path: root/app/bin/cbezier.c

/** \file cbezier.c
 * Bezier Command. Draw or modify a Bezier (Track or Line).
 */
/*  XTrkCad - Model Railroad CAD
*
* Cubic Bezier curves have a definitional representation as an a set of four points.
* The first and fourth are the end points, while the middle two are control points.
* The control points positions define the angle at the ends and by their relative positions the overall
* curvature. This representation is a familiar approach for those who know drawing programs such as Adobe
* Illustrator or CorelDraw.
*
* In XTrackCAD, the Bezier form is also represented and drawn as a set of
* joined circular arcs that approximate the Bezier form within a small tolerance. This is because
* many of the operations we need to do are either computationally difficult or
* impossible using the Bezier equations. For example, creating a parallel Bezier
* which is necessary to draw a track with two lines or sleepers has no easy, stable solution.
* But the program is already able to do these tasks for straight lines and curves.
*
* Note that every time we change the Bezier points we have to recalculate the arc approximation,
* but that means that the majority of the time we are using the simpler approximation.
*
* We do not allow Bezier curves that have loops or cusps as they make no sense for tracks and
* can easily be approximated for lines with multiple unaligned Bezier curves.
*
* This program borrows from particular ideas about converting Bezier curves that Pomax placed into
* open source. The originals in Javascript can be found at github.com/Pomax.
* The web pages that explain many other techniques are located at https://pomax.github.io/bezierinfo
*
*  This program is free software; you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation; either version 2 of the License, or
*  (at your option) any later version.
*
*  This program is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with this program; if not, write to the Free Software
*  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/


#include "common.h"
#include "draw.h"
#include "ccurve.h"
#include "cbezier.h"
#include "tbezier.h"
#include "cstraigh.h"
#include "drawgeom.h"
#include "cjoin.h"
#include "common.h"
#include "track.h"
#include "wcolors.h"
#include "param.h"
#include "fileio.h"
#include "layout.h"
#include "cundo.h"
#include "compound.h"



/*
 * STATE INFO
 */
enum Bezier_States { NONE,
                     POS_1,
                     CONTROL_ARM_1,
                     POS_2,
                     CONTROL_ARM_2,
                     PICK_POINT,
                     POINT_PICKED,
                     TRACK_SELECTED
                   };

typedef struct {
	curveData_t curveData;
	double start;
	double end;
	coOrd pos0;
	coOrd pos1;
} bCurveData_t;

static struct {
	enum Bezier_States state;
	coOrd pos[4];
	int selectPoint;
	track_p trk[2];
	EPINX_T ep[2];
	dynArr_t crvSegs_da;
	int crvSegs_da_cnt;
	trkSeg_t cp1Segs_da[4];
	int cp1Segs_da_cnt;
	trkSeg_t cp2Segs_da[4];
	int cp2Segs_da_cnt;
	BOOL_T unlocked;
	track_p selectTrack;
	BOOL_T track;
	DIST_T minRadius;
	DIST_T trackGauge;
} Da;

static dynArr_t anchors_da;
#define anchors(N) DYNARR_N(trkSeg_t,anchors_da,N)

/**
 * Draw a ControlArm.
 * A control arm has two filled or unfilled circles for endpoints and a straight line between them.
 * If the end or control point is not selectable we don't mark it with a circle.
 * If a selectable end or control point is unlocked place a filled circle on it, otherwise an empty circle.
 * A red color indicates that this arm, end or control point is "active" as it was selected.
 */
int createControlArm(
        trkSeg_t sp[],   //seg pointer for up to 3 trkSegs (ends and line)
        coOrd pos0,     //end on curve
        coOrd pos1,     // control point at other end of line
        BOOL_T track,   // isTrack()? (otherwise Line)
        BOOL_T selectable, 	// can this arm be selected?
        BOOL_T cp_direction_locked, //isFixed to track
        int point_selected, //number of point 0, 1 or -1
        wDrawColor color   //drawColorBlack or drawColorWhite
)
{
	DIST_T d, w;
	d = tempD.scale*0.25;
	w = tempD.scale/tempD.dpi; /*double width*/
	sp[0].u.l.pos[0] = pos0;
	sp[0].u.l.pos[1] = pos1;
	sp[0].type = SEG_STRLIN;
	sp[0].lineWidth = w;
	sp[0].color = (point_selected>=0)?drawColorRed:drawColorBlack;
	int n = 0;
	if (selectable) {
		for (int j=0; j<2; j++) {
			if (j==0 && cp_direction_locked) { continue; }   //Don't show select circle if end locked
			n++;
			sp[n].u.c.center = j==0?pos0:pos1;
			sp[n].u.c.radius = d/4;
			sp[n].lineWidth = w;
			sp[n].color = (j==point_selected)?drawColorRed:drawColorBlack;
			if (j==point_selected && cp_direction_locked) {
				sp[n].type = SEG_FILCRCL;
			} else {
				sp[n].type = SEG_CRVLIN;
				sp[n].u.c.a0 = 0.0;
				sp[n].u.c.a1 = 360.0;
			}
		}
	}
	return n+1;
}

coOrd getPoint(coOrd pos[4], double s)
{
	double mt = 1-s;
	double a = mt*mt*mt;
	double b = mt*mt*s*3;
	double c = mt*s*s*3;
	double d = s*s*s;
	coOrd ret;
	ret.x = a*pos[0].x + b*pos[1].x + c*pos[2].x + d*pos[3].x;
	ret.y = a*pos[0].y + b*pos[1].y + c*pos[2].y + d*pos[3].y;
	return ret;
}
/*
 * Get Error between a Bezier and an arc centered at pc that goes from start to end
 *
 * Because the curve is defined to pass through the start and the end and the middle, the test is
 * to see how much of an error there is between those points. If the sum of the errors is off by more \
 * than 0.5 pixels - that will mean it is not a good fit.
 *
 */
double BezError(coOrd pos[4], coOrd center, coOrd start_point, double start,
                double end)
{
	double quarter = (end - start) / 4;  // take point at 1/4 and 3/4 and check
	coOrd c1 = getPoint(pos, start + quarter);
	coOrd c2 = getPoint(pos, end - quarter);
	double ref = FindDistance(center, start_point); //radius
	double d1  = FindDistance(center, c1);          // distance to quarter
	double d2  = FindDistance(center, c2);          // distance to three quarters
	return fabs(d1-ref) + fabs(d2
	                           -ref);               //total error at quarter points
};

