EVOLUTION-MANAGER

Edit File: ogrocistroke.cpp

/******************************************************************************
 *
 * Purpose:  Oracle curve to linestring stroking (approximation).
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 2008, Frank Warmerdam
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include <stdarg.h>
#include "ogr_oci.h"
#include "cpl_conv.h"
#include "cpl_string.h"

CPL_CVSID("$Id: ogrocistroke.cpp 35911 2016-10-24 15:03:26Z goatbar $");

/************************************************************************/
/*                   OGROCIArcCenterFromEdgePoints()                    */
/*                                                                      */
/*      Compute the center of an arc/circle from three edge points.     */
/************************************************************************/

static int
OGROCIArcCenterFromEdgePoints( double x_c0, double y_c0,
                               double x_c1, double y_c1,
                               double x_c2, double y_c2,
                               double *x_center, double *y_center )

{

/* -------------------------------------------------------------------- */
/*      Handle a degenerate case that occurs in OSNI products by        */
/*      making some assumptions.  If the first and third points are     */
/*      the same assume they are intended to define a full circle,      */
/*      and that the second point is on the opposite side of the        */
/*      circle.                                                         */
/* -------------------------------------------------------------------- */
    if( x_c0 == x_c2 && y_c0 == y_c2 )
    {
        *x_center = (x_c0 + x_c1) * 0.5;
        *y_center = (y_c0 + y_c1) * 0.5;

return TRUE;
    }

/* -------------------------------------------------------------------- */
/*      Compute the inverse of the slopes connecting the first and      */
/*      second points.  Also compute the center point of the two        */
/*      lines ... the point our crossing line will go through.          */
/* -------------------------------------------------------------------- */
    double m1, x1, y1;

if( (y_c1 - y_c0) != 0.0 )
        m1 = (x_c0 - x_c1) / (y_c1 - y_c0);
    else
        m1 = 1e+10;

x1 = (x_c0 + x_c1) * 0.5;
    y1 = (y_c0 + y_c1) * 0.5;

/* -------------------------------------------------------------------- */
/*      Compute the same for the second point compared to the third     */
/*      point.                                                          */
/* -------------------------------------------------------------------- */
    double m2, x2, y2;

if( (y_c2 - y_c1) != 0.0 )
        m2 = (x_c1 - x_c2) / (y_c2 - y_c1);
    else
        m2 = 1e+10;

x2 = (x_c1 + x_c2) * 0.5;
    y2 = (y_c1 + y_c2) * 0.5;

/* -------------------------------------------------------------------- */
/*      Turn these into the Ax+By+C = 0 form of the lines.              */
/* -------------------------------------------------------------------- */
    double      a1, a2, l_b1, l_b2, c1, c2;

a1 = m1;
    a2 = m2;

l_b1 = -1.0;
    l_b2 = -1.0;

c1 = (y1 - m1*x1);
    c2 = (y2 - m2*x2);

/* -------------------------------------------------------------------- */
/*      Compute the intersection of the two lines through the center    */
/*      of the circle, using Kramers rule.                              */
/* -------------------------------------------------------------------- */
    double      det_inv;

if( a1*l_b2 - a2*l_b1 == 0.0 )
        return FALSE;

det_inv = 1 / (a1*l_b2 - a2*l_b1);

*x_center = (l_b1*c2 - l_b2*c1) * det_inv;
    *y_center = (a2*c1 - a1*c2) * det_inv;

return TRUE;
}

/************************************************************************/
/*                OGROCIStrokeArcToOGRGeometry_Angles()                 */
/************************************************************************/

static int
OGROCIStrokeArcToOGRGeometry_Angles( double dfCenterX, double dfCenterY,
                                     double dfRadius,
                                     double dfStartAngle, double dfEndAngle,
                                     double dfMaxAngleStepSizeDegrees,
                                     OGRLineString *poLine )

