TriFaceClipper (Artisynth API documentation)

java.lang.Object
- maspack.geometry.TriFaceClipper

```
public class TriFaceClipper
extends java.lang.Object
```
Worker class that clips line segments to the upper or lower Voronoi regions of an oriented 3D triangular face. Here, upper and lower define the regions directly above or below the face, as defined by the direction of the normal. The regions are bounded on the sides by three planes, each perpendicular to the face and containing one of the triangle edges.
The class can also calculate the maximum (unsigned) distance to the face of the portion of either a line segment or triangle that is clipped to one of these regions. Triangles are clipped as areas, and so the distance returned for them is exact.
The clipping is done with respect to a coordinate frame attached to the face, in which the face lies in the x-y plane so that the distance of a point from the face is simply the absolute value of its z coordinate and the planes bounding the region from the side are perpendicular to the x-y plane.
When a sequence of adjacent triangles is tested using maxClippedDistance(Face,int,boolean), the coordinates computed for the vertices of one triangle can be reused for those it shares with the next.

Constructor Summary

Constructors
Constructor and Description
`TriFaceClipper()` Creates an uninitialized TriFaceClipper.
`TriFaceClipper(Face tri)` Creates a TriFaceClipper initialized to a triangle specified by vertices (in world coordinates) of a `Face`.
`TriFaceClipper(Point3d p0, Point3d p1, Point3d p2)` Creates a TriFaceClipper initialized to a triangle specified by three points oriented counter-clockwise.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`clipSegment(double[] svals, Point3d ps0, Point3d ps1, Point3d p0, Point3d p1, int side)` Clips a line segment to either the upper or lower Voronoi region depending on whether `side` is `1` or `-1`.
`boolean`	`isInitialized()` Queries whether if this clipper is initialized to a non-degenerate triangle.
`double`	`maxClippedDistance(Face tri, int side, boolean checkAdjacent)` Computes the maximum unsigned distance from the face of a triangle `tri` that is clipped to either the upper or lower region, depending on whether `side` is positive or negative.
`double`	`maxClippedDistance(HalfEdge he, int side)` Computes the maximum unsigned distance from the face of an edge that is clipped to either the upper or lower region, depending on whether `side` is positive or negative.
`double`	`maxClippedDistance(Point3d p0, Point3d p1, int side)` Computes the maximum unsigned distance from the face of a line segment that is clipped to either the upper or lower region, depending on whether `side` is positive or negative.
`double`	`maxClippedDistance(Point3d p0, Point3d p1, Point3d p2, int side)` Computes the maximum unsigned distance from the face of a triangle that is clipped to either the upper or lower region, depending on whether `side` is positive or negative.
`void`	`set(Face tri)` Sets the TriFaceClipper to correspond to a triangle specified by the world coordinates of a `Face`.
`boolean`	`set(Point3d p0, Point3d p1, Point3d p2)` Sets this TriFaceClipper to correspond to a triangle specified by three points oriented counter-clockwise.

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - TriFaceClipper
```
public TriFaceClipper()
```
    Creates an uninitialized TriFaceClipper.
  - TriFaceClipper
```
public TriFaceClipper(Point3d p0,
                      Point3d p1,
                      Point3d p2)
```
    Creates a TriFaceClipper initialized to a triangle specified by three points oriented counter-clockwise.
    
    Parameters:
    
    p0 - first triangle point
    
    p1 - second triangle point
    
    p2 - third triangle point
  - TriFaceClipper
```
public TriFaceClipper(Face tri)
```
    Creates a TriFaceClipper initialized to a triangle specified by vertices (in world coordinates) of a Face. The first vertex corresponds to the tail of the face's first half edge.
    
    Parameters:
    
    tri - face defining the triangle
- Method Detail
  - set
```
public boolean set(Point3d p0,
                   Point3d p1,
                   Point3d p2)
```
    Sets this TriFaceClipper to correspond to a triangle specified by three points oriented counter-clockwise. If the triangle is degenerate, the method returns false and the clipper will be set so that isInitialized() returns false.
    
    Parameters:
    
    p0 - first triangle point
    
    p1 - second triangle point
    
    p2 - third triangle point
    
    Returns:
    
    false if the triangle is degenerate
  - set
```
public void set(Face tri)
```
    Sets the TriFaceClipper to correspond to a triangle specified by the world coordinates of a Face. The first vertex corresponds to the tail of the face's first half edge.
    
    Parameters:
    
    tri - face defining the triangle
  - isInitialized
```
public boolean isInitialized()
```
    Queries whether if this clipper is initialized to a non-degenerate triangle.
    
