bool ON_Polyline::CreateStarPolygon(
const ON_Circle& circle,
double other_radius,
int side_count
)
{
bool rc = ( circle.IsValid() && side_count >= 3 && other_radius >= 0.0 )
? true
: false;
if ( rc )
{
SetCapacity(2*side_count+1);
SetCount(2*side_count+1);
double half_a = ON_PI/side_count;
int i;
ON_Circle other_circle = circle;
other_circle.radius = other_radius;
for ( i = 0; i < side_count; i++ )
{
m_a[i*2] = circle.PointAt(half_a*2*i);
m_a[i*2+1] = other_circle.PointAt(half_a*(1+2*i));
}
m_a[side_count*2] = m_a[0];
}
else
Destroy();
return rc;
}
bool ON_Polyline::CreateInscribedPolygon(
const ON_Circle& circle,
int side_count
)
{
bool rc = ( circle.IsValid() && side_count >= 3 ) ? true : false;
if ( rc )
{
SetCapacity(side_count+1);
SetCount(side_count+1);
double a = 2.0*ON_PI/side_count;
int i;
for ( i = 0; i < side_count; i++ )
{
m_a[i] = circle.PointAt(a*i);
}
m_a[side_count] = m_a[0];
}
else
Destroy();
return rc;
}
bool ON_Polyline::CreateCircumscribedPolygon(
const ON_Circle& circle,
int side_count
)
{
bool rc = ( circle.IsValid() && side_count >= 3 ) ? true : false;
if ( rc )
{
SetCapacity(side_count+1);
SetCount(side_count+1);
double half_a = ON_PI/side_count;
int i;
ON_Circle c = circle;
c.radius = circle.radius/cos(half_a);
for ( i = 0; i < side_count; i++ )
{
m_a[i] = c.PointAt(half_a*(1+2*i));
}
m_a[side_count] = m_a[0];
}
else
Destroy();
return rc;
}
int ON_Intersect(
const ON_Line& line,
const ON_Arc& arc,
double* line_t0,
ON_3dPoint& arc_point0,
double* line_t1,
ON_3dPoint& arc_point1
)
{
ON_Circle c = arc;
ON_3dPoint p[2];
double t[2], a[2], s;
ON_BOOL32 b[2] = {false,false};
int i, xcnt = ON_Intersect( line, c, &t[0], p[0], &t[1], p[1] );
if ( xcnt > 0 )
{
// make sure points are on the arc;
ON_Interval arc_domain = arc.DomainRadians();
for ( i = 0; i < xcnt; i++ )
{
b[i] = c.ClosestPointTo(p[i], &a[i]);
if ( b[i] )
{
s = arc_domain.NormalizedParameterAt(a[i]);
if ( s < 0.0 )
{
if ( s >= -ON_SQRT_EPSILON )
{
a[i] = arc_domain[0];
p[i] = c.PointAt(a[i]);
b[i] = line.ClosestPointTo( p[i], &t[i] );
}
else
b[i] = false;
}
else if ( s > 1.0 )
{
if ( s <= 1.0+ON_SQRT_EPSILON )
{
a[i] = arc_domain[1];
p[i] = c.PointAt(a[i]);
b[i] = line.ClosestPointTo( p[i], &t[i] );
}
else
b[i] = false;
}
}
}
if ( !b[0] && !b[1] )
xcnt = 0;
if ( xcnt == 2 )
{
if ( !b[1] )
xcnt = 1;
if ( !b[0] )
{
xcnt = 1;
b[0] = b[1];
t[0] = t[1];
a[0] = a[1];
p[0] = p[1];
b[1] = 0;
}
if ( xcnt == 2 && t[0] == t[1] )
{
xcnt = 1;
b[1] = 0;
ON_3dPoint q = line.PointAt(t[0]);
if ( p[0].DistanceTo(q) > p[1].DistanceTo(q) )
{
a[0] = a[1];
t[0] = t[1];
p[0] = p[1];
}
}
}
if ( xcnt == 1 && !b[0] )
xcnt = 0;
if ( xcnt >= 1 )
{
if ( line_t0 )
*line_t0 = t[0];
arc_point0 = p[0];
}
if ( xcnt == 2 )
{
if ( line_t1 )
*line_t1 = t[1];
arc_point1 = p[1];
}
}
return xcnt;
}