我们的应用程序包含.Net FrameWork3.5和DirectX For Making 2d绘图。 我们坚持精确问题。请给出解决方案来解决精度问题。
我们使用vector3f（向量点）来存储值。而我们在vector3f中存储点的结果只匹配2个精度值。但我们需要5个精度值。
我在这里提到了我的代码..
//功能从Bulge值
中查找ARC参数polylineVertStart = 6919.602,18951.51,0 polylineVertEnd = 6916.602,18951.51,0
Arc StartPoint = 6919.602,18951.5177,0 Endpoint = 6916.602,18951.51,0
public static Arc BulgeToArc(PolylineVertex3d polylineVertStart, PolylineVertex3d polylineVertEnd)
{
PolylineVertex3d polylineVertex3d = polylineVertEnd;
PolylineVertex3d polylineVertex3d1 = polylineVertStart; //get previous point
double x1 = polylineVertex3d1.Position.X; //Assign start and end points
double y1 = polylineVertex3d1.Position.Y;
double x2 = polylineVertex3d.Position.X;
double y2 = polylineVertex3d.Position.Y;
if (y1 == y2)
{
y2 += (y1 * 0.0000001);
}
if (x1 == x2)
{
x2 += (x1 * 0.0000001);
}
double bulge = polylineVertex3d1.Bulge;
double incAngle = 4 * System.Math.Atan(System.Math.Abs(bulge)); //included Angle
double chord = System.Math.Sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1)); //Chord length
double r = 0.5 * chord / System.Math.Cos(0.5 * incAngle - 0.5 * System.Math.PI); //Calculate radius
double Radius = r;
double dx = x2 - x1;
double dy = y2 - y1;
double slope = dy / dx; //slope of two points
double slopeAng = System.Math.Atan(slope);
if (System.Math.Sign(dy) == -1 && System.Math.Sign(dx) == -1)
{
slopeAng = System.Math.PI + slopeAng;
}
else if (System.Math.Sign(dy) == -1 && System.Math.Sign(dx) == 1)
{
slopeAng = 2 * System.Math.PI + slopeAng;
}
else if (System.Math.Sign(dy) == 1 && System.Math.Sign(dx) == -1)
{
slopeAng = System.Math.PI + slopeAng;
}
double d1 = System.Math.Sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
double d2 = d1 / 2;
double startAng = System.Math.Acos(d2 / r); //calculate start angle
double sAngle;
if (System.Math.Abs(bulge) < 1) //get actual start angle based on bulge direction
{
if (System.Math.Sign(bulge) != -1)
{
sAngle = slopeAng + startAng;
}
else
{
sAngle = slopeAng - startAng;
}
}
else
{
if (System.Math.Sign(bulge) != -1)
{
sAngle = slopeAng - startAng;
}
else
{
sAngle = slopeAng + startAng;
}
}
double cx = x1 + r * System.Math.Cos(sAngle);
double cy = y1 + r * System.Math.Sin(sAngle);
Vector3F Center = new Vector3F((float)cx, (float)cy, 0f); //calculate center point
double dx1 = x1 - cx;
double dx2 = x2 - cx;
double dy1 = y1 - cy;
double dy2 = y2 - cy;
double sAng = System.Math.Atan(dy1 / dx1);
double eAng = System.Math.Atan(dy2 / dx2);
if (System.Math.Sign(dy1) == -1 && System.Math.Sign(dx1) == -1)
{
sAng = System.Math.PI + sAng;
}
else if (System.Math.Sign(dy1) == -1 && System.Math.Sign(dx1) != -1)
{
sAng = 2 * System.Math.PI + sAng;
}
else if (System.Math.Sign(dx1) == -1)
{
sAng = System.Math.PI + sAng;
}
if (System.Math.Sign(dy2) == -1 && System.Math.Sign(dx2) == -1)
{
eAng = System.Math.PI + eAng;
}
else if (System.Math.Sign(dy2) == -1 && System.Math.Sign(dx2) != -1)
{
eAng = 2 * System.Math.PI + eAng;
}
else if (System.Math.Sign(dx2) == -1)
{
eAng = System.Math.PI + eAng;
}
double StartAngle;
double EndAngle;
if (System.Math.Sign(bulge) != -1) //finalise start angle and end angle
{
StartAngle = sAng;
EndAngle = eAng;
}
else
{
StartAngle = eAng;
EndAngle = sAng;
}
Direction dir;
if (polylineVertStart.Bulge != 0)
dir = polylineVertStart.Bulge < 0 ? Direction.ClockWise : Direction.CounterClockWise;
else
dir = polylineVertEnd.Bulge < 0 ? Direction.ClockWise : Direction.CounterClockWise;
