Module org.dyn4j

Package org.dyn4j.collision.narrowphase

Sub package of the Collision package handling narrow-phase collision detection, distance checking, and raycasting.

Narrow-phase collision detection is used to determine if two Convex Shapes penetrate, and if so, compute the vector of minimum magnitude able to push the Convex Shapes out of penetration.

The NarrowphaseDetectors can only perform on Convex Shapes. This allows for fast and simple algorithms. Non-convex shapes can be decomposed using a Decomposer into Convex pieces which can then be tested individually.

Even though the NarrowphaseDetectors are fast, performance can be improved substantially if a BroadphaseDetector is used to eliminate obvious non-penetrating pairs.

NarrowphaseDetectors return Penetration objects representing the vector of minimum magnitude able to push the Convex Shapes out of penetration. This information is typically passed onto a ManifoldSolver to find the collision points.

There are two NarrowphaseDetector implementations provided: Sat and Gjk.

NOTE: The Sat algorithm doesn't support the Ellipse and HalfEllipse shapes.

This package also contains a FallbackNarrowphaseDetector class. This class is used to build a hierarchy of NarrowphaseDetectors that can select detection algorithms based on arbitrary conditions. For example, in the case of Ellipse and HalfEllipse, Gjk could be the fallback detector while Sat is the primary. Fallback is determined by the assigned FallbackConditions.

NOTE: The CircleDetector and SegmentDetector classes already being used in the Sat and Gjk classes so no FallbackNarrowphaseDetector is necessary for these.

The Gjk algorithm also implements the DistanceDetector and RaycastDetector interfaces. These interfaces allow performing distance checks and raycasts against Convex Shapes.

The DistanceDetectors can return a Separation object which contains the separation normal, distance and closest points.

The RaycastDetectors can return a Raycast object which contains the point the Ray intersects the shape, the normal and the distance. For raycasting, it's also advisable to perform a raycast against a BroadphaseDetector first to rule out the obvious failures.

Since:

1.0.0

Version:

3.2.0

Author:

William Bittle

Interface Summary

Interface	Description
DistanceDetector	Interface representing an algorithm to detect the distance between two Convex Shapes.
FallbackCondition	Represents a condition that returns true to indicate a fallback NarrowphaseDetector should be used instead of the primary.
MinkowskiPenetrationSolver	Interface representing a sub algorithm for finding the penetration vector and depth using properties of the MinkowskiSum and the Gjk termination information.
NarrowphaseDetector	Represents an algorithm to detect whether two Convex Shapes are penetrating/overlapping each other.
NarrowphasePostProcessor	Interface used to modify the narrow-phase collision information before being sent to listeners.
RaycastDetector	Represents an algorithm for determining whether a Ray and a Convex Shape intersect, given the ray's maximum length and the Convex Shape's Transform.

Class Summary

Class	Description
AbstractFallbackCondition	Abstract implementation of the FallbackCondition interface.
CircleDetector	Class devoted to Circle detection queries.
Epa	Epa, or Expanding Polytope Algorithm, is used to find the penetration depth and vector given the final simplex of Gjk.
FallbackNarrowphaseDetector	Represents a delegating NarrowphaseDetector that uses a primary NarrowphaseDetector and fallback NarrowphaseDetector.
Gjk	Implementation of the Gilbert-Johnson-Keerthi (GJK) algorithm for collision detection.
LinkPostProcessor	A NarrowphasePostProcessor specifically for the Link class to solve the internal edge problem when using a chain of segments.
MinkowskiSum	Represents the Minkowski sum of the given Convex Shapes.
MinkowskiSumPoint	Represents a point in the MinkowskiSum.
PairwiseTypedFallbackCondition	Represents a TypedFallbackCondition that filters on a particular pair of types.
Penetration	Represents a Penetration of one Convex Shape into another.
Raycast	Represents the result of a Ray cast against (intersecting with) a Convex Shape.
Sat	Implementation of the Separating Axis Theorem (SAT) for collision detection.
SegmentDetector	Class devoted to improving performance of Segment detection queries.
Separation	Represents a Separation of one Convex Shape between another.
SingleTypedFallbackCondition	Represents a TypedFallbackCondition that filters on a single type.
TypedFallbackCondition	Represents a FallbackCondition that uses the Convex's class type to determine which pairs will be detected by the fallback NarrowphaseDetector.