These examples cover the basic FRED scripting commands involving entity information:

"Delete" - remove an entity array,

"Get" - retrieve entity attributes,

"Init" - initialize an entity or entity array,

"Is" - query entities,

"Set" - set entity attributes.

The following structures are required for entities:

T_ENTITY

T_ENTITYARRAY

"Delete" an entity array

The array properties of an entity can be deleted without deleting the base entity itself.

arrayid=FindName("lenslet array")
DeleteEntityArray arrayid
Update

"Get" entity data

The standard attributes of an entity can be retrieved using the "Get" commands. These include parent, name, description, traceable, neverTraceable, and axesDrawable and limitsDrawable. While individual commands exist for each attribute, the GetEntity command retrieves the full complement of standard attributes (See T_ENTITY) as shown in this example:

Dim entatrib As T_ENTITY

id=FindName("lens front")

GetEntity id, entatrib

Array parameters can be accessed in essentially the same manner:

Dim arrayatrib As T_ENTITYARRAY

id=FindName("tiles")

GetEntity id, arrayatrib

The individual commands can be used to identify entities with specific properties:

tcount=0

For i=0 To GetEntityCount()-1

 If GetTraceable(i) Then

  tcount=tcount+1

 End If

Next i

"Init" entity or array

The FRED structures T_ENTITY and T_ENTITYARRAY should be initialized to insure valid values exist for each structure element. FRED loads the default values into the declared structure.

Dim en As T_ENTITY

InitEntity en

or

Dim ar As T_ENTITYARRAY

InitEntityArray ar

"Is" query

The query commands serve to confirm entity type. Use these commands as a tool for checking whether specific operations should be imposed. In this example, only descriptions of curves are examined in an effort to find a specific string.

qal="dog"
For i = 0 To GetEntityCount()-1
 If IsCurve(i) And InStr(1, GetDescription(i), qal)>0 Then
  Print "found string at curve node ", i
 End If
Next i

"Set" entity data

When structures are involved, use "Get" commands in concert with "Set" commands to insure only the specified changes are made. This example adds an extra element in both dimensions to an existing array:

Dim elm As T_ENTITYARRAY

arid=FindName("mirror array")

 GetEntityArray arid, elm

elm.aMaxIndex=elm.aMaxIndex+1

elm.bMaxIndex=elm.bMaxIndex+1

 SetEntityArray arid, elm

The SetTraceable command can be used to control whether an entity traceable or not. This example loops over entities and makes only prisms not traceable:

For j = 0 To GetEntityCount()-1

 If IsPrism(i) Then

  SetTraceable i, False

 End If

Next i

See Also….

Advanced Raytrace

Basic Raytrace

Coatings

Curves

Elements

General Ray Data

Gratings

Importance Sampling

Linear Transforms

Materials

Ray Buffer Handling

Ray Data Get/Set

Ray Path

Raytrace Control

Scatter

Sources

Surfaces