Arc arc = dir == Direction.ClockWise ? new Arc(Center, new Vector3F(0f, 0f, 1f), Radius, EndAngle, StartAngle, dir) : new Arc(Center, new Vector3F(0f, 0f, 1f), Radius, StartAngle, EndAngle, dir);
return arc;
}
//Function to find ARC from StartAngle,EndAngle,Radius
public RenderingEngine.Geometry GetGeomtry()
{
RenderingEngine.Geometry geometry = new RenderingEngine.Geometry
{
EntityPrimitiveType = EntityPrimitiveType.LineStrip
};
xPoints.Clear();
yPoints.Clear();
zPoints.Clear();
VertexList.Clear();
List<CustomVertex.PositionColored> vertices = new List<CustomVertex.PositionColored>();
if (direction == Direction.ClockWise)
{
#region clockwise
double WedgeAngle = 0.0; //clock wise
if (EndAngle != StartAngle)
{
if (EndAngle < StartAngle)
{
WedgeAngle = (StartAngle - EndAngle) / NUMPOINTS;
}
else
{
WedgeAngle = ((System.Math.PI * 2) - (EndAngle - StartAngle)) / NUMPOINTS;
}
}
double angle = StartAngle;
for (int i = 0; i <= NUMPOINTS; i++)
{
double theta = angle - (i * WedgeAngle);
double x = center.X + (radius * SystemMath.Cos(theta));
double y = center.Y + (radius * SystemMath.Sin(theta));
double z = center.Z;
CustomVertex.PositionColored positionColored = new CustomVertex.PositionColored
{
Position =
new Vector3((float) x, (float) y,
(float) z),
Color = Color.ToArgb()
};
vertices.Add(positionColored);
xPoints.Add((float)x);
yPoints.Add((float)y);
zPoints.Add((float)z);
VertexList.Add(new Vector3F((float)x, (float)y, (float)z));
}
double startx = Center.X + (Radius * System.Math.Cos(StartAngle));
double starty = Center.Y + (Radius * System.Math.Sin(StartAngle));
double startz = Center.Z;
double endx = Center.X + (Radius * System.Math.Cos(EndAngle));
double endy = Center.Y + (Radius * System.Math.Sin(EndAngle));
double endz = Center.Z;
startPoint = new Vector3F((float)startx, (float)starty, (float)startz);
endPoint = new Vector3F((float)endx, (float)endy, (float)endz);
#endregion clockwise
}
else
{
#region Counter ClockWise
double WedgeAngle = 0.0;
if (EndAngle != StartAngle)
{
if (EndAngle > StartAngle)
{
WedgeAngle = (EndAngle - StartAngle) / NUMPOINTS;
}
else
{
WedgeAngle = ((System.Math.PI * 2 - StartAngle) + EndAngle) / NUMPOINTS;
}
}
double angle = StartAngle;
for (int i = 0; i <= NUMPOINTS; i++)
{
double theta = angle + (i * WedgeAngle);
double x = center.X + (radius * SystemMath.Cos(theta));
double y = center.Y + (radius * SystemMath.Sin(theta));
double z = center.Z;
CustomVertex.PositionColored positionColored = new CustomVertex.PositionColored
{
Position =
new Vector3((float) x, (float) y,
(float) z),
Color = Color.ToArgb()
};
vertices.Add(positionColored);
xPoints.Add((float)x);
yPoints.Add((float)y);
zPoints.Add((float)z);
VertexList.Add(new Vector3F((float)x, (float)y, (float)z));
}
double startx = Center.X + (Radius * System.Math.Cos(StartAngle));
double starty = Center.Y + (Radius * System.Math.Sin(StartAngle));
double startz = Center.Z;
double endx = Center.X + (Radius * System.Math.Cos(EndAngle));
double endy = Center.Y + (Radius * System.Math.Sin(EndAngle));
double endz = Center.Z;
startPoint = new Vector3F((float)startx, (float)starty, (float)startz);
endPoint = new Vector3F((float)endx, (float)endy, (float)endz);
#endregion
}
geometry.Vertices.Add(vertices);
return geometry;
}
Here arc start point and endpoint x value always come correctly but y value is some precision problem.
先谢谢..