OneCAD-Draft/INTEGRATION_GAPS.md

acadrust Integration Gaps

Missing or incomplete integrations between acadrust entity definitions and H7CAD rendering/interaction systems. Ordered by priority within each category.

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Entity Field Gaps (acadrust fields ignored in tessellation)

High Impact

Entity	Ignored Field(s)	Effect
INSERT	column_count, row_count, column_spacing, row_spacing	MINSERT array inserts not expanded — only one copy rendered
LWPolyline	constant_width, vertex start_width / end_width	Polylines always render at zero width; thick/tapered strokes lost
Polyline (legacy)	Vertex2D.start_width / end_width	Same as above for old-format polylines

Medium Impact

Entity	Ignored Field(s)	Effect
Dimension	DIMSCALE, DIMASZ, DIMEXO, DIMEXE (from dimstyle)	Arrow size hardcoded to 0.12; extension line offsets fixed regardless of style
Spline	weights (rational NURBS control point weights)	Circles/conics stored as NURBS lose curvature precision; treated as uniform B-spline
Spline	flags.closed / flags.periodic	Closed splines may have a gap or C1 discontinuity at the join
Text / MText	normal extrusion XY	Entities on tilted planes render flat in XY (rare in 2D drawings)
Hatch	BoundaryEdge::Spline tessellation	Spline boundary edges plotted point-to-point instead of smooth B-spline curve — boundary appears angular
MultiLeader	MultiLeaderPathType::Spline	Spline-type leader lines rendered as straight segments instead of smooth curves
RasterImage	clip_boundary (polygonal/rectangular)	Clip boundary read but not applied — image renders full rectangle regardless of clip region

Low Impact

Entity	Ignored Field(s)	Effect
Arc / Circle / Line / Polyline	thickness	No 3D extrusion along Z; invisible in pure 2D views
LWPolyline	plinegen flag	Linetype pattern resets at each vertex instead of continuing

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Entity Type Gaps (entire types with missing subsystems)

Renders Nothing / Placeholder Only

Entity	Status
Face3D	No tessellation — renders as small cross only; no snap, grip, or properties
OLE2Frame	Bounding box + X mark only; no interactivity

Wire Fallback Only (no full mesh)

Entity	Missing
Solid3D / Region / Body	Only ACIS wire fallback; no grip, no properties panel

Partial Render

Entity	Missing
Viewport (paper space)	Only frame rendered; interior model-space view not composited

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Systemic Gap — OCS→WCS Transform

17 entity types carry a normal extrusion vector defining their Object Coordinate System but none apply the arbitrary-axis OCS→WCS transform during tessellation. When normal ≠ (0, 0, 1) the entity is incorrectly rendered flat in the XY plane.

Affected entities: Arc, Circle, Ellipse, Point, Line, Spline, LwPolyline, Polyline, AttributeDefinition, AttributeEntity, Dimension, Hatch, MLine, Leader, Insert, Shape

Only mitigation today: Arc checks normal.z < 0 to reverse sweep direction — not a real OCS transform.

Impact: Low for typical 2D plan files (nearly all normals are (0,0,1)); high for 3D DXF files with entities on non-horizontal planes.

The DXF arbitrary-axis algorithm:

if |Wx| < 1/64 and |Wy| < 1/64:
    Ax = (0,0,1) × N   (Y-world cross N)
else:
    Ax = (0,1,0) × N   (X-world cross N)
Ax = normalize(Ax)
Ay = N × Ax

Then transform each OCS point: WCS = origin + x*Ax + y*Ay + z*N

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Render Style Gaps (color, linetype, lineweight resolution)

High Impact

Gap	Effect	Location
ByBlock color not resolved through INSERT chain	ByBlock entities render white instead of inheriting INSERT's color	render.rs::render_style_for()
ByBlock linetype not resolved through INSERT chain	ByBlock entities use default linetype instead of INSERT's linetype	render.rs::render_style_for()

Medium Impact

Gap	Effect	Location
ByBlock lineweight resolved from layer instead of INSERT entity	Block children with ByBlock weight don't inherit INSERT's line weight	render.rs lines 213-228

