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Point-level selection

bearcad.select normally targets a whole element. Point-level selection targets an individual vertex instead — a line endpoint or a circle's center — using the same point numbering the interactive Constraint tool uses.

Selecting a line endpoint​

bearcad.select{ kind = "line", index = 0, endpoint = "start" }  -- or "end"

A line handle names the same points: line:start() or line:endpoint("end").

Selecting a rectangle corner​

A rect is four separate lines, so a corner is a line endpoint. Lines run counterclockwise from the (x, y) origin corner — bottom, right, top, left — and each corner is the start of that side:

local sides = bearcad.rect{ width = 80, height = 50 }
bearcad.select(sides[3]:start())  -- the third corner (top-right)

Selecting a circle's center​

kind = "circle" alone selects the whole circle. Pass point = true for its center:

bearcad.select{ kind = "circle", index = 0, point = true }

Selecting a text's anchor​

A sketch text has nine anchor points — box corners, edge midpoints, center. Pass anchor to select one (without it, sketch_text selects the whole text):

bearcad.select{ kind = "sketch_text", index = 0, anchor = "center" }  -- or "top_left", …
bearcad.constrain("coincident",
  { kind = "sketch_text", index = 0, anchor = "center" },
  { kind = "line", index = 0, endpoint = "start" })

Constraining an anchor translates the whole text to satisfy it; rotation and size never change.

Selecting an image's box point, edge, or calibration point​

A tracing image on the sketch's plane has nine box points (corners, edge midpoints, centre), four edges, and two calibration points. Constraining a box or calibration point translates the whole image (scale never changes); an edge is a fixed reference that sketch geometry constrains onto:

bearcad.select{ kind = "image", index = 0, anchor = "center" }   -- or "bottom_left", …
bearcad.select{ kind = "image", index = 0, edge = "left" }       -- or "right"/"top"/"bottom"
bearcad.select{ kind = "image", index = 0, point = 0 }           -- calibration 0 or 1
bearcad.constrain("coincident",
  { kind = "image", index = 0, anchor = "center" },
  { kind = "origin" })

Selecting a face's own vertex or edge​

While a sketch is open directly on a body's face (an extrusion cap or side wall), that face's boundary loop is selectable, so the sketch can be constrained against the face it's drawn on:

bearcad.select{
    kind = "face",
    face = { kind = "extrude_cap", extrusion = 0, profile = "polygon", profile_lines = sides, top = true },
    index = 2,
}

face takes the same table shape as bearcad.begin_sketch; index numbers the boundary loop. This selects the vertex; add edge = true for the edge from that corner to the next:

bearcad.select{
    kind = "face",
    face = { kind = "extrude_side", extrusion = 0, profile = "polygon", profile_lines = sides, edge = 0 },
    index = 0,
    edge = true,
}

Both are fixed by the body's geometry — not draggable — but plug into Coincident, Midpoint, and distance constraints like any sketch point/line. Only the sketch's own face is pickable; imported STL/STEP bodies have no analytic boundary to reference.

Selecting the origin and its axes​

Constrain a point onto an axis (pins that coordinate to 0) or onto the origin:

local a = bearcad.line{ x = 5, y = 5, x1 = 12, y1 = 8 }
bearcad.constrain("coincident", a:start(), { kind = "axis", axis = "x" })
bearcad.constrain("coincident", a:endpoint("end"), { kind = "origin" })

A dimension from the origin to a circle's centre (how far a hole sits from a circular face's centre) is the same { kind = "origin" } table:

bearcad.dimension{ kind = "point_point",
                   anchor = { kind = "origin" },
                   mover  = { kind = "circle", index = 0 },
                   value = "12mm" }

Interactively, dragging a point near an axis or the origin snaps it on and adds the same constraint.

Making two lines collinear​

bearcad.constrain("coincident",
  { kind = "line", index = 0 }, { kind = "line", index = 1 })

Additive selection​

Pass true as the second argument to add to the current selection instead of replacing it:

bearcad.select({ kind = "line", index = 1 }, true)

Worked example: closing a polygon loop purely from a script​

bearcad.new()
local a = bearcad.line{ x = 0, y = 0, x1 = 10, y1 = 0, name = "a" }
local b = bearcad.line{ x = 20, y = 0, x1 = 30, y1 = 0, name = "b" }
bearcad.constrain("coincident", a:endpoint("end"), b:start())

Combine with bearcad.extrude{ profiles = {a, b, c} } to build and extrude an arbitrary closed profile without any GUI interaction.