Entities and Transformations

An Entity has a name, a group, a reference shape, a position, an orientation, and a selector (location, index). The Mobile class is a specialized Entity used for objects that change position frequently (e.g., robots).

Two Shape Representations

The reference shape describes the object in its local coordinate system. The projected shape represents this shape after rotation and translation in the world. Pose transformations rebuild the projection from the reference.

import math
from tiledland import Entity, Convex, Point

objet = Entity(shape=Convex().initSquare(0.8), name="Caisse")
objet.setPose(Point(2.0, 1.0), math.pi / 2)
assert objet.position().asTuple() == (2.0, 1.0)
objet.translate(Point(1.0, 0.0))
assert objet.position().asTuple() == (3.0, 1.0)

Angles are expressed in radians. setOrientation(angle) replaces the orientation; rotate(angle) adds a rotation. setPosition(x, y) replaces the position; translate(vecteur) adds a displacement.

Identity and Ownership

name() is a label. group() is a numerical category. location() indicates the tile and index() the position of the object in its collection; objects added to the tabletop receive indices starting from 1.

These indices can change when an entity is removed. Re-read selector() after a movement instead of keeping an old index.

Copying and Modifying a Shape

copy() creates a new entity with its own position and projection, but notably shares the reference shape and the brush. This is not a deep copy of all attributes. Avoid modifying a shared reference; assign a new shape to the copy:

from tiledland import Entity, Convex

original = Entity(name="Original")
copie = original.copy()
copie.setReferenceShape(Convex().initSquare(0.4))
copie.setCoordinates(2.0, 0.0)
assert original.position().asTuple() == (0.0, 0.0)

For an arrow, use setReferenceShape(Convex().initArrowTip(...)). The setShapeArrowTip() method is currently defective. setProjectedShape() also has a problem when a previous orientation is non-zero: see the limits.