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added more robust orient test

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This commit is contained in:
zzzzrrr 2009-08-11 11:29:33 -04:00
parent 18f8f17cc3
commit 260e7935b9
4 changed files with 105 additions and 33 deletions
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8
src/org/poly2tri/Poly2Tri.scala
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@ -279,12 +279,12 @@ class Poly2TriDemo extends BasicGame("Poly2Tri") {
def selectModel(model: String) {
model match {
case "data/nazca_monkey.dat" =>
//CDT.clearPoint = 50
doCDT = false; drawCDT = false; drawcdtMesh = false
CDT.clearPoint = 50
//doCDT = false; drawCDT = false; drawcdtMesh = false
loadModel(nazcaMonkey, 4.5f, Point(400, 300), 1500)
case "data/bird.dat" =>
doCDT = false; drawCDT = false; drawcdtMesh = false
//CDT.clearPoint = 80
//doCDT = false; drawCDT = false; drawcdtMesh = false
CDT.clearPoint = 80
loadModel(bird, 25f, Point(400, 300), 350)
case "data/i.snake" =>
doCDT = true; drawCDT = true

14
src/org/poly2tri/cdt/CDT.scala
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@ -133,6 +133,8 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
private def sweep {
for(i <- 1 until points.size) {
try {
val point = points(i)
// Process Point event
var triangle = pointEvent(point)
@ -140,8 +142,13 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
if(triangle != null)
point.edges.foreach(e => triangle = edgeEvent(e, triangle))
if(i == CDT.clearPoint) {cleanTri = triangle; mesh.debug += cleanTri}
} catch {
case e: Exception =>
throw new Exception("Systect point = " + i)
}
}
}
// Final step in the sweep-line CDT algo
@ -208,7 +215,7 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
tList.foreach(t => {
t.points.foreach(p => {
if(p != edge.q && p != edge.p) {
if(t.orient(edge.q, edge.p, p) > 0 ) {
if(Util.orient2d(edge.q, edge.p, p) > 0 ) {
// Keep duplicate points out
if(!lPoints.contains(p)) {
lPoints += p
@ -347,7 +354,7 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
}
if(!P.isEmpty) {
val left = Util.orient(a, b, P(i)) < 0
val left = Util.orient2d(a, b, P(i)) > 0
val pB = if(left) P(i) else b
val pC = if(left) b else P(i)
val points = Array(a, pB, pC)
@ -434,6 +441,7 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
val point = t1.points(0)
val oPoint = t2 oppositePoint t1
// Try to avoid creating degenerate triangles
val collinear = t1.collinear(oPoint) || t2.collinear(oPoint, point)
if(illegal(t1.points(1), oPoint, t1.points(2), t1.points(0)) && !collinear) {

34
src/org/poly2tri/shapes/Triangle.scala
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@ -126,23 +126,25 @@ class Triangle(val points: Array[Point]) {
val p = edge.p
val q = edge.q
val e = p - q
val ik = points(2) - points(0)
val ij = points(1) - points(0)
val jk = points(2) - points(1)
val ji = points(0) - points(1)
val kj = points(1) - points(2)
val ki = points(0) - points(2)
if(q == points(0)) {
val ik = points(2) - points(0)
val ij = points(1) - points(0)
val sameSign = Math.signum(ik cross e) == Math.signum(ij cross e)
if(!sameSign) return this
if(neighbors(2) == null) return null
return neighbors(2).locateFirst(edge)
} else if(q == points(1)) {
val jk = points(2) - points(1)
val ji = points(0) - points(1)
val sameSign = Math.signum(jk cross e) == Math.signum(ji cross e)
if(!sameSign) return this
if(neighbors(0) == null) return null
return neighbors(0).locateFirst(edge)
} else if(q == points(2)) {
val kj = points(1) - points(2)
val ki = points(0) - points(2)
val sameSign = Math.signum(kj cross e) == Math.signum(ki cross e)
if(!sameSign) return this
if(neighbors(1) == null) return null
@ -153,29 +155,17 @@ class Triangle(val points: Array[Point]) {
// Locate next triangle crossed by edge
def findNeighbor(e: Point): Triangle = {
if(orient(points(0), points(1), e) >= 0)
if(Util.orient2d(points(0), points(1), e) > 0)
return neighbors(2)
else if(orient(points(1), points(2), e) >= 0)
else if(Util.orient2d(points(1), points(2), e) > 0)
return neighbors(0)
else if(orient(points(2), points(0), e) >= 0)
else if(Util.orient2d(points(2), points(0), e) > 0)
return neighbors(1)
else
// Point must reside inside this triangle
this
}
// Return: positive if point p is left of ab
// negative if point p is right of ab
// zero if points are colinear
// See: http://www-2.cs.cmu.edu/~quake/robust.html
def orient(b: Point, a: Point, p: Point): Float = {
val acx = a.x - p.x
val bcx = b.x - p.x
val acy = a.y - p.y
val bcy = b.y - p.y
acx * bcy - acy * bcx
}
// The neighbor clockwise to given point
def neighborCW(point: Point): Triangle = {
if(point == points(0)) {
@ -260,7 +250,7 @@ class Triangle(val points: Array[Point]) {
}
// Make legalized triangle will not be collinear
def collinear(oPoint: Point): Boolean = Util.collinear(points(0), points(1), oPoint)
def collinear(oPoint: Point): Boolean = Util.collinear(points(1), points(0), oPoint)
// Make sure legalized triangle will not be collinear
def collinear(oPoint: Point, nPoint: Point): Boolean = {