/*
 * Get distance between a point and a line segment
 */

double DistanceToLineSegment(coOrd p, coOrd l1, coOrd l2)
{
	double A = p.x - l1.x;
	double B = p.y - l1.y;
	double C = l2.x - l1.x;
	double D = l2.y - l1.y;

	double dot = A * C + B * D;
	double len_sq = C * C + D * D;
	double param = -1;
	if (len_sq != 0) { //non 0 length line
		param = dot / len_sq;
	}

	double xx, yy;

	if (param < 0) {      // zero length line or beyond end use point 1
		xx = l1.x;
		yy = l1.y;
	}  else if (param > 1) {  // beyond point 2 end of line segment
		xx = l2.x;
		yy = l2.y;
	}  else {					// In the middle
		xx = l1.x + param * C;
		yy = l1.y + param * D;
	}

	double dx = p.x - xx;        //distance to perpendicular (or end point)
	double dy = p.y - yy;
	return sqrt(dx * dx + dy * dy);
}

/*
 * Get Error between a straight line segment and the Bezier curve.
 * Sum distance to straight line of quarter points.
 */

double BezErrorLine(coOrd pos[4], coOrd start_point, coOrd end_point,
                    double start, double end)
{
	double quarter = (end - start) / 4;  // take point at 1/4 and 3/4 and check
	coOrd c1 = getPoint(pos, start + quarter);
	coOrd c2 = getPoint(pos, end - quarter);
	double d1 = DistanceToLineSegment(c1, start_point, end_point);
	double d2 = DistanceToLineSegment(c2, start_point, end_point);
	return fabs(d1)+fabs(d2);
}

/*
 * Add element to DYNARR pointed to by caller from segment handed in
 */
void addSegBezier(dynArr_t * array_p, trkSeg_p seg)
{
	trkSeg_p s;


	DYNARR_APPEND(trkSeg_t,* array_p, 1);          //Adds 1 to cnt
	s = &DYNARR_N(trkSeg_t,*array_p,(array_p->cnt)-1);
	s->type = seg->type;
	s->color = seg->color;
	s->lineWidth = seg->lineWidth;
	DYNARR_INIT( trkSeg_t, s->bezSegs );
	if ((s->type == SEG_BEZLIN || s->type == SEG_BEZTRK) && seg->bezSegs.cnt) {
		s->u.b.angle0 = seg->u.b.angle0;  //Copy all the rest
		s->u.b.angle3 = seg->u.b.angle3;
		s->u.b.length = seg->u.b.length;
		s->u.b.minRadius = seg->u.b.minRadius;
		for (int i=0; i<4; i++) { s->u.b.pos[i] = seg->u.b.pos[i]; }
		s->u.b.radius0 = seg->u.b.radius3;
		// TODO we init'd the DA above, why free it now?
		DYNARR_FREE( trkSeg_t, s->bezSegs );
		//Make sure new space as addr copied in earlier from seg
		for (int i = 0; i<seg->bezSegs.cnt; i++) {
			//recurse for copying embedded Beziers as in Cornu joint
			addSegBezier(&s->bezSegs, &DYNARR_N( trkSeg_t, seg->bezSegs, i ) );
		}
	} else {
		s->u = seg->u;
	}
}

enum BezierType {PLAIN, LOOP, CUSP, INFLECTION, DOUBLEINFLECTION, LINE, ENDS, COINCIDENT } bType;

/*
 * Analyse Bezier.
 *
 * Using results from Maureen C. Stone of XeroxParc and Tony deRose of U of Washington
 * characterise the curve type and find out what features it has.
 * We will eliminate cusps and loops as not useful forms. Line, Plain, Inflection and DoubleInflection are ok.
 *
 */
EXPORT enum BezierType AnalyseCurve(coOrd inpos[4], double *Rfx, double *Rfy,
                                    double *cusp)
{

	*Rfx = *Rfy = 0;
	if (Da.track && inpos[0].x == inpos[3].x && inpos[0].y == inpos[3].y ) {
		return ENDS;
	}

	DIST_T d01 = FindDistance(inpos[0],inpos[1]);
	DIST_T d12 = FindDistance(inpos[1],inpos[2]);
	DIST_T d02 = FindDistance(inpos[0],inpos[2]);
	if (d01+d12 == d02) {								//straight
		DIST_T d23 = FindDistance(inpos[2],inpos[3]);
		DIST_T d03 = FindDistance(inpos[0],inpos[3]);
		if (d02+d23 == d03) { return LINE; }
	}
	int common_points = 0;
	for (int i=0; i<3; i++) {
		if (inpos[i].x == inpos[i+1].x && inpos[i].y == inpos[i+1].y) { common_points++; }
	}
	for (int i=0; i<2; i++) {
		if (inpos[i].x == inpos[i+2].x && inpos[i].y == inpos[i+2].y) { common_points++; }
	}

	if (common_points>2) {
		return COINCIDENT;
	}

	coOrd pos[4];
	coOrd offset2, offset = inpos[0];

	for (int i=0; i<4; i++) {     				//move to zero origin
		pos[i].x = inpos[i].x-offset.x;
		pos[i].y = inpos[i].y-offset.y;
	}

	offset2.x = -offset.x + pos[3].x;
	offset2.y = -offset.y + pos[3].y;
	if (pos[1].y == 0.0) {   					//flip order of points
		for (int i=0; i<4; i++) {
			coOrd temp_pos = pos[i];
			pos[i].x = pos[3-i].x - offset2.x;
			pos[i].y = pos[3-i].y - offset2.y;
			pos[3-i] = temp_pos;
		}
		if (pos[1].y ==
		    0.0) {					//Both ways round the second point has no y left after translation
			return PLAIN;
		}
	}
	double f21 = (pos[2].y)/(pos[1].y);
	double f31 = (pos[3].y)/(pos[1].y);
	if (fabs(pos[2].x-(pos[1].x*f21)) <0.0001) { return PLAIN; }   //defend against divide by zero
	double fx = (pos[3].x-(pos[1].x*f31))/(pos[2].x-(pos[1].x*f21));
	double fy = f31+(1-f21)*fx;
	*Rfx = fx;
	*Rfy = fy;
	*cusp = fabs(fy - (-(fx*fx)+2*fx+3)/4);

	if (fy > 1.0) { return INFLECTION; }
	if (fx >= 1.0) { return PLAIN; }
	if (fabs(fy - (-(fx*fx)+2*fx+3)/4) <0.100) { return CUSP; }
	if (fy < (-(fx*fx)+2*fx+3)/4) {
		if (fx <= 0.0 && fy >= (3*fx-(fx*fx))/3) { return LOOP; }
		if (fx > 0.0 && fy >= (sqrt(3*(4*fx-fx*fx))-fx)/2) { return LOOP; }
		return PLAIN;
	}

	return DOUBLEINFLECTION;
}

/*
 * ConvertToArcs
 * Take a Bezier curve and turn it into a set of circular arcs, such that the error between the arc and the
 * Bezier is under 0.5 pixels at maxiumum zoom.
 *
 * This enables us to use normal methods (operating over the array of arcs)
 * to perform actions on the Bezier and also to export it to DXF.
 *
 */
EXPORT BOOL_T ConvertToArcs (coOrd pos[4], dynArr_t * segs, BOOL_T track,
                             wDrawColor color, LWIDTH_T lineWidth)
{
	double t_s = 0.0, t_e = 1.0;
	double errorThreshold = 0.05;
	bCurveData_t prev_arc;
	prev_arc.end = 0.0;
	bCurveData_t arc;
	DYNARR_RESET( trkSeg_t, *segs ); // wipe out
	BOOL_T safety;
	int col = 0;

