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import * as mathPoint from '../point';
import getLineSegmentIntersectionsIndexes from './getLineSegmentIntersectionsIndexes';
import containsPoint from './containsPoint';
import getNormal2 from './getNormal2';
import { glMatrix, vec3 } from 'gl-matrix';
import getLinesIntersection from './getLinesIntersection';
enum PolylinePointType {
Vertex,
Intersection,
}
// Position of the point related to the intersection region
enum PolylinePointPosition {
Outside = -1,
Edge = 0,
Inside = 1,
}
// Direction from last point to the intersection point to know if it is entering
// or exiting the intersection region
enum PolylinePointDirection {
Exiting = -1,
Unknown = 0,
Entering = 1,
}
type PolylinePoint = {
type: PolylinePointType;
coordinates: Types.Point2;
position?: PolylinePointPosition;
visited: boolean;
next: PolylinePoint;
};
type PolylineIntersectionPoint = PolylinePoint & {
direction: PolylinePointDirection;
cloned?: boolean;
};
/**
* Ensure all polyline point objects are pointing to the next object in case
* it is still not point to anyone.
* @param polylinePoints - Array that contains all polyline points (vertices and intersections)
*/
function ensuresNextPointers(polylinePoints: PolylinePoint[]) {
// Make sure all nodes point to a valid node
for (let i = 0, len = polylinePoints.length; i < len; i++) {
const currentPoint = polylinePoints[i];
if (!currentPoint.next) {
currentPoint.next = polylinePoints[i === len - 1 ? 0 : i + 1];
}
}
}
/**
* Creates one linked list per polyline that contains all vertices and intersections
* found while walking along the edges.
*
* @param targetPolyline - Target polyline
* @param sourcePolyline - Source polyline
* @returns Two linked lists with all vertices and intersections.
*/
function getSourceAndTargetPointsList(
targetPolyline: Types.Point2[],
sourcePolyline: Types.Point2[]
) {
const targetPolylinePoints: PolylinePoint[] = [];
const sourcePolylinePoints: PolylinePoint[] = [];
const sourceIntersectionsCache = new Map<
number,
PolylineIntersectionPoint[]
>();
const isFirstPointInside = containsPoint(sourcePolyline, targetPolyline[0]);
let intersectionPointDirection = isFirstPointInside
? PolylinePointDirection.Exiting
: PolylinePointDirection.Entering;
// Store all vertices and intersection for target contour
for (let i = 0, len = targetPolyline.length; i < len; i++) {
const p1 = targetPolyline[i];
const pointInside = containsPoint(sourcePolyline, p1);
const vertexPoint: PolylinePoint = {
type: PolylinePointType.Vertex,
coordinates: p1,
position: pointInside
? PolylinePointPosition.Inside
: PolylinePointPosition.Outside,
visited: false,
next: null,
};
targetPolylinePoints.push(vertexPoint);
const q1 = targetPolyline[i === len - 1 ? 0 : i + 1];
const intersectionsInfo = getLineSegmentIntersectionsIndexes(
sourcePolyline,
p1,
q1
).map((intersectedLineSegment) => {
const sourceLineSegmentId: number = intersectedLineSegment[0];
const p2 = sourcePolyline[intersectedLineSegment[0]];
const q2 = sourcePolyline[intersectedLineSegment[1]];
// lineSegment.intersectLine returns the midpoint of the four points
// when the lines are parallel or co-incident. Otherwise it will return
// an extension of the line.
const intersectionCoordinate = getLinesIntersection(
p1,
q1,
p2,
q2
) as Types.Point2;
const targetStartPointDistSquared = mathPoint.distanceToPointSquared(
p1,
intersectionCoordinate
);
return {
sourceLineSegmentId,
coordinate: intersectionCoordinate,
targetStartPointDistSquared,
};
});
intersectionsInfo.sort(
(left, right) =>
left.targetStartPointDistSquared - right.targetStartPointDistSquared
);
intersectionsInfo.forEach((intersectionInfo) => {
const { sourceLineSegmentId, coordinate: intersectionCoordinate } =
intersectionInfo;
// Intersection point to be added to the target polyline list
const targetEdgePoint: PolylineIntersectionPoint = {
type: PolylinePointType.Intersection,
coordinates: intersectionCoordinate,
position: PolylinePointPosition.Edge,
direction: intersectionPointDirection,
visited: false,
next: null,
};
// Intersection point to be added to the source polyline list.
