Source code for arcade.physics_engines

"""
Physics engines for top-down or platformers.
"""
# pylint: disable=too-many-arguments, too-many-locals, too-few-public-methods

import math

from arcade import check_for_collision_with_list
from arcade import check_for_collision
from arcade import Sprite
from arcade import SpriteList
from arcade import get_distance

def _circular_check(player, walls):
    """
    This is a horrible kludge to 'guess' our way out of a collision
    Returns:

    """
    original_x = player.center_x
    original_y = player.center_y

    vary = 1
    while True:
        try_list = [[original_x, original_y + vary],
                    [original_x, original_y - vary],
                    [original_x + vary, original_y],
                    [original_x - vary, original_y],
                    [original_x + vary, original_y + vary],
                    [original_x + vary, original_y - vary],
                    [original_x - vary, original_y + vary],
                    [original_x - vary, original_y - vary]
                    ]

        for my_item in try_list:
            x, y = my_item
            player.center_x = x
            player.center_y = y
            check_hit_list = check_for_collision_with_list(player, walls)
            # print(f"Vary {vary} ({self.player_sprite.center_x} {self.player_sprite.center_y}) "
            #       f"= {len(check_hit_list)}")
            if len(check_hit_list) == 0:
                return
        vary *= 2

def _move_sprite(moving_sprite: Sprite, walls: SpriteList, ramp_up: bool):

    # See if we are starting this turn with a sprite already colliding with us.
    if len(check_for_collision_with_list(moving_sprite, walls)) > 0:
        _circular_check(moving_sprite, walls)

    original_x = moving_sprite.center_x
    original_y = moving_sprite.center_y
    original_angle = moving_sprite.angle

    # --- Rotate
    rotating_hit_list = []
    if moving_sprite.change_angle:

        # Rotate
        moving_sprite.angle += moving_sprite.change_angle

        # Resolve collisions caused by rotating
        rotating_hit_list = check_for_collision_with_list(moving_sprite, walls)

        if len(rotating_hit_list) > 0:

            max_distance = (moving_sprite.width + moving_sprite.height) / 2

            # Resolve any collisions by this weird kludge
            _circular_check(moving_sprite, walls)
            if get_distance(original_x, original_y, moving_sprite.center_x, moving_sprite.center_y) > max_distance:
                # Ok, glitched trying to rotate. Reset.
                moving_sprite.center_x = original_x
                moving_sprite.center_y = original_y
                moving_sprite.angle = original_angle

    # --- Move in the y direction
    moving_sprite.center_y += moving_sprite.change_y

    # Check for wall hit
    hit_list_x = check_for_collision_with_list(moving_sprite, walls)
    # print(f"Post-y move {hit_list_x}")
    complete_hit_list = hit_list_x

    # If we hit a wall, move so the edges are at the same point
    if len(hit_list_x) > 0:
        if moving_sprite.change_y > 0:
            while len(check_for_collision_with_list(moving_sprite, walls)) > 0:
                moving_sprite.center_y -= 1
            # print(f"Spot X ({self.player_sprite.center_x}, {self.player_sprite.center_y})"
            #       f" {self.player_sprite.change_y}")
        elif moving_sprite.change_y < 0:
            # Reset number of jumps
            for item in hit_list_x:
                while check_for_collision(moving_sprite, item):
                    # self.player_sprite.bottom = item.top <- Doesn't work for ramps
                    moving_sprite.center_y += 0.25

                if item.change_x != 0:
                    moving_sprite.center_x += item.change_x

            # print(f"Spot Y ({self.player_sprite.center_x}, {self.player_sprite.center_y})")
        else:
            pass
            # TODO: The code below can't execute, as "item" doesn't
            # exist. In theory, this condition should never be arrived at.
            # Collision while player wasn't moving, most likely
            # moving platform.
            # if self.player_sprite.center_y >= item.center_y:
            #     self.player_sprite.bottom = item.top
            # else:
            #     self.player_sprite.top = item.bottom
        moving_sprite.change_y = min(0.0, hit_list_x[0].change_y)