	double prev_e = 0.0;
	// we do a binary search to find the "good `t` closest to no-longer-good"
	do {
		safety=FALSE;
		// step 1: start with the maximum possible arc length
		t_e = 1.0;
		// points:
		coOrd start_point, mid_point, end_point;
		// booleans:
		BOOL_T curr_good = FALSE, prev_good = FALSE, done = FALSE;
		// numbers:
		double t_m, step = 0;
		// step 2: find the best possible arc
		do {						// !done
			prev_good = curr_good;   //remember last time
			t_m = (t_s + t_e)/2;
			step++;
			start_point = getPoint(pos, t_s); //Start of arc
			mid_point = getPoint(pos, t_m);  //Middle of trial arc
			end_point = getPoint(pos, t_e);  //End of trial Arc

			PlotCurve( crvCmdFromChord, start_point, end_point, mid_point,
			           &(arc.curveData), FALSE, 0.0 );  //Find Arc through three points

			arc.start = t_s; 		//remember start
			arc.end = t_e;			//remember end
			arc.pos0 = start_point; //remember start point (used for Straight)
			arc.pos1 = end_point;	// Remember end point (used for Straight)

			if (arc.curveData.type == curveTypeStraight) {
				double error = BezErrorLine(pos,start_point,end_point, t_s, t_e);
				curr_good = (error <= errorThreshold/4);
				//arc.curveData.a0 = FindAngle(start_point,end_point);
				//arc.curveData.a1 = FindAngle(end_point,start_point);

			} else if (arc.curveData.type == curveTypeNone) {
				return FALSE;			//Something wrong
			} else {
				double error = BezError(pos, arc.curveData.curvePos, start_point, t_s, t_e);
				curr_good = (error <= errorThreshold/4);
			};

			done = prev_good && !curr_good; //Was better than this last time?
			if(!done) {
				// this arc is fine: we can move 'e' up to see if we can find a wider arc
				if(curr_good) {
					prev_e = t_e;		  //remember good end only
					prev_arc = arc;
					// if e is already at max, then we're done for this arc.
					if (t_e >= 1.0) {
						// make sure we cap at t=1
						arc.end = prev_e = 1.0;
						// if we capped the arc segment to t=1 we also need to make sure that
						// the arc's end angle is correct with respect to the bezier end point.
						if (t_e > 1.0) {
							if (arc.curveData.type != curveTypeStraight) {
								coOrd d;
								d.x = arc.curveData.curvePos.x + fabs(arc.curveData.curveRadius) * cos(D2R(
								                        arc.curveData.a1));
								d.y = arc.curveData.curvePos.y + fabs(arc.curveData.curveRadius) * sin(D2R(
								                        arc.curveData.a1));

								arc.curveData.a1 += FindAngle(d, getPoint(pos,1.0));
								t_e = 1.0;
							}
						}
						prev_arc = arc;
						done = TRUE;
						break;
					}
					// if not, move it up by half the iteration distance or to end
					t_e = t_e + (t_e-t_s)/2;
					if (t_e > 1.0) { t_e = 1.0; }
				}
				// this is a bad arc: we need to move 'e' down to find a good arc
				else {
					t_e = t_m;
				}
			}         // If !Done end
		} while(!done && safety++<100);
		if(safety>=100) {
			return FALSE;				//Failed to make into arcs
		}
		prev_arc = prev_arc.end==0.0?arc:prev_arc;
		trkSeg_t curveSeg;  			//Now set up tempSeg to copy into array
		curveSeg.lineWidth = track?0:lineWidth;
		if ( prev_arc.curveData.type == curveTypeCurve ) {
			if (track) {
				curveSeg.color = (fabs(prev_arc.curveData.curveRadius)<
				                  (GetLayoutMinTrackRadius()-EPSILON))?exceptionColor:normalColor;
			} else {
				curveSeg.color = color;
			}
			curveSeg.type = track?SEG_CRVTRK:SEG_CRVLIN;
			curveSeg.u.c.a0 = prev_arc.curveData.a0;
			curveSeg.u.c.a1 = prev_arc.curveData.a1;
			curveSeg.u.c.center = prev_arc.curveData.curvePos;
			if (prev_arc.curveData.negative) {
				curveSeg.u.c.radius = -prev_arc.curveData.curveRadius;
			} else {
				curveSeg.u.c.radius = prev_arc.curveData.curveRadius;
			}
		} else {											//Straight Line because all points co-linear
			curveSeg.type = track?SEG_STRTRK:SEG_STRLIN;
			if (track) {
				curveSeg.color = wDrawColorBlack;
			} else {
				curveSeg.color = color;
			}
			curveSeg.u.l.angle = FindAngle(prev_arc.pos0,prev_arc.pos1);
			curveSeg.u.l.pos[0] = prev_arc.pos0;
			curveSeg.u.l.pos[1] = prev_arc.pos1;
			curveSeg.u.l.option = 0;
		}
		addSegBezier(segs, &curveSeg);		//Add to array of segs used
		t_s = prev_e;
		col++;
	} while(prev_e < 1.0);

	return TRUE;
};
/*
 * Draw Bezier while editing it. It consists of three elements - the curve and one or two control arms.
 *
 */

static void DrawBezCurve(trkSeg_p control_arm1,
                         int cp1Segs_cnt,
                         trkSeg_p control_arm2,
                         int cp2Segs_cnt,
                         trkSeg_p curveSegs,
                         int crvSegs_cnt,
                         wDrawColor color
                        )
{
	if (crvSegs_cnt && curveSegs) {
		DrawSegs( &tempD, zero, 0.0, curveSegs, crvSegs_cnt, Da.trackGauge, color );
	}
	if (cp1Segs_cnt && control_arm1) {
		DrawSegs( &tempD, zero, 0.0, control_arm1, cp1Segs_cnt, Da.trackGauge,
		          drawColorBlack );
	}
	if (cp2Segs_cnt && control_arm2) {
		DrawSegs( &tempD, zero, 0.0, control_arm2, cp2Segs_cnt, Da.trackGauge,
		          drawColorBlack );
	}

