smack-a-brother/src/fighter.cpp

#include "fighter.h"
#include "sim.h"
#include <algorithm>

constexpr float AIR_ACCELERATION = 400;
constexpr float BOUNCE_SHAKE = 0.00025f;
constexpr float SLAM_DAMAGE = 0.06f;
constexpr float KNOCK_BASE = 60;
constexpr float KNOCK_LIFT = 0.35f;
constexpr float KNOCK_MAX = 4500;
constexpr float KNOCK_PER_DAMAGE = 30;
constexpr float LAUNCH_START_SPEED = 300;

constexpr float AFTERIMAGE_SPEED = 440;
constexpr float AIR_FRICTION = 600;
constexpr float CLING_SPEED = 60;
constexpr float COYOTE_TIME = 0.1f;
constexpr float DASH_COOLDOWN = 0.8f;
constexpr float DASH_TIME = 0.12f;
constexpr float DEATH_SHAKE = 0.75f;
constexpr float FACING_DEADZONE = 4;
constexpr float FAST_FALL_GRAVITY = 2;
constexpr float FLASH_DECAY = 8;
constexpr float FAST_FALL_SPEED = 700;
constexpr float FALL_EASE = 2000;
constexpr float GROUND_ACCELERATION = 500;
constexpr float GROUND_FRICTION = 3000;
constexpr float JUMP_BUFFER = 0.1f;
constexpr float JUMP_RELEASE_SPEED = 160;
constexpr float KICK_COOLDOWN = 1.2f;
constexpr float LAUNCH_DRAG = 160;
constexpr float LAND_SPEED = 150;
constexpr float MAX_FALL = 520;
constexpr float ROPE_MIN = 24;
constexpr float SLIDE_DUST_INTERVAL = 0.08f;
constexpr float SWING_ACCELERATION = 500;
constexpr float SWING_SPEED_MAX = 420;
constexpr float POUND_AREAS[LEVEL_COUNT] = {15, 20, 25};
constexpr float POUND_DAMAGES[LEVEL_COUNT] = {20, 35, 50};
constexpr float POUND_SCALE_MAX = 3;
constexpr float POUND_SPEED = 700;
constexpr Vec2 HAND_OFFSET = {4, 2};
constexpr Vec2 OFFHAND_OFFSET = {-3, 4};
constexpr Vec2 OFFHAND_FAN = {3, 2};
constexpr float WALL_IMPACT_SPEED = 200;
constexpr float WALL_LIFT = 0.25f;
constexpr float WALL_MEMORY = 0.6f;
constexpr float WALL_REFLECT = 1.2f;
constexpr float WALL_POINT_HEIGHT = 0.4f;
constexpr Vec2 KICK_VELOCITY = {220, -330};
constexpr Vec2 WALL_JUMP_VELOCITY = {180, -JUMP_SPEED};
constexpr float CROUCH_HEIGHT = 0.75f;
constexpr float CROUCH_DAMP = 0.5f;
constexpr float KICK_POSE_TIME = 0.2f;
constexpr float SPIN_GRAVITY = 0.5f;
constexpr float CRAWL_SPEED = 0.35f;
constexpr float DOWNHILL_BOOST = 0.6f;
constexpr float MOMENTUM_DRAG = 400;
constexpr float SLIDE_FRICTION = 150;
constexpr float SLIDE_MAX = 700;
constexpr float SLIDE_MIN = 60;
constexpr float TUMBLE_RATE = 0.012f;
// Footsteps per animation frame walked or crawled: one per four-frame walk cycle, one per half crawl cycle.
constexpr float WALK_STEP_FRAMES = 4;
constexpr float CRAWL_STEP_FRAMES = 2;

constexpr Burst LAND_DUST = {
    .angle = -PI / 2, .gravity = 150, .life = 0.35f, .speed = 90, .spread = PI * 0.45f, .count = 10};
constexpr Burst DEATH_BURST = {.gravity = 300, .life = 0.8f, .size = 4, .speed = 260, .count = 40};
constexpr Burst BOUNCE_DUST = {.gravity = 200, .life = 0.4f, .speed = 160, .count = 10};
constexpr Burst KICK_DUST = {.gravity = 200, .life = 0.35f, .speed = 120, .spread = PI / 3, .count = 8};
constexpr Burst READY_BURST = {.life = 0.4f, .size = 2, .speed = 120, .count = 12};
constexpr Burst SLIDE_DUST = {.gravity = -40, .life = 0.3f, .size = 2, .speed = 30, .spread = PI / 3, .count = 1};
constexpr Burst STEP_DUST = {
    .angle = -PI / 2, .gravity = 150, .life = 0.25f, .size = 2, .speed = 40, .spread = PI / 2, .count = 2};

// Makes this fighter number, with empty loadouts, standing at its spawn.
void Fighter::init(Sim& sim, int number)
{
    index = number;
    std::fill(std::begin(weaponLoadout), std::end(weaponLoadout), -1);
    std::fill(std::begin(trinketLoadout), std::end(trinketLoadout), -1);
    state_reset(sim, 1);
}

// Uses the first weapons and trinkets slots of each loadout, emptying the rest, and holds a slot in use.
void Fighter::slots_set(int weapons, int trinkets)
{
    weaponSlots = weapons;
    trinketSlots = trinkets;
    std::fill(weaponLoadout + weapons, std::end(weaponLoadout), -1);
    std::fill(trinketLoadout + trinkets, std::end(trinketLoadout), -1);
    slot = std::min(slot, weapons - 1);
}

