three.js/src/extras/geometries/CurvePath.js

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

/**************************************************************
 *	Curved Path - a curve path is simply a array of connected
 *  curves, but retains the api of a curve
 **************************************************************/

THREE.CurvePath = function () {

	this.curves = [];
	this.bends = [];

};

THREE.CurvePath.prototype = new THREE.Curve();
THREE.CurvePath.prototype.constructor = THREE.CurvePath;

THREE.CurvePath.prototype.add = function ( curve ) {

	this.curves.push( curve );

};

THREE.CurvePath.prototype.checkConnection = function() {

};

// Add a line curve  if start and end of lines are not connected

THREE.CurvePath.prototype.closePath = function() {

};

// To get accurate point with reference to
// entire path distance at time t,
// following has to be done:

// 1. Length of each sub path have to be known
// 2. Locate and identify type of curve
// 3. Get t for the curve
// 4. Return curve.getPointAt(t')

THREE.CurvePath.prototype.getPoint = function( t ) {

	var d = t * this.getLength();
	var curveLengths = this.getCurveLengths();
	var i = 0, diff, curve;

	// To think about boundaries points.

	while ( i < curveLengths.length ) {

		if ( curveLengths[ i ] >= d ) {

			diff = curveLengths[ i ] - d;
			curve = this.curves[ i ];

			var u = 1 - diff / curve.getLength();

			return curve.getPointAt( u );

			break;
		}

		i ++;

	}

	return null;

	// loop where sum != 0, sum > d , sum+1 <d

};

/*
THREE.CurvePath.prototype.getTangent = function( t ) {
};*/


// We cannot use the default THREE.Curve getPoint() with getLength() because in
// THREE.Curve, getLength() depends on getPoint() but in THREE.CurvePath
// getPoint() depends on getLength

THREE.CurvePath.prototype.getLength = function() {

	var lens = this.getCurveLengths();
	return lens[ lens.length - 1 ];

};

// Compute lengths and cache them
// We cannot overwrite getLengths() because UtoT mapping uses it.

THREE.CurvePath.prototype.getCurveLengths = function() {

	// We use cache values if curves and cache array are same length

	if ( this.cacheLengths && this.cacheLengths.length == this.curves.length ) {

		return this.cacheLengths;

	};

	// Get length of subsurve
	// Push sums into cached array

	var lengths = [], sums = 0;
	var i, il = this.curves.length;

	for ( i = 0; i < il; i ++ ) {

		sums += this.curves[ i ].getLength();
		lengths.push( sums );

	}

	this.cacheLengths = lengths;

	return lengths;

};



// Returns min and max coordinates, as well as centroid

THREE.CurvePath.prototype.getBoundingBox = function () {

	var points = this.getPoints();

	var maxX, maxY;
	var minX, minY;

	maxX = maxY = Number.NEGATIVE_INFINITY;
	minX = minY = Number.POSITIVE_INFINITY;

	var p, i, il, sum;

	sum = new THREE.Vector2();

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

		p = points[ i ];

		if ( p.x > maxX ) maxX = p.x;
		else if ( p.x < minX ) minX = p.x;

		if ( p.y > maxY ) maxY = p.y;
		else if ( p.y < maxY ) minY = p.y;

		sum.addSelf( p.x, p.y );

	}

	return {

		minX: minX,
		minY: minY,
		maxX: maxX,
		maxY: maxY,
		centroid: sum.divideScalar( il )

	};

};

/**************************************************************
 *	Create Geometries Helpers
 **************************************************************/

/// Generate geometry from path points (for Line or ParticleSystem objects)

THREE.CurvePath.prototype.createPointsGeometry = function( divisions ) {

    var pts = this.getPoints( divisions, true );
	return this.createGeometry( pts );

};

// Generate geometry from equidistance sampling along the path

THREE.CurvePath.prototype.createSpacedPointsGeometry = function( divisions ) {

    var pts = this.getSpacedPoints( divisions, true );
	return this.createGeometry( pts );

};

THREE.CurvePath.prototype.createGeometry = function( points ) {

	var geometry = new THREE.Geometry();

    for( var i = 0; i < points.length; i ++ ) {

        geometry.vertices.push( new THREE.Vertex( new THREE.Vector3( points[ i ].x, points[ i ].y, 0 ) ) );

    }

    return geometry;

};


/**************************************************************
 *	Bend / Wrap Helper Methods
 **************************************************************/

// Wrap path / Bend modifiers?

THREE.CurvePath.prototype.addWrapPath = function ( bendpath ) {

	this.bends.push( bendpath );

};

THREE.CurvePath.prototype.getTransformedPoints = function( segments, bends ) {

	var oldPts = this.getPoints( segments ); // getPoints getSpacedPoints
	var i, il;

	if ( !bends ) {

		bends = this.bends;

	}

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

		oldPts = this.getWrapPoints( oldPts, bends[ i ] );

	}

	return oldPts;

};

THREE.CurvePath.prototype.getTransformedSpacedPoints = function( segments, bends ) {

	var oldPts = this.getSpacedPoints( segments );

	var i, il;

	if ( !bends ) {

		bends = this.bends;

	}

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

		oldPts = this.getWrapPoints( oldPts, bends[ i ] );

	}

	return oldPts;

};

// This returns getPoints() bend/wrapped around the contour of a path.
// Read http://www.planetclegg.com/projects/WarpingTextToSplines.html

THREE.CurvePath.prototype.getWrapPoints = function ( oldPts, path ) {

	var bounds = this.getBoundingBox();

	var i, il, p, oldX, oldY, xNorm;

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

		p = oldPts[ i ];

		oldX = p.x;
		oldY = p.y;

		var xNorm = oldX/ bounds.maxX;

		// If using actual distance, for length > path, requires line extrusions
		//xNorm = path.getUtoTmapping(xNorm, oldX); // 3 styles. 1) wrap stretched. 2) wrap stretch by arc length 3) warp by actual distance

		xNorm = path.getUtoTmapping( xNorm, oldX );

		// check for out of bounds?

		var pathPt = path.getPoint( xNorm );
		var normal = path.getNormalVector( xNorm ).multiplyScalar( oldY );

		p.x = pathPt.x + normal.x;
		p.y = pathPt.y + normal.y;

	}

	return oldPts;

};