three.js/src/extras/ShapeUtils.js

/**
 * @author zz85 / http://www.lab4games.net/zz85/blog
 */

THREE.ShapeUtils = {

	triangulateShape: function ( contour, holes ) {

		function point_in_segment_2D_colin( inSegPt1, inSegPt2, inOtherPt ) {

			// inOtherPt needs to be collinear to the inSegment
			if ( inSegPt1.x !== inSegPt2.x ) {

				if ( inSegPt1.x < inSegPt2.x ) {

					return	( ( inSegPt1.x <= inOtherPt.x ) && ( inOtherPt.x <= inSegPt2.x ) );

				} else {

					return	( ( inSegPt2.x <= inOtherPt.x ) && ( inOtherPt.x <= inSegPt1.x ) );

				}

			} else {

				if ( inSegPt1.y < inSegPt2.y ) {

					return	( ( inSegPt1.y <= inOtherPt.y ) && ( inOtherPt.y <= inSegPt2.y ) );

				} else {

					return	( ( inSegPt2.y <= inOtherPt.y ) && ( inOtherPt.y <= inSegPt1.y ) );

				}

			}

		}

		function intersect_segments_2D( inSeg1Pt1, inSeg1Pt2, inSeg2Pt1, inSeg2Pt2, inExcludeAdjacentSegs ) {

			var EPSILON = 0.0000000001;

			var seg1dx = inSeg1Pt2.x - inSeg1Pt1.x,   seg1dy = inSeg1Pt2.y - inSeg1Pt1.y;
			var seg2dx = inSeg2Pt2.x - inSeg2Pt1.x,   seg2dy = inSeg2Pt2.y - inSeg2Pt1.y;

			var seg1seg2dx = inSeg1Pt1.x - inSeg2Pt1.x;
			var seg1seg2dy = inSeg1Pt1.y - inSeg2Pt1.y;

			var limit		= seg1dy * seg2dx - seg1dx * seg2dy;
			var perpSeg1	= seg1dy * seg1seg2dx - seg1dx * seg1seg2dy;

			if ( Math.abs( limit ) > EPSILON ) {

				// not parallel

				var perpSeg2;
				if ( limit > 0 ) {

					if ( ( perpSeg1 < 0 ) || ( perpSeg1 > limit ) ) 		return [];
					perpSeg2 = seg2dy * seg1seg2dx - seg2dx * seg1seg2dy;
					if ( ( perpSeg2 < 0 ) || ( perpSeg2 > limit ) ) 		return [];

				} else {

					if ( ( perpSeg1 > 0 ) || ( perpSeg1 < limit ) ) 		return [];
					perpSeg2 = seg2dy * seg1seg2dx - seg2dx * seg1seg2dy;
					if ( ( perpSeg2 > 0 ) || ( perpSeg2 < limit ) ) 		return [];

				}

				// i.e. to reduce rounding errors
				// intersection at endpoint of segment#1?
				if ( perpSeg2 === 0 ) {

					if ( ( inExcludeAdjacentSegs ) &&
						 ( ( perpSeg1 === 0 ) || ( perpSeg1 === limit ) ) )		return [];
					return [ inSeg1Pt1 ];

				}
				if ( perpSeg2 === limit ) {

					if ( ( inExcludeAdjacentSegs ) &&
						 ( ( perpSeg1 === 0 ) || ( perpSeg1 === limit ) ) )		return [];
					return [ inSeg1Pt2 ];

				}
				// intersection at endpoint of segment#2?
				if ( perpSeg1 === 0 )		return [ inSeg2Pt1 ];
				if ( perpSeg1 === limit )	return [ inSeg2Pt2 ];

				// return real intersection point
				var factorSeg1 = perpSeg2 / limit;
				return	[ { x: inSeg1Pt1.x + factorSeg1 * seg1dx,
							y: inSeg1Pt1.y + factorSeg1 * seg1dy } ];

			} else {

				// parallel or collinear
				if ( ( perpSeg1 !== 0 ) ||
					 ( seg2dy * seg1seg2dx !== seg2dx * seg1seg2dy ) ) 			return [];

				// they are collinear or degenerate
				var seg1Pt = ( ( seg1dx === 0 ) && ( seg1dy === 0 ) );	// segment1 is just a point?
				var seg2Pt = ( ( seg2dx === 0 ) && ( seg2dy === 0 ) );	// segment2 is just a point?
				// both segments are points
				if ( seg1Pt && seg2Pt ) {

					if ( ( inSeg1Pt1.x !== inSeg2Pt1.x ) ||
						 ( inSeg1Pt1.y !== inSeg2Pt1.y ) )		return [];	// they are distinct  points
					return [ inSeg1Pt1 ];                 						// they are the same point

