Scheme Extensions

 

 

Technical Article
Scheme is a public domain programming language, based on the LISP language, that uses an interpreter to run commands. ACIS provides extensions (written in C++) to the native Scheme language that can be used by an application to interact with ACIS through its Scheme Interpreter. The C++ source files for ACIS Scheme extensions are provided with the product. Spatial's Scheme based demonstration application, Scheme ACIS Interface Driver Extension (Scheme AIDE), also uses these Scheme extensions and the Scheme Interpreter.

edge:facet

Action
Returns facets that approximate a curve.

Filename
fct/fct_scm/fct_scm.cxx

APIs
api_facet_edge, api_facet_curve

Syntax
(edge:facet edge [max_points = 20]
     ["scm_string"][acis-opts])

Arg Types
edge entity| ( entity ....)
max_points integer
scm_string string
acis-opts acis-options

Returns
(position.real | position.real....)
Description
This extension computes a list of points and parameter values that approximate the given curve to within one or more specified tolerances.
Arguments

edge specifies input curve to approximate with linear facets.

max_points specifies the max number of points and parameters to generate. The default value is 20.

"scm_string" specifies the set of input parameter values: "tol=.1,len=0,ang=0,curve,position,start_param=0,end_param=1".
You may substitute "edge" for "curve" (start_param and end_param are ignored) and "AF_POINT" for "position". Use "ro" to return a rendering object. At least one of the arguments "tol", "len", and "ang" must be non-zero. All three may be non-zero; in this case all the three tolerances will be met.

acis-opts contains information related to versioning and journaling.
; edge:facet
; Create a circular edge
(define c1 (edge:circular (position 0 0 0) 10))
;; c1
;Facet the edge.
(edge:facet c1 "ro")
*** Warning (spaacis/src:FAC_MAX_NPTS)
    max npts exceeded and facets may not cover edge
;; (("count of facet points" . 24) ("count of problems" . 0)
("rendering object" . #[rendering-object 185977b8]))

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entity:count-facets

Action
Counts the number of facets in an entity.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(entity:count-facets [entity])

Arg Types
entity entity

Returns
integer

Description
This extension counts the number of facets in the input entity. This procedure does not facet the entities. The user must call entity:facet to facet them or nothing prints.

; entity:count-facets
; Create a solid block.
(define block1
    (solid:block (position 0 0 0)
    (position 10 10 10)))
;; block1
; Facet the block.
(entity:facet block1)
;; 12
; Count the number of facets in the block.
(entity:count-facets block1)
;; 12

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entity:delete-facets

Action
Deletes the facets from an entity or list of entities.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(entity:delete-facets entity-list [apply_to_descendents])

Arg Types

entity-list

entity | (entity ...)

apply_to_descendents

boolean

Returns
(entity ...)
Agruments
The argument entity-list specifies the facets of an entity or list of entities to delete. This extension returns the input entity-list.

When apply_to_descendents is set to #t, the scheme deletes facets from descendent entities .
; entity:delete-facets
; Create and facet a block, then delete the facets.
(define block1
    (solid:block (position 0 0 0)
    (position 20 20 20)))
;; block1
(entity:facet block1)
;; 12
(entity:delete-facets block1 #t)
;; #[entity 2 1]
(entity:count-facets block1)
;; 0

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entity:display-facets

Action
Displays the facets of an entity or list of entities.

Filename
scm/scmext/dfct/dfct_scm.cpp

APIs
None

Syntax
(entity:display-facets entity-list [view] [hide])

Arg Types
entity-list entity | (entity ...)
view view
hide boolean

Returns
integer

Description
This extension returns the number of facets displayed from the input entity-list. This is a temporary display and does not stay permanently on the screen.

Arguments
The optional argument view specifies the view to display the entity; the default is the active view.

If the optional hide argument is #t, the back facing polygons are not displayed. A polygon is considered back facing if the surface normal at all vertices points away from the viewer.
; entity:display-facets
; Create and facet a block, then display the facets.
(define block1
    (solid:block (position 0 0 0)
    (position 25 25 25)))
;; block1
; Facet the solid block.
(entity:facet block1)
;; 12
; Display the facets of the solid block.
(entity:display-facets block1)
;; ()

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entity:facet

Action
Facets an entity or list of entities.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
api_facet_entity, api_facet_entities, api_facet_unfaceted_entity, api_facet_unfaceted_entities

Syntax
(entity:facet entity-list [view] [unfaceted-only]
    [acis-opts])

Arg Types
entity-list entity | (entity ...)
view view
unfaceted-only boolean
acis-opts acis-options

Returns
integer
Arguments
The argument entity-list specifies the facets of an entity or list of entities to save. The facets produced become part of the part. When facets are saved with the part, refinements cannot be modified unless the entity:delete-facets extension is applied. New refinement modifications must then be faceted with the entity to be saved with that entity.