    Returns:
    
    true if clipper is initialzed
  - clipSegment
```
public boolean clipSegment(double[] svals,
                           Point3d ps0,
                           Point3d ps1,
                           Point3d p0,
                           Point3d p1,
                           int side)
```
    Clips a line segment to either the upper or lower Voronoi region depending on whether side is 1 or -1. The segment is assumed to lie between the points p0 and p1, such that points on it are defined by
```
 p = (1-s) p0 + s p1
 
```
    where s is a scalar parameter in the range [0, 1].
    Parameters:
    
    svals - If non-null, must be of length >= 2 and will be used to return the parameter range of the segment after clipping. If all of the segment lies in the region, svals will contain [0,1]. If none of the segment lies in the region, then it will be set to contain [1,0].
    
    ps0 - if non-null and the segment is not completely clipped, returns the clipped segment point corresponding to svals[0]
    
    ps1 - if non-null and the segment is not completely clipped, returns the clipped segment point corresponding to svals[1]
    
    p0 - first point of the segment
    
    p1 - last point of the segment
    
    side - clips to the upper region if positive or the lower region if negative. Must not be 0.
    
    Returns:
    
    false if no part of the segment lies in the region and so any values returned by ps0 and ps1 are undefined
  - maxClippedDistance
```
public double maxClippedDistance(HalfEdge he,
                                 int side)
```
    Computes the maximum unsigned distance from the face of an edge that is clipped to either the upper or lower region, depending on whether side is positive or negative. The edge is specified by the world coordinates of the vertices of a half-edge.
    
    Parameters:
    
    he - edge to check
    
    side - clips to the upper region if positive or the lower region if negative. Must not be 0.
    
    Returns:
    
    non-signed maximum distance of the clipped half edge from the face, or -1 if no part of the half-edge is in the region.
  - maxClippedDistance
```
public double maxClippedDistance(Point3d p0,
                                 Point3d p1,
                                 int side)
```
    Computes the maximum unsigned distance from the face of a line segment that is clipped to either the upper or lower region, depending on whether side is positive or negative. The segment is specified by the points p0 and p1.
    
    Parameters:
    
    p0 - first segment point
    
    p1 - second segment point
    
    side - clips to the upper region if positive or the lower region if negative. Must not be 0.
    
    Returns:
    
    non-signed maximum distance of the clipped segment from the face, or -1 if no part of the segment is in the region
  - maxClippedDistance
```
public double maxClippedDistance(Face tri,
                                 int side,
                                 boolean checkAdjacent)
```
    Computes the maximum unsigned distance from the face of a triangle tri that is clipped to either the upper or lower region, depending on whether side is positive or negative. The triangle is evaluated in world coordinates.
    As with maxClippedDistance(Point3d,Point3d,Point3d,int), the triangle is clipped as an area and so the distance returned is exact.
    The argument checkAdjacent is used to help efficiently compute the maximum distance for a clipped triangle strip. If set true, then for each vertex of tri which is shared with the triangle most recently tested by this method, the coordinates computed for that vertex are reused instead of being recomputed. This does not affect the value returned; it is purely an optimization, and callers should set it false if the vertex positions may have changed since the previous call.
    
    Parameters:
    
    tri - triangle to check
    
    side - clips to the upper region if positive or the lower region if negative. Must not be 0.
    
    checkAdjacent - if true, reuses coordinates for vertices shared with the most recent triangle tested with this method
    
    Returns:
    
    non-signed maximum distance of the clipped triangle from the face, or -1 if no part of the triangle is in the region.
  - maxClippedDistance
```
public double maxClippedDistance(Point3d p0,
                                 Point3d p1,
                                 Point3d p2,
                                 int side)
```
    Computes the maximum unsigned distance from the face of a triangle that is clipped to either the upper or lower region, depending on whether side is positive or negative. The triangle is defined by three points specified in counter-clockwise order.
    The triangle is clipped as an area, and so the distance returned is exact. In particular, the method detects the case in which the triangle's interior intersects the region while none of its edges do.
    The computation is done in the triangle coordinate frame, where the face lies in the x-y plane and the distance of a point from the face is simply the absolute value of its z coordinate. The three planes bounding the region from the side are then perpendicular to the x-y plane, and the triangle is clipped to them using the (2d) edge descriptions.
    
    Parameters:
    
    p0 - first triangle point
    
    p1 - second triangle point
    
    p2 - third triangle point
    
    side - clips to the upper region if positive or the lower region if negative. Must not be 0.
    
    Returns:
    
    non-signed maximum distance of the clipped triangle from the face, or -1 if no part of the triangle is in the region.

Class TriFaceClipper

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

TriFaceClipper

TriFaceClipper

TriFaceClipper

Method Detail

set

set

isInitialized

clipSegment

maxClippedDistance

maxClippedDistance

maxClippedDistance

maxClippedDistance