isEarHashed function
bool
isEarHashed(
- dynamic ear,
- dynamic minX,
- dynamic minY,
- dynamic invSize,
)
Implementation
bool isEarHashed(ear, minX, minY, invSize) {
var a = ear.prev, b = ear, c = ear.next;
if (area(a, b, c) >= 0) return false; // reflex, can't be an ear
// triangle bbox; min & max are calculated like this for speed
var minTX = a.x < b.x ? (a.x < c.x ? a.x : c.x) : (b.x < c.x ? b.x : c.x),
minTY = a.y < b.y ? (a.y < c.y ? a.y : c.y) : (b.y < c.y ? b.y : c.y),
maxTX = a.x > b.x ? (a.x > c.x ? a.x : c.x) : (b.x > c.x ? b.x : c.x),
maxTY = a.y > b.y ? (a.y > c.y ? a.y : c.y) : (b.y > c.y ? b.y : c.y);
// z-order range for the current triangle bbox;
var minZ = zOrder(minTX, minTY, minX, minY, invSize),
maxZ = zOrder(maxTX, maxTY, minX, minY, invSize);
var p = ear.prevZ, n = ear.nextZ;
// look for points inside the triangle in both directions
while (p != null && p.z >= minZ && n != null && n.z <= maxZ) {
if (p != ear.prev &&
p != ear.next &&
pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
area(p.prev, p, p.next) >= 0) return false;
p = p.prevZ;
if (n != ear.prev &&
n != ear.next &&
pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
area(n.prev, n, n.next) >= 0) return false;
n = n.nextZ;
}
// look for remaining points in decreasing z-order
while (p != null && p.z >= minZ) {
if (p != ear.prev &&
p != ear.next &&
pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
area(p.prev, p, p.next) >= 0) return false;
p = p.prevZ;
}
// look for remaining points in increasing z-order
while (n != null && n.z <= maxZ) {
if (n != ear.prev &&
n != ear.next &&
pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
area(n.prev, n, n.next) >= 0) return false;
n = n.nextZ;
}
return true;
}