Status: pre-alpha. Based on OpenSCAD cheatsheet v2021.01.

Missing primitives

• [x] text(text, size, font, direction, language, script, halign, valign, spacing) — 2D text generation (v1: direction/language/script not implemented)
• [x] surface(file, center, invert, convexity) — heightmap from DAT/PNG files
  • [x] Basic implementation: PNG (grayscale) + DAT, planar merge, UnifySameDomain
  • [x] center — center on XY (via bbox translation in scl.py)
  • [x] Closed solid body: bottom face at z = min(data) - 1, vertical side walls, Sewing → MakeSolid → OrientClosedSolid
  • [x] PNG luminance formula — OpenSCAD linear sRGB: Y = 0.2126R + 0.7152G + 0.0722B

Missing transformations

• [x] resize(newsize, auto, convexity) — scale to absolute dimensions
• [x] multmatrix(m) — arbitrary 4×4 affine matrix (shear, skew)

Missing linear_extrude parameters

• [x] center — center on Z axis
• [x] slices — segment count for twist (accepted, ignored for OCCT)
• [x] scale — scale along height (tapered extrusion)

Missing import() parameters

• [x] center — center imported geometry

Missing control flow / list comprehension features

• [x] intersection_for(i = ...) { ... } — loop with intersection of results
• [x] each in list comprehensions — unwrap inner list: [for (a = list) each a]
• [x] C-style for in list comprehensions — [for (a=0,b=1; a<10; a=a+1) expr]
• [x] Multi-generator list comprehensions — [for (a = list1), for (b = list2) expr]

Missing functions

• [x] search(match_value, string_or_vector, num_returns_per_match, index_col_num) — search in strings/lists/tables
• [x] lookup(key, key_value_pairs) — linear interpolation lookup table
• [x] parent_module(n) — name of module n levels up in instantiation stack

Missing special variables

• [ ] $vpr — viewport rotation
• [ ] $vpt — viewport translation
• [ ] $vpd — viewport camera distance
• [ ] $vpf — viewport field of view
• [x] $parent_modules — number of modules in instantiation stack

Missing animation

• [ ] $t special variable (0..1) — animation time parameter, set by GUI
• [ ] Animation controls (play/pause, FPS, frame count) — re-renders scene with $t advancing from 0 to 1
• [ ] $vpr/$vpt/$vpd/$vpf — viewport variables usable in animation context

$fn polygon threshold (bcad-specific)

$fn in OpenSCAD has dual meaning: small values (3-12) specify polygon geometry (hexagonal prisms, etc.), while large values (20, 32, 100) specify rendering quality (smoothness). bcad resolves this ambiguity with a configurable threshold (Preferences > General):

• $fn <= threshold → polygon (hexagon, octagon, etc.)
• $fn > threshold → ideal geometry (smooth circle/cylinder)
• $fn == 0 → always ideal geometry

Default threshold: 12. Applied in cylinder(), circle(), and rotate_extrude() context methods.

rotate_extrude with $fn <= threshold creates a polygonal revolution path (N flat segments) via ThruSections(ruled=True), matching OpenSCAD behavior. Segment count uses OpenSCAD formula: ceil(max($fn, 3)) * abs(angle) / 360.