klampt.model.collide module

Functions and classes for managing collision tests between multiple objects.

This module defines the WorldCollider class, which makes it easy to ignore various collision pairs in a WorldModel.

For groups of objects, the self_collision_iter() and group_collision_iter() functions perform broad-phase collision detection to speed up collision testing.

The ray_cast() function is a convenient way to return the first point of intersection for a ray and a group of objects.

Functions:

bb_create(*ptlist)

Creates a bounding box from an optional set of points.

bb_empty(bb)

Returns True if the bounding box is empty

bb_intersect(a, b)

Returns true if the bounding boxes (a[0]->a[1]) and (b[0]->b[1]) intersect

bb_contains(bb, x)

Returns true if x is inside the bounding box bb

bb_intersection(*bbs)

Returns the bounding box representing the intersection the given bboxes.

bb_union(*bbs)

Returns the smallest bounding box containing the given bboxes

self_collision_iter(geomlist[, pairs])

Performs efficient self collision testing for a list of geometries.

group_collision_iter(geomlist1, geomlist2[, ...])

Tests whether two sets of geometries collide.

group_subset_collision_iter(geomlist, alist, ...)

Tests whether two subsets of geometries collide.

ray_cast(geomlist, s, d)

Finds the first collision among the geometries in geomlist with the ray at source s and direction d.

Classes:

WorldCollider(world[, ignore])

Used in planning routines to mask out objects in the world to check / ignore when doing collision detection.
klampt.model.collide.bb_create(*ptlist)[source]

Creates a bounding box from an optional set of points. If no points are provided, creates an empty bounding box.

Return type:

Tuple[Sequence[float], Sequence[float]]

klampt.model.collide.bb_empty(bb)[source]

Returns True if the bounding box is empty

Return type:

bool

klampt.model.collide.bb_intersect(a, b)[source]

Returns true if the bounding boxes (a[0]->a[1]) and (b[0]->b[1]) intersect

Return type:

bool

klampt.model.collide.bb_contains(bb, x)[source]

Returns true if x is inside the bounding box bb

Return type:

bool

klampt.model.collide.bb_intersection(*bbs)[source]

Returns the bounding box representing the intersection the given bboxes. The result may be empty.

klampt.model.collide.bb_union(*bbs)[source]

Returns the smallest bounding box containing the given bboxes

klampt.model.collide.self_collision_iter(geomlist, pairs='all')[source]

Performs efficient self collision testing for a list of geometries.

Return type:

Iterator[Tuple[int, int]]

Parameters:

  • geomlist (list of Geometry3D) – the list of geometries

  • pairs –

    can be:

    • ’all’: all pairs are tested.

    • a function test(i,j) -> bool taking geometry indices and returning true if they should be tested

    • list of pairs (i,j) of collision indices.

Uses a quick bounding box reject test.

Returns:

Iterator over colliding pairs (i,j) where i and j are indices into geomlist.

klampt.model.collide.group_collision_iter(geomlist1, geomlist2, pairs='all')[source]

Tests whether two sets of geometries collide.

Return type:

Iterator[Tuple[int, int]]

Parameters:

  • geomlist1 (list of Geometry3D) – set 1

  • geomlist2 (list of Geometry3D) – set 2

  • pairs –

    can be:

    • ’all’: all pairs are tested.

    • a function test(i,j) -> bool, taking geomlist1 index i and geomlist2 index j, and returning true if they should be tested

    • list of pairs (i,j) of collision indices.

Uses a quick bounding box reject test.

Returns:

Iterator over colliding pairs (i,j) where i is an index into geomlist1 and j is an index into geomlist.

klampt.model.collide.group_subset_collision_iter(geomlist, alist, blist, pairs='all')[source]

Tests whether two subsets of geometries collide. Can be slightly faster than group_collision_iter if alist and blist overlap.

Return type:

Iterator[Tuple[int, int]]

Parameters:

  • geomlist (list of Geometry3D) – a list of all possible geometries

  • alist (list of int) – collision set 1, containing indices into geomlist

  • blist (list of int) – collision set 2, containing indices into geomlist

  • pairs –

    can be:

    • ’all’: all pairs are tested.

