Intersections2D

Methods

<static> clipTriangleAtAxisAlignedThreshold

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.

Parameters:

Name	Type	Argument	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	Number[]	<optional>	The array into which to copy the result. If this parameter is not supplied, a new array is constructed and returned.

Returns:

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

<static> computeBarycentricCoordinates

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

Parameters:

Name	Type	Argument	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:

Cartesian3 The barycentric coordinates of the position within the triangle.

Example

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