From 55cb971ae63fe8565f0f58da229b5dff3dac6d6e Mon Sep 17 00:00:00 2001 From: Phil Rosenberg Date: Mon, 15 Jun 2015 19:48:58 +0100 Subject: [PATCH] Change to the notcrossed function in plfill. The existing method sometimes flagged two lines as nearly parallel when they were actually nearly perpendicular. --- include/plplot.h | 10 ++++++---- src/plfill.c | 17 +++++++---------- 2 files changed, 13 insertions(+), 14 deletions(-) diff --git a/include/plplot.h b/include/plplot.h index 3b8eaf9..e6866a0 100644 --- a/include/plplot.h +++ b/include/plplot.h @@ -151,12 +151,14 @@ #if defined ( PL_DOUBLE ) || defined ( DOUBLE ) typedef double PLFLT; -#define PLFLT_MAX DBL_MAX -#define PLFLT_MIN DBL_MIN +#define PLFLT_MAX DBL_MAX +#define PLFLT_MIN DBL_MIN +#define PLFLT_EPSILON DBL_EPSILON #else typedef float PLFLT; -#define PLFLT_MAX FLT_MAX -#define PLFLT_MIN FLT_MIN +#define PLFLT_MAX FLT_MAX +#define PLFLT_MIN FLT_MIN +#define PLFLT_EPSILON FLT_EPSILON #endif #if ( defined ( PL_HAVE_STDINT_H ) && !defined ( __cplusplus ) ) || \ diff --git a/src/plfill.c b/src/plfill.c index 6a91601..648d867 100644 --- a/src/plfill.c +++ b/src/plfill.c @@ -1940,7 +1940,7 @@ notcrossed( PLINT * xintersect, PLINT * yintersect, PLINT xA1, PLINT yA1, PLINT xA2, PLINT yA2, PLINT xB1, PLINT yB1, PLINT xB2, PLINT yB2 ) { - PLFLT factor, factor_NBCC, fxintersect, fyintersect; + PLFLT factor, fxintersect, fyintersect, limit; // These variables are PLFLT not for precision, but to // avoid integer overflows if they were typed as PLINT. PLFLT xA2A1, yA2A1, xB2B1, yB2B1; @@ -1969,15 +1969,12 @@ notcrossed( PLINT * xintersect, PLINT * yintersect, xB2B1 = xB2 - xB1; yB2B1 = yB2 - yB1; - factor = xA2A1 * yB2B1 - yA2A1 * xB2B1; - factor_NBCC = PL_NBCC * ( fabs( xA2A1 ) + fabs( yB2B1 ) + fabs( yA2A1 ) + fabs( xB2B1 ) ); - if ( fabs( factor ) <= factor_NBCC ) - { - if ( fabs( factor ) > 0. ) - status = status | PL_NEAR_PARALLEL; - else - status = status | PL_PARALLEL; - } + factor = xA2A1 * yB2B1 - yA2A1 * xB2B1; + limit = PLFLT_EPSILON * 2. * MAX( xA2A1 * yB2B1, yA2A1 * xB2B1 ); + if ( factor == 0 ) + status = status | PL_PARALLEL; + else if ( fabs( factor ) < limit ) + status = status | PL_NEAR_PARALLEL; else { xB1A1 = xB1 - xA1; -- 2.1.4