				}
				// segment#1  is a single point
				if ( seg1Pt ) {

					if ( ! point_in_segment_2D_colin( inSeg2Pt1, inSeg2Pt2, inSeg1Pt1 ) )		return [];		// but not in segment#2
					return [ inSeg1Pt1 ];

				}
				// segment#2  is a single point
				if ( seg2Pt ) {

					if ( ! point_in_segment_2D_colin( inSeg1Pt1, inSeg1Pt2, inSeg2Pt1 ) )		return [];		// but not in segment#1
					return [ inSeg2Pt1 ];

				}

				// they are collinear segments, which might overlap
				var seg1min, seg1max, seg1minVal, seg1maxVal;
				var seg2min, seg2max, seg2minVal, seg2maxVal;
				if ( seg1dx !== 0 ) {

					// the segments are NOT on a vertical line
					if ( inSeg1Pt1.x < inSeg1Pt2.x ) {

						seg1min = inSeg1Pt1; seg1minVal = inSeg1Pt1.x;
						seg1max = inSeg1Pt2; seg1maxVal = inSeg1Pt2.x;

					} else {

						seg1min = inSeg1Pt2; seg1minVal = inSeg1Pt2.x;
						seg1max = inSeg1Pt1; seg1maxVal = inSeg1Pt1.x;

					}
					if ( inSeg2Pt1.x < inSeg2Pt2.x ) {

						seg2min = inSeg2Pt1; seg2minVal = inSeg2Pt1.x;
						seg2max = inSeg2Pt2; seg2maxVal = inSeg2Pt2.x;

					} else {

						seg2min = inSeg2Pt2; seg2minVal = inSeg2Pt2.x;
						seg2max = inSeg2Pt1; seg2maxVal = inSeg2Pt1.x;

					}

				} else {

					// the segments are on a vertical line
					if ( inSeg1Pt1.y < inSeg1Pt2.y ) {

						seg1min = inSeg1Pt1; seg1minVal = inSeg1Pt1.y;
						seg1max = inSeg1Pt2; seg1maxVal = inSeg1Pt2.y;

					} else {

						seg1min = inSeg1Pt2; seg1minVal = inSeg1Pt2.y;
						seg1max = inSeg1Pt1; seg1maxVal = inSeg1Pt1.y;

					}
					if ( inSeg2Pt1.y < inSeg2Pt2.y ) {

						seg2min = inSeg2Pt1; seg2minVal = inSeg2Pt1.y;
						seg2max = inSeg2Pt2; seg2maxVal = inSeg2Pt2.y;

					} else {

						seg2min = inSeg2Pt2; seg2minVal = inSeg2Pt2.y;
						seg2max = inSeg2Pt1; seg2maxVal = inSeg2Pt1.y;

					}

				}
				if ( seg1minVal <= seg2minVal ) {

					if ( seg1maxVal <  seg2minVal )	return [];
					if ( seg1maxVal === seg2minVal )	{

						if ( inExcludeAdjacentSegs )		return [];
						return [ seg2min ];

					}
					if ( seg1maxVal <= seg2maxVal )	return [ seg2min, seg1max ];
					return	[ seg2min, seg2max ];

				} else {

					if ( seg1minVal >  seg2maxVal )	return [];
					if ( seg1minVal === seg2maxVal )	{

						if ( inExcludeAdjacentSegs )		return [];
						return [ seg1min ];

					}
					if ( seg1maxVal <= seg2maxVal )	return [ seg1min, seg1max ];
					return	[ seg1min, seg2max ];

				}

			}

		}

		function isPointInsideAngle( inVertex, inLegFromPt, inLegToPt, inOtherPt ) {

			// The order of legs is important

			var EPSILON = 0.0000000001;

			// translation of all points, so that Vertex is at (0,0)
			var legFromPtX	= inLegFromPt.x - inVertex.x,  legFromPtY	= inLegFromPt.y - inVertex.y;
			var legToPtX	= inLegToPt.x	- inVertex.x,  legToPtY		= inLegToPt.y	- inVertex.y;
			var otherPtX	= inOtherPt.x	- inVertex.x,  otherPtY		= inOtherPt.y	- inVertex.y;

			// main angle >0: < 180 deg.; 0: 180 deg.; <0: > 180 deg.
			var from2toAngle	= legFromPtX * legToPtY - legFromPtY * legToPtX;
			var from2otherAngle	= legFromPtX * otherPtY - legFromPtY * otherPtX;

			if ( Math.abs( from2toAngle ) > EPSILON ) {

				// angle != 180 deg.