}

/*
 * Undraw the temp Bezier
 */

/*
 * If Track, make it red if the radius is below minimum
 */
void DrawTempBezier(BOOL_T track)
{
	if (track) {
		DrawBezCurve(Da.cp1Segs_da,Da.cp1Segs_da_cnt,Da.cp2Segs_da,Da.cp2Segs_da_cnt,
		             &DYNARR_N(trkSeg_t,Da.crvSegs_da,0),Da.crvSegs_da_cnt,
		             fabs(Da.minRadius)<(GetLayoutMinTrackRadius()-EPSILON)?exceptionColor:
		             normalColor);
	} else {
		DrawBezCurve(Da.cp1Segs_da,Da.cp1Segs_da_cnt,Da.cp2Segs_da,Da.cp2Segs_da_cnt,
		             &DYNARR_N(trkSeg_t,Da.crvSegs_da,0),Da.crvSegs_da_cnt,
		             drawColorBlack);        //Add Second Arm
	}
}

void CreateBothControlArms(int selectPoint, BOOL_T track)
{
	if (selectPoint == -1) {
		Da.cp1Segs_da_cnt = createControlArm(Da.cp1Segs_da, Da.pos[0],
		                                     Da.pos[1], track, TRUE, Da.trk[0]!=NULL, -1,
		                                     drawColorBlack);
		Da.cp2Segs_da_cnt = createControlArm(Da.cp2Segs_da, Da.pos[3],
		                                     Da.pos[2], track, TRUE, Da.trk[1]!=NULL, -1,
		                                     drawColorBlack);
	} else if (selectPoint == 0 || selectPoint == 1) {
		Da.cp1Segs_da_cnt = createControlArm(Da.cp1Segs_da, Da.pos[0],
		                                     Da.pos[1], track, TRUE, Da.trk[0]!=NULL, selectPoint,
		                                     drawColorBlack);
		Da.cp2Segs_da_cnt = createControlArm(Da.cp2Segs_da, Da.pos[3],
		                                     Da.pos[2], track, FALSE, Da.trk[1]!=NULL, -1,
		                                     drawColorBlack);
	} else {
		Da.cp1Segs_da_cnt = createControlArm(Da.cp1Segs_da, Da.pos[0],
		                                     Da.pos[1], track, FALSE, Da.trk[0]!=NULL, -1,
		                                     drawColorBlack);
		Da.cp2Segs_da_cnt = createControlArm(Da.cp2Segs_da, Da.pos[3],
		                                     Da.pos[2], track, TRUE, Da.trk[1]!=NULL,
		                                     3-selectPoint, drawColorBlack);
	}
}

void CreateMoveAnchor(coOrd pos,BOOL_T fill)
{
	double d = tempD.scale*0.15;
	DYNARR_APPEND(trkSeg_t,anchors_da,1);
	int inx = anchors_da.cnt-1;
	anchors(inx).type = fill?SEG_FILCRCL:SEG_CRVLIN;
	anchors(inx).u.c.a0 = 0.0;
	anchors(inx).u.c.a1 = 360.0;
	anchors(inx).lineWidth = 0;
	anchors(inx).color = wDrawColorBlue;
	anchors(inx).u.c.radius = d/4;
	anchors(inx).u.c.center = pos;
}

/*
 * AdjustBezCurve
 *
 * Called to adjust the curve either when creating it or modifying it
 * States are "PICK_POINT" and "POINT_PICKED" and "TRACK_SELECTED".
 *
 * In PICK_POINT, the user can select an end-point to drag and release in POINT_PICKED. They can also
 * hit Enter (which saves the changes) or ESC (which cancels them).
 *
 * Only those points which can be picked are shown with circles - locked end-points are not shown.
 *
 * SHIFT at release will lock , re-locking any end-points that are aligned with like items at the same position
 * (Track to unconnected Track, Line to any Line end).
 *
 */
EXPORT STATUS_T AdjustBezCurve(
        wAction_t action,
        coOrd pos,
        BOOL_T track,
        wDrawColor color,
        LWIDTH_T lineWidth,
        bezMessageProc message )
{
	track_p t;
	DIST_T d;
	ANGLE_T angle1, angle2;
	static coOrd pos0, /* pos3,*/ p;
	enum BezierType b;
	DIST_T dd;
	EPINX_T ep;
	double fx, fy, cusp;
//	int controlArm = -1;


	if (Da.state != PICK_POINT && Da.state != POINT_PICKED
	    && Da.state != TRACK_SELECTED) { return C_CONTINUE; }

	switch ( action & 0xFF) {

	case C_START:
		Da.selectPoint = -1;
		CreateBothControlArms(Da.selectPoint, track);
		if (ConvertToArcs(Da.pos,&Da.crvSegs_da,track,color,lineWidth)) { Da.crvSegs_da_cnt = Da.crvSegs_da.cnt; }
		Da.minRadius = BezierMinRadius(Da.pos,Da.crvSegs_da);
		Da.unlocked = FALSE;
		if (track) {
			InfoMessage( _("Select End-Point - Ctrl unlocks end-point") );
		} else {
			InfoMessage( _("Select End-Point") );
		}
		return C_CONTINUE;

	case wActionMove:
		DYNARR_RESET(trkSeg_t,anchors_da);
		if (Da.state != PICK_POINT) { return C_CONTINUE; }
		if (Da.state != PICK_POINT) { return C_CONTINUE; }
		for (int i=0; i<4; i++) {
			if (i==0 && Da.trk[0]) { continue; }
			if (i==3 && Da.trk[1]) { continue; }   //ignore locked points
			d = FindDistance(Da.pos[i],pos);
			if (IsClose(d))	{ CreateMoveAnchor(Da.pos[i],TRUE); }
		}
		break;

	case C_DOWN:
		if (Da.state != PICK_POINT) { return C_CONTINUE; }
		dd = DIST_INF;
		Da.selectPoint = -1;
		for (int i=0; i<4; i++) {
			d = FindDistance(Da.pos[i],pos);
			if (d < dd) {
				if (i==0 && Da.trk[0]) { continue; }
				if (i==3 && Da.trk[1]) { continue; }   //ignore locked points
				dd = d;
				Da.selectPoint = i;
			}

		}
		if (!IsClose(dd) )	{ Da.selectPoint = -1; }
		DYNARR_RESET(trkSeg_t,anchors_da);
		if (Da.selectPoint == -1) {
			InfoMessage( _("Not close enough to any valid, selectable point, reselect") );
			return C_CONTINUE;
		} else {
			pos = Da.pos[Da.selectPoint];
			CreateMoveAnchor(pos,TRUE);
			Da.state = POINT_PICKED;
			InfoMessage( _("Drag point %d to new location and release it"),
			             Da.selectPoint+1 );
		}
		CreateBothControlArms(Da.selectPoint, track);
		if (ConvertToArcs(Da.pos, &Da.crvSegs_da, track, color,lineWidth)) { Da.crvSegs_da_cnt = Da.crvSegs_da.cnt; }
		Da.minRadius = BezierMinRadius(Da.pos, Da.crvSegs_da);
		return C_CONTINUE;

