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Get rid of a potential divide-by-zero in new arc code.

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git-svn-id: file:///fltk/svn/fltk/branches/branch-1.1@2200 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
This commit is contained in:
Michael R Sweet
2002-05-07 00:17:07 +00:00
parent c2aa513a5a
commit d37c6483ab
1 changed files with 12 additions and 12 deletions
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src/fl_arc.cxx
+12 -12
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@@ -1,5 +1,5 @@
//
// "$Id: fl_arc.cxx,v 1.4.2.3.2.5 2002/05/03 19:33:39 easysw Exp $"
// "$Id: fl_arc.cxx,v 1.4.2.3.2.6 2002/05/07 00:17:07 easysw Exp $"
//
// Arc functions for the Fast Light Tool Kit (FLTK).
//
@@ -34,10 +34,10 @@ void fl_arc(double x, double y, double r, double start, double end) {
// draw start point accurately:
double A = start*(M_PI/180); // Initial angle (radians)
double X = r*cos(A); // Initial displacement, (X,Y)
double Y = -r*sin(A); // from center to initial point
fl_vertex(x+X,y+Y); // Insert initial point
double A = start*(M_PI/180); // Initial angle (radians)
double X = r*cos(A); // Initial displacement, (X,Y)
double Y = -r*sin(A); // from center to initial point
fl_vertex(x+X,y+Y); // Insert initial point
// Maximum arc length to approximate with chord with error <= 0.125
@@ -47,17 +47,17 @@ void fl_arc(double x, double y, double r, double start, double end) {
double r2 = hypot(fl_transform_dx(0,r), // Vertical "radius"
fl_transform_dy(0,r));
if (r2 < r1) r1 = r2; // r1 = minimum "radius"
r2 = 1.0 - 0.125/r1; // r2 = cos(epsilon/2)
if (r2 < 0.5) r2 = 0.5; // minimum 3 chords/circle
epsilon = 2*acos(r2); // Maximum arc angle
if (r1 > r2) r1 = r2; // r1 = minimum "radius"
if (r1 < 2.) r1 = 2.; // radius for circa 9 chords/circle
epsilon = 2*acos(1.0 - 0.125/r1); // Maximum arc angle
}
A = end*(M_PI/180) - A; // Displacement angle (radians)
int i = int(ceil(fabs(A)/epsilon)); // Segments in approximation
if (i) {
epsilon = A/i; // Arc length for equal-size steps
double cos_e = cos(epsilon);// Rotation coefficients
epsilon = A/i; // Arc length for equal-size steps
double cos_e = cos(epsilon); // Rotation coefficients
double sin_e = sin(epsilon);
do {
double Xnew = cos_e*X + sin_e*Y;
@@ -74,5 +74,5 @@ void fl_circle(double x,double y,double r) {
#endif
//
// End of "$Id: fl_arc.cxx,v 1.4.2.3.2.5 2002/05/03 19:33:39 easysw Exp $".
// End of "$Id: fl_arc.cxx,v 1.4.2.3.2.6 2002/05/07 00:17:07 easysw Exp $".
//