Intersections2D

Methods

staticIntersections2D.clipTriangleAtAxisAlignedThreshold(threshold, keepAbove, u0, u1, u2, result) → Array.<Number>

Splits a 2D triangle at given axis-aligned threshold value and returns the resulting polygon on a given side of the threshold. The resulting polygon may have 0, 1, 2, 3, or 4 vertices.

Name	Type	Description
threshold	Number	The threshold coordinate value at which to clip the triangle.
keepAbove	Boolean	true to keep the portion of the triangle above the threshold, or false to keep the portion below.
u0	Number	The coordinate of the first vertex in the triangle, in counter-clockwise order.
u1	Number	The coordinate of the second vertex in the triangle, in counter-clockwise order.
u2	Number	The coordinate of the third vertex in the triangle, in counter-clockwise order.
result	Array.<Number>	optional The array into which to copy the result. If this parameter is not supplied, a new array is constructed and returned.

Returns:

The polygon that results after the clip, specified as a list of vertices. The vertices are specified in counter-clockwise order. Each vertex is either an index from the existing list (identified as a 0, 1, or 2) or -1 indicating a new vertex not in the original triangle. For new vertices, the -1 is followed by three additional numbers: the index of each of the two original vertices forming the line segment that the new vertex lies on, and the fraction of the distance from the first vertex to the second one.

Example:

var result = Cesium.Intersections2D.clipTriangleAtAxisAlignedThreshold(0.5, false, 0.2, 0.6, 0.4);
// result === [2, 0, -1, 1, 0, 0.25, -1, 1, 2, 0.5]

Source: Core/Intersections2D.js, line 46

staticIntersections2D.computeBarycentricCoordinates(x, y, x1, y1, x2, y2, x3, y3, result) → Cartesian3

Compute the barycentric coordinates of a 2D position within a 2D triangle.

Name	Type	Description
x	Number	The x coordinate of the position for which to find the barycentric coordinates.
y	Number	The y coordinate of the position for which to find the barycentric coordinates.
x1	Number	The x coordinate of the triangle's first vertex.
y1	Number	The y coordinate of the triangle's first vertex.
x2	Number	The x coordinate of the triangle's second vertex.
y2	Number	The y coordinate of the triangle's second vertex.
x3	Number	The x coordinate of the triangle's third vertex.
y3	Number	The y coordinate of the triangle's third vertex.
result	Cartesian3	optional The instance into to which to copy the result. If this parameter is undefined, a new instance is created and returned.

Returns:

The barycentric coordinates of the position within the triangle.

Example:

var result = Cesium.Intersections2D.computeBarycentricCoordinates(0.0, 0.0, 0.0, 1.0, -1, -0.5, 1, -0.5);
// result === new Cesium.Cartesian3(1.0 / 3.0, 1.0 / 3.0, 1.0 / 3.0);

Source: Core/Intersections2D.js, line 236