	case C_MOVE:
		if (Da.state != POINT_PICKED) {
			InfoMessage(_("Pick any circle to adjust it - Enter to confirm, ESC to abort"));
			return C_CONTINUE;
		}
		DYNARR_RESET(trkSeg_t,anchors_da);
		//If locked, reset pos to be on line from other track
		if (Da.selectPoint == 1 || Da.selectPoint == 2) {  //CPs
			int controlArm = Da.selectPoint-1;			//Snap to direction of track
			if (Da.trk[controlArm]) {
				angle1 = NormalizeAngle(GetTrkEndAngle(Da.trk[controlArm], Da.ep[controlArm]));
				angle2 = NormalizeAngle(FindAngle(pos, Da.pos[Da.selectPoint==1?0:3])-angle1);
				if (angle2 > 90.0 && angle2 < 270.0) {
					Translate( &pos, Da.pos[Da.selectPoint==1?0:3], angle1,
					           -FindDistance( Da.pos[Da.selectPoint==1?0:3], pos )*cos(D2R(angle2)) );
				} else { pos = Da.pos[Da.selectPoint==1?0:3]; }
			} // Dont Snap control points
		} else { SnapPos(&pos); }
		Da.pos[Da.selectPoint] = pos;
		CreateMoveAnchor(pos,TRUE);
		CreateBothControlArms(Da.selectPoint, track);
		if (ConvertToArcs(Da.pos,&Da.crvSegs_da,track, color, lineWidth)) { Da.crvSegs_da_cnt = Da.crvSegs_da.cnt; }
		Da.minRadius = BezierMinRadius(Da.pos,Da.crvSegs_da);
		if (Da.track) {
			b = AnalyseCurve(Da.pos,&fx,&fy,&cusp);
			if (b==ENDS) {
				wBeep();
				InfoMessage(_("Bezier Curve Invalid has identical end points Change End Point"),
				            b==CUSP?"Cusp":"Loop");
			} else if ( b == CUSP || b == LOOP) {
				wBeep();
				InfoMessage(_("Bezier Curve Invalid has %s Change End Point"),
				            b==CUSP?"Cusp":"Loop");
			} else if ( b == COINCIDENT ) {
				wBeep();
				InfoMessage(_("Bezier Curve Invalid has three co-incident points"),
				            b==CUSP?"Cusp":"Loop");
			} else if ( b == LINE ) {
				InfoMessage(_("Bezier is Straight Line"));
			} else
				InfoMessage(
				        _("Bezier %s : Min Radius=%s Length=%s fx=%0.3f fy=%0.3f cusp=%0.3f"),
				        track?"Track":"Line",
				        FormatDistance(Da.minRadius>=100000?0:Da.minRadius),
				        FormatDistance(BezierLength(Da.pos,Da.crvSegs_da)),fx,fy,cusp);
		} else
			InfoMessage( _("Bezier %s : Min Radius=%s Length=%s"),track?"Track":"Line",
			             FormatDistance(Da.minRadius>=100000?0:Da.minRadius),
			             FormatDistance(BezierLength(Da.pos,Da.crvSegs_da)));
		return C_CONTINUE;

	case C_UP:
		if (Da.state != POINT_PICKED) { return C_CONTINUE; }
		//Take last pos and decide if it should be snapped to a track because SHIFT is held (pos0 and pos3)
		ep = 0;
		BOOL_T found = FALSE;
		DYNARR_RESET(trkSeg_t,anchors_da);
		p = pos;
		if (track && (Da.selectPoint == 0 || Da.selectPoint == 3)) {  //EPs
			if ((MyGetKeyState() & WKEY_SHIFT) != 0) {   //Snap Track
				if ((t = OnTrackIgnore(&p, FALSE, TRUE,
				                       Da.selectTrack)) != NULL) { //Snap to endPoint
					ep = PickUnconnectedEndPointSilent(p, t);
					if (ep != -1) {
						Da.trk[Da.selectPoint/3] = t;
						Da.ep[Da.selectPoint/3] = ep;
						pos0 = Da.pos[(Da.selectPoint == 0)?1:2];
						pos = GetTrkEndPos(t, ep);
						found = TRUE;
					}
				} else {
					wBeep();
					InfoMessage(_("No unconnected End Point to lock to"));
				}
			}
		}
		if (found) {
			angle1 = NormalizeAngle(GetTrkEndAngle(Da.trk[Da.selectPoint/3],
			                                       Da.ep[Da.selectPoint/3]));
			angle2 = NormalizeAngle(FindAngle(pos, pos0)-angle1);
			Translate(&Da.pos[Da.selectPoint==0?1:2], Da.pos[Da.selectPoint==0?0:3], angle1,
			          FindDistance(Da.pos[Da.selectPoint==0?1:2],pos)*cos(D2R(angle2)));
		}

		Da.selectPoint = -1;
		CreateBothControlArms(Da.selectPoint,track);
		if (ConvertToArcs(Da.pos,&Da.crvSegs_da,track,color,lineWidth)) { Da.crvSegs_da_cnt = Da.crvSegs_da.cnt; }
		Da.minRadius = BezierMinRadius(Da.pos,Da.crvSegs_da);
		if (Da.track) {
			b = AnalyseCurve(Da.pos,&fx,&fy,&cusp);
			if (b==ENDS) {
				wBeep();
				InfoMessage(_("Bezier curve invalid has identical end points Change End Point"),
				            b==CUSP?"Cusp":"Loop");
			} else if ( b == CUSP || b == LOOP) {
				wBeep();
				InfoMessage(_("Bezier curve invalid has %s Change End Point"),
				            b==CUSP?"Cusp":"Loop");
			} else if ( b == COINCIDENT ) {
				wBeep();
				InfoMessage(_("Bezier curve invalid has three co-incident points"),
				            b==CUSP?"Cusp":"Loop");
			} else if ( b == LINE) {
				InfoMessage(_("Bezier curve is straight line"));
			}
			InfoMessage(_("Pick any circle to adjust it - Enter to confirm, ESC to abort"));
		} else {
			InfoMessage(
			        _("Pick any circle to adjust it - Enter to confirm, ESC to abort"));
		}
		Da.state = PICK_POINT;

		return C_CONTINUE;