// Back at its spawn and still: no velocity, nothing charging, no echoes, not launched or stuck in hitstop.
void Fighter::position_reset(Sim& sim)
{
    position_set(sim, sim.world.spawns[index]);
}

// Puts the fighter still with its feet at a point, nothing charging.
void Fighter::position_set(Sim& sim, Vec2 spawn)
{
    charge_cancel(sim);
    body = {.box = {spawn.x - BOX_WIDTH / 2, spawn.y - BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT}};
    cornerPrevious = {body.box.x, body.box.y};
    safe = spawn;
    echoes.clear();
    hitstop = 0;
    isLaunched = false;
}

// Back at its spawn, alive, at full health and still, holding its first slot, with nothing charging or cooling
// down. Loadouts and levels stay as they are.
void Fighter::state_reset(Sim& sim, float maxHealth)
{
    position_reset(sim);
    std::fill(std::begin(cooldowns), std::end(cooldowns), 0.0f);
    flash = 0;
    health = maxHealth;
    std::fill(std::begin(slotSwitches), std::end(slotSwitches), 0);
    slot = 0;
    isAlive = true;
}

// Loses health with a flash and hitstop, and gets knocked away from where the hit came from (and a little upward),
// up to a speed that grows with the damage (see knock_take). Shock Absorber softens it. Running out of health kills it
// in a burst, and its attacks vanish with it.
void Fighter::damage_take(Sim& sim, Damage damage)
{
    // Races and the sandbox never cost health.
    bool isRacing = sim.match.is_racing();
    health -= isRacing || sim.match.state == MATCH_PRACTICE ? 0 : damage.amount;
    flash = 1;
    hitstop = std::max(hitstop, damage.hitstop);

    Vec2 away = center_get() - damage.source;
    Vec2 direction = vec2_normalize(vec2_normalize(vec2_length(away) > 1 ? away : Vec2{0, -1}) + Vec2{0, -KNOCK_LIFT});
    float knock = std::min(KNOCK_MAX, KNOCK_BASE + damage.amount * KNOCK_PER_DAMAGE) * damage.knock *
                  (isRacing ? RACE_KNOCK : 1) * knock_absorb_get();
    knock_take(direction * knock, damage.owner);
    if (health > 0)
        return;

    isAlive = false;
    charge_cancel(sim);
    for (Attack& attack : sim.weapons.attacks)
        attack.isDead |= attack.owner == index;
    sim.cues->sound_play(SOUND_DEATH);
    sim.cues->burst_spawn(DEATH_BURST, center_get(), 0, index);
    sim.cues->shake_add(DEATH_SHAKE);
}

void Fighter::update(Sim& sim)
{
    // Out of the round, it still keeps track of its buttons, so a held one (like Ready on the results) counts once.
    if (!isAlive)
    {
        buttonsPrevious = controls.buttons;
        return;
    }
    cornerPrevious = {body.box.x, body.box.y};
    flash = std::max(0.0f, flash - FLASH_DECAY * TICK);
    shockCooldown -= TICK;
    if (hitstop > 0)
    {
        hitstop -= TICK;
        return;
    }

    for (float& cooldown : cooldowns)
        cooldown = std::max(0.0f, cooldown - TICK);
    kickTime += TICK;
    Attack* hook = sim.weapons.hook_get(*this);
    slot_update(sim);
    // A slide keeps rolling through the air for as long as S is held, like off a kicker or jumping mid-slide.
    bool wasCrouching = isCrouching;
    bool isTucked = is_down(CONTROL_DOWN) && !isLaunched;
    isCrouching = body.isGrounded && isTucked;
    if (isCrouching != wasCrouching && body.isGrounded && !isSliding)
        sim.cues->sound_play(isCrouching ? SOUND_DUCK : SOUND_UNDUCK);
    bool isSlideKept = isSliding && (std::abs(body.velocity.x) > SLIDE_MIN || !body.isGrounded);
    isSliding = isTucked && (body.isGrounded ? body.slope != 0 || isSlideKept : isSliding);
    size_update();
    isSpinning = sim.weapons.is_spinning(*this);
    run_update(hook);
    body.isDropping = is_down(CONTROL_DOWN);

    bool isJumpHeld = is_down(CONTROL_JUMP) || (!hook && is_down(CONTROL_UP));
    bool isJumpPressed = is_pressed(CONTROL_JUMP) || (!hook && is_pressed(CONTROL_UP));
    jumpBuffer = isJumpPressed ? JUMP_BUFFER : jumpBuffer - TICK;
    coyoteTimer = body.isGrounded ? COYOTE_TIME : coyoteTimer - TICK;
    Vec2 feet = {center_get().x, body.box.y + body.box.h};
    climb_update(sim);

    if (jumpBuffer > 0 && coyoteTimer > 0 && !isLaunched)
    {
        body.velocity.y = -JUMP_SPEED;
        jumpBuffer = 0;
        coyoteTimer = 0;
        isJumping = true;
        sim.cues->sound_play(SOUND_JUMP);
        sim.cues->burst_spawn(STEP_DUST, feet, 0, index);
    }
    dash_update(sim, isJumpPressed);

