Module moog.physics.constant_speed

Constant speed corrective physics.

The ConstantSpeed class is a physics object that forces sprites in specified layers to have constant speed. It is typically used as a corrective physics.

Classes

class ConstantSpeed (layer_names, speed)
Expand source code 
class ConstantSpeed(abstract_physics.AbstractPhysics):
    """Constant speed physics class.
    
    Forces sprites in specified layers to have constant speed by normalizing
    their velocities.
    """

    def __init__(self, layer_names, speed):
        """Constructor.

        Args:
            layer_names: String or iterable of strings corresponding to layers
                in environment state. All sprites in these layers will have
                speed equal to `speed` argument.
            speed: Float. Sprite velocities will be normalized to have norm
                equal to this (or zero if their velocity is zero).
        """
        if not isinstance(layer_names, (list, tuple)):
            layer_names = [layer_names]
        self._layer_names = layer_names
        self._speed = speed

    def apply_physics(self, state, updates_per_env_step):
        """Apply the physics.
        
        Args:
            state: Environment state.
            updates_per_env_step: Int. Number of times the physics is applied
                per environment step.
        """
        sprites = [s for k in self._layer_names for s in state[k]]
        for s in sprites:
            norm_velocity = np.linalg.norm(s.velocity)
            if norm_velocity:
                s.velocity = self._speed * s.velocity / norm_velocity

Constant speed physics class.

Forces sprites in specified layers to have constant speed by normalizing their velocities.

Constructor.

Args

layer_names
String or iterable of strings corresponding to layers in environment state. All sprites in these layers will have speed equal to speed argument.
speed
Float. Sprite velocities will be normalized to have norm equal to this (or zero if their velocity is zero).

Ancestors

Methods

def apply_physics(self, state, updates_per_env_step)
Expand source code 
def apply_physics(self, state, updates_per_env_step):
    """Apply the physics.
    
    Args:
        state: Environment state.
        updates_per_env_step: Int. Number of times the physics is applied
            per environment step.
    """
    sprites = [s for k in self._layer_names for s in state[k]]
    for s in sprites:
        norm_velocity = np.linalg.norm(s.velocity)
        if norm_velocity:
            s.velocity = self._speed * s.velocity / norm_velocity

Apply the physics.

Args

state
Environment state.
updates_per_env_step
Int. Number of times the physics is applied per environment step.

Inherited members