public static bool TryCreateFromVertices(double x1, double y1, double bulge, double x2, double y2, out DxfArc arc)
{
// To the best of my knowledge, 3D Arcs are not defined via z but a normal vector.
// Thus, simply ignore non-zero z values.
if (Math.Abs(bulge) < 1e-10)
{
//throw new ArgumentException("arc bulge too small: " + bulge);
arc = null;
return(false);
}
var deltaX = x2 - x1;
var deltaY = y2 - y1;
var deltaLength = Math.Sqrt(deltaX * deltaX + deltaY * deltaY);
if (deltaLength < 1e-10)
{
//throw new ArgumentException("arc startpoint == endpoint");
arc = null;
return(false);
}
var alpha = 4.0 * Math.Atan(bulge);
var radius = deltaLength / (2.0 * Math.Abs(Math.Sin(alpha * 0.5)));
var deltaNormX = deltaX / deltaLength;
var deltaNormY = deltaY / deltaLength;
int bulgeSign = Math.Sign(bulge);
// 2D only solution (z=0)
var normalX = -deltaNormY * bulgeSign;
var normalY = +deltaNormX * bulgeSign;
var centerX = (x1 + x2) * 0.5 + normalX * Math.Cos(alpha * 0.5) * radius;
var centerY = (y1 + y2) * 0.5 + normalY * Math.Cos(alpha * 0.5) * radius;
// bulge<0 indicates CW arc, but DxfArc is CCW always
double startAngleDeg;
double endAngleDeg;
if (bulge > 0)
{
startAngleDeg = NormalizedAngleDegree(x1, y1, centerX, centerY);
endAngleDeg = NormalizedAngleDegree(x2, y2, centerX, centerY);
}
else
{
endAngleDeg = NormalizedAngleDegree(x1, y1, centerX, centerY);
startAngleDeg = NormalizedAngleDegree(x2, y2, centerX, centerY);
}
arc = new DxfArc(new DxfPoint(centerX, centerY, 0), radius, startAngleDeg, endAngleDeg);
return(true);
}
public static bool TryCreateFromVertices(DxfVertex v1, DxfVertex v2, out DxfArc arc)
{
// To the best of my knowledge, 3D Arcs are not defined via z but a normal vector.
// Thus, simply ignore non-zero z values.
var bulge = v1.Bulge;
if (Math.Abs(bulge) < 1e-10)
{
//throw new ArgumentException("arc bulge too small: " + bulge);
arc = null;
return(false);
}
var startPoint = v1.Location;
var endPoint = v2.Location;
var delta = endPoint - startPoint;
var length = delta.Length;
if (length <= double.Epsilon)
{
//throw new ArgumentException("arc startpoint == endpoint");
arc = null;
return(false);
}
var alpha = 4.0 * Math.Atan(bulge);
var radius = length / (2.0 * Math.Abs(Math.Sin(alpha * 0.5)));
var deltaNorm = delta.Normalize();
int bulgeSign = Math.Sign(bulge);
// 2D only solution (z=0)
var normal = new DxfVector(-deltaNorm.Y, +deltaNorm.X, 0.0) * bulgeSign;
var center = (startPoint + endPoint) * 0.5
+ normal * Math.Cos(alpha * 0.5) * radius;
// bulge<0 indicates CW arc, but DxfArc is CCW always
double startAngleDeg;
double endAngleDeg;
if (bulge > 0)
{
startAngleDeg = NormalizedAngleDegree(startPoint, center);
endAngleDeg = NormalizedAngleDegree(endPoint, center);
}
else
{
endAngleDeg = NormalizedAngleDegree(startPoint, center);
startAngleDeg = NormalizedAngleDegree(endPoint, center);
}
arc = new DxfArc(center, radius, startAngleDeg, endAngleDeg);
return(true);
}
public static bool ContainsAngle(this DxfArc arc, double angle)
{
var start = arc.StartAngle;
var end = arc.EndAngle;
// normalize angles such that start is always less than end
if (start > end)
{
// arcs specify angles in degrees
start -= 360.0;
}
return(start <= angle && end >= angle);
}
public static bool ContainsAngle(this DxfArc arc, double angle)
{
// normalize all angles
var start = NormalizeAngleDegree(arc.StartAngle);
var end = NormalizeAngleDegree(arc.EndAngle);
angle = NormalizeAngleDegree(angle);
// simple case: CCW arc from small to large angle.
