gov.nasa.worldwind.geom
Class Triangle

java.lang.Object
  gov.nasa.worldwind.geom.Triangle

public class Triangle
extends Object

Provides operations on triangles.

Nested Class Summary

protected static class

Triangle.TriangleIntersection Defines a line segment representing the intersection of a line with and in the plane of a triangle.

Constructor Summary

Triangle(Vec4 a, Vec4 b, Vec4 c)
Construct a triangle from three counter-clockwise ordered vertices.

Method Summary

protected static Triangle.TriangleIntersection	compute_intervals_isectline(Vec4[] v, double vv0, double vv1, double vv2, double d0, double d1, double d2, double d0d1, double d0d2)
boolean	contains(Vec4 p) Indicates whether a specified point is on the triangle.
protected static boolean	coplanarTriangles(Vec4 n, Vec4[] v, Vec4[] u)
protected static boolean	edgeEdgeTest(double[] v0, double[] u0, double[] u1, int i0, int i1, double ax, double ay)
static void	expandTriangleFan(List<Integer> indices, FloatBuffer inBuf, FloatBuffer outBuf) Expands a buffer of indexed triangle fan vertices to a buffer of non-indexed general-triangle vertices.
static void	expandTriangleFan(List<Integer> indices, IntBuffer outBuf)
static void	expandTriangles(List<Integer> indices, FloatBuffer inBuf, FloatBuffer outBuf) Expands a buffer of indexed triangle vertices to a buffer of non-indexed triangle vertices.
static void	expandTriangles(List<Integer> indices, IntBuffer outBuf)
static void	expandTriangleStrip(List<Integer> indices, FloatBuffer inBuf, FloatBuffer outBuf) Expands a buffer of indexed triangle strip vertices to a buffer of non-indexed general-triangle vertices.
static void	expandTriangleStrip(List<Integer> indices, IntBuffer outBuf)
Vec4	getA() Returns the first vertex.
Vec4	getB() Returns the second vertex.
Vec4	getC() Returns the third vertex.
Vec4	intersect(Line line) Determine the intersection of the triangle with a specified line.
static Intersection	intersect(Line line, double vax, double vay, double vaz, double vbx, double vby, double vbz, double vcx, double vcy, double vcz) Determines the intersection of a specified line with a triangle specified by individual coordinates.
static Intersection	intersect(Line line, Vec4 a, Vec4 b, Vec4 c) Determines the intersection of a specified line with a specified triangle.
protected static Triangle.TriangleIntersection	intersect(Vec4 v0, Vec4 v1, Vec4 v2, double vv0, double vv1, double vv2, double d0, double d1, double d2)
static List<Intersection>	intersectTriangles(Line line, FloatBuffer vertices) Compute the intersections of a line with a collection of triangles.
static List<Intersection>	intersectTriangles(Line line, FloatBuffer vertices, IntBuffer indices) Compute the intersections of a line with a collection of triangles.
static int	intersectTriangles(Vec4[] v, Vec4[] u, Vec4[] intersectionVertices) Intersects two triangles and returns their intersection vertices.
static List<Intersection>	intersectTriangleTypes(Line line, FloatBuffer vertices, IntBuffer indices, int triangleType) Compute the intersections of a line with a triangle collection.
static List<Intersection>	intersectTriFan(Line line, FloatBuffer vertices, IntBuffer indices) Compute the intersections of a line with a triangle fan.
static List<Intersection>	intersectTriFan(Line line, Vec4[] vertices, IntBuffer indices) Compute the intersections of a line with a triangle fan.
static List<Intersection>	intersectTriStrip(Line line, FloatBuffer vertices, IntBuffer indices) Compute the intersections of a line with a triangle strip.
static List<Intersection>	intersectTriStrip(Line line, Vec4[] vertices, IntBuffer indices) Compute the intersections of a line with a triangle strip.
protected static boolean	pointInTri(double[] v0, double[] u0, double[] u1, double[] u2, int i0, int i1)
String	toString()
protected static boolean	triangleEdgeTest(double[] v0, double[] v1, double[] u0, double[] u1, double[] u2, int i0, int i1)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Triangle

public Triangle(Vec4 a,
                Vec4 b,
                Vec4 c)

Construct a triangle from three counter-clockwise ordered vertices. The front face of the triangle is determined by the right-hand rule.

Parameters:

a - the first vertex.

b - the second vertex.

c - the third vertex.

Throws:

IllegalArgumentException - if any vertex is null.

Method Detail

compute_intervals_isectline

protected static Triangle.TriangleIntersection compute_intervals_isectline(Vec4[] v,
                                                                           double vv0,
                                                                           double vv1,
                                                                           double vv2,
                                                                           double d0,
                                                                           double d1,
                                                                           double d2,
                                                                           double d0d1,
                                                                           double d0d2)

contains

public boolean contains(Vec4 p)

Indicates whether a specified point is on the triangle.

