battery/game/player.py

"""The player character and all of its physics.

Movement: A / D to run, Space (or W) to jump with variable height, S to drop
through one-way platforms. Collision is swept-axis AABB against the level's
solid rects, with separate handling for one-way platforms and moving platforms
the player can ride.
"""

import pygame

from . import settings as S


class InputState:
    __slots__ = ("left", "right", "down", "jump_pressed", "jump_held")

    def __init__(self):
        self.left = self.right = self.down = False
        self.jump_pressed = False  # edge: pressed this frame
        self.jump_held = False  # level: currently down


class Player:
    def __init__(self, level):
        self.level = level
        self.w = int(level.tile * 0.72)
        self.h = int(level.tile * 0.92)
        self.rect = pygame.Rect(0, 0, self.w, self.h)
        self.respawn()

    def respawn(self):
        sx, sy = self.level.spawn
        # center the player horizontally in its spawn tile, feet at tile bottom
        self.fx = float(sx + (self.level.tile - self.w) / 2)
        self.fy = float(sy + (self.level.tile - self.h))
        self.vx = 0.0
        self.vy = 0.0
        self.on_ground = False
        self.coyote = 0.0
        self.jump_buffer = 0.0
        self.facing = 1
        self.drop_through_timer = 0.0
        self.was_jump_held = False
        self.crushed = False
        self.carry = (0.0, 0.0)
        self._sync_rect()

    def _sync_rect(self):
        self.rect.x = round(self.fx)
        self.rect.y = round(self.fy)

    # --- main update ---------------------------------------------------------
    def update(self, dt, inp):
        self._ride_platforms()
        self._push_by_movers()
        self._horizontal(dt, inp)
        self._vertical(dt, inp)
        self.crushed = self._check_crush()

    def _push_by_movers(self):
        """A solid moving horizontally into our side shoves us along that axis.

        Without this the player never resolves against a block that walks into
        them (they aren't moving), and the vertical pass then mis-reads the side
        overlap as a downward collision — burying them in the floor.
        """
        p = self.rect
        for rect, dx, dy in self.level.carriers():
            if dx == 0 or not p.colliderect(rect):
                continue
            # Only treat it as a side hit when we share a real chunk of height —
            # a shallow overlap just means we're standing on top of the block.
            v_overlap = min(p.bottom, rect.bottom) - max(p.top, rect.top)
            if v_overlap < self.h * 0.5:
                continue
            # Push out the *nearer* horizontal side, not blindly the way the
            # block is travelling — otherwise hitting its trailing face (e.g.
            # jumping into the left side of a right-moving block) teleports us
            # clear across it. Minimal displacement keeps the shove-along and
            # shove-into-wall behaviours intact.
            pen_right = rect.right - p.left  # displacement to exit rightward
            pen_left = p.right - rect.left  # displacement to exit leftward
            if pen_right <= pen_left:
                p.left = rect.right
            else:
                p.right = rect.left
            self.fx = float(p.x)

    def _check_crush(self):
        """A crush = a moving block pressing us against a solid on the opposite
        side (squished into the floor/ceiling/wall, or pinned while riding).

        We probe a thin strip on each side of the player: if a solid backs us on
        one side and a *moving* block is closing in from the other side on the
        same axis, we're pinched and die.
        """
        movers = [(r, dx, dy) for (r, dx, dy) in self.level.carriers() if dx or dy]
        if not movers:
            return False

        solids = self.level.solid_rects()
        p = self.rect
        e = 4  # probe depth (a touch larger than a fast block's per-frame step)
        up = pygame.Rect(p.left + 2, p.top - e, max(1, p.width - 4), e)
        down = pygame.Rect(p.left + 2, p.bottom, max(1, p.width - 4), e)
        left = pygame.Rect(p.left - e, p.top + 2, e, max(1, p.height - 4))
        right = pygame.Rect(p.right, p.top + 2, e, max(1, p.height - 4))

        def backed(probe):
            return any(probe.colliderect(s) for s in solids)

        bu, bd = backed(up), backed(down)
        bl, br = backed(left), backed(right)

        # Are we actually compressed? After this frame's resolution we still
        # overlap a solid because we couldn't be separated. If a descending
        # block stops with us fitting underneath, there's no overlap — no crush.
        pinned = any(p.colliderect(s) for s in solids)

        for r, dx, dy in movers:
            if (
                dy > 0 and bd and pinned and r.colliderect(up)
            ):  # squished down onto floor
                return True
            if (
                dy < 0 and bu and pinned and r.colliderect(down)
            ):  # squished up into ceiling
                return True
            if dx > 0 and br and r.colliderect(left):  # pushed right into a wall
                return True
            if dx < 0 and bl and r.colliderect(right):  # pushed left into a wall
                return True