if (start <= end)
{
return(start <= angle && angle <= end);
}
// if end < start consider two areas
return((start <= angle && angle < 360) || // start ccw ... 360°
(0 <= angle && angle <= end)); // overflow: 0° ... end
}
private static bool TryGetArcBoundingBox(DxfVertex v1, DxfVertex v2, out DxfBoundingBox bbox)
{
if (!DxfArc.TryCreateFromVertices(v1, v2, out var arc))
{
bbox = default(DxfBoundingBox);
return(false);
}
var boundingBox = arc.GetBoundingBox();
if (!boundingBox.HasValue)
{
bbox = default(DxfBoundingBox);
return(false);
}
bbox = boundingBox.Value;
return(true);
}
public static bool TryCreateFromVertices(DxfLwPolylineVertex v1, DxfLwPolylineVertex v2, out DxfArc arc)
{
return(TryCreateFromVertices(v1.X, v1.Y, v1.Bulge, v2.X, v2.Y, out arc));
}
public static bool TryCreateFromVertices(DxfVertex v1, DxfVertex v2, out DxfArc arc)
{
return(TryCreateFromVertices(v1.Location.X, v1.Location.Y, v1.Bulge, v2.Location.X, v2.Location.Y, out arc));
}
internal static DxfEntity FromBuffer(DxfCodePairBufferReader buffer)
{
var first = buffer.Peek();
buffer.Advance();
DxfEntity entity;
switch (first.StringValue)
{
case "3DFACE":
entity = new Dxf3DFace();
break;
case "3DSOLID":
entity = new Dxf3DSolid();
break;
case "ACAD_PROXY_ENTITY":
entity = new DxfProxyEntity();
break;
case "ARC":
entity = new DxfArc();
break;
case "ARCALIGNEDTEXT":
entity = new DxfArcAlignedText();
break;
case "ATTDEF":
entity = new DxfAttributeDefinition();
break;
case "ATTRIB":
entity = new DxfAttribute();
break;
case "BODY":
entity = new DxfBody();
break;
case "CIRCLE":
entity = new DxfCircle();
break;
case "DIMENSION":
entity = new DxfDimensionBase();
break;
case "ELLIPSE":
entity = new DxfEllipse();
break;
case "HELIX":
entity = new DxfHelix();
break;
case "IMAGE":
entity = new DxfImage();
break;
case "INSERT":
entity = new DxfInsert();
break;
case "LEADER":
entity = new DxfLeader();
break;
case "LIGHT":
entity = new DxfLight();
break;
case "LINE":
case "3DLINE":
entity = new DxfLine();
break;
case "LWPOLYLINE":
entity = new DxfLwPolyline();
break;
case "MLINE":
entity = new DxfMLine();
break;
case "MTEXT":
entity = new DxfMText();
break;
case "OLEFRAME":
entity = new DxfOleFrame();
break;
case "OLE2FRAME":
entity = new DxfOle2Frame();
break;
case "POINT":
entity = new DxfModelPoint();
break;
case "POLYLINE":
entity = new DxfPolyline();
break;
case "RAY":
entity = new DxfRay();
break;
case "REGION":
entity = new DxfRegion();
break;
case "RTEXT":
entity = new DxfRText();
break;
case "SECTION":
entity = new DxfEntitySection();
break;
case "SEQEND":
entity = new DxfSeqend();
break;
case "SHAPE":
entity = new DxfShape();
break;
case "SOLID":
entity = new DxfSolid();
break;
case "SPLINE":
entity = new DxfSpline();
break;
case "TEXT":
entity = new DxfText();
break;
case "TOLERANCE":
entity = new DxfTolerance();
break;
case "TRACE":
entity = new DxfTrace();
break;
case "UNDERLAY":
entity = new DxfUnderlay();
break;
case "DGNUNDERLAY":
entity = new DxfDgnUnderlay();
break;
case "DWFUNDERLAY":
entity = new DxfDwfUnderlay();
break;