Parameters:

p - the point to test. If null, the method returns false.

Returns:

true if the point is on the triangle, otherwise false.

coplanarTriangles

protected static boolean coplanarTriangles(Vec4 n,
                                           Vec4[] v,
                                           Vec4[] u)

edgeEdgeTest

protected static boolean edgeEdgeTest(double[] v0,
                                      double[] u0,
                                      double[] u1,
                                      int i0,
                                      int i1,
                                      double ax,
                                      double ay)

expandTriangleFan

public static void expandTriangleFan(List<Integer> indices,
                                     FloatBuffer inBuf,
                                     FloatBuffer outBuf)

Expands a buffer of indexed triangle fan vertices to a buffer of non-indexed general-triangle vertices.

Parameters:

indices - the triangle indices.

inBuf - the vertex buffer the indices refer to, in the order x, y, z, x, y, z, ...

outBuf - the buffer in which to place the expanded triangle vertices. The buffer must have a limit sufficient to hold the output vertices.

Throws:

IllegalArgumentException - if the index list or the input or output buffer is null, or if the output buffer size is insufficient.

expandTriangleFan

public static void expandTriangleFan(List<Integer> indices,
                                     IntBuffer outBuf)

expandTriangles

public static void expandTriangles(List<Integer> indices,
                                   FloatBuffer inBuf,
                                   FloatBuffer outBuf)

Expands a buffer of indexed triangle vertices to a buffer of non-indexed triangle vertices.

Parameters:

indices - the triangle indices.

inBuf - the vertex buffer the indices refer to, in the order x, y, z, x, y, z, ...

outBuf - the buffer in which to place the expanded triangle vertices. The buffer must have a limit sufficient to hold the output vertices.

Throws:

IllegalArgumentException - if the index list or the input or output buffer is null, or if the output buffer size is insufficient.

expandTriangles

public static void expandTriangles(List<Integer> indices,
                                   IntBuffer outBuf)

expandTriangleStrip

public static void expandTriangleStrip(List<Integer> indices,
                                       FloatBuffer inBuf,
                                       FloatBuffer outBuf)

Expands a buffer of indexed triangle strip vertices to a buffer of non-indexed general-triangle vertices.

Parameters:

indices - the triangle indices.

inBuf - the vertex buffer the indices refer to, in the order x, y, z, x, y, z, ...

outBuf - the buffer in which to place the expanded triangle vertices. The buffer must have a limit sufficient to hold the output vertices.

Throws:

IllegalArgumentException - if the index list or the input or output buffer is null, or if the output buffer size is insufficient.

expandTriangleStrip

public static void expandTriangleStrip(List<Integer> indices,
                                       IntBuffer outBuf)

getA

public Vec4 getA()

Returns the first vertex.

Returns:

the first vertex.

getB

public Vec4 getB()

Returns the second vertex.

Returns:

the second vertex.

getC

public Vec4 getC()

Returns the third vertex.

Returns:

the third vertex.

intersect

public Vec4 intersect(Line line)

Determine the intersection of the triangle with a specified line.

Parameters:

line - the line to test.

Returns:

the point of intersection if the line intersects the triangle, otherwise null.

Throws:

IllegalArgumentException - if the line is null.

intersect

public static Intersection intersect(Line line,
                                     double vax,
                                     double vay,
                                     double vaz,
                                     double vbx,
                                     double vby,
                                     double vbz,
                                     double vcx,
                                     double vcy,
                                     double vcz)

Determines the intersection of a specified line with a triangle specified by individual coordinates.

Parameters:

line - the line to test.

vax - the X coordinate of the first vertex of the triangle.

vay - the Y coordinate of the first vertex of the triangle.

vaz - the Z coordinate of the first vertex of the triangle.

vbx - the X coordinate of the second vertex of the triangle.

vby - the Y coordinate of the second vertex of the triangle.

vbz - the Z coordinate of the second vertex of the triangle.

vcx - the X coordinate of the third vertex of the triangle.

vcy - the Y coordinate of the third vertex of the triangle.

vcz - the Z coordinate of the third vertex of the triangle.

Returns:

the point of intersection if the line intersects the triangle, otherwise null.

intersect

public static Intersection intersect(Line line,
                                     Vec4 a,
                                     Vec4 b,
                                     Vec4 c)

Determines the intersection of a specified line with a specified triangle. The triangle is specified by three points ordered counterclockwise. The triangle's front face is determined by the right-hand rule.

Parameters:

line - the line to test.

a - the first vertex of the triangle.

b - the second vertex of the triangle.

c - the third vertex of the triangle.

Returns:

the point of intersection if the line intersects the triangle, otherwise null.