    # print(f"Spot D ({self.player_sprite.center_x}, {self.player_sprite.center_y})")
    moving_sprite.center_y = round(moving_sprite.center_y, 2)
    # print(f"Spot Q ({self.player_sprite.center_x}, {self.player_sprite.center_y})")

    # --- Move in the x direction
    if moving_sprite.change_x:
        almost_original_y = moving_sprite.center_y

        direction = math.copysign(1, moving_sprite.change_x)
        exit_loop = False
        cur_x_change = abs(moving_sprite.change_x)
        cur_y_change = 0
        while not exit_loop:
            if cur_x_change > abs(moving_sprite.change_x):
                cur_x_change = abs(moving_sprite.change_x)

            moving_sprite.center_x = original_x + cur_x_change * direction

            collision_check = check_for_collision_with_list(moving_sprite, walls)

            for sprite in collision_check:
                if sprite not in complete_hit_list:
                    complete_hit_list.append(sprite)

            if len(collision_check) > 0:
                if ramp_up:
                    cur_y_change = cur_x_change
                    moving_sprite.center_y = original_y + cur_y_change

                    collision_check = check_for_collision_with_list(moving_sprite, walls)
                    if len(collision_check) > 0:
                        cur_y_change -= cur_x_change
                    else:
                        while(len(collision_check) == 0) and cur_y_change > 0:
                            cur_y_change -= 1
                            moving_sprite.center_y = almost_original_y + cur_y_change
                            collision_check = check_for_collision_with_list(moving_sprite, walls)
                        cur_y_change += 1
                        collision_check = []

                if cur_x_change > 1 and len(collision_check) > 0:
                    cur_x_change -= 1
                else:
                    exit_loop = True

            else:
                exit_loop = True

        # print(cur_x_change * direction, cur_y_change)
        moving_sprite.center_x = original_x + cur_x_change * direction
        moving_sprite.center_y = almost_original_y + cur_y_change
        # print(f"({moving_sprite.center_x}, {moving_sprite.center_y}) {cur_x_change * direction}, {cur_y_change}")

    # Add in rotating hit list
    for sprite in rotating_hit_list:
        if sprite not in complete_hit_list:
            complete_hit_list.append(sprite)
    return complete_hit_list