{
    double             dfArcX, dfArcY, dfSlice;
    int                iPoint, iAppendLocation, nVertexCount;
    double             dfEps = dfRadius / 100000.0;

nVertexCount = (int)
        ceil(fabs(dfEndAngle - dfStartAngle)/dfMaxAngleStepSizeDegrees) + 1;
    nVertexCount = MAX(2,nVertexCount);
    dfSlice = (dfEndAngle-dfStartAngle)/(nVertexCount-1);
    iAppendLocation = poLine->getNumPoints();

for( iPoint=0; iPoint < nVertexCount; iPoint++ )
    {
        double      dfAngle;

dfAngle = (dfStartAngle + iPoint * dfSlice) * M_PI / 180.0;

dfArcX = dfCenterX + cos(dfAngle) * dfRadius;
        dfArcY = dfCenterY + sin(dfAngle) * dfRadius;

if( iPoint == 0 )
        {
            if( poLine->getNumPoints() > 0
                && fabs(poLine->getX(poLine->getNumPoints()-1)-dfArcX) < dfEps
                && fabs(poLine->getY(poLine->getNumPoints()-1)-dfArcY) < dfEps)
            {
                poLine->setNumPoints(
                    poLine->getNumPoints() + nVertexCount - 1 );
            }
            else
            {
                poLine->setNumPoints(
                    poLine->getNumPoints() + nVertexCount - 1 );
                poLine->setPoint( iAppendLocation++, dfArcX, dfArcY );
            }
        }
        else
            poLine->setPoint( iAppendLocation++, dfArcX, dfArcY );
    }

return TRUE;
}

/************************************************************************/
/*                OGROCIStrokeArcToOGRGeometry_Points()                 */
/************************************************************************/

int
OGROCIStrokeArcToOGRGeometry_Points( double dfStartX, double dfStartY,
                                     double dfAlongX, double dfAlongY,
                                     double dfEndX, double dfEndY,
                                     double dfMaxAngleStepSizeDegrees,
                                     int bForceWholeCircle,
                                     OGRLineString *poLine )

{
    double      dfStartAngle, dfEndAngle, dfAlongAngle;
    double      dfCenterX, dfCenterY, dfRadius;

if( !OGROCIArcCenterFromEdgePoints( dfStartX, dfStartY,
                                        dfAlongX, dfAlongY,
                                        dfEndX, dfEndY,
                                        &dfCenterX, &dfCenterY ) )
        return FALSE;

if( bForceWholeCircle || (dfStartX == dfEndX && dfStartY == dfEndY) )
    {
        dfStartAngle = 0.0;
        dfEndAngle = 360.0;
    }
    else
    {
        double  dfDeltaX, dfDeltaY;

dfDeltaX = dfStartX - dfCenterX;
        dfDeltaY = dfStartY - dfCenterY;
        dfStartAngle = atan2(dfDeltaY,dfDeltaX) * 180.0 / M_PI;

dfDeltaX = dfAlongX - dfCenterX;
        dfDeltaY = dfAlongY - dfCenterY;
        dfAlongAngle = atan2(dfDeltaY,dfDeltaX) * 180.0 / M_PI;

dfDeltaX = dfEndX - dfCenterX;
        dfDeltaY = dfEndY - dfCenterY;
        dfEndAngle = atan2(dfDeltaY,dfDeltaX) * 180.0 / M_PI;

// Try positive (clockwise?) winding.
        while( dfAlongAngle < dfStartAngle )
            dfAlongAngle += 360.0;

while( dfEndAngle < dfAlongAngle )
            dfEndAngle += 360.0;

// If that doesn't work out, then go anticlockwise.
        if( dfEndAngle - dfStartAngle > 360.0 )
        {
            while( dfAlongAngle > dfStartAngle )
                dfAlongAngle -= 360.0;

while( dfEndAngle > dfAlongAngle )
                dfEndAngle -= 360.0;
        }
    }

dfRadius = sqrt( (dfCenterX - dfStartX) * (dfCenterX - dfStartX)
                     + (dfCenterY - dfStartY) * (dfCenterY - dfStartY) );

int bResult;

bResult =
        OGROCIStrokeArcToOGRGeometry_Angles( dfCenterX, dfCenterY,
                                             dfRadius,
                                             dfStartAngle, dfEndAngle,
                                             dfMaxAngleStepSizeDegrees,
                                             poLine );

/* -------------------------------------------------------------------- */
/*      Force the points for arcs, to avoid odd rounding/math           */
/*      issues.  Perhaps we should do this for the start too, but       */
/*      this is a bit tricky since it isn't obvious which point is      */
/*      the start.                                                      */
/* -------------------------------------------------------------------- */
    if( bResult && !bForceWholeCircle )
    {
        poLine->setPoint( poLine->getNumPoints() - 1,
                          dfEndX, dfEndY );
    }

return bResult;
}