Physics Tuning

What it does

When your agent uses it

• The user mentions physics feel
• Bouncing/unstable physics
• Collision layers

Example prompts

• “/physics-tuning”

Requirements

• Compatibility (from SKILL.md): Engine-agnostic concepts. Pairs with godot-physics (_physics_process) and unity-physics (FixedUpdate, Rigidbody); snippets in GDScript/C#-like pseudocode.

Workflow steps

4 steps, taken from the step headings in SKILL.md.

1. 1Fixed timestep for simulation, render interpolation for smoothness
2. 2Stop tunneling: CCD + a speed cap
3. 3Body tuning: mass, drag, gravity scale, material
4. 4Collision layers and masks (who collides with whom)

What it can do on your machine

Read from SKILL.md and the folder at commit eac84e0. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are gdscript).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Engine-agnostic concepts. Pairs with godot-physics (_physics_process) and unity-physics (FixedUpdate, Rigidbody); snippets in GDScript/C#-like pseudocode.

  From compatibility in the SKILL.md frontmatter.

Context cost

Physics Tuning loads about 1.9k tokens when it runs, and up to ~3.1k if it reads all its reference files. Until then it costs about 98 tokens; SKILL.md has 594 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~98

When it runs · the whole SKILL.md, loaded when a task matches

~1.9k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~3.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from ukanwat/overtime at commit eac84e0, republished under its Apache-2.0 licence (© ukanwat). 594 words, ~1,949 tokens.

name

physics-tuning

description

Tune game physics for stable, good-feeling motion — fixed vs variable timestep, render interpolation, mass/gravity/drag, continuous collision detection (CCD) to stop tunneling, fixing jitter, and collision layers/masks. Engine-neutral. Use when the user mentions physics feel, jitter, tunneling, fixed timestep, FixedUpdate, CCD, bouncing/unstable physics, or collision layers.

compatibility

Engine-agnostic concepts. Pairs with godot-physics (_physics_process) and unity-physics (FixedUpdate, Rigidbody); snippets in GDScript/C#-like pseudocode.

license

Apache-2.0

metadata.engine

none

metadata.category

disciplines

metadata.difficulty

intermediate

# Physics callback: runs at the FIXED rate. Use its dt for all integration.
func _physics_process(dt):                  # Unity: void FixedUpdate()
    velocity += gravity * dt                # integrate with the FIXED dt
    move_and_slide()                        # engine resolves collisions this step
    _prev_pos = _curr_pos; _curr_pos = global_position   # record for interpolation

# Render frame: runs as fast as the display. Interpolate between physics states.
func _process(_frame_dt):                   # Unity: void Update()
    var alpha = Engine.get_physics_interpolation_fraction()  # 0..1 within the tick
    visual.global_position = _prev_pos.lerp(_curr_pos, alpha)
# RIGHT: integrate in the fixed step, render via interpolation.
# WRONG: applying forces in _process/Update with frame dt — speed and collisions
# then depend on frame rate and jitter under load.

# Fast, small bodies skip past thin colliders between ticks. Two fixes:
body.continuous_cd = true            # RigidBody3D bool (RigidBody2D: CCD_MODE_* enum). Unity: rb.collisionDetectionMode = Continuous
# Cap velocity so a single step can't move more than ~one collider thickness.
const MAX_SPEED := 40.0
if velocity.length() > MAX_SPEED:
    velocity = velocity.normalized() * MAX_SPEED
# Rule of thumb: max_distance_per_step (= speed / physics_hz) should be < the
# thinnest wall. Raise physics_hz or enable CCD when that fails.

# Mass is RELATIVE weight in collisions; it does NOT change fall speed (gravity
# accelerates all masses equally). Use drag and gravity_scale to shape feel.
body.mass = 2.0                      # heavier pushes lighter in collisions
body.linear_damp = 0.5               # air drag: higher = stops sooner (Unity: drag)
body.gravity_scale = 1.5             # per-object gravity multiplier (snappier fall)
# Bounce/slide come from the physics material, not code:
material.bounce = 0.2                # restitution 0..1 (Unity: bounciness)
material.friction = 0.8              # surface grip

# A body is ON its layer(s) and SCANS the layers in its mask. Both directions of a
# pair must be configured for them to interact.
player.collision_layer = LAYER_PLAYER
player.collision_mask  = LAYER_WORLD | LAYER_ENEMY     # player detects world+enemies
pickup.collision_layer = LAYER_PICKUP
pickup.collision_mask  = LAYER_PLAYER                  # pickup only reacts to player
# Unity equivalent: assign GameObject layers and edit the Physics collision matrix
# (or Physics.IgnoreLayerCollision). Keep a named layer constant table, not magic numbers.

© ukanwat, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in .claude/skills/physics-tuning of ukanwat/overtime.

• SKILL.md
• references/timestep-and-ccd.md

Open the folder on GitHubat commit eac84e0

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in ukanwat/overtime, which our catalogue first saw on October 7, 2026.

• gamedev-skills/awesome-gamedev-agent-skillsskills/disciplines/physics-tuning