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Text & Style Gaps

Medium Impact

Gap	Effect	Location
TextStyle is_backward flag ignored	Text with backward flag renders left-to-right instead of mirrored	src/entities/text_support.rs::resolve_text_style()
TextStyle is_upside_down flag ignored	Text with upside-down flag renders normally instead of flipped vertically	src/entities/text_support.rs::resolve_text_style()

Low-Medium Impact

Gap	Effect	Location
Complex linetype text shapes not rendered	Linetypes with embedded text elements (e.g. GAS_LINE with "GAS" text) show only geometry gaps	src/scene/complex_lt.rs

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Polyline3D Vertex Type Gap

acadrust Vertex3D carries VertexFlags (SPLINE_VERTEX, SPLINE_CONTROL) but tessellate_polyline3d() ignores them entirely — all vertices treated as plain points regardless of spline flag.

Effect: Polyline3D entities with spline fitting render as straight segments instead of smooth curves.
Location: src/entities/polyline.rs::tessellate_polyline3d()
Impact: Medium.

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Snap Point Gaps

Critical / High

Entity	Missing Snap	Effect	Location
INSERT	Insertion snap point entirely absent	Cannot snap to block reference insertion point with OSNAP Insertion	src/entities/insert.rs — no snap_pts in TruckEntity
INSERT	Nested entity snap points not traversed	Cannot snap to geometry inside a block without exploding it	src/snap/mod.rs — only top-level wire snap_pts checked
Hatch	All snap points empty	Cannot snap to hatch boundary vertices/arcs with Endpoint or Midpoint	src/scene/tessellate.rs:558 — returns snap_pts: vec![]

Medium

Entity	Missing Snap	Effect	Location
Dimension	No snap hints on geometry	Cannot snap to dimension defpoints, line endpoints	src/scene/tessellate.rs:247 — snap_pts: vec![]
Spline	Fit/control points not in snap_pts	Cannot snap to spline construction points	src/entities/spline.rs:42
MultiLeader	Vertices not in snap_pts	Cannot snap to leader line endpoints	src/entities/multileader.rs:116
MLine	Vertices not in snap_pts	Cannot snap to multiline segment endpoints	src/entities/mline.rs:97

Low

Entity	Missing Snap	Effect	Location
Ellipse (partial arc)	Endpoints not in pre-baked snap_pts	Arc endpoints emitted only as Center; functional via wire tessellation but semantically wrong	src/entities/ellipse.rs:108
Hatch	Elevation Z ignored	Snap Z is always 0 instead of hatch.elevation	src/scene/tessellate.rs:564 — hardcoded 0.0

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Grip Gaps

Entity	Missing Grip	Effect	Location
LWPolyline	Midpoint grips between vertices (arc segment handles)	Cannot drag a segment midpoint to adjust arc bulge	src/entities/lwpolyline.rs

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Text Rendering Gaps

Gap	Effect	Location
TextStyle is_backward flag not applied	Text with backward flag renders left-to-right	src/entities/text_support.rs::resolve_text_style()
TextStyle is_upside_down flag not applied	Text with upside-down flag renders normally	src/entities/text_support.rs::resolve_text_style()
Unicode characters not in CXF fonts silently dropped	Non-ASCII characters render as blank gaps with no warning	src/scene/cxf.rs:174

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DXF Reader Unit Gaps (acadrust bugs we work around)

These are fixed in our post-load fix_dxf_dimension_rotations() in src/io/mod.rs, documented here for reference.

Entity	Field	DXF Code	Bug	Fix Location
Dimension (Linear)	rotation	50	Stored in degrees, used as radians	io/mod.rs::fix_dxf_dimension_rotations()
Dimension (all)	text_rotation	53	Code 53 never parsed; always 0	tessellate.rs::dimension_text_natural_rotation()
AttributeEntity	rotation	50	No .to_radians() in reader	Needs fixup (not yet applied)
AttributeDefinition	rotation	50	No .to_radians() in reader	Needs fixup (not yet applied)
Shape	rotation	50	No .to_radians() in reader	Shape not currently rendered — low priority

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Coverage Summary

Subsystem	Coverage
Tessellation	34/41 entity types fully, 4 legacy fallback, 3 missing
Snap points	36/41 (Face3D, Solid3D, Region, Body, OLE2Frame missing)
Grip points	36/41 (same 5 missing)
Properties panel	36/41 (same 5 missing)
Hit testing	41/41 (all via fallback)