Throws:

IllegalArgumentException - if the line or any of the triangle vertices is null.

intersect

protected static Triangle.TriangleIntersection intersect(Vec4 v0,
                                                         Vec4 v1,
                                                         Vec4 v2,
                                                         double vv0,
                                                         double vv1,
                                                         double vv2,
                                                         double d0,
                                                         double d1,
                                                         double d2)

intersectTriangles

public static List<Intersection> intersectTriangles(Line line,
                                                    FloatBuffer vertices)

Compute the intersections of a line with a collection of triangles.

Parameters:

line - the line to intersect.

vertices - the triangles, arranged in a buffer as GL_TRIANGLES (9 floats per triangle).

Returns:

the list of intersections with the line and the triangles, or null if there are no intersections.

Throws:

IllegalArgumentException - if the line or vertex buffer is null.

intersectTriangles

public static List<Intersection> intersectTriangles(Line line,
                                                    FloatBuffer vertices,
                                                    IntBuffer indices)

Compute the intersections of a line with a collection of triangles.

Parameters:

line - the line to intersect.

vertices - the triangles, arranged in a buffer as GL_TRIANGLES (9 floats per triangle).

indices - the indices forming the triangles.

Returns:

the list of intersections with the line and the triangle fan, or null if there are no intersections.

Throws:

IllegalArgumentException - if the line, vertex buffer or index buffer is null.

intersectTriangles

public static int intersectTriangles(Vec4[] v,
                                     Vec4[] u,
                                     Vec4[] intersectionVertices)

Intersects two triangles and returns their intersection vertices.

Parameters:

v - the Cartesian coordinates of the first triangle.

u - the Cartesian coordinates of the second triangle.

intersectionVertices - a pre-allocated two-element array in which the intersection vertices, if any, are returned.

Returns:

-1 if there is no intersection, 1 if there is an intersection, or 0 if the triangles are co-planar.

intersectTriangleTypes

public static List<Intersection> intersectTriangleTypes(Line line,
                                                        FloatBuffer vertices,
                                                        IntBuffer indices,
                                                        int triangleType)

Compute the intersections of a line with a triangle collection.

Parameters:

line - the line to intersect.

vertices - the tri-fan vertices, in the order x, y, z, x, y, z, ...

indices - the indices forming the tri-fan.

triangleType - the type of triangle collection, either GL.GL_TRIANGLE_STRIP or GL.GL_TRIANGLE_FAN.

Returns:

the list of intersections with the line and the triangle fan, or null if there are no intersections.

intersectTriFan

public static List<Intersection> intersectTriFan(Line line,
                                                 FloatBuffer vertices,
                                                 IntBuffer indices)

Compute the intersections of a line with a triangle fan.

Parameters:

line - the line to intersect.

vertices - the tri-fan vertices.

indices - the indices forming the tri-fan.

Returns:

the list of intersections with the line and the triangle fan, or null if there are no intersections.

Throws:

IllegalArgumentException - if the line, vertex buffer or index buffer is null.

intersectTriFan

public static List<Intersection> intersectTriFan(Line line,
                                                 Vec4[] vertices,
                                                 IntBuffer indices)

Compute the intersections of a line with a triangle fan.

Parameters:

line - the line to intersect.

vertices - the tri-fan vertices.

indices - the indices forming the tri-fan.

Returns:

the list of intersections with the line and the triangle fan, or null if there are no intersections.

Throws:

IllegalArgumentException - if the line, vertex array or index buffer is null.

intersectTriStrip

public static List<Intersection> intersectTriStrip(Line line,
                                                   FloatBuffer vertices,
                                                   IntBuffer indices)

Compute the intersections of a line with a triangle strip.

Parameters:

line - the line to intersect.

vertices - the tri-strip vertices.

indices - the indices forming the tri-strip.

Returns:

the list of intersections with the line and the tri-strip, or null if there are no intersections.

Throws:

IllegalArgumentException - if the line, vertex buffer or index buffer is null.

intersectTriStrip

public static List<Intersection> intersectTriStrip(Line line,
                                                   Vec4[] vertices,
                                                   IntBuffer indices)

Compute the intersections of a line with a triangle strip.

Parameters:

line - the line to intersect.

vertices - the tri-strip vertices.

indices - the indices forming the tri-strip.

Returns:

the list of intersections with the line and the triangle strip, or null if there are no intersections.

Throws:

IllegalArgumentException - if the line, vertex array or index buffer is null.

pointInTri

protected static boolean pointInTri(double[] v0,
                                    double[] u0,
                                    double[] u1,
                                    double[] u2,
                                    int i0,
                                    int i1)

toString

public String toString()

Overrides:

toString in class Object

triangleEdgeTest

protected static boolean triangleEdgeTest(double[] v0,
                                          double[] v1,
                                          double[] u0,
                                          double[] u1,
                                          double[] u2,
                                          int i0,
                                          int i1)