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openIE CAD

OCL language

OCL (openIE CAD Language) describes designs as code. The evaluator turns OCL into geometry and populates the UDD; the viewer renders the result. Agents call it through eval_ocl (parse + evaluate) and parse_ocl (parse only) — see MCP tools. For a gentle introduction, start with OCL basics.

Bindings

Section titled “Bindings”

The interactive form of an OCL program is a sequence of let bindings. Each binds a name to a value:

let base = box(40mm, 20mm, 10mm)
let lid  = box(40mm, 20mm, 2mm)

Units

Section titled “Units”

Lengths carry an explicit unit (mm). OCL enforces dimensional analysis — mixing incompatible dimensions is an error, not a silent bug.

let w = 40mm
let plate = box(w, 20mm, 2mm)

Primitives

Section titled “Primitives”
PrimitiveArguments
box(width, height, depth)three lengths
cylinder(radius, height)two lengths

Transforms — the pipe

Section titled “Transforms — the pipe”

|> feeds a value into a transform, applied left to right:

let post = cylinder(1.6mm, 8mm) |> translate(10mm, 5mm, 0mm)

translate(x, y, z) moves a solid by the given offsets.

Whole-product form

Section titled “Whole-product form”

Beyond interactive bindings, OCL can describe a complete product — enclosure, schematic, circuit, and bill of materials — in a single source. The evaluator populates the UDD from it, so every downstream view (viewer, agent, fab) reads from one place:

product "USB Temperature Logger" {
  body Case {
    let shell = box(46mm, 24mm, 16mm)
  }
  schematic Main {
    place U1 at (8mm, 10mm)    -- MCU
    place U2 at (24mm, 10mm)   -- sensor
    wire(U1.SDA, U2.SDA)
    wire(U1.SCL, U2.SCL)
  }
  circuit Power {
    V1(VCC, GND) = 3.3V
    R1(VCC, LED) = 330ohm
  }
  bom {
    entry U1 { mpn = "ESP32-C3-MINI-1", unit_price = 1.70 }
    entry U2 { mpn = "SHT40-AD1B-R2",   unit_price = 2.10 }
  }
}

The mechanical body, the schematic, the circuit, and the bom share identifiers — change a component once and every section follows.

Tooling

Section titled “Tooling”

OCL ships with a lexer, parser, evaluator, and an LSP server (with a VS Code extension) in the cad-ocl and cad-ocl-lsp crates — see the crate map.

Section titled “Related”