	case C_OK:                            //C_OK is not called by Modify.
		if ( Da.state == PICK_POINT ) {
//			char c = (unsigned char)(action >> 8);
			if (Da.track && Da.pos[0].x == Da.pos[3].x && Da.pos[0].y == Da.pos[3].y ) {
				wBeep();
				ErrorMessage(_("Invalid Bezier Track - end points are identical"));
				return C_CONTINUE;
			}
			if (Da.track) {
				b = AnalyseCurve(Da.pos,&fx,&fy,&cusp);
				if ( b == CUSP || b == LOOP ) {
					wBeep();
					ErrorMessage(_("Invalid Bezier Curve has a %s - Adjust"),b==CUSP?"Cusp":"Loop");
					return C_CONTINUE;
				} else if (b==COINCIDENT) {
					wBeep();
					ErrorMessage(_("Invalid Bezier Curve has three coincident points - Adjust"));
					return C_CONTINUE;
				} else if(b==ENDS) {
					ErrorMessage(_("Invalid Bezier Track - end points are identical"));
					return C_CONTINUE;
				}
			}
			Da.minRadius = BezierMinRadius(Da.pos,Da.crvSegs_da);
			UndoStart( _("Create Bezier"), "newBezier - CR" );
			if (Da.track) {
				t = NewBezierTrack( Da.pos, &DYNARR_N(trkSeg_t,Da.crvSegs_da,0),
				                    Da.crvSegs_da.cnt);
				for (int i=0; i<2; i++)
					if (Da.trk[i] != NULL) { ConnectAbuttingTracks(t,i,Da.trk[i],Da.ep[i]); }
			} else { t = NewBezierLine(Da.pos, &DYNARR_N(trkSeg_t,Da.crvSegs_da,0), Da.crvSegs_da.cnt,color,lineWidth); }
			UndoEnd();
			DYNARR_RESET(trkSeg_t,anchors_da);
			DYNARR_FREE( trkSeg_t, Da.crvSegs_da );
			DrawNewTrack(t);
			Da.state = NONE;
			return C_TERMINATE;

		}
		return C_CONTINUE;

	case C_REDRAW:
		if (Da.state != NONE) {
			DrawTempBezier(Da.track);
		}
		DrawSegsDA( &tempD, NULL, zero, 0.0, &anchors_da, trackGauge, wDrawColorBlack,
		            0 );
		return C_CONTINUE;

	default:
		return C_CONTINUE;
	}

	return C_CONTINUE;


}

/*
 * CmdBezModify
 *
 * Called from Modify Command - this function deals with the real (old) track and calls AdjustBezCurve to tune up the new one
 * Sequence is this -
 * - The C_START is called from CmdModify C_DOWN action if a track has being selected. The old track is hidden, the editable one is shown.
 * - C_MOVES will be ignored until a C_UP ends the track selection and moves the state to PICK_POINT,
 * - C_DOWN then hides the track and shows the Bezier handles version. Selects a point (if close enough and available) and the state moves to POINT_PICKED
 * - C_MOVE drags the point around modifying the curve
 * - C_UP puts the state back to PICK_POINT (pick another)
 * - C_OK (Enter/Space) creates the new track, deletes the old and shows the changed track.
 * - C_CANCEL (Esc) sets the state to NONE and reshows the original track unchanged.
 *
 * Note: Available points are shown - if a Bezier track is attached to its neighbor, only the control point on that side is selectable.
 * Any free end-point can be locked to a unconnected end point using SHIFT during drag.
 */
STATUS_T CmdBezModify (track_p trk, wAction_t action, coOrd pos, DIST_T trackG)
{
	BOOL_T track = TRUE;
//	double width = 1.0;
//	long mode = 0;
//	long cmd;

	struct extraDataBezier_t *xx = GET_EXTRA_DATA(trk, T_NOTRACK,
	                               extraDataBezier_t);
//	cmd = VP2L(commandContext);
	Da.trackGauge = trackG;

	switch (action&0xFF) {
	case C_START:
		Da.state = NONE;
		DYNARR_RESET(trkSeg_t,Da.crvSegs_da);
		Da.cp1Segs_da_cnt = 0;
		Da.cp2Segs_da_cnt = 0;
		Da.selectPoint = -1;
		Da.selectTrack = NULL;

		if (IsTrack(trk)) {
			Da.track = TRUE;
			Da.trk[0] = GetTrkEndTrk( trk, 0 );
			if (Da.trk[0]) { Da.ep[0] = GetEndPtConnectedToMe(Da.trk[0],trk); }
			Da.trk[1] = GetTrkEndTrk( trk, 1 );
			if (Da.trk[1]) { Da.ep[1] = GetEndPtConnectedToMe(Da.trk[1],trk); }
		} else { Da.track = FALSE; }

		Da.selectTrack = trk;

		for (int i=0; i<4; i++) { Da.pos[i] = xx->pos[i]; }            //Copy parms from old trk
		InfoMessage(_("%s picked - now select a Point"),track?"Track":"Line");
		Da.state = TRACK_SELECTED;
		DrawTrack(Da.selectTrack,&mainD,
		          wDrawColorWhite);                    //Wipe out real track, draw replacement
		return AdjustBezCurve(C_START, pos, Da.track, xx->segsColor, xx->segsLineWidth,
		                      InfoMessage);

	case wActionMove:
		if (Da.state == NONE) { return C_CONTINUE; }
		return AdjustBezCurve(wActionMove, pos, Da.track, xx->segsColor,
		                      xx->segsLineWidth,
		                      InfoMessage);
	case C_DOWN:
		if (Da.state == TRACK_SELECTED) { return C_CONTINUE; }                   //Ignore until first up
		UndrawNewTrack( Da.selectTrack );
		return AdjustBezCurve(C_DOWN, pos, Da.track, xx->segsColor, xx->segsLineWidth,
		                      InfoMessage);


	case C_MOVE:
		if (Da.state == TRACK_SELECTED) { return C_CONTINUE; }                   //Ignore until first up and down
		return AdjustBezCurve(C_MOVE, pos, Da.track, xx->segsColor, xx->segsLineWidth,
		                      InfoMessage);

	case C_UP:
		if (Da.state == TRACK_SELECTED) {
			Da.state =
			        PICK_POINT;                                           //First time up, next time pick a point
		}
		return AdjustBezCurve(C_UP, pos, Da.track, xx->segsColor, xx->segsLineWidth,
		                      InfoMessage);					//Run Adjust

	case C_TEXT:
		if ((action>>8) != 32) {
			return C_CONTINUE;
		}
	/* no break */
	case C_OK:
		if (Da.state != PICK_POINT) {										//Too early - abandon
			InfoMessage(_("No changes made"));
			Da.state = NONE;
			return C_CANCEL;
		}
		UndoStart( _("Modify Bezier"), "newBezier - CR" );
		UndoModify( trk );

		Da.state = NONE;
//		wDrawColor color = wDrawColorBlack;
//		LWIDTH_T lineWidth = 0;
//		if ( !Da.track ) {
//			color = xx->segsColor;
//			lineWidth = xx->segsLineWidth;
//		}
		SetBezierData( trk, Da.pos, xx->segsColor, xx->segsLineWidth );

		DrawNewTrack( trk );
		UndoEnd();
		InfoMessage(_("Modify Bezier Complete"));
		return C_TERMINATE;

	case C_CANCEL:
		InfoMessage(_("Modify Bezier Cancelled"));
		Da.state = NONE;
		return C_TERMINATE;

	case C_REDRAW:
		return AdjustBezCurve(C_REDRAW, pos, Da.track, xx->segsColor, xx->segsLineWidth,
		                      InfoMessage);
	}

	return C_CONTINUE;

