Isometric Grid Math
Use when converting between grid coordinates and screen pixels in a 2:1 isometric projection, including screen-to-grid for mouse picking.
Install
$ agentstack add skill-0xheycat-isometric-game-skills-isometric-grid-math ✓ scanned · ✓ verified, works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ✓ Network access No
- ✓ Filesystem access No
- ✓ Shell / process execution No
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
Verified badge
Passed review? Show it. Paste this badge into your README, it links to the public security report.
Links to your public security report.[](https://agentstack.voostack.com/security/report/skill-0xheycat-isometric-game-skills-isometric-grid-math) Reliability & compatibility
Declared compatibility
Compatibility is declared by the source manifest. End-to-end runtime verification is coming, see below.
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Isometric Grid Math
Overview
Every isometric bug eventually traces back to the coordinate transform. This skill gives the exact, tested gridscreen formulas for a 2:1 projection so placement and picking are pixel-correct.
When to Use
- Tiles render in the wrong place or overlap.
- Mouse clicks select the wrong tile.
- You are starting a renderer and need the core transform.
Process
- Fix tile width W and height H (2:1 means W = 2*H).
- grid->screen: screenX = (col - row) (W/2); screenY = (col + row) (H/2).
- Add the world origin offset so (0,0) is where you want it on screen.
- screen->grid (for picking): invert the transform using W and H.
- Round screen->grid results to integer tile coords.
- Validate round-trip: grid -> screen -> grid returns the original tile.
- Document the anchor (tile top vs tile center) and stay consistent.
const screenX = (col - row) * (W / 2);
const screenY = (col + row) * (H / 2);
// inverse
const col = ((screenX / (W/2)) + (screenY / (H/2))) / 2;
const row = ((screenY / (H/2)) - (screenX / (W/2))) / 2;Rationalizations (Stop Lying to Yourself)
| Excuse | Reality | |---|---| | "I will tweak offsets until it looks right" | Magic offsets break on resize/zoom. Derive the transform. | | "Rounding does not matter" | Unrounded screen->grid selects the wrong tile near edges. Round it. |
Red Flags - STOP if you catch yourself:
- Hard-coded pixel offsets instead of a derived transform.
- No screen->grid inverse for picking.
- Round-trip grid->screen->grid does not return the same tile.
Verification
You are NOT done until every box is checked:
- [ ] grid->screen and screen->grid are both implemented.
- [ ] Round-trip conversion is exact for integer tiles.
- [ ] Anchor convention is documented and consistent.
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: 0xheycat
- Source: 0xheycat/isometric-game-skills
- License: MIT
- Homepage: https://0xheycat.github.io/isometric-game-skills/demo/
Install and usage instructions live in the source repository linked above.
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Versions
- v0.1.0 Imported from the upstream source.