// At this point there is no way to know if the point is entering or
// exiting the intersection region but that is not going to be used
// hence it is set to "unknown".
const sourceEdgePoint: PolylineIntersectionPoint = {
...targetEdgePoint,
direction: PolylinePointDirection.Unknown,
cloned: true,
};
if (intersectionPointDirection === PolylinePointDirection.Entering) {
targetEdgePoint.next = sourceEdgePoint;
} else {
sourceEdgePoint.next = targetEdgePoint;
}
let sourceIntersectionPoints =
sourceIntersectionsCache.get(sourceLineSegmentId);
if (!sourceIntersectionPoints) {
sourceIntersectionPoints = [];
sourceIntersectionsCache.set(
sourceLineSegmentId,
sourceIntersectionPoints
);
}
targetPolylinePoints.push(targetEdgePoint);
sourceIntersectionPoints.push(sourceEdgePoint);
// Switches from "exiting" to "entering" and vice-versa
intersectionPointDirection *= -1;
});
}
// Store all vertices and intersections for source contour
for (let i = 0, len = sourcePolyline.length; i < len; i++) {
const lineSegmentId: number = i;
const p1 = sourcePolyline[i];
const vertexPoint: PolylinePoint = {
type: PolylinePointType.Vertex,
coordinates: p1,
visited: false,
next: null,
};
sourcePolylinePoints.push(vertexPoint);
const sourceIntersectionPoints =
sourceIntersectionsCache.get(lineSegmentId);
if (!sourceIntersectionPoints?.length) {
continue;
}
// Calculate the distance between each intersection point to the start point
// of the line segment, sort them by distance and return a sorted array that
// contains all intersection points.
sourceIntersectionPoints
.map((intersectionPoint) => ({
intersectionPoint,
lineSegStartDistSquared: mathPoint.distanceToPointSquared(
p1,
intersectionPoint.coordinates
),
}))
.sort(
(left, right) =>
left.lineSegStartDistSquared - right.lineSegStartDistSquared
)
.map(({ intersectionPoint }) => intersectionPoint)
.forEach((intersectionPoint) =>
sourcePolylinePoints.push(intersectionPoint)
);
}
ensuresNextPointers(targetPolylinePoints);
ensuresNextPointers(sourcePolylinePoints);
return { targetPolylinePoints, sourcePolylinePoints };
}
/**
* Get the next unvisited polyline points that is outside the intersection region.
* @param polylinePoints - All polyline points (vertices and intersections)
* @returns Any unvisited point that is outside the intersection region if it
* exists or `undefined` otherwise
*/
function getUnvisitedOutsidePoint(polylinePoints: PolylinePoint[]) {
for (let i = 0, len = polylinePoints.length; i < len; i++) {
const point = polylinePoints[i];
if (!point.visited && point.position === PolylinePointPosition.Outside) {
return point;
}
}
}
/**
* Merge two planar polylines (2D)
*/
function mergePolylines(
targetPolyline: Types.Point2[],
sourcePolyline: Types.Point2[]
) {
const targetNormal = getNormal2(targetPolyline);
const sourceNormal = getNormal2(sourcePolyline);
const dotNormals = vec3.dot(sourceNormal, targetNormal);
// Both polylines need to be CW or CCW to be merged and one of them needs to
// be reversed if theirs orientation are not the same
if (!glMatrix.equals(1, dotNormals)) {
sourcePolyline = sourcePolyline.slice().reverse();
}
const { targetPolylinePoints } = getSourceAndTargetPointsList(
targetPolyline,
sourcePolyline
);
const startPoint: PolylinePoint =
getUnvisitedOutsidePoint(targetPolylinePoints);
// Source polyline contains target polyline
if (!startPoint) {
return targetPolyline.slice();
}
const mergedPolyline = [startPoint.coordinates];
let currentPoint = startPoint.next;
while (currentPoint !== startPoint) {
if (
currentPoint.type === PolylinePointType.Intersection &&
(<PolylineIntersectionPoint>currentPoint).cloned
) {
currentPoint = currentPoint.next;
continue;
}
mergedPolyline.push(currentPoint.coordinates);
currentPoint = currentPoint.next;
}
return mergedPolyline;
}
/**
* Subtract two planar polylines (2D)
*/
function subtractPolylines(
targetPolyline: Types.Point2[],
sourcePolyline: Types.Point2[]
): Types.Point2[][] {
const targetNormal = getNormal2(targetPolyline);
const sourceNormal = getNormal2(sourcePolyline);
const dotNormals = vec3.dot(sourceNormal, targetNormal);
// The polylines need to have different orientation (CW+CCW or CCW+CW) to be
// subtracted and one of them needs to be reversed if theirs orientation are
// the same
if (!glMatrix.equals(-1, dotNormals)) {
sourcePolyline = sourcePolyline.slice().reverse();
}
const { targetPolylinePoints } = getSourceAndTargetPointsList(
targetPolyline,
sourcePolyline
);
let startPoint: PolylinePoint = null;
const subtractedPolylines = [];
while ((startPoint = getUnvisitedOutsidePoint(targetPolylinePoints))) {
const subtractedPolyline = [startPoint.coordinates];
let currentPoint = startPoint.next;
startPoint.visited = true;
while (currentPoint !== startPoint) {
currentPoint.visited = true;
if (
currentPoint.type === PolylinePointType.Intersection &&
(<PolylineIntersectionPoint>currentPoint).cloned
) {
currentPoint = currentPoint.next;
continue;
}
subtractedPolyline.push(currentPoint.coordinates);
currentPoint = currentPoint.next;
}
subtractedPolylines.push(subtractedPolyline);
}
return subtractedPolylines;
}
export { mergePolylines, subtractPolylines };
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