    isJumping &= body.velocity.y < 0 && !hook;
    if (isJumping && !isJumpHeld && body.velocity.y < -JUMP_RELEASE_SPEED)
        body.velocity.y = -JUMP_RELEASE_SPEED;

    if (hook)
        rope_update(*hook);

    bool wasGrounded = body.isGrounded;
    float fallSpeed = body.velocity.y;
    float runSpeed = body.velocity.x;
    sim.weapons.solids_add(*this, sim.world);
    sim.world.body_move(body);
    sim.world.obstacles.clear();
    sim.world.ledges.clear();
    if (isLaunched)
        bounce_resolve(sim, {runSpeed, fallSpeed});
    safe_update(sim);

    wallMemory -= TICK;
    bool isWallHit = body.velocity.x == 0 && std::abs(runSpeed) > WALL_IMPACT_SPEED;
    if (isWallHit && is_trinket_equipped(TRINKET_CLIMBING))
    {
        wallSpeed = std::abs(runSpeed);
        wallMemory = WALL_MEMORY;
    }
    if (wallMemory <= 0)
        wallSpeed = 0;
    if (vec2_length(body.velocity) > AFTERIMAGE_SPEED || dashTimer > 0)
        sim.cues->fighter_afterimage_spawn(*this);
    feet = {center_get().x, body.box.y + body.box.h};

    if (body.isGrounded && !wasGrounded && fallSpeed > LAND_SPEED)
    {
        sim.cues->sound_play(SOUND_LAND);
        sim.cues->burst_spawn(LAND_DUST, feet, 0, index);
    }
    // Iron Weights slam: landing faster than a plain fall can go (on anything, platforms too), and the harder the
    // landing, the harder the blast. Every copy adds to its damage and radius. Damage follows the landing speed, and
    // the radius its square root.
    if (body.isGrounded && !wasGrounded && fallSpeed > MAX_FALL && is_trinket_equipped(TRINKET_WEIGHTS))
    {
        float impact = std::min(fallSpeed / POUND_SPEED, POUND_SCALE_MAX);
        sim.weapons.blast_spawn(sim, {.position = feet,
                                      .area = trinket_sum_get(TRINKET_WEIGHTS, POUND_AREAS) * std::sqrt(impact),
                                      .damage = trinket_sum_get(TRINKET_WEIGHTS, POUND_DAMAGES) * impact,
                                      .owner = index,
                                      .sound = SOUND_POUND});
    }

    // A kick holds its pose briefly, and a launch tumbles faster the faster it flies.
    kickPose -= TICK;
    float spin = body.velocity.x < 0 ? -1 : 1;
    tumble = isLaunched ? tumble + spin * vec2_length(body.velocity) * TUMBLE_RATE * TICK : 0;
    // The ball rolls without slipping: on the ground it spins with its speed along the surface, and in the air it
    // keeps the spin it left with.
    float rollBefore = roll;
    if (body.isGrounded)
        rollSpin = body.velocity.x * std::sqrt(1 + body.slope * body.slope) / (ROLL_RADIUS * scale);
    roll = isSliding ? roll + rollSpin * TICK : 0;

    // Footsteps only while walking on purpose or crawling, and a roll bumps once every half turn. Steps go by ground
    // covered, in time with the legs (whose animation steps a frame per stride), so they quicken with speed; the first
    // lands as the walk starts.
    bool isMoving = is_down(CONTROL_LEFT) || is_down(CONTROL_RIGHT);
    bool isWalking =
        body.isGrounded && !isCrouching && !isLaunched && isMoving && std::abs(body.velocity.x) > STEP_SPEED;
    if (isWalking || is_crawling())
    {
        stepDistance -= std::abs(body.velocity.x) * TICK;
        if (stepDistance <= 0)
        {
            stepDistance += isWalking ? WALK_STRIDE * WALK_STEP_FRAMES : CRAWL_STRIDE * CRAWL_STEP_FRAMES;
            sim.cues->sound_play(isWalking ? SOUND_STEP : SOUND_CRAWL);
            if (isWalking)
                sim.cues->burst_spawn(STEP_DUST, feet, 0, index);
        }
    }
    else
        stepDistance = 0;
    if (isSliding && body.isGrounded && std::floor(roll / PI) != std::floor(rollBefore / PI))
        sim.cues->sound_play(SOUND_ROLL);

    // Facing follows the cursor's side of the body, holding still when it's nearly straight above or below, so the
    // hand (which sits on the facing side) can't flip back and forth under it.
    float cursorX = controls.cursor.x - center_get().x;
    if (std::abs(cursorX) > FACING_DEADZONE)
        isFacingLeft = cursorX < 0;
    aim = vec2_normalize(controls.cursor - hand_get());
    charge_update(sim);
    buttonsPrevious = controls.buttons;
}

