# IntersectionTests

Core/IntersectionTests.js 13
Functions for computing the intersection between geometries such as rays, planes, triangles, and ellipsoids.

### Methods

#### static Cesium.IntersectionTests.grazingAltitudeLocation(ray, ellipsoid) → Cartesian3
Core/IntersectionTests.js 585

Provides the point along the ray which is nearest to the ellipsoid.

Name | Type | Description
--- | --- | ---
`ray` | Ray | The ray.
`ellipsoid` | Ellipsoid | The ellipsoid.

##### Returns:

The nearest planetodetic point on the ray.

#### static Cesium.IntersectionTests.lineSegmentPlane(endPoint0, endPoint1, plane, result) → Cartesian3
Core/IntersectionTests.js 702

Computes the intersection of a line segment and a plane.

Name | Type | Description
--- | --- | ---
`endPoint0` | Cartesian3 | An end point of the line segment.
`endPoint1` | Cartesian3 | The other end point of the line segment.
`plane` | Plane | The plane.
`result` | Cartesian3 | optional The object onto which to store the result.

##### Returns:

The intersection point or undefined if there is no intersection.

##### Example:

    var origin = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
    var normal = ellipsoid.geodeticSurfaceNormal(origin);
    var plane = Cesium.Plane.fromPointNormal(origin, normal);

    var p0 = new Cesium.Cartesian3(...);
    var p1 = new Cesium.Cartesian3(...);

    // find the intersection of the line segment from p0 to p1 and the tangent plane at origin.
    var intersection = Cesium.IntersectionTests.lineSegmentPlane(p0, p1, plane);

#### static Cesium.IntersectionTests.lineSegmentSphere(p0, p1, sphere, result) → Interval
Core/IntersectionTests.js 349

Computes the intersection points of a line segment with a sphere.

Name | Type | Description
--- | --- | ---
`p0` | Cartesian3 | An end point of the line segment.
`p1` | Cartesian3 | The other end point of the line segment.
`sphere` | BoundingSphere | The sphere.
`result` | Interval | optional The result onto which to store the result.

##### Returns:

The interval containing scalar points along the ray or undefined if there are no intersections.

#### static Cesium.IntersectionTests.lineSegmentTriangle(v0, v1, p0, p1, p2, cullBackFaces, result) → Cartesian3
Core/IntersectionTests.js 210

Computes the intersection of a line segment and a triangle.

Name | Type | Default | Description
--- | --- | --- | ---
`v0` | Cartesian3 |  | The an end point of the line segment.
`v1` | Cartesian3 |  | The other end point of the line segment.
`p0` | Cartesian3 |  | The first vertex of the triangle.
`p1` | Cartesian3 |  | The second vertex of the triangle.
`p2` | Cartesian3 |  | The third vertex of the triangle.
`cullBackFaces` | Boolean | `false` | optional If `true`, will only compute an intersection with the front face of the triangle and return undefined for intersections with the back face.
`result` | Cartesian3 |  | optional The `Cartesian3` onto which to store the result.

##### Returns:

The intersection point or undefined if there is no intersections.

#### static Cesium.IntersectionTests.rayEllipsoid(ray, ellipsoid) → Interval
Core/IntersectionTests.js 389

Computes the intersection points of a ray with an ellipsoid.

Name | Type | Description
--- | --- | ---
`ray` | Ray | The ray.
`ellipsoid` | Ellipsoid | The ellipsoid.

##### Returns:

The interval containing scalar points along the ray or undefined if there are no intersections.

#### static Cesium.IntersectionTests.rayPlane(ray, plane, result) → Cartesian3
Core/IntersectionTests.js 29

Computes the intersection of a ray and a plane. 计算一个射线和一个平面的交点

Name | Type | Description
--- | --- | ---
`ray` | Ray | The ray.
`plane` | Plane | The plane.
`result` | Cartesian3 | optional The object onto which to store the result.

##### Returns:

The intersection point or undefined if there is no intersections.

#### static Cesium.IntersectionTests.raySphere(ray, sphere, result) → Interval
Core/IntersectionTests.js 318

Computes the intersection points of a ray with a sphere.

Name | Type | Description
--- | --- | ---
`ray` | Ray | The ray.
`sphere` | BoundingSphere | The sphere.
`result` | Interval | optional The result onto which to store the result.

##### Returns:

The interval containing scalar points along the ray or undefined if there are no intersections.

#### static Cesium.IntersectionTests.rayTriangle(ray, p0, p1, p2, cullBackFaces, result) → Cartesian3
Core/IntersectionTests.js 180

Computes the intersection of a ray and a triangle as a Cartesian3 coordinate. Implements {@link https://cadxfem.org/inf/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf| Fast Minimum Storage Ray/Triangle Intersection} by Tomas Moller and Ben Trumbore.

Name | Type | Default | Description
--- | --- | --- | ---
`ray` | Ray |  | The ray.
`p0` | Cartesian3 |  | The first vertex of the triangle.
`p1` | Cartesian3 |  | The second vertex of the triangle.
`p2` | Cartesian3 |  | The third vertex of the triangle.
`cullBackFaces` | Boolean | `false` | optional If `true`, will only compute an intersection with the front face of the triangle and return undefined for intersections with the back face.
`result` | Cartesian3 |  | optional The `Cartesian3` onto which to store the result.

##### Returns:

The intersection point or undefined if there is no intersections.

#### static Cesium.IntersectionTests.rayTriangleParametric(ray, p0, p1, p2, cullBackFaces) → Number
Core/IntersectionTests.js 85

Computes the intersection of a ray and a triangle as a parametric distance along the input ray. The result is negative when the triangle is behind the ray. Implements {@link https://cadxfem.org/inf/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf| Fast Minimum Storage Ray/Triangle Intersection} by Tomas Moller and Ben Trumbore.

Name | Type | Default | Description
--- | --- | --- | ---
`ray` | Ray |  | The ray.
`p0` | Cartesian3 |  | The first vertex of the triangle.
`p1` | Cartesian3 |  | The second vertex of the triangle.
`p2` | Cartesian3 |  | The third vertex of the triangle.
`cullBackFaces` | Boolean | `false` | optional If `true`, will only compute an intersection with the front face of the triangle and return undefined for intersections with the back face.

##### Returns:

The intersection as a parametric distance along the ray, or undefined if there is no intersection.

#### static Cesium.IntersectionTests.trianglePlaneIntersection(p0, p1, p2, plane) → Object
Core/IntersectionTests.js 763

Computes the intersection of a triangle and a plane

Name | Type | Description
--- | --- | ---
`p0` | Cartesian3 | First point of the triangle
`p1` | Cartesian3 | Second point of the triangle
`p2` | Cartesian3 | Third point of the triangle
`plane` | Plane | Intersection plane

##### Returns:

An object with properties `positions` and `indices`, which are arrays that represent three triangles that do not cross the plane. (Undefined if no intersection exists)

##### Example:

    var origin = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
    var normal = ellipsoid.geodeticSurfaceNormal(origin);
    var plane = Cesium.Plane.fromPointNormal(origin, normal);

    var p0 = new Cesium.Cartesian3(...);
    var p1 = new Cesium.Cartesian3(...);
    var p2 = new Cesium.Cartesian3(...);

    // convert the triangle composed of points (p0, p1, p2) to three triangles that don't cross the plane
    var triangles = Cesium.IntersectionTests.trianglePlaneIntersection(p0, p1, p2, plane);