				var other2toAngle		= otherPtX * legToPtY - otherPtY * legToPtX;
				// console.log( "from2to: " + from2toAngle + ", from2other: " + from2otherAngle + ", other2to: " + other2toAngle );

				if ( from2toAngle > 0 ) {

					// main angle < 180 deg.
					return	( ( from2otherAngle >= 0 ) && ( other2toAngle >= 0 ) );

				} else {

					// main angle > 180 deg.
					return	( ( from2otherAngle >= 0 ) || ( other2toAngle >= 0 ) );

				}

			} else {

				// angle == 180 deg.
				// console.log( "from2to: 180 deg., from2other: " + from2otherAngle  );
				return	( from2otherAngle > 0 );

			}

		}


		function removeHoles( contour, holes ) {

			var shape = contour.concat(); // work on this shape
			var hole;

			function isCutLineInsideAngles( inShapeIdx, inHoleIdx ) {

				// Check if hole point lies within angle around shape point
				var lastShapeIdx = shape.length - 1;

				var prevShapeIdx = inShapeIdx - 1;
				if ( prevShapeIdx < 0 )			prevShapeIdx = lastShapeIdx;

				var nextShapeIdx = inShapeIdx + 1;
				if ( nextShapeIdx > lastShapeIdx )	nextShapeIdx = 0;

				var insideAngle = isPointInsideAngle( shape[ inShapeIdx ], shape[ prevShapeIdx ], shape[ nextShapeIdx ], hole[ inHoleIdx ] );
				if ( ! insideAngle ) {

					// console.log( "Vertex (Shape): " + inShapeIdx + ", Point: " + hole[inHoleIdx].x + "/" + hole[inHoleIdx].y );
					return	false;

				}

				// Check if shape point lies within angle around hole point
				var lastHoleIdx = hole.length - 1;

				var prevHoleIdx = inHoleIdx - 1;
				if ( prevHoleIdx < 0 )			prevHoleIdx = lastHoleIdx;

				var nextHoleIdx = inHoleIdx + 1;
				if ( nextHoleIdx > lastHoleIdx )	nextHoleIdx = 0;

				insideAngle = isPointInsideAngle( hole[ inHoleIdx ], hole[ prevHoleIdx ], hole[ nextHoleIdx ], shape[ inShapeIdx ] );
				if ( ! insideAngle ) {

					// console.log( "Vertex (Hole): " + inHoleIdx + ", Point: " + shape[inShapeIdx].x + "/" + shape[inShapeIdx].y );
					return	false;

				}

				return	true;

			}

			function intersectsShapeEdge( inShapePt, inHolePt ) {

				// checks for intersections with shape edges
				var sIdx, nextIdx, intersection;
				for ( sIdx = 0; sIdx < shape.length; sIdx ++ ) {

					nextIdx = sIdx + 1; nextIdx %= shape.length;
					intersection = intersect_segments_2D( inShapePt, inHolePt, shape[ sIdx ], shape[ nextIdx ], true );
					if ( intersection.length > 0 )		return	true;

				}

				return	false;

			}

			var indepHoles = [];

			function intersectsHoleEdge( inShapePt, inHolePt ) {

				// checks for intersections with hole edges
				var ihIdx, chkHole,
					hIdx, nextIdx, intersection;
				for ( ihIdx = 0; ihIdx < indepHoles.length; ihIdx ++ ) {

					chkHole = holes[ indepHoles[ ihIdx ]];
					for ( hIdx = 0; hIdx < chkHole.length; hIdx ++ ) {

						nextIdx = hIdx + 1; nextIdx %= chkHole.length;
						intersection = intersect_segments_2D( inShapePt, inHolePt, chkHole[ hIdx ], chkHole[ nextIdx ], true );
						if ( intersection.length > 0 )		return	true;

					}

				}
				return	false;

			}

			var holeIndex, shapeIndex,
				shapePt, holePt,
				holeIdx, cutKey, failedCuts = [],
				tmpShape1, tmpShape2,
				tmpHole1, tmpHole2;

			for ( var h = 0, hl = holes.length; h < hl; h ++ ) {

				indepHoles.push( h );

			}

			var minShapeIndex = 0;
			var counter = indepHoles.length * 2;
			while ( indepHoles.length > 0 ) {

				counter --;
				if ( counter < 0 ) {

					console.log( "Infinite Loop! Holes left:" + indepHoles.length + ", Probably Hole outside Shape!" );
					break;

				}

				// search for shape-vertex and hole-vertex,
				// which can be connected without intersections
				for ( shapeIndex = minShapeIndex; shapeIndex < shape.length; shapeIndex ++ ) {

					shapePt = shape[ shapeIndex ];
					holeIndex	= - 1;