[docs]class PhysicsEngineSimple: """ Simplistic physics engine for use in games without gravity, such as top-down games. It is easier to get started with this engine than more sophisticated engines like PyMunk. Note, it does not currently handle rotation. """ def __init__(self, player_sprite: Sprite, walls: SpriteList): """ Create a simple physics engine. :param Sprite player_sprite: The moving sprite :param SpriteList walls: The sprites it can't move through """ assert(isinstance(player_sprite, Sprite)) assert(isinstance(walls, SpriteList)) self.player_sprite = player_sprite self.walls = walls
[docs] def update(self): """ Move everything and resolve collisions. :Returns: SpriteList with all sprites contacted. Empty list if no sprites. """ complete_hit_list = _move_sprite(self.player_sprite, self.walls, ramp_up=False) return complete_hit_list
[docs]class PhysicsEnginePlatformer: """ Simplistic physics engine for use in a platformer. It is easier to get started with this engine than more sophisticated engines like PyMunk. Note, it does not currently handle rotation. """ def __init__(self, player_sprite: Sprite, platforms: SpriteList, gravity_constant: float = 0.5, ladders: SpriteList = None, ): """ Create a physics engine for a platformer. :param Sprite player_sprite: The moving sprite :param SpriteList platforms: The sprites it can't move through :param float gravity_constant: Downward acceleration per frame :param SpriteList ladders: Ladders the user can climb on """ if ladders is not None and not isinstance(ladders, SpriteList): raise TypeError("Fourth parameter should be a SpriteList of ladders") self.player_sprite = player_sprite self.platforms = platforms self.gravity_constant = gravity_constant self.jumps_since_ground = 0 self.allowed_jumps = 1 self.allow_multi_jump = False self.ladders = ladders
[docs] def is_on_ladder(self): """ Return 'true' if the player is in contact with a sprite in the ladder list. """ # Check for touching a ladder if self.ladders: hit_list = check_for_collision_with_list(self.player_sprite, self.ladders) if len(hit_list) > 0: return True return False
[docs] def can_jump(self, y_distance=5) -> bool: """ Method that looks to see if there is a floor under the player_sprite. If there is a floor, the player can jump and we return a True. :returns: True if there is a platform below us :rtype: bool """ # Move down to see if we are on a platform self.player_sprite.center_y -= y_distance # Check for wall hit hit_list = check_for_collision_with_list(self.player_sprite, self.platforms) self.player_sprite.center_y += y_distance if len(hit_list) > 0: self.jumps_since_ground = 0 if len(hit_list) > 0 or self.allow_multi_jump and self.jumps_since_ground < self.allowed_jumps: return True else: return False
[docs] def enable_multi_jump(self, allowed_jumps: int): """ Enables multi-jump. allowed_jumps should include the initial jump. (1 allows only a single jump, 2 enables double-jump, etc) If you enable multi-jump, you MUST call increment_jump_counter() every time the player jumps. Otherwise they can jump infinitely. :param int allowed_jumps: """ self.allowed_jumps = allowed_jumps self.allow_multi_jump = True
[docs] def disable_multi_jump(self): """ Disables multi-jump. Calling this function also removes the requirement to call increment_jump_counter() every time the player jumps. """ self.allow_multi_jump = False self.allowed_jumps = 1 self.jumps_since_ground = 0
[docs] def jump(self, velocity: int): """ Have the character jump. """ self.player_sprite.change_y = velocity self.increment_jump_counter()
[docs] def increment_jump_counter(self): """ Updates the jump counter for multi-jump tracking """ if self.allow_multi_jump: self.jumps_since_ground += 1
[docs] def update(self): """ Move everything and resolve collisions. :Returns: SpriteList with all sprites contacted. Empty list if no sprites. """ # print(f"Spot A ({self.player_sprite.center_x}, {self.player_sprite.center_y})") # --- Add gravity if we aren't on a ladder if not self.is_on_ladder(): self.player_sprite.change_y -= self.gravity_constant # print(f"Spot F ({self.player_sprite.center_x}, {self.player_sprite.center_y})") # print(f"Spot B ({self.player_sprite.center_x}, {self.player_sprite.center_y})") complete_hit_list = _move_sprite(self.player_sprite, self.platforms, ramp_up=True) for platform in self.platforms: if platform.change_x != 0 or platform.change_y != 0: platform.center_x += platform.change_x if platform.boundary_left is not None \ and platform.left <= platform.boundary_left: platform.left = platform.boundary_left if platform.change_x < 0: platform.change_x *= -1 if platform.boundary_right is not None \ and platform.right >= platform.boundary_right: platform.right = platform.boundary_right if platform.change_x > 0: platform.change_x *= -1 if check_for_collision(self.player_sprite, platform): if platform.change_x < 0: self.player_sprite.right = platform.left if platform.change_x > 0: self.player_sprite.left = platform.right platform.center_y += platform.change_y if platform.boundary_top is not None \ and platform.top >= platform.boundary_top: platform.top = platform.boundary_top if platform.change_y > 0: platform.change_y *= -1 if platform.boundary_bottom is not None \ and platform.bottom <= platform.boundary_bottom: platform.bottom = platform.boundary_bottom if platform.change_y < 0: platform.change_y *= -1 # print(f"Spot Z ({self.player_sprite.center_x}, {self.player_sprite.center_y})") # Return list of encountered sprites return complete_hit_list