    • a function test(i,j) -> bool, taking geomlist1 index i and geomlist2 index j, and returning true if they should be tested

    • list of pairs (i,j) of collision indices. In this case, alist and blist are ignored and can be set to None.

Uses a quick bounding box reject test.

Returns:

Iterator over colliding pairs (i,j) where i is an index into alist and j is an index into glist.

klampt.model.collide.ray_cast(geomlist, s, d)[source]

Finds the first collision among the geometries in geomlist with the ray at source s and direction d.

Return type:

Tuple[int, Sequence[float]]

Returns:

  • index is the index of the geometry in geomlist

  • point is the collision point in world coordinates.

Returns None if no collision is found.

Return type:

A pair (index,point) if a collision is found, where

class klampt.model.collide.WorldCollider(world, ignore=[])[source]

Bases: object

Used in planning routines to mask out objects in the world to check / ignore when doing collision detection.

You should not need to interact directly with this object’s attributes. Instead, use the methods provided.

geomList

a list of (object,geom) pairs for all non-empty objects in the world.

Type:

list

mask

indicating which items are activated for collision detection. Basically, a sparse, symmetric boolean matrix over len(geomList)*len(geomList) possible collision pairs.

Type:

list of sets of ints

terrains

contains the geomList indices of each terrain in the world.

Type:

list of ints

rigidObjects

contains the geomList indices of each object in the world

Type:

list of ints

robots

contains the geomList indices of each robot in the world.

Type:

list of list of ints

Args: world (WorldModel): the world to use ignore (list, optional): a list of items to pass to ignoreCollision

Methods:

ignoreCollision(ign)

Permanently removes an object or a pair of objects from consideration.

isCollisionEnabled(obj_or_pair)

Returns true if the object or pair of objects are considered for collision.

collisionTests([filter1, filter2, bb_reject])

Returns an iterator over potential colliding pairs, which should be tested for collisions.

collisions([filter1, filter2])

Returns an iterator over the colliding pairs of objects, optionally that satisfies the filter(s).

robotSelfCollisions([robot])

Yields an iterator over robot self collisions.

robotObjectCollisions(robot[, object])

Yields an iterator over robot-object collision pairs.

robotTerrainCollisions(robot[, terrain])

Yields an iterator over robot-terrain collision pairs.

objectTerrainCollisions(object[, terrain])

Yields an iterator over object-terrain collision pairs.

objectObjectCollisions(object, object2)

Yields an iterator over object-terrain collision pairs.

rayCast(s, d[, indices])

Finds the first collision between a ray and objects in the world.

rayCastRobot(robot, s, d)

Finds the first collision between a ray and a robot.
ignoreCollision(ign)[source]

Permanently removes an object or a pair of objects from consideration.

Return type:

None

Parameters:

ign – either a single body (RobotModelLink, RigidObjectModel, TerrainModel) in the world, or a pair of bodies. In the former case all collisions with that body will be ignored.

isCollisionEnabled(obj_or_pair)[source]

Returns true if the object or pair of objects are considered for collision.

Return type:

bool

Parameters:

obj_or_pair – either a single body (RobotModelLink, RigidObjectModel, TerrainModel) in the world, or a pair of bodies. In the former case, True is returned if the body is checked with anything.

collisionTests(filter1=None, filter2=None, bb_reject=True)[source]

Returns an iterator over potential colliding pairs, which should be tested for collisions.

Return type:

Iterator[Tuple[Tuple[Union[RobotModelLink, RigidObjectModel, TerrainModel], Geometry3D], Tuple[Union[RobotModelLink, RigidObjectModel, TerrainModel], Geometry3D]]]

Usage:

To test collisions, you call:

for i,j in worldCollider.collisionTests():
    if i[1].collides(j[1]):
        print("Object",i[0].getName(),"collides with",j[0].getName())

(Note that for this purpose is easier to just call collisions(); however you may want to use collisionTests to perform other queries like proximity detection.)

Parameters:

  • filter1 (function, optional) – has form f(object) -> bool

  • filter2 (function, optional) – has form f(object) -> bool

  • bb_reject (bool, optional) – True if we should quick reject objects whose bounding boxes are not overlapping (broad phase collision detection). If false, all non-ignored collision pairs are returned.

