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OneSpace Designer: ME10 Dynamic Drafting MI Interfacing


Geometry Elements Section (#~62)

The Geometry Elements section contains entities that define the simple geometric elements used in drafting. These elements include lines, arcs, and circles.

The entities do not contain coordinates. Instead, the entities contain pointers to P in the Geometry Points section.

There may also be pointers to the Simple Properties section, for example to Associated Text Properties (ASSP).

When reading this section, note the following:

ARC (Arc 3-Point)

An arc is a circular line drawn from the begin point to the end point around the center point. The arc orientation determines which direction the arc is drawn, clockwise or counterclockwise.

The begin point, end point, or center point must not coincide.

Pointer Tree


Figure 36. Pointer Tree for ARC

Identification Data

ARC Entity Type.
n+ Entity Sequence Number.

Attribute Data

n+ Color.
n+ Line Type.
n+ Line Width.
n+ Display.

Property Data

n+ Property Count.

PTR First Property Pointer.
:  

PTR Last Property Pointer.

Parameter Data

PTR Pointer to Arc Center Point.
PTR Pointer to Arc Begin Point.
PTR Pointer to Arc End Point.

[0,1] Arc Orientation. Determines the direction in which the arc is drawn from the arc begin point to the arc end point.
  0 Anticlockwise (mathematical positive).
  1 Clockwise (mathematical negative).

In ME10, the arc orientation is always 0.

|~ End of Entity.

BSPL (B-Spline)

A spline consists of a series of one or more spline segments, which are polynomials, joined end to end so that the parametric gradients are continuous across the joints. A mathematical description of the Parametric B-Spline is given in Appendix B.

Figure 37 shows a simple spline with its control polygon. Points on the spline curve are called interpolation points, points on the control polygon are called control points.


Figure 37. Spline Components

The Start Point is the beginning of the first spline segment, and the End Point is the end of the last spline segment.

Pointer Tree


Figure 38. Pointer Tree for BSPL

Identification Data

BSPL Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer
.  
.  
.  
PTR Last Property Pointer

Parameter Data

n+ The order of the B-spline.
[0,1,-1] Open/closed flag:
0 false, the B-spline is open
1 true, the B-spline is closed and not periodic
-1 true, the B-spline is closed and periodic.
REAL Parameter value of first visible point on spline.
REAL Parameter value of last visible point on spline.
PTR Pointer to the start point of the spline.
PTR Pointer to the end point of the spline.
n+ Number of control points.
PTR Pointer to the first control point.
.  
.  
.  
PTR Pointer to the last control point.
n+ Number of knot vector entries.
REAL First knot vector entry.
.  
.  
.  
REAL Last knot vector entry.
n+ Number of curve points.

PTR Pointer to the curve point
REAL Parameter value of curve point
n+ Type of condition at this point
 0. no condition
 1. tangency condition
 2. curvature condition
 3. tangency and curvature condition.
REAL Tangency angle at this point. The angle is measured with respect to the horizontal x-axis, in the units defined in the Setup section.
REAL Weight of the tangency condition (>=0.0)
  The weight can be imagined as an attraction of a magnet on the spline (i.e. how strong the spline nestles against the tangent).
REAL x - value of curvature vector.
REAL y - value of curvature vector
  The curvature vector points to the center of the curvature circle, its length is defined as 1 / radius of curvature circle
  (Zero curvature is indicated as zero vector).

|~ End of Entity

CCIR (Construction Circle)

A construction circle is an auxiliary circle that helps to set up geometry. It is defined by a center point and radius.

Pointer Tree


Figure 39. Pointer Tree for CCIR

Identification Data

CCIR Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer
:  

PTR Last Property Pointer

Parameter Data

PTR Pointer to Circle Center Point
REAL Radius of Circle, must be greater than zero

|~ End of Entity

CHA (Chamfer)

A chamfer is a straight line that removes the sharp corner between two intersecting elements. The distance between the two end points of the line must not be zero.

Apart from the entity name, this entity has the same syntax as the line entity (LIN). The appearance of the chamfer entity in the MI file, instead of the line entity, indicates that the line has a special use.

Chamfers are not used by ME10. During load, a CHA is converted to a LIN entity. During store, only LIN is stored.

Pointer Tree


Figure 40. Pointer Tree for CHA

Identification Data

CHA Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer
: 

PTR Last Property Pointer

Parameter Data

PTR Pointer to First Point
PTR Pointer to Second Point

|~ End of Entity

CIR (Circle)

A circle is defined by a center point and a point on the circumference. The center point and circumference point must not coincide.

Pointer Tree


Figure 41. Pointer Tree for CIR

Identification Data

CIR Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer
:  
PTR Last Property Pointer

Parameter Data

PTR Pointer to Circle Center Point
PTR Pointer to Circle Circumference Point

|~ End of Entity

CLIN (Construction Line)

Defines a construction line.

Pointer Tree


Figure 42. Pointer Tree for CLIN

Identification Data

CLIN Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer
:  

PTR Last Property Pointer

Parameter Data

PTR Pointer to the Foot Point. This is a point on the line.

2×REAL X,Y Components of Orientation Vector, giving the direction of the construction line passing through the foot point.

