CharacterBody2D Implementation

Expert CharacterBody2D feel systems — not beginner move_and_slide tutorials.

NEVER Do

• NEVER use RigidBody2D for standard player controllers — RigidBody is for physics-simulated objects. For responsive, feel-driven player movement, always use CharacterBody2D.
• NEVER multiply velocity by delta before move_and_slide() — move_and_slide() handles delta internally. Manual multiplication makes movement framerate-dependent.
• NEVER use global_position updates for gameplay movement — Use velocity + move_and_slide(). Direct position hacks bypass collision, floor snap, and one-way rules.
• NEVER "fall through" one-ways by nudging position.y — Use one-way collision shapes + layer/mask (and temporary mask disable / collide-with-areas patterns). See godot-2d-physics.
• NEVER ignore floor/wall/ceiling state right after move_and_slide() — is_on_floor(), is_on_wall(), is_on_ceiling(), and slide collisions drive coyote, wall jump, and bonk logic.
• NEVER rely on default floor_snap_length for fast stair-climbing — Default snapping is too small for high-velocity characters. Use custom raycast-based stair logic.
• NEVER apply gravity while is_on_floor() is true — Constant downward force causes micro-jitter and fights floor-snap. Reset velocity.y on land.
• NEVER use Area2D as primary ground detection — Prefer is_on_floor() / shapecasts; Areas are for triggers, not floor truth.
• NEVER forget ceiling bonk — Reset velocity.y when is_on_ceiling() or the player floats into the ceiling until gravity wins.
• NEVER round physics positions for pixel art — Keep physics high-precision; round sprite positions in _process only (subpixel_movement_rounding.gd).
• NEVER spam queue_free() for hordes — Pool bullets/enemies when spawn/despawn is frequent (performance_character_pooling.gd).

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When to Use CharacterBody2D

Need	Body
Feel-driven player / NPC / enemy locomotion	CharacterBody2D
Rolling debris, ragdoll-ish props, force piles	RigidBody2D
Static level colliders	StaticBody2D / TileMapLayer physics

Decision Tree → MANDATORY Scripts

Task	Do First	Then (optional)	Do NOT Load
Platformer foundation (coyote, buffer, accel/friction)	expert_physics_2d.gd	—	Inline tutorial controllers
Isolate coyote/buffer only	frame_perfect_coyote_time.gd	—	Duplicate coyote blocks in SKILL
Variable jump / short hop	variable_jump_height.gd	—	—
Slopes / stairs	slope_stair_snapping.gd	godot-raycasting-queries	—
Wall slide / wall jump	wall_slide_jump_refined.gd or wall_jump_controller.gd	—	Both unless comparing
Dash + i-frames	dash_state_controller.gd or dash_controller.gd	—	Both unless comparing
Air control polish	aerial_drift_acceleration.gd	—	—
Ceiling stick / bonk	ceiling_bonk_detection.gd	—	—
Knockback / wind impulses	impulse_response_handler.gd	—	—
Pixel-art visuals	subpixel_movement_rounding.gd	—	Rounding global_position in physics
Many AI bodies	performance_character_pooling.gd	—	—
One-way platforms	Tile/StaticBody one-way + layers/masks	godot-tilemap-mastery / godot-2d-physics	position.y += 1 drop-through hacks
Top-down / tank locomotion	movement-recipes.md	—	Inline 8-way tutorials
Jump arc debug tuning	game_feel_profiler.gd	—	—
Animation root motion	root_motion_controller.gd	godot-2d-animation	—

Golden path: Read expert_physics_2d.gd first. Add dash/wall/jump scripts only after that controller is in place. Do not re-inline coyote/buffer/accel loops in the scene when the script already owns them.

One-Way Platforms (correct recipe)

1. Author one-way on the platform collider (CollisionShape2D one-way / TileSet physics one-way), not by teleporting the player.
2. Put platforms and player on explicit collision layers/masks so drop-through can temporarily clear the platform bit (or disable collide-with) while holding down + jump — then restore next physics frames.
3. Keep drop-through on the physics tick; never bypass move_and_slide with position nudges.
4. For tile one-ways, align TileSet physics layers with CharacterBody masks — see godot-tilemap-mastery + godot-2d-physics.