See collisions() for an explanation of how filter1 and filter2 are interpreted

Returns:

Iterates over ((object1,geom1),(object2,geom2)) pairs indicating which objects should be tested for collision. They have type:

  • object1, object2: a RobotModelLink, RigidObjectModel, or

    TerrainModel

  • geom1, geom2: Geometry3D corresponding to those objects.

collisions(filter1=None, filter2=None)[source]

Returns an iterator over the colliding pairs of objects, optionally that satisfies the filter(s).

Return type:

Iterator[Tuple[Tuple[Union[RobotModelLink, RigidObjectModel, TerrainModel], Geometry3D], Tuple[Union[RobotModelLink, RigidObjectModel, TerrainModel], Geometry3D]]]

Parameters:

  • filter1 (function, optional) – has form f(object) -> bool

  • filter2 (function, optional) – has form f(object) -> bool

filter1 and filter2 are predicates to allow subsets of objects to collide. The argument can be a RobotModelLink, RigidObjectModel or TerrainModel.

If neither filter1 nor filter2 are provided, then all pairs are checked.

If filter1 is provided but filter2 is not, then objects in the set filter1 will be collided against each other.

If filter1 and filter2 are provided, then objects that satisfy filter1 will be collided against objects that satisfy filter2. (Note: in this case there is no checking of duplicates, i.e., the sets should be disjoint to avoid duplicating work).

robotSelfCollisions(robot=None)[source]

Yields an iterator over robot self collisions.

Return type:

Iterator[Tuple[RobotModelLink, RobotModelLink]]

Parameters:

  • robot (RobotModel or int, optional) – If None (default), all

  • only (robots are tested. If an index or a RobotModel object) –

  • tested (collisions for that robot are) –

Returns:

Iterates over colliding (RobotModelLink,RobotModelLink) pairs.

robotObjectCollisions(robot, object=None)[source]

Yields an iterator over robot-object collision pairs.

Return type:

Iterator[Tuple[RobotModelLink, RigidObjectModel]]

Parameters:

  • robot (RobotModel or int) – the robot to test

  • object (RigidObjectModel or int, optional) – the object to test, or None to all objects.

Returns:

Iterates over colliding (RobotModelLink,RigidObjectModel) pairs.

robotTerrainCollisions(robot, terrain=None)[source]

Yields an iterator over robot-terrain collision pairs.

Return type:

Iterator[Tuple[RobotModelLink, TerrainModel]]

Parameters:

  • robot (RobotModel or int) – the robot to test

  • terrain (TerrainModel or int, optional) – the terrain to test, or None to all terrains.

Returns:

Iterates over colliding (RobotModelLink,TerrainModel) pairs.

objectTerrainCollisions(object, terrain=None)[source]

Yields an iterator over object-terrain collision pairs.

Return type:

Iterator[Tuple[RigidObjectModel, TerrainModel]]

Parameters:

  • object (RigidObjectModel or int) – the object to test

  • terrain (TerrainModel or int, optional) – the terrain to test, or None to all terrains.

Returns:

Iterates over colliding (RigidObjectModel,TerrainModel) pairs.

objectObjectCollisions(object, object2)[source]

Yields an iterator over object-terrain collision pairs.

Return type:

Iterator[Tuple[RigidObjectModel, RigidObjectModel]]

Parameters:
Returns:

Iterates over colliding (RigidObjectModel,TerrainModel) pairs.

rayCast(s, d, indices=None)[source]

Finds the first collision between a ray and objects in the world.

Return type:

Optional[Tuple[Union[RobotModelLink, RigidObjectModel, TerrainModel], Sequence[float]]]

Parameters:

  • s (list of 3 floats) – the ray source

  • d (list of 3 floats) – the ray direction

  • indices (list of ints, optional) – if given, the indices of geometries in geomList to test.

Returns:

The (object,point) pair or None if no collision is found.

rayCastRobot(robot, s, d)[source]

Finds the first collision between a ray and a robot.

Return type:

Optional[Tuple[RobotModelLink, Sequence[float]]]

Parameters:

  • robot (RobotModel or int) – the robot

  • s (list of 3 floats) – the ray source

  • d (list of 3 floats) – the ray direction

Returns:

The (object,point) pair or None if no collision is found.