The intersection test is provided by intersect(). It takes two primitives and returns a boolean indicating if the primitives intersect. Some overloads return the point of intersection in an output argument. The overloads for intersect() are summarized in the table below.
| Arg 1 | Arg 2 | Additional arguments and notes |
|---|---|---|
| Triangle | Triangle | include boundaries1 (default false) |
| Ray | Segment | return intersection point. 2D only. |
| Segment | BoundingBox | return intersection point |
| Ray | BoundingBox | return intersection point |
| BoundingBox | BoundingBox | |
| Sphere | Sphere | specify tolerance |
| Triangle | BoundingBox | |
| Triangle | Ray | return parameterized intersection point (on Ray), return barycentric intersection point (on Triangle) |
| Triangle | Segment | return parameterized intersection point (on Segment), return barycentric intersection point (on Triangle) |
| OrientedBoundingBox | OrientedBoundingBox | specify tolerance |
The example below tests for intersection between two triangles, a ray, and a BoundingBox.
../../examples/primal_introduction.cpp
../../examples/primal_introduction.cpp
In the diagram, the point where the ray enters the bounding box is shown as the intersection point (not the exit point or some point inside the box). This is because if a ray intersects a bounding box at more than one point, the first intersection point along the ray (the intersection closest to the ray's origin) is reported as the intersection. If a ray originates inside a bounding box, the ray's origin will be reported as the point of intersection.
By default, the triangle intersection algorithm considers only the triangles' interiors, so that non-coplanar triangles that share two vertices are not reported as intersecting. The caller to
intersect()can specify an optional argument to include triangle boundaries in the intersection test.↩