sep-pm-platformer/project/physics/PhysicsElementsHandler.py

import random
from typing import Optional

from physics.CollisionDirection import CollisionDirection
from physics.TickData import TickData
from sprite.BoundingBox import BoundingBox
from sprite.DynamicSprite import DynamicSprite
from sprite.Sprite import Sprite
from sprite.StaticSprite import StaticSprite
from ui_elements.UiElement import UiElement

MAX_COLLIDER_DISTANCE = 50
MAX_COLLIDER_CHECK_SPRITES = 10
MOTION_STEPS = 10
TOLERANCE = 1


class PhysicsElementsHandler:
    def __init__(self):
        self.collision_callbacks = []

    def add_collision_callback(self, callback):
        self.collision_callbacks.append(callback)

    def remove_collision_callback(self, callback):
        self.collision_callbacks.remove(callback)

    def tick(self, tick_data: TickData, layers: dict[str, list[UiElement]]):
        sprites = []
        for layer in layers:
            for sprite in layers[layer]:
                sprite.tick(tick_data)
                if isinstance(sprite, Sprite):
                    sprites.append(sprite)

        # handle motion and collisions. To do this:
        # 1. Find all sprites that have collision enabled and store them in a list
        # 2. Create a list of all sprites that are dynamic sprites
        # 3. Sort the sprites by their y position
        # 4. Find the MAX_COLLIDER_CHECK_SPRITES sprites that are closest to the sprite that are colliders but not the
        #    sprite itself
        #  4.1 Filter out all that are further than MAX_COLLIDER_DISTANCE
        # 5. For each sprite:
        #  5.1. Divide the motion into MOTION_STEPS steps
        #  5.2. For each step:
        #   5.2.1. Check if the sprite collides with any other sprite from the list of colliders generated in step 4
        #   5.2.2. If it does, move the sprite back to the previous position and stop the motion
        #   5.2.3. If it doesn't, move the sprite to the new position

        colliders = [sprite for sprite in sprites
                     if isinstance(sprite, StaticSprite) and (sprite.is_collider or sprite.register_collisions)]

        for collider in colliders:
            collider.reset_collides_with()

        dynamic_sprites = [sprite for sprite in sprites if isinstance(sprite, DynamicSprite)]
        sorted_dynamic_sprites = sorted(dynamic_sprites, key=lambda spr: spr.position_scale.position[1])

        skip_sprites = []
        for sprite in sorted_dynamic_sprites:
            if sprite.last_effective_motion == (0, 0) and random.randint(0, 100) > 50 \
                    and not sprite.id == 'player':
                skip_sprites.append(sprite)
                continue

        closest_sprites: dict[UiElement, list[tuple[int, StaticSprite]]] = {}

        buffered_bounding_boxes: dict[UiElement, BoundingBox] = {}
        for collider in colliders:
            buffered_bounding_boxes[collider] = collider.get_bounding_box()

        for sprite in sorted_dynamic_sprites:
            closest_sprites[sprite] = []
            current_closest_sprites = closest_sprites[sprite]

            if sprite not in buffered_bounding_boxes:
                buffered_bounding_boxes[sprite] = sprite.get_bounding_box()

            for collider in colliders:
                if collider is sprite:
                    continue

                distance = int(buffered_bounding_boxes[collider].distance(buffered_bounding_boxes[sprite]))

                if len(current_closest_sprites) < MAX_COLLIDER_CHECK_SPRITES:
                    current_closest_sprites.append((distance, collider))
                else:
                    max_index = -1
                    max_distance = -1
                    for i in range(len(current_closest_sprites)):
                        if distance < current_closest_sprites[i][0]:
                            if current_closest_sprites[i][0] > max_distance:
                                max_distance = current_closest_sprites[i][0]
                                max_index = i

                    if max_index != -1:
                        current_closest_sprites[max_index] = (distance, collider)

        for sprite in closest_sprites:
            closest_sprites[sprite] = [closest_sprite for closest_sprite in closest_sprites[sprite]
                                       if closest_sprite[0] < MAX_COLLIDER_DISTANCE]

        # set visible false for all those that are not in the closest_sprites list
        # for collider in colliders:
        #     found = False
        #     for sprite in sorted_dynamic_sprites:
        #         for _, c in closest_sprites[sprite]:
        #             if c is collider:
        #                 found = True
        #                 break
        #         if found:
        #             break
        #     collider.visible = not found