The optional argument view specifies which view to facet the entities, and it is usually used when view-dependent refinements have been set; the default is the active view.

When the optional argument unfaceted-only is set to #t, only unfaceted geometry is faceted. This extension returns the number of facets.

The optional argument acis-opts can be used to enable journaling and versioning options.
; entity:facet
; Create a block.
(define block1
    (solid:block (position 0 0 0)
    (position 25 18 10)))
;; block1
; Facet the block.
(entity:facet block1)
;; 12
(entity:display-facets block1)
;; ()

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entity:facet-area

Action
Returns the area of the facets currently attached to the entity.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
api_facet_area

Syntax
(entity:facet-area entity-list [acis-opts])

Arg Types
entity-list entity | (entity ...)
acis-opts acis-options

Returns
real

Description
Gets the area of the facets currently attached to the entity. The entity must be already faceted for this to be effective. Any parts of the entity not faceted will be ignored.

Arguments
The argument entity-list specifies the facets of an entity or list of entities.

The optional argument acis-opts can be used to enable journaling and versioning options.
; entity:facet-area
; Create a solid sphere.
(define sphere1 (solid:sphere (position 0 0 0) 9))
;; sphere1
; Facet the sphere.
(entity:facet sphere1)
;; 698
; Calculate the area of the facets of the sphere.
(entity:facet-area sphere1)
;; 1010.65030563994

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entity:faceted?

Action
Determines if an entity is faceted.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(entity:faceted? entity)

Arg Types
entity entity

Returns
boolean

Description
This extension returns #t if the entity is a face and has been faceted or if the entity is a higher-level entity and all the faces it contains have been faceted; otherwise, it returns #f.

; entity:faceted?
; Create a cylinder.
(define cyl1
    (solid:cylinder (position 0 0 0)
    (position 8 8 8) 20))
;; cyl1
; Determine if the cylinder is faceted.
(entity:faceted? cyl1)
;; #f
; Facet the cylinder.
(entity:facet cyl1)
;; 96
(entity:display-facets cyl1)
;; ()
; Determine if the cylinder is faceted.
(entity:faceted? cyl1)
;; #t

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entity:print-facets

Action
Prints the facets of an entity or list of entities.

Filename
scm/scmext/dfct/dfct_scm.cpp

APIs
None

Syntax
(entity:print-facets [entity-list]
    [view] [scale] [hide] [acis-opts])

Arg Types
entity-list entity | (entity ...)
view view
scale real
hide boolean
acis-opts acis-options

Returns
unspecified

Description
This extension prints the facets of an entity or a list of entities. If no entities are specified, then all entities that are both displayed and faceted are printed. This procedure does not facet the entities. The user must call entity:facet to facet them or nothing prints.

Arguments
The optional argument view is used as the base view to determine the orientation of the printed display. It defaults to the active view.

The optional argument scale controls the size of the image. If scale is not specified, then the area printed is the same as the size of the base view. For example, if the base view is 300 x 300 pixels, an area of 300x300 dots prints. If the printer resolution is 300 dots per inch, this means that the size of the printed image is 1 square inch. If scale is 5 in this example, then the size of the image is 5 inches by 5 inches.

If the optional hide argument is #t, the back facing polygons are not printed. A polygon is considered back facing if the surface normal at all vertices points away from the viewer.

The optional argument acis-opts can be used to enable journaling and versioning options.
Limitations
This scheme extension is available on Windows and Windows NT platforms only.
Also, this scheme extension does not currently work with HOOPS.
; entity:print-facets
; Create a solid block.
(define block1
    (solid:block (position 0 0 0)
    (position 10 10 10)))
;; block1
; Facet the block.
(entity:facet block1)
;; 12
(entity:display-facets block1)
;; ()
; Print the list of facets.
(entity:print-facets block1)
;; ()

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entity:refinement

Action
Gets an entity's faceting refinement.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
api_get_entity_refinement

Syntax
(entity:refinement entity [acis-opts])

Arg Types
entity entity
acis-opts acis-options

Returns
refinement | boolean

Description
This extension returns the entity's refinement. If no refinement is assigned, this extension returns #f. The optional argument acis-opts can be used to enable journaling and versioning options.

