# CollisionTraverser¶

class CollisionTraverser

Bases: Namable

This class manages the traversal through the scene graph to detect collisions. It holds ownership of a number of collider objects, each of which is a CollisionNode and an associated CollisionHandler.

When traverse() is called, it begins at the indicated root and detects all collisions with any of its collider objects against nodes at or below the indicated root, calling the appropriate CollisionHandler for each detected collision.

Inheritance diagram

explicit CollisionTraverser(std::string const &name = "ctrav")
CollisionTraverser(CollisionTraverser const&) = default
void add_collider(NodePath const &collider, CollisionHandler *handler)

Adds a new CollisionNode, representing an object that will be tested for collisions into other objects, along with the handler that will serve each detected collision. Each CollisionNode may be served by only one handler at a time, but a given handler may serve many CollisionNodes.

The handler that serves a particular node may be changed from time to time by calling add_collider() again on the same node.

void clear_colliders(void)

Completely empties the set of collision nodes and their associated handlers.

void clear_recorder(void)

Removes the CollisionRecorder from the traverser and restores normal low- overhead operation.

static TypeHandle get_class_type(void)
NodePath get_collider(int n) const

Returns the nth CollisionNode that has been added to the traverser via add_collider().

CollisionHandler *get_handler(NodePath const &collider) const

Returns the handler that is currently assigned to serve the indicated collision node, or NULL if the node is not on the traverser’s set of active nodes.

int get_num_colliders(void) const

Returns the number of CollisionNodes that have been added to the traverser via add_collider().

CollisionRecorder *get_recorder(void) const

Returns the CollisionRecorder currently assigned, or NULL if no recorder is assigned.

bool get_respect_prev_transform(void) const

Returns the flag that indicates whether the prev_transform stored on a node is respected to calculate collisions. See set_respect_prev_transform().

bool has_collider(NodePath const &collider) const

Returns true if the indicated node is current in the set of nodes that will be tested each frame for collisions into other objects.

bool has_recorder(void) const

Returns true if the CollisionTraverser has a CollisionRecorder object currently assigned, false otherwise.

void hide_collisions(void)

Undoes the effect of a previous call to show_collisions().

void output(std::ostream &out) const
bool remove_collider(NodePath const &collider)

Removes the collider (and its associated handler) from the set of CollisionNodes that will be tested each frame for collisions into other objects. Returns true if the definition was found and removed, false if it wasn’t present to begin with.

void set_recorder(CollisionRecorder *recorder)

Uses the indicated CollisionRecorder object to start recording the intersection tests made by each subsequent call to traverse() on this object. A particular CollisionRecorder object can only record one traverser at a time; if this object has already been assigned to another traverser, that assignment is broken.

This is intended to be used in a debugging mode to try to determine what work is being performed by the collision traversal. Usually, attaching a recorder will impose significant runtime overhead.

This does not transfer ownership of the CollisionRecorder pointer; maintenance of that remains the caller’s responsibility. If the CollisionRecorder is destructed, it will cleanly remove itself from the traverser.

void set_respect_prev_transform(bool flag)

Sets the flag that indicates whether the prev_transform stored on a node (as updated via set_fluid_pos(), etc.) is respected to calculate collisions. If this is true, certain types of collision tests will be enhanced by the information about objects in motion. If this is false, objects are always considered to be static. The default is false.

CollisionVisualizer *show_collisions(NodePath const &root)

This is a high-level function to create a CollisionVisualizer object to render the collision tests performed by this traverser. The supplied root should be any node in the scene graph; typically, the top node (e.g. render). The CollisionVisualizer will be attached to this node.

void traverse(NodePath const &root)

Perform the traversal. Begins at the indicated root and detects all collisions with any of its collider objects against nodes at or below the indicated root, calling the appropriate CollisionHandler for each detected collision.

void write(std::ostream &out, int indent_level) const