// Horizontal control and gravity. Holding S in the air falls faster (Iron Weights speeding up both how fast it gets
// there and how fast it goes), and letting go eases back to a plain fall rather than stopping short. Holding W floats
// with the Feather, and a spinning flail's pull lightens gravity. Slopes change the top speed, and crouch-slides answer
// only to the slope. Crouching on flat ground waddles along slowly.
// Airborne on a rope, moving left and right pumps the swing instead.
// Above run speed in the air, launch momentum bleeds off slowly unless steered against. Launched by a hit, there's no
// control at all, just gravity and the knock dying down.
void Fighter::run_update(Attack* hook)
{
    float direction = (float)is_down(CONTROL_RIGHT) - (float)is_down(CONTROL_LEFT);
    float speed = std::abs(body.velocity.x);
    float sign = body.velocity.x < 0 ? -1 : 1;
    float boots = trinket_get(TRINKET_BOOTS, 1);
    float runSpeed = RUN_SPEED * boots * (1 + trinket_get(TRINKET_SPEEDOMETER, 0)) * (isCrouching ? CRAWL_SPEED : 1);
    if (dashTimer > 0)
        return;
    if (isLaunched)
    {
        body.velocity =
            body.velocity * (1 - KNOCK_DECAY * TICK) + Vec2{0, GRAVITY * (isSpinning ? SPIN_GRAVITY : 1) * TICK};
        return;
    }

    bool isAirborne = !body.isGrounded && !hook;
    bool isFastFalling = isAirborne && is_down(CONTROL_DOWN) && !isSliding;
    bool isFloating = isAirborne && is_down(CONTROL_UP);
    float weights = isFastFalling ? trinket_get(TRINKET_WEIGHTS, 1) : 1;
    float gravity = GRAVITY * (isFastFalling ? FAST_FALL_GRAVITY * weights : 1);
    gravity *= isFloating ? trinket_get(TRINKET_FEATHER, 1) : 1;
    gravity *= isSpinning ? SPIN_GRAVITY : 1;
    float maxFall = isFastFalling ? FAST_FALL_SPEED * weights : MAX_FALL;
    if (body.velocity.y > maxFall)
        body.velocity.y = std::max(maxFall, body.velocity.y - FALL_EASE * TICK);
    else
        body.velocity.y = std::min(body.velocity.y + gravity * TICK, maxFall);

    // Sliding: the slope pulls it downhill and little else slows it.
    if (isSliding)
    {
        float slope = body.slope;
        body.velocity.x += GRAVITY * slope / (1 + slope * slope) * TICK;
        float slowed = std::max(0.0f, std::abs(body.velocity.x) - SLIDE_FRICTION * TICK);
        body.velocity.x = std::clamp(std::copysign(slowed, body.velocity.x), -SLIDE_MAX, SLIDE_MAX);
        return;
    }

    if (hook && !body.isGrounded)
    {
        if (direction * body.velocity.x <= 0 || speed < SWING_SPEED_MAX)
            body.velocity.x += direction * SWING_ACCELERATION * TICK;
        return;
    }

    // On a slope, the top speed drops climbing and rises descending, with the angle.
    float slope = body.isGrounded ? body.slope : 0;
    if (slope != 0 && direction != 0)
    {
        float cosine = 1 / std::sqrt(1 + slope * slope);
        bool isUphill = direction * slope < 0;
        runSpeed *= isUphill ? cosine : 1 + DOWNHILL_BOOST * std::abs(slope) * cosine;
    }

    // Faster than running, momentum bleeds off slowly unless steered against (or let go of on the ground).
    if (speed > runSpeed && direction * body.velocity.x >= 0 && (direction != 0 || !body.isGrounded))
    {
        float drag = body.isGrounded ? MOMENTUM_DRAG : LAUNCH_DRAG;
        body.velocity.x = sign * std::max(runSpeed, speed - drag * TICK);
        return;
    }

    float acceleration = (body.isGrounded ? GROUND_ACCELERATION : AIR_ACCELERATION) * boots;
    float friction = body.isGrounded ? GROUND_FRICTION : AIR_FRICTION;
    bool isTurning = direction * body.velocity.x < 0;
    float rate = (direction == 0 ? friction : acceleration + (isTurning ? friction : 0)) * TICK;
    body.velocity.x = std::clamp(direction * runSpeed, body.velocity.x - rate, body.velocity.x + rate);
}

// Up and Down reel the rope, or a charged hook yanks it in until short (slower under Shock Absorber). When the next
// step would leave the rope's reach, the step is pulled back onto the circle, so outward motion becomes swing and
// reeling in drags the player along.
void Fighter::rope_update(Attack& hook)
{
    float reel = (float)is_down(CONTROL_DOWN) - (float)is_down(CONTROL_UP);
    reel *= WEAPON_DEFS[hook.weapon].levels[hook.key >= 0 ? slot_level_get(hook.key) : 0].reel;
    if (hook.isPulling)
        reel = -hook.stats.speed * trinket_get(TRINKET_ABSORBER, 1);
    hook.length = std::clamp(hook.length + reel * TICK, ROPE_MIN, hook.stats.range);
    hook.isPulling &= hook.length > ROPE_MIN;

    Vec2 center = center_get();
    Vec2 offset = center + body.velocity * TICK - hook.position;
    if (vec2_length(offset) <= hook.length)
        return;

    Vec2 next = hook.position + vec2_normalize(offset) * hook.length;
    body.velocity = (next - center) * (1 / TICK);
}