case "PDFUNDERLAY":
entity = new DxfPdfUnderlay();
break;
case "VERTEX":
entity = new DxfVertex();
break;
case "WIPEOUT":
entity = new DxfWipeout();
break;
case "XLINE":
entity = new DxfXLine();
break;
default:
SwallowEntity(buffer);
entity = null;
break;
}
if (entity != null)
{
entity = entity.PopulateFromBuffer(buffer);
}
return(entity);
}
internal static DxfEntity FromBuffer(DxfCodePairBufferReader buffer)
{
var first = buffer.Peek();
buffer.Advance();
DxfEntity entity;
switch (first.StringValue)
{
case "3DFACE":
entity = new Dxf3DFace();
break;
case "3DSOLID":
entity = new Dxf3DSolid();
break;
case "ACAD_PROXY_ENTITY":
entity = new DxfProxyEntity();
break;
case "ARC":
entity = new DxfArc();
break;
case "ARCALIGNEDTEXT":
entity = new DxfArcAlignedText();
break;
case "ATTDEF":
entity = new DxfAttributeDefinition();
break;
case "ATTRIB":
entity = new DxfAttribute();
break;
case "BODY":
entity = new DxfBody();
break;
case "CIRCLE":
entity = new DxfCircle();
break;
case "DIMENSION":
entity = new DxfDimensionBase();
break;
case "ELLIPSE":
entity = new DxfEllipse();
break;
case "HELIX":
entity = new DxfHelix();
break;
case "IMAGE":
entity = new DxfImage();
break;
case "INSERT":
entity = new DxfInsert();
break;
case "LEADER":
entity = new DxfLeader();
break;
case "LIGHT":
entity = new DxfLight();
break;
case "LINE":
case "3DLINE":
entity = new DxfLine();
break;
case "LWPOLYLINE":
entity = new DxfLwPolyline();
break;
case "MLINE":
entity = new DxfMLine();
break;
case "MLEADERSTYLE":
entity = new DxfMLeaderStyle();
break;
case "MTEXT":
entity = new DxfMText();
break;
case "OLEFRAME":
entity = new DxfOleFrame();
break;
case "OLE2FRAME":
entity = new DxfOle2Frame();
break;
case "POINT":
entity = new DxfModelPoint();
break;
case "POLYLINE":
entity = new DxfPolyline();
break;
case "RAY":
entity = new DxfRay();
break;
case "REGION":
entity = new DxfRegion();
break;
case "RTEXT":
entity = new DxfRText();
break;
case "SECTION":
entity = new DxfEntitySection();
break;
case "SEQEND":
entity = new DxfSeqend();
break;
case "SHAPE":
entity = new DxfShape();
break;
case "SOLID":
entity = new DxfSolid();
break;
case "SPLINE":
entity = new DxfSpline();
break;
case "SUN":
entity = new DxfSun();
break;
case "TEXT":
entity = new DxfText();
break;
case "TOLERANCE":
entity = new DxfTolerance();
break;
case "TRACE":
entity = new DxfTrace();
break;
case "UNDERLAY":
entity = new DxfUnderlay();
break;
case "DGNUNDERLAY":
entity = new DxfDgnUnderlay();
break;
case "DWFUNDERLAY":
entity = new DxfDwfUnderlay();
break;
case "PDFUNDERLAY":
entity = new DxfPdfUnderlay();
break;
case "VERTEX":
entity = new DxfVertex();
break;
case "WIPEOUT":
entity = new DxfWipeout();
break;
case "XLINE":
entity = new DxfXLine();
break;
default:
SwallowEntity(buffer);
entity = null;
break;
}
if (entity != null)
{
entity = entity.PopulateFromBuffer(buffer);
}
return entity;
}
private void WriteArc(DxfArc arc)
{
WriteItemType(DxbItemType.Arc);
WriteN(arc.Center.X);
WriteN(arc.Center.Y);
WriteN(arc.Radius);
WriteA(arc.StartAngle);
WriteA(arc.EndAngle);
}