The types of valid refinements to control the faceting are (refer to class REFINEMENT for default values):
"surface tolerance" is the maximum distance between facet and true surface.
"last used surface tolerance" specifies the previously set surface tolerance.
"normal tolerance" is the maximum difference between any two normals of facet
"aspect ratio" is the approximate aspect ratio of each cell in grid.
"max edge length" is the maximum size of an edge of a facet.
"min v grid lines" is the minimum number v grid lines used to display a face.
"min u grid lines" is the minimum number u grid lines used to display a face
"max grid lines" limits the grid lines of a parametric grid for the surface of a face.
"grading" adjusts facets to get better parametric aspect ratio of a grid cell.
"grid mode" specifies whether a grid is used and whether the points where the grid cuts the edge is inserted to the edge.
"triang mode" specifies how much triangulation to do.
"adjust mode" specifies type of triangle smoothing to do. Determines if facet nodes should be adjusted for smoothing. Also determines if the grid points should be adjusted or not.
"surf mode" specifies the type of surface.
Available surface types are:
AF_SURF_ALL all surface type
AF_SURF_REGULAR a surface with planar cells
AF_SURF_IRREGULAR a surface with possibly nonplanar cells
AF_SURF_PLANE a planar surface
AF_SURF_CONE a cylindrical or conical surface
AF_SURF_SPHERE a spherical surface
AF_SURF_TORUS toroidal surface
AF_SURF_SPLINE a spline surface
; entity:refinement
; Create a solid cylinder.
(define cyl1
    (solid:cylinder (position 0 0 0)
    (position 30 30 0) 20))
;; cyl1
; Create a refinement.
(define refine1 (refinement))
;; refine1
; Get the default refinement values.
(refinement:props refine1)
;; (("surface tolerance" . -1)
;; ("normal tolerance" . 15)
;; ("aspect ratio" . 0)
;; ("max edge length" . 0)
;; ("min v_grid lines" . 0)
;; ("min u_grid lines" . 0)
;; ("max grid lines" . 3000)
;; ("grading" . #f)
;; ("grid mode" . "AF_GRID_INTERIOR")
;; ("triang mode" . "AF_TRIANG_FRINGE_2")
;; ("adjust mode" . "AF_ADJUST_NONE")
;; ("surf mode" . "AF_SURF_ALL"))
; Set the properties of the refinement.
(refinement:set-prop refine1 "surface tolerance" 0.5)
;; ()
; Attach the refinement to the cylinder.
(define refine (entity:set-refinement cyl1 refine1))
;; refine
; Get the cylinder's refinement.
(define get-refine (entity:refinement cyl1))
;; get-refine

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entity:refinements

Action
Gets all the faceting refinements attached to an ENTITY.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(entity:refinements entity)

Arg Types
entity entity

Returns
(refinement ...) | boolean

Description
This extension returns a list of all the refinements attached to an ENTITY. Refer to Scheme extension entity:refinement for more information.

; entity:refinements
; Create a solid cylinder.
(define cyl1
    (solid:cylinder (position 0 0 0)
    (position 30 30 0) 20))
;; cyl1
; Create a refinement.
(define refine1 (refinement))
;; refine1
; Get the default refinement values.
(refinement:props refine1)
;; (("surface tolerance" . -1)
;; ("normal tolerance" . 15)
;; ("aspect ratio" . 0) ("max edge length" . 0)
;; ("min v_grid lines" . 0)
;; ("min u_grid lines" . 0)
;; ("max grid lines" . 3000)
;; ("grading" . #f)
;; ("grid mode" . "AF_GRID_INTERIOR")
;; ("triang mode" . "AF_TRIANG_FRINGE_2")
;; ("adjust mode" . "AF_ADJUST_NONE")
;; ("surf mode" . "AF_SURF_ALL"))
; Set the properties of the refinement.
(refinement:set-prop refine1 "normal tolerance" 15)
;; ()
; Attach the refinement to the cylinder.
(define attach (entity:set-refinement cyl1 refine1))
;; attach
; Get the cylinder's refinement.
(entity:refinement cyl1)
;; #[entity 3 1]
; Get all the cylinder's refinements.
(define all (entity:refinements cyl1))
;; all

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entity:set-refinement

Action
Attaches a faceting refinement to an entity or list of entities.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
api_set_entity_refinement

Syntax
(entity:set-refinement entity-list refine [acis-opts])

Arg Types
entity-list entity | (entity ...)
refine refinement | boolean
acis-opts acis-options

Returns
(entity ...)

Description
The argument entity-list specifies an entity or list of entities to attach a refinement. This extension returns the input entity-list. Refer to Scheme extension entity:refinement for more information.