        # A platform that carries us *sideways* into a wall is NOT a crush: the
        # carrier is under our feet, perpendicular to the wall, so it can't pinch
        # us against it. The X pass simply stops us at the wall edge while the
        # platform keeps sliding underneath. (A genuine horizontal crush — a
        # mover closing on our side against a backing wall — is the dx cases
        # above. Vertical carry crushes are the dy cases above.)
        return False

    def _ride_platforms(self):
        # If standing on a moving platform, inherit its motion this frame.
        self.carry = (0.0, 0.0)
        for rect, dx, dy in self.level.carriers():
            if (
                abs(self.rect.bottom - rect.top) <= 3
                and self.rect.right > rect.left + 1
                and self.rect.left < rect.right - 1
            ):
                self.fx += dx
                self.fy += dy
                self._sync_rect()
                self.carry = (dx, dy)
                break

    def _horizontal(self, dt, inp):
        target = 0.0
        if inp.left:
            target -= S.MOVE_SPEED
            self.facing = -1
        if inp.right:
            target += S.MOVE_SPEED
            self.facing = 1

        if target != 0.0:
            accel = S.ACCEL if self.on_ground else S.AIR_ACCEL
            if self.vx < target:
                self.vx = min(self.vx + accel * dt, target)
            else:
                self.vx = max(self.vx - accel * dt, target)
        else:
            # friction toward zero (only meaningful decel on the ground)
            fr = S.FRICTION if self.on_ground else S.AIR_ACCEL * 0.5
            if self.vx > 0:
                self.vx = max(0.0, self.vx - fr * dt)
            elif self.vx < 0:
                self.vx = min(0.0, self.vx + fr * dt)

        self.fx += self.vx * dt
        self._sync_rect()
        self._resolve_axis(axis="x")

    def _vertical(self, dt, inp):
        # timers
        self.coyote = self.coyote - dt if self.coyote > 0 else 0.0
        if inp.jump_pressed:
            self.jump_buffer = S.JUMP_BUFFER
        else:
            self.jump_buffer = max(0.0, self.jump_buffer - dt)
        self.drop_through_timer = max(0.0, self.drop_through_timer - dt)
        if inp.down and inp.jump_pressed:
            # Space + S: drop through one-way platforms.
            self.drop_through_timer = 0.12

        # jump (buffered + coyote)
        if (
            self.jump_buffer > 0
            and (self.on_ground or self.coyote > 0)
            and self.drop_through_timer <= 0
        ):
            self.vy = -S.JUMP_SPEED
            self.on_ground = False
            self.coyote = 0.0
            self.jump_buffer = 0.0

        # variable jump height: the frame Space is released mid-rise, cut the
        # remaining upward velocity once (a quick tap = a short hop).
        if self.was_jump_held and not inp.jump_held and self.vy < 0:
            self.vy *= S.JUMP_CUT
        self.was_jump_held = inp.jump_held

        # gravity
        self.vy = min(self.vy + S.GRAVITY * dt, S.MAX_FALL)

        was_on_ground = self.on_ground
        self.on_ground = False
        self.fy += self.vy * dt
        self._sync_rect()
        self._resolve_axis(axis="y")

        # start coyote window the frame we walk off a ledge
        if was_on_ground and not self.on_ground and self.vy >= 0:
            self.coyote = S.COYOTE_TIME

    # --- collision -----------------------------------------------------------
    def _resolve_axis(self, axis):
        solids = self.level.solid_rects()
        if axis == "x":
            for s in solids:
                if self.rect.colliderect(s):
                    # Resolve toward the nearer edge (not by velocity sign) so
                    # clipping a block's corner can't warp us across it. But only
                    # if the overlap is *more horizontal than vertical* — a block
                    # sitting on top of us is a vertical collision; pushing us
                    # sideways out from under it would dodge a crush.
                    pen_left = self.rect.right - s.left  # sank in from the left
                    pen_right = s.right - self.rect.left  # sank in from the right
                    pen_y = min(self.rect.bottom - s.top, s.bottom - self.rect.top)
                    if min(pen_left, pen_right) > pen_y:
                        continue  # let the Y pass handle it
                    if pen_right <= pen_left:
                        self.rect.left = s.right
                    else:
                        self.rect.right = s.left
                    self.fx = float(self.rect.x)
                    self.vx = 0.0
        else:  # y
            for s in solids:
                if self.rect.colliderect(s):
                    # Resolve toward the nearer edge, not by velocity sign — so a
                    # block descending onto us can't pop us out its top.
                    overlap_top = self.rect.bottom - s.top  # sank onto its top
                    overlap_bottom = s.bottom - self.rect.top  # rose into its underside
                    if overlap_top <= overlap_bottom:
                        self.rect.bottom = s.top
                        self.on_ground = True
                    else:
                        self.rect.top = s.bottom
                    self.fy = float(self.rect.y)
                    self.vy = 0.0
            # one-way platforms: land only when falling and the feet just
            # crossed the platform's top edge this frame.
            if self.vy >= 0 and self.drop_through_timer <= 0:
                max_pen = self.vy / S.FPS + 8  # how far feet could have sunk this frame
                for o in self.level.oneway_rects():
                    if self.rect.colliderect(o):
                        penetration = self.rect.bottom - o.top
                        if 0 <= penetration <= max_pen:
                            self.rect.bottom = o.top
                            self.fy = float(self.rect.y)
                            self.vy = 0.0
                            self.on_ground = True

    # --- rendering -----------------------------------------------------------
    def draw(self, surface, assets):
        ox, oy = self.level.render_offset
        surface.blit(
            assets.get("player", self.rect.w, self.rect.h), self.rect.move(ox, oy)
        )