Schemas / Geometry / paint

`rig.paint.brush`

v0.31.0 · draft 14 fields 2 required

Fields

Field	Type		Meaning
`shape`	enumround · flat · filbert · fan · rigger · mop	required	round, flat, filbert, fan, rigger, mop. The shape a maker sells, not a worn splay
`ferruleWidthMm`	float	optional	Optional. Bristle bundle width where it leaves the ferrule (the size you bought). Upper bound on `maxWidthMm` when stated
`bristleLengthMm`	float	optional	Optional. Hair length out of the ferrule. Hard ceiling on `taperHeightMm` when stated
`tipWidthMm`	float	optional	Optional. Mark width (mm) at zero penetration, tip just touching; absent = 0.3
`maxWidthMm`	float	required	Mark width (mm) at full taper depth
`taperHeightMm`	float	optional	Optional. Plunge depth (mm below contact) over which the tip widens to max; absent = 4. Zero is a constant-width pen expressed with the same schema
`taperP1`	vec2	optional	Optional. First cubic Bezier handle of the width-vs-depth profile. Endpoints are fixed at (0,0) and (1,1). X is depth fraction (clamped 0-1); Y is width fraction (free, so the sides may bow past max or pinch inside the tip). Absent = (1/3, 1/3)
`taperP2`	vec2	optional	Optional. Second handle; absent = (2/3, 2/3). Together with `taperP1` the default is a straight ramp
`loadCapacityMm`	float	optional	Optional. Plotted travel (mm) one dip sustains before the mark fails; absent = 400
`lagTipMm`	float	optional	Optional. Contact-patch lag (mm) at zero penetration: the patch trails the handle axis by this much when the tip just touches. Absent = 0 (rigid pen)
`lagMaxMm`	float	optional	Optional. Contact-patch lag (mm) at full taper depth. Absent = `lagTipMm`
`lagP1`	vec2	optional	Optional. First cubic Bezier handle of the lag-vs-depth profile. Endpoints are fixed at (0,0) and (1,1). X is depth fraction (clamped 0-1); Y is lag fraction. Absent = (1/3, 1/3)
`lagP2`	vec2	optional	Optional. Second handle; absent = (2/3, 2/3). Together with `lagP1` the default is a straight ramp from `lagTipMm` to `lagMaxMm`
`gapMaxMm`	float	optional	Optional. Tip-to-patch-center gap (mm) at full taper depth. Zero at touch, linear in depth. Absent = 0

Measured facts about a physical paint brush in a holder.

This is the hair in the ferrule, not the machine that plunges it. Contact Z, feeds, leads, and dip stations stay on the host tool / bed. Colour stays on rig.paint.solid. Stroke width on a drawable stays on rig.paint.stroke.

Digital / screen brushes (stamp masks, renderers, opacity, flow, spacing) are out of scope — those are host rendering settings, not measured facts. A digital painter may reference a rig.paint.brush entity to simulate or export for a physical tip (the taper profile answers width-vs-depth either way); exporters clamp stamp sizes to tipWidthMm..maxWidthMm. Digital brush presets that need persistence ride x.rigkit.* until a second host reads them.

Compose rig.meta.named for the label / stableId. Consumers point at that id the way a plot layer already points at a tool preset stem.

Required: shape, maxWidthMm.

A host that plunges the brush answers "how wide is the mark at this Z" from tipWidthMm, maxWidthMm, taperHeightMm, and the two taper handles. A host that compensates the toolpath answers "where is the contact patch relative to the handle" from lagTipMm, lagMaxMm, the two lag handles, and gapMaxMm. Live paint level, dip counters, and stamp textures stay in the host.

Do not put stiffness or dry-fade here until a fulfillment reads them.

JSON Schema

Resolves at https://rig.works/schemas/rig.paint.brush.schema.json — raw file.

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://rig.works/schemas/rig.paint.brush.schema.json",
  "title": "rig.paint.brush",
  "type": "object",
  "additionalProperties": false,
  "properties": {
    "shape": {
      "type": "string",
      "enum": [
        "round",
        "flat",
        "filbert",
        "fan",
        "rigger",
        "mop"
      ]
    },
    "ferruleWidthMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "bristleLengthMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "tipWidthMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "maxWidthMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "taperHeightMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "taperP1": {
      "$ref": "./_defs.schema.json#/$defs/vec2"
    },
    "taperP2": {
      "$ref": "./_defs.schema.json#/$defs/vec2"
    },
    "loadCapacityMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "lagTipMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "lagMaxMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    },
    "lagP1": {
      "$ref": "./_defs.schema.json#/$defs/vec2"
    },
    "lagP2": {
      "$ref": "./_defs.schema.json#/$defs/vec2"
    },
    "gapMaxMm": {
      "$ref": "./_defs.schema.json#/$defs/float"
    }
  },
  "required": [
    "shape",
    "maxWidthMm"
  ]
}

Seen in

paint-brush.json