82
src/org/poly2tri/utils/Util.scala
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@ -8,8 +8,11 @@ import shapes.Point
object Util {
// Almost zero
val COLLINEAR_SLOP = 0.1f
val COLLINEAR_SLOP = 0.25f
val epsilon = exactinit
val ccwerrboundA = (3.0 + 16.0 * epsilon) * epsilon
// From "Scala By Example," by Martin Odersky
def msort[A](less: (A, A) => Boolean)(xs: List[A]): List[A] = {
def merge(xs1: List[A], xs2: List[A]): List[A] =
@ -49,9 +52,37 @@ object Util {
}
// Return: positive if point p is left of ab
// negative if point p is right of ab
// zero if points are colinear
/* From Jonathan Shewchuk's "Adaptive Precision Floating-Point Arithmetic
* and Fast Robust Predicates for Computational Geometry"
* See: http://www.cs.cmu.edu/~quake/robust.html
*/
def exactinit = {
var every_other = true
var half = 0.5
var splitter = 1.0
var epsilon = 1.0
var check = 1.0
var lastcheck = 0.0
do {
lastcheck = check
epsilon *= half
if (every_other) {
splitter *= 2.0
}
every_other = !every_other
check = 1.0 + epsilon
} while ((check != 1.0) && (check != lastcheck))
epsilon
}
// Approximate 2D orientation test. Nonrobust.
// Return: positive if point a, b, and c are counterclockwise
// negative if point a, b, and c are clockwise
// zero if points are collinear
// See: http://www-2.cs.cmu.edu/~quake/robust.html
def orient(b: Point, a: Point, p: Point): Float = {
val acx = a.x - p.x
@ -60,7 +91,50 @@ object Util {
val bcy = b.y - p.y
acx * bcy - acy * bcx
}
// Adaptive exact 2D orientation test. Robust. By Jonathan Shewchuk
// Return: positive if point a, b, and c are counterclockwise
// negative if point a, b, and c are clockwise
// zero if points are collinear
// See: http://www-2.cs.cmu.edu/~quake/robust.html
def orient2d(pa: Point, pb: Point, pc: Point): Double = {
val detleft: Double = (pa.x - pc.x) * (pb.y - pc.y)
val detright: Double = (pa.y - pc.y) * (pb.x - pc.x)
val det = detleft - detright
var detsum = 0.0
if (detleft > 0.0) {
if (detright <= 0.0) {
return det;
} else {
detsum = detleft + detright
}
} else if (detleft < 0.0) {
if (detright >= 0.0) {
return det
} else {
detsum = -detleft - detright
}
} else {
return det
}
val errbound = Util.ccwerrboundA * detsum
if ((det >= errbound) || (-det >= errbound)) {
return det
} else {
println(pa + "," + pb + "," + pc)
println(detleft + "," + detright)
println("Det = " + det + " , errbound = " + errbound)
throw new Exception("Degenerate triangle")
}
// Not implemented;
// http://www.cs.cmu.edu/afs/cs/project/quake/public/code/predicates.c
// return orient2dadapt(pa, pb, pc, detsum)
}
}
/** The object <code>Random</code> offers a default implementation