diff options
Diffstat (limited to 'src/fl_arc.cxx')
| -rw-r--r-- | src/fl_arc.cxx | 52 |
1 files changed, 23 insertions, 29 deletions
diff --git a/src/fl_arc.cxx b/src/fl_arc.cxx index f234711f3..58857c811 100644 --- a/src/fl_arc.cxx +++ b/src/fl_arc.cxx @@ -1,6 +1,4 @@ // -// "$Id$" -// // Arc functions for the Fast Light Tool Kit (FLTK). // // Copyright 1998-2016 by Bill Spitzak and others. @@ -9,11 +7,11 @@ // the file "COPYING" which should have been included with this file. If this // file is missing or damaged, see the license at: // -// http://www.fltk.org/COPYING.php +// https://www.fltk.org/COPYING.php // -// Please report all bugs and problems on the following page: +// Please see the following page on how to report bugs and issues: // -// http://www.fltk.org/str.php +// https://www.fltk.org/bugs.php // /** @@ -28,7 +26,7 @@ #include <FL/fl_draw.H> #include <FL/math.h> -// avoid problems with some platforms that don't +// avoid problems with some platforms that don't // implement hypot. static double _fl_hypot(double x, double y) { return sqrt(x*x + y*y); @@ -52,35 +50,35 @@ static double _fl_hypot(double x, double y) { void Fl_Graphics_Driver::arc(double x, double y, double r, double start, double end) { // draw start point accurately: - - double A = start*(M_PI/180); // Initial angle (radians) - double X = r*cos(A); // Initial displacement, (X,Y) - double Y = -r*sin(A); // from center to initial point - fl_vertex(x+X,y+Y); // Insert initial point + + double A = start*(M_PI/180); // Initial angle (radians) + double X = r*cos(A); // Initial displacement, (X,Y) + double Y = -r*sin(A); // from center to initial point + fl_vertex(x+X,y+Y); // Insert initial point // Maximum arc length to approximate with chord with error <= 0.125 - + double epsilon; { double r1 = _fl_hypot(fl_transform_dx(r,0), // Horizontal "radius" - fl_transform_dy(r,0)); + fl_transform_dy(r,0)); double r2 = _fl_hypot(fl_transform_dx(0,r), // Vertical "radius" - fl_transform_dy(0,r)); - - if (r1 > r2) r1 = r2; // r1 = minimum "radius" - if (r1 < 2.) r1 = 2.; // radius for circa 9 chords/circle - - epsilon = 2*acos(1.0 - 0.125/r1); // Maximum arc angle + fl_transform_dy(0,r)); + + if (r1 > r2) r1 = r2; // r1 = minimum "radius" + if (r1 < 2.) r1 = 2.; // radius for circa 9 chords/circle + + epsilon = 2*acos(1.0 - 0.125/r1); // Maximum arc angle } - A = end*(M_PI/180) - A; // Displacement angle (radians) - int i = int(ceil(fabs(A)/epsilon)); // Segments in approximation - + A = end*(M_PI/180) - A; // Displacement angle (radians) + int i = int(ceil(fabs(A)/epsilon)); // Segments in approximation + if (i) { - epsilon = A/i; // Arc length for equal-size steps - double cos_e = cos(epsilon); // Rotation coefficients + epsilon = A/i; // Arc length for equal-size steps + double cos_e = cos(epsilon); // Rotation coefficients double sin_e = sin(epsilon); do { double Xnew = cos_e*X + sin_e*Y; - Y = -sin_e*X + cos_e*Y; + Y = -sin_e*X + cos_e*Y; fl_vertex(x + (X=Xnew), y + Y); } while (--i); } @@ -90,7 +88,3 @@ void Fl_Graphics_Driver::arc(double x, double y, double r, double start, double \} \endcond */ - -// -// End of "$Id$". -// |