# 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.

- **Type:** Skill
- **Install:** `agentstack add skill-0xheycat-isometric-game-skills-isometric-grid-math`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [0xheycat](https://agentstack.voostack.com/s/0xheycat)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [0xheycat](https://github.com/0xheycat)
- **Source:** https://github.com/0xheycat/isometric-game-skills/tree/master/skills/isometric-grid-math
- **Website:** https://0xheycat.github.io/isometric-game-skills/demo/

## Install

```sh
agentstack add skill-0xheycat-isometric-game-skills-isometric-grid-math
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# 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

1. Fix tile width W and height H (2:1 means W = 2*H).
2. grid->screen: screenX = (col - row) * (W/2); screenY = (col + row) * (H/2).
3. Add the world origin offset so (0,0) is where you want it on screen.
4. screen->grid (for picking): invert the transform using W and H.
5. Round screen->grid results to integer tile coords.
6. Validate round-trip: grid -> screen -> grid returns the original tile.
7. Document the anchor (tile top vs tile center) and stay consistent.

```js
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](https://github.com/0xheycat)
- **Source:** [0xheycat/isometric-game-skills](https://github.com/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.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-0xheycat-isometric-game-skills-isometric-grid-math
- Seller: https://agentstack.voostack.com/s/0xheycat
- Browse the marketplace: https://agentstack.voostack.com/browse

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