					// search for hole which can be reached without intersections
					for ( var h = 0; h < indepHoles.length; h ++ ) {

						holeIdx = indepHoles[ h ];

						// prevent multiple checks
						cutKey = shapePt.x + ":" + shapePt.y + ":" + holeIdx;
						if ( failedCuts[ cutKey ] !== undefined )			continue;

						hole = holes[ holeIdx ];
						for ( var h2 = 0; h2 < hole.length; h2 ++ ) {

							holePt = hole[ h2 ];
							if ( ! isCutLineInsideAngles( shapeIndex, h2 ) )		continue;
							if ( intersectsShapeEdge( shapePt, holePt ) )		continue;
							if ( intersectsHoleEdge( shapePt, holePt ) )		continue;

							holeIndex = h2;
							indepHoles.splice( h, 1 );

							tmpShape1 = shape.slice( 0, shapeIndex + 1 );
							tmpShape2 = shape.slice( shapeIndex );
							tmpHole1 = hole.slice( holeIndex );
							tmpHole2 = hole.slice( 0, holeIndex + 1 );

							shape = tmpShape1.concat( tmpHole1 ).concat( tmpHole2 ).concat( tmpShape2 );

							minShapeIndex = shapeIndex;

							// Debug only, to show the selected cuts
							// glob_CutLines.push( [ shapePt, holePt ] );

							break;

						}
						if ( holeIndex >= 0 )	break;		// hole-vertex found

						failedCuts[ cutKey ] = true;			// remember failure

					}
					if ( holeIndex >= 0 )	break;		// hole-vertex found

				}

			}

			return shape; 			/* shape with no holes */

		}


		var i, il, f, face,
			key, index,
			allPointsMap = {};

		// To maintain reference to old shape, one must match coordinates, or offset the indices from original arrays. It's probably easier to do the first.

		var allpoints = contour.concat();

		for ( var h = 0, hl = holes.length; h < hl; h ++ ) {

			Array.prototype.push.apply( allpoints, holes[ h ] );

		}

		//console.log( "allpoints",allpoints, allpoints.length );

		// prepare all points map

		for ( i = 0, il = allpoints.length; i < il; i ++ ) {

			key = allpoints[ i ].x + ":" + allpoints[ i ].y;

			if ( allPointsMap[ key ] !== undefined ) {

				console.warn( "THREE.Shape: Duplicate point", key );

			}

			allPointsMap[ key ] = i;

		}

		// remove holes by cutting paths to holes and adding them to the shape
		var shapeWithoutHoles = removeHoles( contour, holes );

		var triangles = THREE.FontUtils.Triangulate( shapeWithoutHoles, false ); // True returns indices for points of spooled shape
		//console.log( "triangles",triangles, triangles.length );

		// check all face vertices against all points map

		for ( i = 0, il = triangles.length; i < il; i ++ ) {

			face = triangles[ i ];

			for ( f = 0; f < 3; f ++ ) {

				key = face[ f ].x + ":" + face[ f ].y;

				index = allPointsMap[ key ];

				if ( index !== undefined ) {

					face[ f ] = index;

				}

			}

		}

		return triangles.concat();

	},

	isClockWise: function ( pts ) {

		return THREE.FontUtils.Triangulate.area( pts ) < 0;

	},

	// Bezier Curves formulas obtained from
	// http://en.wikipedia.org/wiki/B%C3%A9zier_curve

	// Quad Bezier Functions

	b2p0: function ( t, p ) {

		var k = 1 - t;
		return k * k * p;

	},

	b2p1: function ( t, p ) {

		return 2 * ( 1 - t ) * t * p;

	},

	b2p2: function ( t, p ) {

		return t * t * p;

	},

	b2: function ( t, p0, p1, p2 ) {

		return this.b2p0( t, p0 ) + this.b2p1( t, p1 ) + this.b2p2( t, p2 );

	},

	// Cubic Bezier Functions

	b3p0: function ( t, p ) {

		var k = 1 - t;
		return k * k * k * p;

	},

	b3p1: function ( t, p ) {

		var k = 1 - t;
		return 3 * k * k * t * p;

	},

	b3p2: function ( t, p ) {

		var k = 1 - t;
		return 3 * k * t * t * p;

	},

	b3p3: function ( t, p ) {

		return t * t * t * p;

	},

	b3: function ( t, p0, p1, p2, p3 ) {

		return this.b3p0( t, p0 ) + this.b3p1( t, p1 ) + this.b3p2( t, p2 ) +  this.b3p3( t, p3 );

	}

};