Arguments
The argument refine specifies the refinement entity to attach or #f to remove refinement from an entity.

The optional argument acis-opts can be used to enable journaling and versioning options.
; entity:set-refinement
; Create a solid cylinder.
(define cyl1
    (solid:cylinder (position 0 0 0)
    (position 8 8 0) 20))
;; cyl1
; Create a refinement.
(define refine1 (refinement))
;; refine1
; Get the default refinement values.
(refinement:props refine1)
;; (("surface tolerance" . -1)
;; ("normal tolerance" . 15)
;; ("aspect ratio" . 0) ("max edge length" . 0)
;; ("min v_grid lines" . 0)
;; ("min u_grid lines" . 0)
;; ("max grid lines" . 3000) ("grading" . #f)
;; ("grid mode" . "AF_GRID_INTERIOR")
;; ("triang mode" . "AF_TRIANG_FRINGE_2")
;; ("adjust mode" . "AF_ADJUST_NONE")
;; ("surf mode" . "AF_SURF_ALL"))
; Set the properties of the refinement.
(refinement:set-prop
    refine1 "aspect ratio" 0.5)
;; ()
; Set the refinement on the cylinder.
(define refine (entity:set-refinement cyl1 refine1))
;; refine
; Remove the refinement from the cylinder.
(define remove (entity:set-refinement cyl1 #f))
;; remove

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entity:write-facets

Action
Writes facets to a file.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(entity:write-facets entity-list filename)

Arg Types
entity-list entity | (entity ...)
filename string

Returns
boolean

Description
The argument entity-list specifies the entity or list of entities to include facet information. This extension returns #t if the operation is successful.

Arguments
The argument filename specifies the name of the file to create.
; entity:write-facets
; Create a solid block.
(define block1
    (solid:block (position 0 0 0)
    (position 15 15 15)))
;; block1
; Facet the block.
(entity:facet block1)
;; 12
; Write the list of facets to a file.
(entity:write-facets block1 "eraseme")
;; ()

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entity:write-raw-facets

Action
Writes facets to a file.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(entity:write-raw-facets entity-list filename)

Arg Types
entity-list entity | (entity ...)
filename string

Returns
boolean

Description
The argument entity-list specifies the entity or list of entities to include facet information. This extension returns #t if the operation is successful. The format of the file is one triangle per line as follows: v1.X v1.Y v1.Z v2.X v2.Y v2.Z v3.X v3.Y v3.Z

Arguments
The argument filename specifies the name of the file to create.
; entity:write-raw-facets
; Create a solid block.
(define block1(solid:block (position 0 0 0)
    (position 15 15 15)))
;; block1
; Facet the block.
(entity:facet block1)
;; 12
; Write the list of facets to a file.
(entity:write-raw-facets block1 "eraseme")
;; ()

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refinement

Action
Creates a refinement for the active part.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(refinement)

Arg Types
None

Returns
refinement

Description
A refinement is an entity created in the active part that controls how closely the surfaces of entities are approximated by their faceted representation. A refinement is associated with a face, shell, lump, or solid body. The properties of the refinement are set using refinement:set-prop. Refer to Scheme extension entity:refinement for more information.

; refinement
; Create a new refinement.
(define refine (refinement))
;; refine

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refinement:default

Action
Gets the default refinement.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
api_get_default_refinement

Syntax
(refinement:default)

Arg Types
None

Returns
refinement

Description
This extension returns the current default refinement. Refer to Scheme extension entity:refinement for more information. Refer to class REFINEMENT for the default values.

; refinement:default
; Create a new refinement.
(define refine1 (refinement))
;; refine1
; Set the properties of refine.
(refinement:set-prop refine1 "max edge length" 11)
;; ()
; Determine the properties of refine.
(refinement:props refine1)
;; (("surface tolerance" . -1)
;; ("normal tolerance" . 15)
;; ("aspect ratio" . 0) ("max edge length" . 11)
;; ("min v_grid lines" . 0)
;; ("min u_grid lines" . 0)
;; ("max grid lines" . 3000) ("grading" . #f)
;; ("grid mode" . "AF_GRID_INTERIOR")
;; ("triang mode" . "AF_TRIANG_FRINGE_2")
;; ("adjust mode" . "AF_ADJUST_NONE")
;; ("surf mode" . "AF_SURF_ALL"))
; Set refine as the default.
(refinement:set-default refine1)
;; ()
; Create a new refinement with default properties.
(define refine2 (refinement))
;; refine2
; Get the default refinement
(define refine (refinement:default))
;; refine

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refinement:props

Action
Gets the current property list of a refinement.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(refinement:props refinement)

Arg Types
refinement refinement

Returns
((string . real | integer) ...)

