvel:
        self.speed = -self.maxvel

My movement code:

if (key[K_UP]):
    newShip.speed += 1
    newShip.moving = 1

if (key[K_DOWN]):
    newShip.speed -= 1
    newShip.moving = 1

if (key[K_LEFT]):
    newShip.angle += 4

if (key[K_RIGHT]):
    newShip.angle -= 4

My full code is here: http://pastebin.com/19rHq97R To run there are only 2 images required, you can really use anything I guess.

I think the problem has something to do with the reversal of the x or y velocity on detection of a collision, but I can't nail the exact problem. Any insight is appreciated.

EDIT: I did some more investigation. I wonder if the sudden jumps are because I don't have any sort of acceleration programmed in. http://pastebin.com/vFy9tjyN excerpt from my terminal log. I print out relevant variables from my program.

Answer 1

Try this:

DirDict = {"left": (-speed, 0), "right": (speed, 0), "up": (0, -speed), "left": (0, speed)}

if w:
    Direction = DirDict["left"]

I think this will be more stable; it's always worked for me.