// The controls' slot picks a weapon slot, wrapping around, and the level buttons level the weapon copy in it. The
// weapon switched away from becomes the off-hand weapon for Dual Wield (a copy of the same weapon counts when weapons
// stack), and a thrown flail ball is dropped.
void Fighter::slot_update(Sim& sim)
{
    int previous = slot;
    if (controls.slot != -1)
        slot = (controls.slot % weaponSlots + weaponSlots) % weaponSlots;

    int held = weapon_get();
    if (slot != previous)
        sim.cues->sound_play(SOUND_SELECT);
    if (slot != previous && weaponLoadout[previous] >= 0 && weapon_key(previous) != weapon_key(slot))
    {
        slotSwitches[previous] = ++switches;
        sim.weapons.attacks_release(*this, ATTACK_FLAIL);
    }

    int step = (int)is_pressed(CONTROL_LEVEL_UP) - (int)is_pressed(CONTROL_LEVEL_DOWN);
    if (step != 0 && held >= 0 && sim.match.state == MATCH_PRACTICE)
        level_step(sim, weaponSlotLevels[slot], step);
}

// Shrinker, Embiggener and crouching: resizes the box around the feet to the fighter's current size.
void Fighter::size_update()
{
    scale = trinket_get(TRINKET_SHRINKER, 1) * trinket_get(TRINKET_EMBIGGENER, 1);
    float height = BOX_HEIGHT * scale * (isCrouching || isSliding ? CROUCH_HEIGHT : 1);
    Vec2 feet = {center_get().x, body.box.y + body.box.h};
    body.box = {feet.x - BOX_WIDTH * scale / 2, feet.y - height, BOX_WIDTH * scale, height};
}

// Wings: a jump press in the air that nothing else used (no ground, coyote or wall jump) dashes toward the
// cursor, adding a push on top of the current velocity and holding it briefly without gravity. Stacked copies don't
// add speed (the best copy's counts) but each holds a dash: the cooldown builds up a dash's worth per dash, and dashing
// works while there's a dash's worth left to build up before all of them are spent.
void Fighter::dash_update(Sim& sim, bool isJumpPressed)
{
    float speed = trinket_best_get(TRINKET_WINGS, 0);
    dashTimer -= TICK;
    dashCooldown = std::max(0.0f, dashCooldown - TICK);

    bool isUnused = isJumpPressed && jumpBuffer > 0 && !body.isGrounded && coyoteTimer <= 0;
    int dashes = trinket_count(TRINKET_WINGS);
    if (speed <= 0 || !isUnused || dashCooldown > DASH_COOLDOWN * (dashes - 1) || isLaunched)
        return;

    jumpBuffer = 0;
    burst_add(aim * speed);
    dashCooldown += DASH_COOLDOWN;
    sim.cues->sound_play(SOUND_DASH);
    sim.cues->burst_spawn(STEP_DUST, center_get(), 0, index);
}

// Climb Claw, by level. 1: pushing into a wall slows the slide down it, trailing dust. 2: pressing away kicks
// off, on a cooldown so it can't climb forever. 3: Jump wall jumps freely.
void Fighter::climb_update(Sim& sim)
{
    int level = trinket_get(TRINKET_CLIMBING, 0);
    int wall = wall_get(sim);
    kickTimer -= TICK;
    slideWall = 0;
    if (level == 0 || wall == 0 || body.isGrounded || isLaunched)
        return;

    float direction = (float)is_down(CONTROL_RIGHT) - (float)is_down(CONTROL_LEFT);
    slideTimer -= TICK;
    if (direction == wall && body.velocity.y > 0)
    {
        body.velocity.y = std::min(body.velocity.y, CLING_SPEED);
        slideWall = wall;
        if (slideTimer <= 0)
            sim.cues->burst_spawn(SLIDE_DUST, wall_point_get(wall), wall > 0 ? PI : 0, index);
        slideTimer = slideTimer <= 0 ? SLIDE_DUST_INTERVAL : slideTimer;
    }

    Control away = wall > 0 ? CONTROL_LEFT : CONTROL_RIGHT;
    if (level >= 2 && kickTimer <= 0 && is_pressed(away))
    {
        wall_push(sim, wall, KICK_VELOCITY);
        kickTimer = KICK_COOLDOWN;
        isJumping = false;
    }
    if (level >= 3 && jumpBuffer > 0)
    {
        wall_push(sim, wall, WALL_JUMP_VELOCITY);
        jumpBuffer = 0;
        isJumping = true;
    }
}

// Pushes off the wall with at least the base velocity. A hard hit into the wall in the last moment is reflected
// back out, a little stronger, with some of it turned into extra lift.
void Fighter::wall_push(Sim& sim, int wall, Vec2 base)
{
    float outward = std::max(base.x, wallSpeed * WALL_REFLECT);
    body.velocity = {-wall * outward, base.y - wallSpeed * WALL_LIFT};
    wallSpeed = 0;
    kickPose = KICK_POSE_TIME;
    sim.cues->sound_play(SOUND_JUMP);
    sim.cues->burst_spawn(KICK_DUST, wall_point_get(wall), wall > 0 ? PI : 0, index);
}

