Sketches

Sketches are 2D profiles you can later extrude or revolve into 3D solids. CodeCAD’s sketch helpers operate on fixed planes for simplicity:

• poly_xy and rect create profiles on the XY plane (Z = 0).
• profile_xz creates profiles on the XZ plane (Y = 0), which is convenient for revolved parts.

Use sketches to describe outlines, ribs, grooves, and lathe-like shapes in a compact, parametric way.

Tip

A closed profile (a loop) can form a face and be extruded into a solid. An open profile is usually for revolve (e.g., a lathe path) or remains an edge curve.

poly_xy(pts)

Builds a planar polygonal face on the XY plane from a list of points. The polygon is closed by default.

--- pts: array of 2D points on XY.
--- You can pass {x=..., y=...} or tuple-like {x, y}.
local s = poly_xy({
{0, 0},
{40, 0},
{30, 20},
{10, 25},
{0, 10},
})

Parameters

• pts: Points must define a non-self-intersecting loop in either clockwise or counter-clockwise order.
• Returns: Shape — a planar face on Z = 0.

Why use it?

Great for arbitrary brackets, gussets, and plates that you’ll later extrude.

Example: Extrude a 2D plate

local plate = extrude(
    poly_xy({
        { -30, 0 },
        { 30,  0 },
        { 0,   30 },
    }),
    5
)
plate = scale(plate, 0.5)
emit(plate)

profile_xz(pts, closed?)

Builds a polyline on the XZ plane (Y = 0). By default it is open. Set closed=true to close it into a loop (forming a face on XZ).

--- pts: array of {x,z} or tuple-like {x, z}
--- closed: optional boolean, default false
local p = profile_xz({
{0, 0},
{10, 0},
{10, 20},
{5, 25},
})

Parameters

• pts: ({[1]:number,[2]:number}|{x:number,z:number})[]
• closed?: boolean (default false)
• Returns Shape — an edge (open) or a planar face (if closed=true) on Y = 0.

Common use: revolve about Z-axis Supply an open profile that describes the radius vs. height, then revolve it around the Z-axis.

Example

-- Bottle-like shape by revolving an open XZ profile around Z.
-- X is radius, Z is height. Start at the axis (x=0) for a sealed top/bottom.
local outline = profile_xz({
    { 0,  0 }, -- on axis
    { 25, 0 }, -- outer radius at base
    { 28, 5 },
    { 30, 15 },
    { 20, 3 },
    { 18, 50 },
    { 10, 60 },
    { 0,  70 },
}, true)

local body = revolve(outline, 360)
body = scale(body, 0.2)
emit(body)

Note

If you need a capped revolved solid but your curve does not touch the axis, add points that go to x=0 at the ends (i.e., meet the Z-axis) or pass closed=true to make a face first and revolve that.

rect(w, h)

Draws an axis-aligned rectangle on the XY plane with its lower-left corner at (0,0).

local r = rect(40, 20) -- width=40, height=20

Parameters

• w: number — width along +X
• h: number — height along +Y
• Returns Shape — a rectangular face on Z = 0.

Point Formats

You can mix either style within one call:

• Tuple-like: {x, y} or {x, z}
• Named fields: {x=..., y=...} or {x=..., z=...}

local s = poly_xy({
{0,0}, {50,0}, {x=50,y=30}, {x=0,y=30}
})

Practical Patterns

• Holes in plates: Create outer face with poly_xy, extrude, then difference a cylinder or another poly_xy/extrude for cutouts.
• Lathe parts: Draft an open profile_xz where x is radius and revolve.
• Parametric design: Store dimensions in variables and compute points; small math changes reshape the whole model.

Gotchas & Tips

• Winding / self-intersections: Ensure polygon points don’t cross; ambiguous loops cannot form faces.
• Planarity: Sketch helpers lock you to XY or XZ; for other orientations, sketch first then rotate_* or translate.
• Closing profiles for revolve: An open profile_xz that touches the Z-axis at its ends produces a sealed revolve. Otherwise, add axis-touching points or use closed=true before revolve.

With these three tools - poly_xy, profile_xz, and rect - you can author most 2D outlines needed for mechanical parts, then lift them into 3D using extrude or revolve.