}

/*
 * Find length by adding up the underlying segments. The segments can be straights, curves or bezier.
 */
DIST_T BezierLength(coOrd pos[4],dynArr_t segs)
{

	DIST_T dd = 0.0;
	if (segs.cnt == 0 ) { return dd; }
	for (int i = 0; i<segs.cnt; i++) {
		trkSeg_t t = DYNARR_N(trkSeg_t, segs, i);
		if (t.type == SEG_CRVTRK || t.type == SEG_CRVLIN) {
			dd += fabs(t.u.c.radius*D2R(t.u.c.a1));
		} else if (t.type == SEG_BEZLIN || t.type == SEG_BEZTRK) {
			dd +=BezierLength(t.u.b.pos,t.bezSegs);
		} else if (t.type == SEG_STRLIN || t.type == SEG_STRTRK ) {
			dd += FindDistance(t.u.l.pos[0],t.u.l.pos[1]);
		}
	}
	return dd;
}

DIST_T BezierOffsetLength(dynArr_t segs, double offset)
{
	DIST_T dd = 0.0;
	if (segs.cnt == 0 ) { return dd; }
	for (int i = 0; i<segs.cnt; i++) {
		trkSeg_t t = DYNARR_N(trkSeg_t, segs, i);
		if (t.type == SEG_CRVTRK || t.type == SEG_CRVLIN) {
			dd += fabs((t.u.c.radius+(t.u.c.radius>0?offset:-offset))*D2R(t.u.c.a1));
		} else if (t.type == SEG_BEZLIN || t.type == SEG_BEZTRK) {
			dd +=BezierOffsetLength(t.bezSegs,offset);
		} else if (t.type == SEG_STRLIN || t.type == SEG_STRTRK ) {
			dd += FindDistance(t.u.l.pos[0],t.u.l.pos[1]);
		}
	}
	return dd;
}


DIST_T BezierMinRadius(coOrd pos[4],dynArr_t segs)
{
	DIST_T r = DIST_INF, rr;
	if (segs.cnt == 0 ) { return r; }
	for (int i = 0; i<segs.cnt; i++) {
		trkSeg_t t = DYNARR_N(trkSeg_t, segs, i);
		if (t.type == SEG_CRVTRK || t.type == SEG_CRVLIN) {
			rr = fabs(t.u.c.radius);
		} else if (t.type == SEG_BEZLIN || t.type == SEG_BEZTRK) {
			rr = BezierMinRadius(t.u.b.pos, t.bezSegs);
		} else { rr = DIST_INF; }
		if (rr<r) { r = rr; }
	}
	return r;
}

static void CreateEndAnchor(coOrd p, wBool_t lock)
{
	DIST_T d = tempD.scale*0.15;

	DYNARR_APPEND(trkSeg_t,anchors_da,1);
	int i = anchors_da.cnt-1;
	anchors(i).type = lock?SEG_FILCRCL:SEG_CRVLIN;
	anchors(i).color = wDrawColorBlue;
	anchors(i).u.c.center = p;
	anchors(i).u.c.radius = d/2;
	anchors(i).u.c.a0 = 0.0;
	anchors(i).u.c.a1 = 360.0;
	anchors(i).lineWidth = 0;
}

/*
 * Create a Bezier Curve (Track or Line)
 * Sequence is
 * 1. Place 1st End (snapping if needed)
 * 2.Drag out 1st Control Arm (in one direction if snapped)
 * 3.Place 2nd End (again snapping)
 * 4.Drag out 2nd Control Arm (constrained if snapped)
 * 5 to n. Select and drag around points until done
 * n+1. Confirm with enter or Cancel with Esc
 */
STATUS_T CmdBezCurve( wAction_t action, coOrd pos )
{
	track_p t;
//	static int segCnt;
	static BOOL_T lock;
	static coOrd movePos;
//	STATUS_T rc = C_CONTINUE;
//	long curveMode = 0;
	long cmd;
	if (action>>8) {
		cmd = action>>8;
	} else { cmd = VP2L(commandContext); }

	Da.trackGauge = trackGauge;

	switch (action&0xFF) {

	case C_START:

		Da.track = (cmd == bezCmdModifyTrack || cmd == bezCmdCreateTrack)?TRUE:FALSE;
		if (Da.track ) {
			lineColor = wDrawColorBlack;
		}

		Da.state = POS_1;
		Da. selectPoint = -1;
		for (int i=0; i<4; i++) {
			Da.pos[i] = zero;
		}
		Da.trk[0] = Da.trk[1] = NULL;
		//tempD.orig = mainD.orig;

		DYNARR_RESET(trkSeg_t,Da.crvSegs_da);
		Da.cp1Segs_da_cnt = 0;
		Da.cp2Segs_da_cnt = 0;
		InfoMessage( _("Place 1st endpoint of Bezier - snap to %s"),
		             Da.track?"unconnected Track":"line" );
		return C_CONTINUE;


	case C_DOWN:
		DYNARR_RESET(trkSeg_t,anchors_da);
		if ( Da.state == POS_1 || Da.state == POS_2) {   //Set the first or third point
			coOrd p = pos;
//			BOOL_T found = FALSE;
			int end = Da.state==POS_1?0:1;
			EPINX_T ep;
			if (Da.track) {
				if (lock) {
					pos = movePos;
					if ((t = OnTrack(&p, FALSE, TRUE)) != NULL) {
						ep = PickUnconnectedEndPointSilent(p, t);
						if (ep != -1) {
							if (GetTrkGauge(t) != GetScaleTrackGauge(GetLayoutCurScale())) {
								wBeep();
								InfoMessage(_("Track is different gauge"));
								ep = -1;
								t = NULL;
							} else {
								Da.trk[end] = t;
								Da.ep[end] = ep;
								pos = GetTrkEndPos(t, ep);
//								found = TRUE;
							}
						}
					}
				}
			} else {													//Snap Bez Line to Lines
				if (lock) {
					pos = movePos;
				}
			}
			if (Da.state == POS_1) {
				Da.pos[0] = pos;
				Da.pos[1] = pos;
				Da.state = CONTROL_ARM_1;  //Draw the first control arm
				Da.selectPoint = 1;
				InfoMessage( _("Drag end of first control arm") );
				Da.cp1Segs_da_cnt = createControlArm(Da.cp1Segs_da, Da.pos[0], Da.pos[1],
				                                     Da.track,TRUE,Da.trk[1]!=NULL,1,wDrawColorBlack);
			} else {
				Da.pos[3] = pos;  //2nd End Point
				Da.pos[2] = pos;  //2nd Ctl Point
				Da.state = POINT_PICKED; // Drag out the second control arm
				Da.selectPoint = 2;
				InfoMessage( _("Drag end of second control arm") );
				Da.cp1Segs_da_cnt = createControlArm(Da.cp1Segs_da, Da.pos[0], Da.pos[1],
				                                     Da.track,FALSE,Da.trk[0]!=NULL,-1,wDrawColorBlack);
				Da.cp2Segs_da_cnt = createControlArm(Da.cp2Segs_da, Da.pos[3], Da.pos[2],
				                                     Da.track,TRUE,Da.trk[1]!=NULL,1,wDrawColorBlack);
				if (ConvertToArcs(Da.pos,&Da.crvSegs_da,Da.track,lineColor,lineWidth)) { Da.crvSegs_da_cnt = Da.crvSegs_da.cnt; }
			}
			return C_CONTINUE;
		} else  {
			return AdjustBezCurve( action&0xFF, pos, Da.track, lineColor, lineWidth,
			                       InfoMessage );
		}
		return C_CONTINUE;