REAL Z-Coordinate of Orientation Vector. Only exists if the Global Space Dimension Switch is set to 3D.

|~ End of Entity

FIL (Fillet)

A fillet is a circular arc connecting two other elements in a tangential manner, so that a sharp edge formed by intersection of the two elements is eliminated. The arc is drawn in a clockwise or counterclockwise direction from a begin point to an end point, around a center point. None of these points must coincide.

Apart from the entity name, this entity has the same syntax as the arc entity (ARC). The appearance of the fillet entity in the MI file, instead of the arc entity, indicates that the arc has a special use.

Pointer Tree


Figure 43. Pointer Tree for FIL

Identification Data

FIL Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count
PTR First Property Pointer
: 
PTR Last Property Pointer

Parameter Data

PTR Pointer to Arc Center Point
PTR Pointer to Arc Begin Point
PTR Pointer to Arc End Point
[0,1] Arc Orientation. Determines the direction in which the arc is drawn from the begin point to the end point.
  0 Counterclockwise (mathematical positive)
  1 Clockwise (mathematical negative)

In ME10, the arc orientation is always 0.

|~ End of Entity

LIN (Line)

This entity defines a straight line drawn between two points, known as the begin point and end point. These two points must be different.

Pointer Tree


Figure 44. Pointer Tree for LIN

Identification Data

LIN Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer
:  
PTR Last Property Pointer

Parameter Data

PTR Pointer to Line Begin Point (P)
PTR Pointer to Line End Point (P)
|~ End of Entity

PLN (Polyline)

A polyline is a set of straight lines connecting a series of points. In ME10/30 they are used to define the boundary of a manual hatch area, so they are not visible on the screen.

If a polyline is used for hatching, the Hatch Flag must be set to 1.

Pointer Tree


Figure 45. Pointer Tree for PLN

Identification Data

PLN Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count
PTR First Property Pointer
:  
PTR Last Property Pointer

Parameter Data

[0,1] Hatch Flag. Specifies whether or not the polyline is used for hatching.
  0 Not used for hatching
  1 Used for hatching

n+ Number of Points in Polyline

PTR Pointer to First Point of Polyline
[0,1] Pen Up Flag. Allows for gaps in the polyline.
  0 Pen is down. Line is drawn to next point.
  1 Pen is up. Line is not drawn to next point.
PTR Pointer to the Last Point of Polyline
[0,1] Pen Up Flag

|~ End of Entity

PMA (Polymarker)

Geometry points can be highlighted by the use of polymarkers such as small squares, circles and triangles.

Only one Geometry Point is referenced, so a separate polymarker entity is required for each marked point.

Note that the PMA entity may also contain a pointer to a DZP (Dimension Zero Point) property in the Property Data section.

Pointer Tree


Figure 46. Pointer Tree for PMA

Identification Data

PMA Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Marker Type. The following table gives the values corresponding to the different markers.
  • 1 = dot
  • 2 = plus
  • 3 = asterisk
  • 4 = circle
  • 5 = diagonal cross
  • 6 = triangle
  • 7 = square
  • 8 = diamond
  • 9 = zero

n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer

: 

PTR Last Property Pointer

Parameter Data

n+ Point Count. Number of points to be marked by the polymarker. This will be 1 in the MI files produced by ME10.

PTR Pointer to First Point
:  
PTR Pointer to Last Point

|~ End of Entity

SPL (Spline)


Note
The description in this section refers to cubic splines and is included for convenience. Refer to BSPL (Spline) earlier in this chapter for B-spline descriptions.

A spline consists of a series of one or more spline segments, which are polynomials, joined end to end so that the parametric gradients are continuous across the joints.

The splines described here contain a damping factor that affects their rigidity.

Four different types of spline are available in MI, each with different boundary conditions at the Start Point and End Point. The Start Point is the beginning of the first spline segment, and the End Point is the end of the last spline segment, as shown in the figure.


Figure 47. Components of a Splinee

Pointer Tree


Figure 48. Pointer Tree for SPL

Identification Data

SPL Entity Type
n+ Entity Sequence Number

Attribute Data

n+ Color
n+ Line Type
n+ Line Width
n+ Display

Property Data

n+ Property Count

PTR First Property Pointer
:  

PTR Last Property Pointer

Parameter Data

n+ Number of Points in Spline. Must be at least 3.
[14] Spline Type. The values have the following meanings:
  1. Natural. The second derivatives at the Start Point and End Point are equal to zero.

  2. Tangential. The angles at the Start Point and End Point are specified. The values are given in the parameters below. See Start Angle and End Angle.

  3. Periodic. The first derivatives at the Start Point and End Point are identical. Also, the second derivatives at the Start Point and End Point are identical.

  4. Cyclic. Identical to Spline Type 3, with the additional condition that the Start Point and End Point are equal.

REAL Start Angle
REAL End Angle

  The start angle and end angle are only used for Spline Type 2, and will have a value of 0 for other spline types. They are measured with respect to the horizontal X axis, in the angle units defined in the Setup section.

REAL Damp Value for First Point of Spline
PTR Pointer to First Point of Spline
REAL Damp Value for Second Point of Spline
PTR Pointer to Second Point of Spline
:  
REAL Damp Value for Last Point of Spline
PTR Pointer to the Last Point of Spline
  The damp values specified above are the values of a parameter in the spline equation. This parameter affects the rigidity of the spline segment beginning at the specified point. See the description of spline equations in Appendix B.
  The damp values must be either zero or positive.
  The damp value for the last point in the spline has no effect because there is no spline segment to follow.

|~ End of Entity


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