simvx.core.physics.shapes2d

Role

The 2D sibling of :mod:~simvx.core.physics.shapes. A Shape2D is a plain collision-geometry resource (a value), not a scene node. It is held by a

class:

~simvx.core.physics.nodes2d.CollisionShape2D node (via a Property) or set directly on a body as a convenience collider. A body never branches on shape kind: it calls shape.build(world) and each subclass dispatches to the 2D seam’s matching world.create_* factory, keeping body nodes open/closed over new shape kinds.

Mirrors shapes.py (naming/structure/validation), carrying Vec2 geometry and 2D-only kinds (segment, convex/concave polygon). RectangleShape2D uses the design’s node name but dispatches to the seam’s create_box factory.

These resources are NOT exported via any facade this stage (parity with the 3D shapes.py); tests import them via this module path. The facade flip is a later stage.

Shape resources for the 2D physics seam (Stage T2f).

Module Contents

Classes

Shape2D	Abstract 2D collision-geometry resource.
CircleShape2D	A circle collision shape of a given radius (2D sibling of SphereShape3D).
RectangleShape2D	An axis-aligned (body-local) box collision shape centred at the origin.
CapsuleShape2D	A Y-axis capsule collision shape (a segment swept by a circle).
SegmentShape2D	A thick line-segment collision shape (2D-only, no 3D equivalent).
ConvexPolygonShape2D	A convex polygon collision shape from counter-clockwise points.
ConcavePolygonShape2D	A STATIC edge-soup collision shape (2D analogue of ConcaveMeshShape3D).

Data

__all__

API

simvx.core.physics.shapes2d.__all__

[‘Shape2D’, ‘CircleShape2D’, ‘RectangleShape2D’, ‘CapsuleShape2D’, ‘SegmentShape2D’, ‘ConvexPolygonS…

class simvx.core.physics.shapes2d.Shape2D

Bases: abc.ABC

Abstract 2D collision-geometry resource.

A Shape2D knows how to turn itself into an opaque seam shape handle via

Meth:

build. Bodies call shape.build(world) and never inspect the concrete kind, so adding a new shape requires no body changes.

abstractmethod build(world: simvx.core.physics.world2d.Physics2DWorld) → simvx.core.physics.world2d.ShapeHandle

Create the backend shape for this resource and return its handle.

Each subclass dispatches to the matching world.create_* factory.

Args: world: The :class:~simvx.core.physics.world2d.Physics2DWorld whose shape factory builds the opaque handle.

Returns: An opaque ShapeHandle for use with world.create_body.

__slots__

()

class simvx.core.physics.shapes2d.CircleShape2D(radius: float = 0.5)

Bases: simvx.core.physics.shapes2d.Shape2D

A circle collision shape of a given radius (2D sibling of SphereShape3D).

Args: radius: Circle radius in world units (must be > 0).

Initialization

build(world: simvx.core.physics.world2d.Physics2DWorld) → simvx.core.physics.world2d.ShapeHandle

__slots__

()

class simvx.core.physics.shapes2d.RectangleShape2D(half_extents: simvx.core.math.Vec2 | tuple[float, float] = (0.5, 0.5))

Bases: simvx.core.physics.shapes2d.Shape2D

An axis-aligned (body-local) box collision shape centred at the origin.

Named per the design node taxonomy (RectangleShape2D); the 2D seam factory is create_box, so :meth:build dispatches there.

Args: half_extents: Half-sizes along x/y. Coerced to Vec2 (float32); every component must be > 0.

Initialization

build(world: simvx.core.physics.world2d.Physics2DWorld) → simvx.core.physics.world2d.ShapeHandle

__slots__

()

class simvx.core.physics.shapes2d.CapsuleShape2D(radius: float = 0.5, height: float = 2.0)

Bases: simvx.core.physics.shapes2d.Shape2D

A Y-axis capsule collision shape (a segment swept by a circle).

height is the TOTAL extent along Y, including the two semicircular caps, so the central segment half-length is max(0.0, height / 2 - radius). When height <= 2 * radius the segment collapses to a point and the capsule degenerates to a circle of the given radius: a valid, documented case (parity with CapsuleShape3D and the segment-reduction maths in the builtin backend), NOT an error. Accordingly height >= 2 * radius is NOT validated.

Args: radius: Capsule radius in world units (must be > 0). height: Total extent along Y including both caps (must be > 0).

Initialization

build(world: simvx.core.physics.world2d.Physics2DWorld) → simvx.core.physics.world2d.ShapeHandle

__slots__

()

class simvx.core.physics.shapes2d.SegmentShape2D(a: simvx.core.math.Vec2 | tuple[float, float] = (-0.5, 0.0), b: simvx.core.math.Vec2 | tuple[float, float] = (0.5, 0.0), radius: float = 0.0)

Bases: simvx.core.physics.shapes2d.Shape2D

A thick line-segment collision shape (2D-only, no 3D equivalent).

A “beam” from a to b (body-local), useful for thin static walls / floors and one-way platforms.

Args: a: Segment start, body-local (Vec2). b: Segment end, body-local (Vec2). Must differ from a (a zero-length segment is degenerate). radius: Segment thickness radius (>= 0); 0 is an infinitely thin line.

Initialization

build(world: simvx.core.physics.world2d.Physics2DWorld) → simvx.core.physics.world2d.ShapeHandle

__slots__

()

class simvx.core.physics.shapes2d.ConvexPolygonShape2D(points: collections.abc.Sequence[simvx.core.math.Vec2 | tuple[float, float]])

Bases: simvx.core.physics.shapes2d.Shape2D

A convex polygon collision shape from counter-clockwise points.

The 2D analogue of ConvexHullShape3D. At least 3 points are required (a polygon needs a triangle). Convexity / winding is NOT re-checked at the resource layer (the backend tolerates the cloud); pass CCW points.

Args: points: Iterable of >= 3 points (Vec2 or (x, y) tuples), coerced to a single (N, 2) float32 array. Must be finite.

Initialization

build(world: simvx.core.physics.world2d.Physics2DWorld) → simvx.core.physics.world2d.ShapeHandle

__slots__

()

class simvx.core.physics.shapes2d.ConcavePolygonShape2D(segments: collections.abc.Sequence[object] | numpy.ndarray)

Bases: simvx.core.physics.shapes2d.Shape2D

A STATIC edge-soup collision shape (2D analogue of ConcaveMeshShape3D).

Holds N line segments (an [start, end] pair of Vec2 each), body-local. The 2D analogue of a static triangle mesh: STATIC-ONLY level geometry with no inertia / mass. Placing it on a non-STATIC body is an error raised at body creation (the static-only contract is enforced at the world seam, not here).

Args: segments: (N, 2, 2) float32 array (or an iterable coercible to it) of N segments, each an [start, end] pair of Vec2 points. N must be >= 1 and every coordinate finite.

Initialization

build(world: simvx.core.physics.world2d.Physics2DWorld) → simvx.core.physics.world2d.ShapeHandle

__slots__

()