// Launched fighters bounce off whatever stopped them, keeping most of their speed, with a thud, dust and shake that
// grow with the impact. Hard impacts slam them for damage, credited to their launcher. The launch ends once they've
// slowed down.
void Fighter::bounce_resolve(Sim& sim, Vec2 before)
{
    float impact = 0;
    Vec2 normal = body.normal;
    float into = vec2_dot(before, normal);
    if (into < -BOUNCE_MIN)
    {
        body.velocity = before - normal * (into * (1 + BOUNCE_KEEP));
        impact = -into;
    }
    else
    {
        if (body.velocity.x == 0 && std::abs(before.x) > BOUNCE_MIN)
        {
            body.velocity.x = -before.x * BOUNCE_KEEP;
            impact = std::abs(before.x);
        }
        if (body.velocity.y == 0 && std::abs(before.y) > BOUNCE_MIN)
        {
            body.velocity.y = -before.y * BOUNCE_KEEP;
            impact = std::max(impact, std::abs(before.y));
        }
    }
    if (impact > 0)
    {
        sim.cues->sound_play(SOUND_BOUNCE);
        sim.cues->burst_spawn(BOUNCE_DUST, center_get(), 0, index);
        sim.cues->shake_add(impact * BOUNCE_SHAKE);
    }
    int slam = (impact - SLAM_SPEED) * SLAM_DAMAGE;
    if (slam > 0)
        sim.weapons.damage_deal(sim, {.point = center_get(),
                                      .source = center_get(),
                                      .knock = 0,
                                      .amount = slam,
                                      .owner = launcher,
                                      .target = index,
                                      .sound = SOUND_HIT_BLUNT_HEAVY});
    isLaunched = vec2_length(body.velocity) >= LAUNCH_END_SPEED;
}

// Remembers where the feet last stood with solid support under both edges, and puts the fighter back there, still and
// in a puff, when it touches a pit.
void Fighter::safe_update(Sim& sim)
{
    World& world = sim.world;
    Rect box = body.box;
    float feet = box.y + box.h;
    auto isSupported = [&](float x) {
        Tile tile = world.tile_at({x, feet + 1});
        return tile == TILE_SOLID || tile == TILE_PLATFORM;
    };
    if (body.isGrounded && isSupported(box.x) && isSupported(box.x + box.w - 1))
        safe = {box.x + box.w / 2, feet};
    if (!world.is_touching(box, TILE_PIT))
        return;

    sim.cues->burst_spawn(LAND_DUST, center_get(), 0, index);
    sim.cues->sound_play(SOUND_FALL);
    charge_cancel(sim);
    body.box.x = safe.x - box.w / 2;
    body.box.y = safe.y - box.h;
    body.velocity = {};
    cornerPrevious = {body.box.x, body.box.y};
    isLaunched = false;
    sim.cues->burst_spawn(LAND_DUST, center_get(), 0, index);
}

// Where the player touches the wall on the given side, around hand height.
Vec2 Fighter::wall_point_get(int wall)
{
    Rect box = body.box;
    return {wall > 0 ? box.x + box.w : box.x, box.y + box.h * WALL_POINT_HEIGHT};
}

// Which side a wall touches the player on: -1 left, 1 right, 0 neither.
int Fighter::wall_get(Sim& sim)
{
    Rect box = body.box;
    float middle = box.y + box.h / 2;
    float low = box.y + box.h - 2;
    auto isWall = [&](float x) {
        return sim.world.is_solid_at({x, middle}) ||
               (sim.world.tile_at({x, low}) == TILE_SLOPE && sim.world.is_solid_at({x, low}));
    };
    if (isWall(box.x - 1))
        return -1;
    if (isWall(box.x + box.w + 1))
        return 1;
    return 0;
}

// Attack fires normal attacks, repeating while held, and letting it go sends any gathered Grimoire wisps. Charge
// charges and fires on release, falling back to a normal attack if let go early. Charge lives on the player so it
// survives weapon swaps. A fresh press of either lets go of a grapple, keeping the swing's momentum. Charge calls the
// boomerangs back once they're all out, and either reels in a flail.
void Fighter::charge_update(Sim& sim)
{
    Attack* hook = sim.weapons.hook_get(*this);
    bool isLeftPressed = is_pressed(CONTROL_ATTACK);
    bool isRightPressed = is_pressed(CONTROL_CHARGE);
    if (is_released(CONTROL_ATTACK))
        sim.weapons.wisps_release(*this);

    if (hook && (isLeftPressed || isRightPressed))
    {
        sim.weapons.attacks_release(*this, ATTACK_HOOK);
        isFireBlocked = isLeftPressed;
        return;
    }
    if (sim.weapons.is_recalled(sim, *this))
    {
        isFireBlocked = isLeftPressed;
        return;
    }

    isFireBlocked &= is_down(CONTROL_ATTACK);
    if (is_down(CONTROL_ATTACK) && !isFireBlocked)
        sim.weapons.fire(sim, *this, 0);

    if (isRightPressed && weapon_get() >= 0)
        isCharging = true;

    if (isCharging && is_down(CONTROL_CHARGE) && charge < 1)
    {
        float previous = charge;
        charge = std::min(1.0f, charge + TICK / CHARGE_TIME * trinket_get(TRINKET_DRINK, 1));
        if (previous < CHARGE_VISIBLE && charge >= CHARGE_VISIBLE)
            sim.cues->charge_play(*this);
        if (charge >= 1)
        {
            sim.cues->charge_stop(*this);
            sim.cues->sound_play(SOUND_READY);
            sim.cues->burst_spawn(READY_BURST, hand_get(), 0, index);
        }
    }

    if (isCharging && is_released(CONTROL_CHARGE))
    {
        sim.weapons.fire(sim, *this, charge);
        sim.cues->charge_stop(*this);
        charge = 0;
        isCharging = false;
    }
}