Description
This extension returns a list of pairs of refinement criteria and their values.

; refinement:props
; Create a refinement.
(define refine1 (refinement))
;; refine1
; Determine the properties of a refinement.
(refinement:props refine1)
;; (("surface tolerance" . -1)
;; ("normal tolerance" . 15)
;; ("aspect ratio" . 0) ("max edge length" . 0)
;; ("min v_grid lines" . 0)
;; ("min u_grid lines" . 0)
;; ("max grid lines" . 3000) ("grading" . #f)
;; ("grid mode" . "AF_GRID_INTERIOR")
;; ("triang mode" . "AF_TRIANG_FRINGE_2")
;; ("adjust mode" . "AF_ADJUST_NONE")
;; ("surf mode" . "AF_SURF_ALL"))

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refinement:set-default

Action
Sets the default refinement to the specified refinement.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
api_set_default_refinement

Syntax
(refinement:set-default refinement [acis-opts])

Arg Types
refinement refinement
acis-opts acis-options

Returns
unspecified

Description
Input argument refinement is set as the default refinement.

Arguments
The optional argument acis-opts can be used to enable journaling and versioning options.
; refinement:set-default
; Create a refinement.
(define refine1 (refinement))
;; refine1
; Set the default refinement.
(refinement:set-default refine1)
;; ()

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refinement:set-prop

Action
Sets a property of a refinement.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(refinement:set-prop refinement [name value |
    name-value-list])

Arg Types
name string
refinement refinement
value real | integer
name-value-list pair

Returns
real | integer

Description
This extension returns the property's previous value. Refer to Scheme extension entity:refinement for more information.

Arguments
name specifies the name of property to set.

refinement specifies a refinement entity.

value specifies the new value for the named property.
; refinement:set-prop
; Create a new refinement.
(define refine1 (refinement))
;; refine1
; Set a property of the refinement.
(refinement:set-prop
    refine1 "aspect ratio" 0.5)
;; ()
; Determine the properties of a refinement.
(refinement:props refine1)
;; (("surface tolerance" . -1)
;; ("normal tolerance" . 15)
;; ("aspect ratio" . 0.5) ("max edge length" . 0)
;; ("min v_grid lines" . 0)
;; ("min u_grid lines" . 0)
;; ("max grid lines" . 3000) ("grading" . #f)
;; ("grid mode" . "AF_GRID_INTERIOR")
;; ("triang mode" . "AF_TRIANG_FRINGE_2")
;; ("adjust mode" . "AF_ADJUST_NONE")
;; ("surf mode" . "AF_SURF_ALL"))
; Set the default property of the refinement.
(refinement:set-default refine1)
;; ()

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refinement?

Action
Determines if a Scheme object is a refinement.

Filename
scm/scmext/fct/fct_scm.cpp

APIs
None

Syntax
(refinement? object)

Arg Types
object scheme-object

Returns
boolean
; refinement?
; Create a refinement.
(define refine1 (refinement))
;; refine1
; Determine the refinement is actually a refinement.
(refinement? refine1)
;; #t

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vertex-template:set-default

Action
Creates a default vertex template for use with faceting.

Filename
scm/scmext/fct/vtmp_scm.cpp

APIs
api_set_default_vertex_template

Syntax
(vertex-template:set-default)

Arg Types
None

Returns
boolean

Description
This extension creates a data structure, VERTEX_TEMPLATE. The newly created structure sets up storage for the tokens used for position, normal, color, and uv. When the model is subsequently faceted, the polygon's vertices contain data for each of these tokens.

Limitations
Visible only with Advanced Rendering Component linked in. The model must have a material with a "base" color shader type.
; vertex-template:set-default
; Set up the default vertex template.
(vertex-template:set-default)
;   Use-count  :   0
;   Tokens     :
;      POSITION_TOKEN
;      NORMAL_TOKEN
;      COLOR_TOKEN
;      UV_TOKENS
;; #t
; Create a solid block.
(define block1
    (solid:block (position -10 -10 -10)
    (position 5 10 15)))
;; block1
; Set up a material.
(define mat1 (material))
;; mat1
(material:set-color-type mat1 "blue marble")
;; ()
(entity:set-material block1 mat1)
;; ()
; Facet the block.
(entity:facet block1)
;; 12
; Set the facet color.
(define color (entity:set-facet-color block1
    (gvector 1 1 1)))
;; color

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