physics.py

import math

def _limit(value, min_value, max_value):
    """Limit value by min_value and max_value."""

    if value < min_value:
        return min_value
    if value > max_value:
        return max_value
    return value


def _apply_acceleration(speed, speed_limit, forward=True):
    """Change speed — accelerate or brake — according to force direction."""

    speed_limit = abs(speed_limit)

    speed_fraction = speed / speed_limit

    # если корабль стоит на месте, дергаем резко
    # если корабль уже летит быстро, прибавляем медленно
    delta = math.cos(speed_fraction) * 0.75

    if forward:
        result_speed = speed + delta
    else:
        result_speed = speed - delta

    result_speed = _limit(result_speed, -speed_limit, speed_limit)

    # если скорость близка к нулю, то останавливаем корабль
    if abs(result_speed) < 0.1:
        result_speed = 0

    return result_speed


def update_speed(row_speed, column_speed, rows_direction, columns_direction, row_speed_limit=2, column_speed_limit=2, fading=0.8):
    """Update speed smootly to make control handy for player. Return new speed value (row_speed, column_speed)
    
    rows_direction — is a force direction by rows axis. Possible values:
       -1 — if force pulls up
       0  — if force has no effect
       1  — if force pulls down

    columns_direction — is a force direction by colums axis. Possible values:
       -1 — if force pulls left
       0  — if force has no effect
       1  — if force pulls right
    """

    if rows_direction not in (-1, 0, 1):
        raise ValueError(f'Wrong rows_direction value {rows_direction}. Expects -1, 0 or 1.')

    if columns_direction not in (-1, 0, 1):
        raise ValueError(f'Wrong columns_direction value {columns_direction}. Expects -1, 0 or 1.')
    
    if fading < 0 or fading > 1:
        raise ValueError(f'Wrong columns_direction value {fading}. Expects float between 0 and 1.')
        

    # гасим скорость, чтобы корабль останавливался со временем
    row_speed *= fading
    column_speed *= fading

    row_speed_limit, column_speed_limit = abs(row_speed_limit), abs(column_speed_limit)

    if rows_direction != 0:
        row_speed = _apply_acceleration(row_speed, row_speed_limit, rows_direction > 0)

    if columns_direction != 0:
        column_speed = _apply_acceleration(column_speed, column_speed_limit, columns_direction > 0)

    return row_speed, column_speed