Expert Character Architectures

1. Wall Cling (Variable Friction)

Monitor is_on_wall() while falling; scale velocity.y by a friction factor (optionally from tile custom data) instead of a binary wall-slide bool. Prefer wall_slide_jump_refined.gd over a bespoke cling fork.

2. Animation-Driven Movement (Root Motion)

Pull AnimationTree.get_root_motion_position(), convert to 2D, assign velocity = motion / delta, then move_and_slide(). Keeps feet locked to authored clips; pair with godot-2d-animation.

3. Game-Feel Profiler (Jump Arcs)

Debug-draw historical positions + current velocity in _draw() to visualize apex, coyote, and buffer windows while tuning exports on expert_physics_2d.gd — game_feel_profiler.gd.

MANDATORY for top-down/tank recipes, moving platforms, slide-collision response, and gotcha tables: movement-recipes.md. Do NOT Load when expert_physics_2d.gd already covers your platformer scope.

Reference

Progressive disclosure: open Official Documentation links only when researching a specific API; load Related Skills when routing work to a peer domain — do not preload the whole lattice.

Official Documentation

• Using CharacterBody2D — Canonical move_and_slide / floor-wall-ceiling contracts; do not set position for gameplay motion.
• CharacterBody2D — API for velocity, snap, is_on_floor / wall / ceiling, and slide-collision accessors.
• Physics introduction — Why CharacterBody vs RigidBody/StaticBody, and how layers/masks gate every contact.
• Collision shapes (2D) — Capsule/box sizing and why scaled CollisionShape2D nodes corrupt normals and floor detect.
• 2D movement — Input axes into velocity for top-down and platformer starters before juice systems.
• Kinematic character (2D) — Classic slide/collision loop patterns that still inform custom stair and slope handling.
• Troubleshooting physics issues — One-way platforms, tunneling, and jitter diagnoses that show up in CharacterBody feel bugs.
• Ray-casting — Direct-space rays for stair snaps, ledge checks, and ground probes beyond is_on_floor().
• KinematicCollision2D — Per-slide normals/remainders from get_slide_collision for wall jumps and ceiling bonks.
• Physics interpolation introduction — Smooth visuals at high refresh while keeping jump/coyote logic on the physics tick.
• InputEvent — Action just-pressed timing that jump buffers and coyote windows depend on.

Related Skills

Prerequisites

• godot-project-foundations — Default gravity, physics tick rate, and 2D layer names must be set before coyote/jump feel is tunable.
• godot-gdscript-mastery — Typed _physics_process, timers, and move_toward discipline underpin every movement script here.
• godot-2d-physics — Collision layer/mask matrices, one-way shapes, and query hygiene CharacterBody motion sits on.
• godot-input-handling — Physics-step action sampling so jump buffer / coyote windows stay frame-stable.

Complements

• godot-raycasting-queries — Stair snaps, wall cling probes, and ledge rays that extend beyond is_on_* helpers.
• godot-tilemap-mastery — One-way tiles and tile physics layers must match CharacterBody masks for platforms.
• godot-2d-animation — Drive walk/jump/fall clips from floor/air/dash state without fighting move_and_slide.
• godot-state-machine-advanced — Dash, wall-slide, and airborne states scale cleaner than giant _physics_process switches.
• godot-camera-systems — Follow/look-ahead cameras couple tightly to CharacterBody velocity and landing snaps.
• godot-signal-architecture — Landed/dashed/wall-jumped events need clean ownership so UI/VFX listeners do not spam.

Downstream / consumers

• godot-genre-platformer — Genre-level platformer feel consumes coyote, buffer, slopes, and one-ways from this skill.
• godot-genre-metroidvania — Ability-gated movement (wall jump, dash) builds on the controllers defined here.
• godot-combat-system — Knockback and hitstun apply impulses through the same velocity + slide loop.
• godot-monte-carlo-balancer — Coyote frames, jump height, dash cooldown, and air accel are balance knobs — simulate them instead of guessing.

Master

• godot-master — Library router and mirrored entry point for CharacterBody2D alongside sibling domains.