OpenSlideRule is a web simulator and authoring tool for slide rules. It ships with
the Chinese 1002 vector log-log double-sided rule (1002 型矢量重对数双面计算尺)
and the Type 57 pocket rule, and it can load or design any rule described by a
RuleDefinition JSON - straight or circular (disc). Values are obtained the way
they are on the physical instrument, by sliding and aligning rather than typing a
sum, and the built-in designer turns the same renderer into a rule-authoring
tool. It is for anyone who wants to read and operate a rule - students and
teachers of slide rules, collectors - and for anyone who wants to author and
preview one of their own.
A GitHub Pages deployment is defined in
.github/workflows/deploy.yml; pushing to
master or main builds and publishes the app. To run it locally:
npm install
npm run devThen open http://localhost:3000 (Vite opens it for you). Node.js 20.19.4 or newer is required.
Simulator
- Pick the model from the title selector: the 1002, the single-faced Type 57 pocket rule, or a rule you imported.
- View one face at a time or both faces together (dual face); the Type 57 is single-faced.
- Drag the slide (or rotate the rotor of a circular rule) and reset it to the aligned position.
- Work with several cursors: click the rule to add one, drag one to move it, or type a value in the readings panel to move it to the position that reads that value.
- Hover anywhere on the rule for a live read-out of every scale under the pointer.
- Read every scale at each cursor in the readings panel, and edit a reading to move its cursor.
- Zoom from 1X to 6X.
- Choose from six themes (plastic, bamboo, contrast, aluminum, ivory, blueprint); a theme also restyles the surrounding interface.
- Switch the interface language between Simplified Chinese (zh-CN) and English (en-US).
- Export the current view as PNG or SVG, or export the operation history as Markdown.
- Print or save to PDF at 1:1 scale.
- Take the first-run tutorial, and open the model-information dialog for the dimensions, scales and parts of the current rule.
Rule designer
- Seed from a built-in model or start from a starter template (a linear log rule or a circular C/D rule).
- Edit the rule metadata, the linear layout (face size, rows, gutters) or the disc dimensions of a circular rule.
- Add, reorder and remove scales; edit each scale's fields and its calculations.
- Preview the result live through the same renderer the simulator uses.
- Select a scale by clicking it in the preview or in the list.
- Watch the validation status bar and export a draft as
<id>.spec.jsonor a finished rule definition as<id>.rule.json.
Use the Import button in the toolbar, or drop a .json file onto the
simulator view. The file must be a RuleDefinition - the same schema the
designer and the generator produce. A malformed, invalid or unsupported file is
reported without disturbing the current view. Circular rules are supported as
well as linear ones.
The user guide explains how to use the app. For the physical instrument, see how slide rules work and the 1002 model; the glossary collects the terminology. The documentation index lists everything. Developers should start with docs/dev/ and CONTRIBUTING.md.
This project was developed by vibe coding: nearly all of the code was written in AI-assisted, prompt-driven sessions, with a human directing the work, checking the results and curating the data. The measured rule data and the domain notes were verified against the prototype photographs, but the codebase as a whole has not had the sustained human review a project of this size would normally receive.
If you contribute to or reuse this project, please keep that in mind: read the code before trusting it, run the tests, and expect rough edges. Corrections and hardening are welcome.
GNU General Public License v3.0 - see LICENSE.