10.3 The session

10.3 The session

Step 1

Start FEMGEN and define four parameters

CONSTRUCT PARAM IRAD 15

CONSTRUCT PARAM ORAD 30

CONSTRUCT PARAM CLN1 40

CONSTRUCT PARAM CLN2 80

Step 2

Create five points to define the geometry and re-scale

GEO POINT 0

GEO POINT IRAD

GEO POINT ORAD

GEO POINT 0 IRAD

GEO POINT 0 ORAD

EYE FRAME

Step 3

Create a surface ready for sweeping

Step 4

Define two translation transformations

CONSTRUCT TRAN TRAN TR1 0 0 CLN1

CONSTRUCT TRAN TRAN TR2 0 0 CLN2

Step 5

Sweep the surface

Sweep the surface and make the resulting points dependent on the original points

GEO SW S1 TR1 DEPENDENT

Sweep the resulting surface without the DEPENDENT switch; which is the default

GEO SW S2 TR2

The points that define the first surface and its copy are parametric, in contrast the points that define the final swept surface are completely independent of the parameters (as if they had been created with GEOMETRY POINT).

Step 6

List the current parameters

To find what parameters already exist and their current settings use:

UTILITY TABULATE PARAM

Step 7

Change the parameters

To see the effect of changing parameters and how dependency works try changing the existing parameters. Change a parameter by redefining it:

CONSTRUCT PARAMETER CLN1 20

DRAWING DISPLAY

CONSTRUCT PARAMETER IRAD 10

DRAWING DISPLAY

As can be seen the points defining the final surface (S7) have not moved at all. The points defining the first surface are defined parametrically by IRAD and ORAD. When the parameters IRAD and ORAD are changed, the points on the first surface change. Similarly because the first sweep included DEPENDENT the points created from the sweep are repositioned whenever any change takes place to the original points.

It is important to note that a number of operations can make use of the DEPENDENT feature; these are GEOMETRY COPY, GEOMETRY SWEEP and GEOMETRY POINT ONLINE. In all of these commands (when DEPENDENT is used) any changes to the original points will be reflected in the subsequent points.

It is worth noting that although the DEPENDENT option is used in this example with parameters, it also has a similar effect without parameters being used.