// How much of a trinket's own cooldown is left, from 1 just used to 0 ready. Wings dashes and Climb Claw kicks
// have one, and every other trinket is always 0.
float Fighter::trinket_cooldown_get(int trinket)
{
    if (trinket == TRINKET_WINGS)
    {
        int spare = std::max(0, trinket_count(TRINKET_WINGS) - 1);
        return std::clamp((dashCooldown - DASH_COOLDOWN * spare) / DASH_COOLDOWN, 0.0f, 1.0f);
    }
    if (trinket == TRINKET_CLIMBING)
        return std::max(0.0f, kickTimer) / KICK_COOLDOWN;
    return 0;
}

// The radius an Iron Weights slam would blast if the fighter landed at its current speed, or 0 if it isn't falling
// fast enough to slam at all.
float Fighter::pound_area_get()
{
    if (!is_trinket_equipped(TRINKET_WEIGHTS) || body.isGrounded || body.velocity.y <= MAX_FALL)
        return 0;
    float impact = std::min(body.velocity.y / POUND_SPEED, POUND_SCALE_MAX);
    return trinket_sum_get(TRINKET_WEIGHTS, POUND_AREAS) * std::sqrt(impact);
}

// Moves the fighter's middle to centre, keeping its momentum, without drawing it sliding across (teleports).
void Fighter::teleport_to(Vec2 centre)
{
    body.box.x = centre.x - body.box.w / 2;
    body.box.y = centre.y - body.box.h / 2;
    cornerPrevious = {body.box.x, body.box.y};
}

// An outside push, like a blast, recoil or a lunge. It counts as a launch, so releasing jump won't cut it short.
// Crouching halves it (knockback, already halved before it gets here, isn't damped again).
void Fighter::impulse_add(Vec2 impulse, bool isDamped)
{
    body.velocity = body.velocity + impulse * (isDamped && isCrouching ? CROUCH_DAMP : 1);
    isJumping = false;
}

// A knock from another fighter's hit or blast, softened while crouching. It tops up the speed already going its way
// rather than stacking, so rapid small knocks can't juggle, and a hard enough one launches it (that fighter getting
// the credit for whatever it bounces into).
void Fighter::knock_take(Vec2 knock, int owner)
{
    knock = knock * (isCrouching ? CROUCH_DAMP : 1);
    float strength = vec2_length(knock);
    Vec2 direction = vec2_normalize(knock);
    impulse_add(direction * std::max(0.0f, strength - vec2_dot(body.velocity, direction)), false);
    launcher = owner;
    isLaunched |= strength >= LAUNCH_START_SPEED;
}

// A push held briefly without gravity or friction, so it carries even along the ground. Used by dashes and lunges.
void Fighter::burst_add(Vec2 impulse)
{
    impulse_add(impulse);
    dashTimer = DASH_TIME;
}

// Drops any charge in progress and silences its sound.
void Fighter::charge_cancel(Sim& sim)
{
    sim.cues->charge_stop(*this);
    charge = 0;
    isCharging = false;
}

// The weapon in the selected hotbar slot, or -1 if the slot is empty.
int Fighter::weapon_get()
{
    return weaponLoadout[slot];
}

// The slot whose cooldown, attacks and Doubler echoes a weapon slot's weapon uses: its own (each copy of a weapon is a
// weapon of its own), or -1 for an empty slot.
int Fighter::weapon_key(int weaponSlot)
{
    return weaponLoadout[weaponSlot] < 0 ? -1 : weaponSlot;
}

// A weapon slot's level, its copy's own.
int Fighter::slot_level_get(int weaponSlot)
{
    return weaponSlotLevels[weaponSlot];
}

const LevelDef& Fighter::level_get(int weaponSlot)
{
    return WEAPON_DEFS[weaponLoadout[weaponSlot]].levels[slot_level_get(weaponSlot)];
}

// Puts an item in a slot (or empties it, with -1) at the item's level.
void Fighter::item_set(bool isTrinket, int itemSlot, int item)
{
    (isTrinket ? trinketLoadout : weaponLoadout)[itemSlot] = item;
    if (item >= 0)
        (isTrinket ? trinketSlotLevels : weaponSlotLevels)[itemSlot] =
            (isTrinket ? trinketItemLevels : weaponItemLevels)[item];
}

// Every item and every copy at one level, as a match sets them each round.
void Fighter::levels_fill(int weaponLevel, int trinketLevel)
{
    std::fill(std::begin(weaponItemLevels), std::end(weaponItemLevels), weaponLevel);
    std::fill(std::begin(weaponSlotLevels), std::end(weaponSlotLevels), weaponLevel);
    std::fill(std::begin(trinketItemLevels), std::end(trinketItemLevels), trinketLevel);
    std::fill(std::begin(trinketSlotLevels), std::end(trinketSlotLevels), trinketLevel);
}

