PolyhedronBoxIntersector

Inheritance diagram for PolyhedronBoxIntersector ↕

Convex polyhedron / AABB intersection.

Public Types

IntersectorBase< Polyhedron, Box3F >

Parent

Polyhedron

PolyhedronType

Protected Attributes

Box3F

mBounds

Bounds of the polyhedron.

Vector< Point3F >

mEdgeLines

Edge line equations.

Point3I

mNumEdgeLines

Number of silhouette edges for each of the orthographic projections.

Vector< PlaneF >

mPlanes

World-space planes.

Protected Functions

void

_preprocess(const MatrixF & objToWorld, const Point3F & scale)

Run the preprocessing step on the current polyhedron.

Point2F

_project(U32 axis, const Point3F & p)

Project the point orthogonally down the given axis such that the orientation of the resulting coordinate system remains right-handed.

Public Functions

PolyhedronBoxIntersector()

PolyhedronBoxIntersector(const PolyhedronType & polyhedron, const MatrixF & objToWorld, const Point3F & scale, const Box3F & wsBounds)

OverlapTestResult

test(const Box3F & box)

Detailed Description

Convex polyhedron / AABB intersection.

This class implements the algorithm described in "Detecting Intersection of a Rectangular Solid and a Convex Polyhedron", Graphics Gems IV, Chapter 1.7, by Ned Greene.

The polyhedron is preprocessed when an object of this class is constructed.

This class also assumes that the polyhedron is represented in object space and thus also stores local copies of the polyhedron's planes transformed into world space.

The approach of the algorithm is simple. It uses a maximum of three successive stages to determine intersection. Each stage can early out if it can draw a conclusive result already.

Simple tests of the polyhedron's bounding box against the input box.
Standard test on plane set.
Plane tests reduced to 2D and done for each of the orthographic side projections.

note:
The intersector depends on planes facing inwards.