picking-and-hit-testing SKILL.md skillA
picking-and-hit-testing from yuiseki/map-from-scratch is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add yuiseki/map-from-scratch/picking-and-hit-testing@git:20261026.79a684ePins git:20261026.79a684e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- yuiseki/map-from-scratch
- Path
.agents/skills/picking-and-hit-testing/SKILL.md- Versions recorded
- 1
- Latest version
- git:20261026.79a684e, committed Oct 26, 2026
- Size
- 30,573 bytes
- Repository stars
- 24
- License
- GPL-3.0
How map engines answer "what is under the pointer" (GPU id buffers, Canvas hit canvases, CPU indexes and analytic tests, precomputed id grids, terrain raycasts), with the stalls, id limits, tolerance bugs and cross-tile identity problems they measured and reverted. Load it when a map-from-scratch request needs tap, click or hover to identify, highlight or select features, a coordinate or height under the cursor, or "everything under the finger", before writing `architecture_selection` or any…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Picking and hit testing: what is under the pointer, and how to ask A pick turns a screen position into a feature id (or a ground coordinate), and the id into the attributes the user asked for. A general engine must pick any geometry, styled any way, moved by any shader, from any number of layers and tiles. Most of them therefore render the scene a second time with ids as colours and read the pixel back, and then spend years on what that costs: GPU stalls, id-range limits, antialiased ids, picks that disagree with what was drawn, and features split across tiles. A renderer made for one request knows what is pickable, how it is drawn and how many there are, and can often answer from data it already holds on the CPU. The repo has both ends already: a 1x1 id render on a phone (02, pick p95 0.9 ms at 4x CPU throttle) [1], a brute-force CPU hover over 7,342 cities (07, p95 0.25-0.3 ms, no index) [2], and `isPointInPath` over 47 prefectures (01, p95 0.01 ms) [3]. Per-engine detail and the smaller related decisions are in [references/engines.md](references/engines.md). Numbers in brackets refer to the Sources list at the end of this file. …
Read the whole file at its exact version.
How to install
mdr add yuiseki/map-from-scratch/picking-and-hit-testing@sha256:7d62a23aa0f86a65The line at the top of this page pins the label git:20261026.79a684e, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_6mrlblk3i4gmg6it)
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Versions
The registry has recorded 1 version of this file, committed on Oct 26, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (30573 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
yuiseki/map-from-scratch · 24 stars · license GPL-3.0 · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_6mrlblk3i4gmg6it GET https://markdownregistry.com/api/v1/resolve?ref=yuiseki/map-from-scratch/picking-and-hit-testing GET https://markdownregistry.com/api/v1/blob/7d62a23aa0f86a65325869d30dbbb0043f5d3388ff7ec6a255cd992c7143c42e
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.