        # for sprite in sorted_dynamic_sprites:
        #     sprite.visible = True

        for sprite in sorted_dynamic_sprites:
            collides_with = self.attempt_move(tick_data,
                                              sprite,
                                              [collider for _, collider in closest_sprites[sprite]],
                                              MOTION_STEPS)
            if collides_with is not None:
                for callback in self.collision_callbacks:
                    callback(sprite, collides_with)

    def attempt_move(self, tick_data: TickData, sprite: DynamicSprite, colliders: list[StaticSprite],
                     motion_steps: int) -> Optional[StaticSprite]:
        total_motion = sprite.motion
        motion_step = ((total_motion[0] * tick_data.dt) / motion_steps, (total_motion[1] * tick_data.dt) / motion_steps)

        collides_with_last = None
        collided = [False, False]
        effective_motion = [0, 0]

        for i in range(motion_steps):
            if not collided[0]:
                sprite.position_scale.position = (
                    sprite.position_scale.position[0] + motion_step[0],
                    sprite.position_scale.position[1]
                )

                collides_with = self.check_collides(sprite, colliders)
                if len(collides_with) == 0:
                    effective_motion[0] += motion_step[0]

                for collider in collides_with:
                    if collider is not None:
                        if sprite.is_collider and collider.is_collider:
                            if sprite.motion[0] > 0:
                                if sprite.register_collisions:
                                    sprite.add_collides_with(
                                        CollisionDirection(CollisionDirection.RIGHT, sprite, collider))
                                if collider.register_collisions:
                                    collider.add_collides_with(
                                        CollisionDirection(CollisionDirection.LEFT, collider, sprite))

                            if sprite.motion[0] < 0:
                                if sprite.register_collisions:
                                    sprite.add_collides_with(
                                        CollisionDirection(CollisionDirection.LEFT, sprite, collider))
                                if collider.register_collisions:
                                    collider.add_collides_with(
                                        CollisionDirection(CollisionDirection.RIGHT, collider, sprite))
                        else:
                            if sprite.register_collisions:
                                sprite.add_collides_with(
                                    CollisionDirection(CollisionDirection.INSIDE, sprite, collider))
                            if collider.register_collisions:
                                collider.add_collides_with(
                                    CollisionDirection(CollisionDirection.INSIDE, collider, sprite))

                        if collider.is_collider:
                            sprite.position_scale.position = (
                                sprite.position_scale.position[0] - motion_step[0],
                                sprite.position_scale.position[1]
                            )

                            sprite.motion = (sprite.motion[0] * sprite.bounce_factor, sprite.motion[1])

                            collides_with_last = collider
                            collided[0] = True

            if not collided[1]:
                sprite.position_scale.position = (
                    sprite.position_scale.position[0],
                    sprite.position_scale.position[1] + motion_step[1]
                )

                collides_with = self.check_collides(sprite, colliders)
                if len(collides_with) == 0:
                    effective_motion[1] += motion_step[1]

                for collider in collides_with:
                    if collider is not None:
                        if sprite.is_collider and collider.is_collider:
                            if sprite.motion[1] > 0:
                                if sprite.register_collisions:
                                    sprite.add_collides_with(
                                        CollisionDirection(CollisionDirection.BOTTOM, sprite, collider))
                                if collider.register_collisions:
                                    collider.add_collides_with(
                                        CollisionDirection(CollisionDirection.TOP, collider, sprite))

                            if sprite.motion[1] < 0:
                                if sprite.register_collisions:
                                    sprite.add_collides_with(
                                        CollisionDirection(CollisionDirection.TOP, sprite, collider))
                                if collider.register_collisions:
                                    collider.add_collides_with(
                                        CollisionDirection(CollisionDirection.BOTTOM, collider, sprite))
                        else:
                            if sprite.register_collisions:
                                sprite.add_collides_with(
                                    CollisionDirection(CollisionDirection.INSIDE, sprite, collider))
                            if collider.register_collisions:
                                collider.add_collides_with(
                                    CollisionDirection(CollisionDirection.INSIDE, collider, sprite))

                        if collider.is_collider:
                            sprite.position_scale.position = (
                                sprite.position_scale.position[0],
                                sprite.position_scale.position[1] - motion_step[1]
                            )

                            sprite.motion = (sprite.motion[0], sprite.motion[1] * sprite.bounce_factor)

                            collides_with_last = collider
                            collided[1] = True

        sprite.last_effective_motion = (sprite.motion[0], sprite.motion[1])

        return collides_with_last

    def check_collides(self, sprite: StaticSprite, colliders: list[StaticSprite]) -> list[StaticSprite]:
        collides_with = []

        for collider in colliders:
            if sprite is not collider:
                if sprite.collides_with(collider, TOLERANCE):
                    collides_with.append(collider)
                    if len(collides_with) > 5:
                        break

        return collides_with