Individual skill
melonjs-math
Use this skill for vector and matrix maths in melonJS — Vector2d, Vector3d, their observable variants, Matrix2d, Matrix3d, and the math utility functions. Covers which methods mutate and which allocate, the vector pool and when clone() is the wrong tool, interpolation with lerp, slerp, damp and moveTowards, and the argument defaults that silently drop a component. Triggers on: Vector2d, Vector3d, ObservableVector2d, ObservableVector3d, Matrix2d, Matrix3d, vector, vector maths, dot, cross, normalize, length, distance, angle, lerp, slerp, damp, moveTowards, project, clamp, degToRad, radToDeg, clone, vector pool, vector3dPool, setMuted, setCallback, my vector is wrong, z is zero, scale ignores z., moveTowards ignores z, projectN, currentTransform, setTransform, matrix, transform matrix, column-major, val, Float32Array, basis matrix, orientation matrix, Noise, getNoise1d, flicker, wobble.
packages/melonjs/skills/melonjs-math/SKILL.md
Source commit a41d6a328557d69a0441d79bbeb9cd6c430275b5
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- Matches the observed repository HEAD
- Yes
- Scanner rules are current
- Yes
- Repository scan complete
- No
- Skill scan complete
- No
- Observed behavior
- Network or broad shell
- Last checked
- Nov 5, 2026
These are observations at the recorded commit, not a guarantee of safety. Review the source before running it.
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Repository context
- Repository stars (not skill ratings)
- 6,440
- Repository last updated
- Nov 7, 2026
- License
- MIT
Observed agent integration: No specific integration evidence. Standard SKILL.md installation does not imply verified compatibility.
- html5-game-engine Repository topic
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- 2d Repository topic
- agent-skills Repository topic
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- engineering Derived category
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# Vectors, matrices and maths
## The one rule that explains most surprises
**Methods mutate `this` and return it. They do not return a new vector.**
```js
const a = new Vector3d(1, 0, 0);
const b = new Vector3d(0, 1, 0);
a.cross(b); // a IS NOW the cross product; the original a is gone
a.add(b).normalize().scale(3, 3, 3); // chains, all in place
```