// What a trinket does, from its equipped copies, or the neutral value without any. Copies add what each does beyond
// neutral (Boots 1.3x and 1.3x make 1.6x, Pebble Helmets' damages add), except that ones taking something away (below
// a neutral of 1, like Shrinker or Feather) multiply, so they never pass zero; the trinket's cap holds the total.
float Fighter::trinket_get(TrinketId trinket, float neutral)
{
    const TrinketDef& def = TRINKET_DEFS[trinket];
    float total = neutral;
    bool isFirst = true;
    for (int i = 0; i < trinketSlots; i++)
    {
        if (trinketLoadout[i] != trinket)
            continue;
        // The first copy counts exactly as it is (adding and taking back the neutral value would round it).
        float value = def.values[trinketSlotLevels[i]];
        total = isFirst ? value : neutral != 0 && value < neutral ? total * value / neutral : total + value - neutral;
        isFirst = false;
    }
    return def.cap > 0 ? std::min(total, def.cap) : total;
}

// The best equipped copy's value, or the neutral value without any.
float Fighter::trinket_best_get(TrinketId trinket, float neutral)
{
    int level = trinket_level_get(trinket);
    return level < 0 ? neutral : TRINKET_DEFS[trinket].values[level];
}

// A per-level number for a trinket (like Iron Weights' slam damage): the copies' added up, or 0 without any.
float Fighter::trinket_sum_get(int trinket, const float* table)
{
    float total = 0;
    for (int i = 0; i < trinketSlots; i++)
        total += trinketLoadout[i] == trinket ? table[trinketSlotLevels[i]] : 0;
    return total;
}

// The best equipped copy's level, or -1 without any.
int Fighter::trinket_level_get(int trinket)
{
    int level = -1;
    for (int i = 0; i < trinketSlots; i++)
        if (trinketLoadout[i] == trinket)
            level = std::max(level, trinketSlotLevels[i]);
    return level;
}

int Fighter::trinket_count(int trinket)
{
    return std::count(trinketLoadout, trinketLoadout + trinketSlots, trinket);
}

// What Shock Absorber leaves of knockback taken: part of the way to what it leaves of weapon movement.
float Fighter::knock_absorb_get()
{
    return 1 - (1 - trinket_get(TRINKET_ABSORBER, 1)) * ABSORB_KNOCK_SHARE;
}

bool Fighter::is_trinket_equipped(int trinket)
{
    for (int item : trinketLoadout)
        if (item == trinket)
            return true;
    return false;
}

bool Fighter::is_down(Control control)
{
    return controls.buttons >> control & 1;
}

// Whether any button went down since the last tick, for readying up while the fighter is frozen. It keeps the held
// buttons up to date, so buttons held over from the last round don't count until pressed again.
bool Fighter::is_any_pressed()
{
    bool isPressed = (controls.buttons & ~buttonsPrevious) != 0;
    buttonsPrevious = controls.buttons;
    return isPressed;
}

bool Fighter::is_pressed(Control control)
{
    return is_down(control) && !(buttonsPrevious >> control & 1);
}

bool Fighter::is_released(Control control)
{
    return !is_down(control) && buttonsPrevious >> control & 1;
}

// Dual Wield's off-hand weapon slots, one per copy, written to slots: the other slots holding weapons, the ones most
// recently switched away from first, then any never switched to, in slot order. Returns how many.
int Fighter::off_slots_get(int* slots)
{
    int held = weapon_key(slot);
    int count = 0;
    for (int i = 0; i < weaponSlots; i++)
        if (weaponLoadout[i] >= 0 && weapon_key(i) != held)
            slots[count++] = i;
    std::stable_sort(slots, slots + count, [&](int a, int b) { return slotSwitches[a] > slotSwitches[b]; });
    return std::min(count, trinket_count(TRINKET_DUAL));
}

// The weapon slot a hand holds: the selected one in the main hand (0), and Dual Wield's in the off-hands (1 up), or -1
// for an off-hand holding nothing.
int Fighter::hand_slot_get(int hand)
{
    if (hand == 0)
        return slot;
    int slots[SLOT_MAX];
    return hand <= off_slots_get(slots) ? slots[hand - 1] : -1;
}

// Moves the box alpha of the way through the last tick. Only for drawing.
void Fighter::blend(float alpha)
{
    body.box.x = math_lerp(cornerPrevious.x, body.box.x, alpha);
    body.box.y = math_lerp(cornerPrevious.y, body.box.y, alpha);
}

Vec2 Fighter::center_get()
{
    return {body.box.x + body.box.w / 2, body.box.y + body.box.h / 2};
}

// Where a hand holds its weapon: the main hand (0) in front, and Dual Wield's off-hands (1 up) behind the body, the
// first just behind it and the rest fanned out further back, alternating up and down.
Vec2 Fighter::hand_get(int hand)
{
    Vec2 offset = HAND_OFFSET;
    if (hand > 0)
    {
        int step = hand / 2;
        offset = OFFHAND_OFFSET + Vec2{-OFFHAND_FAN.x * step, (hand % 2 == 0 ? -1 : 1) * OFFHAND_FAN.y * step};
    }
    return center_get() + Vec2{is_left() ? -offset.x : offset.x, offset.y} * scale;
}

// Full charge pulses white on and off, shared by the charge bar and the held weapon.
bool Fighter::is_crawling()
{
    return isCrouching && !isSliding && std::abs(body.velocity.x) > STEP_SPEED / 2;
}

bool Fighter::is_left()
{
    return isFacingLeft;
}