	case wActionMove:
		DYNARR_RESET(trkSeg_t,anchors_da);
		lock = FALSE;
		if ( Da.state != POS_1 && Da.state != POS_2) { return C_CONTINUE; }  //Don't snap CPs
		if (Da.track)  {
			if (((MyGetKeyState() & WKEY_ALT) == 0) == magneticSnap) {
				if ((t = OnTrack(&pos, FALSE, TRUE)) != NULL) {
					EPINX_T ep = PickUnconnectedEndPointSilent(pos, t);
					if (ep != -1) {
						lock = TRUE;
						movePos = pos;
						if (GetTrkGauge(t) == GetScaleTrackGauge(GetLayoutCurScale())) {
							pos = GetTrkEndPos(t, ep);
							CreateEndAnchor(pos,FALSE);
						}
					}
				}
			}
		} else {
			if (((MyGetKeyState() & WKEY_ALT) == 0) == magneticSnap) {
				if ((t = OnTrack(&pos,FALSE, FALSE)) != NULL) {
					CreateEndAnchor(pos,TRUE);
					lock = TRUE;
					movePos = pos;
				}
			}
		}
		if (!lock && SnapPos(&pos)) {
			CreateEndAnchor(pos,TRUE);
			lock = TRUE;
			movePos = pos;
		}
		if (anchors_da.cnt)	{ return C_CONTINUE; }
	/* no break */
	case C_MOVE:
		if (Da.state == POS_1) {
			InfoMessage( _("Place 1st endpoint of Bezier - snap to %s"),
			             Da.track?"unconnected track":"line" );
			return C_CONTINUE;
		}
		if (Da.state == POS_2) {
			InfoMessage( _("Select other end of Bezier - snap to %s end"),
			             Da.track?"unconnected track":"line" );
		}
		if (Da.state == CONTROL_ARM_1 ) {
			if (Da.trk[0]) {
//				EPINX_T ep = 0;
				ANGLE_T angle1,angle2;
				angle1 = NormalizeAngle(GetTrkEndAngle(Da.trk[0],Da.ep[0]));
				angle2 = NormalizeAngle(FindAngle(pos, Da.pos[0])-angle1);
				if (angle2 > 90.0 && angle2 < 270.0) {
					Translate( &pos, Da.pos[0], angle1, -FindDistance( Da.pos[0],
					                pos )*cos(D2R(angle2)));
				} else { pos = Da.pos[0]; }
			} // Don't Snap control points
			Da.pos[1] = pos;
			Da.cp1Segs_da_cnt = createControlArm(Da.cp1Segs_da, Da.pos[0], Da.pos[1],
			                                     Da.track, TRUE, Da.trk[0]!=NULL, 1, wDrawColorBlack);
		} else {
			return AdjustBezCurve( action&0xFF, pos, Da.track, lineColor, lineWidth,
			                       InfoMessage );
		}
		return C_CONTINUE;

	case C_UP:
		if (Da.state == CONTROL_ARM_1) {
			if (Da.trk[0]) {
//				EPINX_T ep = Da.ep[0];
				ANGLE_T angle1,angle2;
				angle1 = NormalizeAngle(GetTrkEndAngle(Da.trk[0],Da.ep[0]));
				angle2 = NormalizeAngle(FindAngle(pos, Da.pos[0])-angle1);
				if (angle2 > 90.0 && angle2 < 270.0) {
					Translate( &pos, Da.pos[0], angle1, -FindDistance( Da.pos[0],
					                pos )*cos(D2R(angle2)));
				} else { pos = Da.pos[0]; }
			} // Don't Snap control points
			Da.pos[1] = pos;
			if (FindDistance(Da.pos[0],Da.pos[1]) <=minLength) {
				InfoMessage( _("Control Arm 1 is too short, try again") );
				Da.state = POS_1;
				return C_CONTINUE;
			}
			Da.state = POS_2;
			InfoMessage( _("Select other end of Bezier - snap to %s end"),
			             Da.track?"Unconnected Track":"Line" );
			Da.cp1Segs_da_cnt = createControlArm(Da.cp1Segs_da, Da.pos[0], Da.pos[1],
			                                     Da.track, FALSE, Da.trk[0]!=NULL, -1, wDrawColorBlack);
			return C_CONTINUE;
		} else {
			return AdjustBezCurve( action&0xFF, pos, Da.track, lineColor, lineWidth,
			                       InfoMessage );
		}
	case C_TEXT:
		if (Da.state != PICK_POINT || (action>>8) != ' ') { //Space is same as Enter.
			return C_CONTINUE;
		}
	/* no break */
	case C_OK:
		if (Da.state != PICK_POINT) { return C_CONTINUE; }
		return AdjustBezCurve( C_OK, pos, Da.track, lineColor, lineWidth, InfoMessage);

	case C_REDRAW:
		if ( Da.state != NONE ) {
			DrawBezCurve(Da.cp1Segs_da,Da.cp1Segs_da_cnt,Da.cp2Segs_da,Da.cp2Segs_da_cnt,
			             &DYNARR_N( trkSeg_t, Da.crvSegs_da, 0 ),
			             Da.crvSegs_da.cnt, lineColor);
		}
		DrawSegsDA( &tempD, NULL, zero, 0.0, &anchors_da, trackGauge, wDrawColorBlack,
		            0 );
		return C_CONTINUE;

	case C_CANCEL:
		if (Da.state != NONE) {
			Da.cp1Segs_da_cnt = 0;
			Da.cp2Segs_da_cnt = 0;
			Da.crvSegs_da_cnt = 0;
			for (int i=0; i<2; i++) {
				Da.trk[i] = NULL;
				Da.ep[i] = -1;
			}
			DYNARR_FREE( trkSeg_t, Da.crvSegs_da );
		}
		Da.state = NONE;
		return C_CONTINUE;

	default:

		return C_CONTINUE;
	}

}


//#include "bitmaps/bezier-track.xpm"
//#include "bitmaps/bezier-line.xpm"

EXPORT void InitCmdBezier( wMenu_p menu )
{

}