Scheme Extensions |
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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.
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ihl:clean
- Action
-
Removes interactive hidden line data attributes from the model.
Filename-
scm/scmext/ihl/ihl_scm.cpp
APIs-
api_ihl_clean
Syntax-
(ihl:clean [token=0] body-list)
Arg Types-
Returns-
unspecified
Description
This extension removes and deletes any IHL attributes with a matching view
token from the list of bodies. When bodies are cleaned, attributes are
removed and are not stored. These attributes cannot be retrieved using
the ihl:retrieve extension.
- Arguments
-
The optional token is an integer
index; the default is 0. When token
is 0, no action is taken. A nonzero token
causes hidden line data to be removed from attributes attached to the
bodies for the view matching that view token; attributes for other views
are not affected.
-
body-list is the list of bodies that
are to be cleaned.
; ihl:clean
; Compute the hidden lines for two different views,
; storing the data in attributes attached to the
; body. Then retrieve and display each view. Clean
; the attributes and redraw.
(define block1
(solid:block (position -10 -25 -35)
(position 10 25 35)))
;; block1
; Set a color for the block.
(entity:set-color block1 2)
;; ()
(define cyl1
(solid:cylinder (position 0 0 -20)
(position 0 0 20) 30))
;; cyl1
; Set a color for the cylinder.
(entity:set-color cyl1 3)
;; ()
; OUTPUT Original
(define combo (bool:unite cyl1 block1))
;; combo
(define ihldata1 (ihl:compute 1 combo))
;; ihldata1
(ihl:draw ihldata1)
;; #[ihl-data 40248e60]
(ihl:clean 1 combo)
;; ()
(define ihldata1 (ihl:retrieve 1 combo))
;; ihldata1
(ihl:draw ihldata1)
;; #[ihl-data 402471b8]
; OUTPUT Result
  
Figure.
ihl:clean |
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ihl:compute
- Action
-
Computes interactive hidden line data and optionally stores it on the
model as attributes.
Filename-
scm/scmext/ihl/ihl_scm.cpp
APIs-
api_ihl_compute
Syntax-
(ihl:compute [token=0] body-list [view=active]
[unfaceted=#f])
Arg Types-
Returns-
ihl-data
Description
This extension computes the interactive hidden line data for the given
viewing parameters and list of bodies. The ihl-data returned is a list
of line segments with attached visibility information.
- Arguments
-
The optional token is an integer
index to a view; the default is 0. When token
is 0, hidden line data is computed for drawing, but it is not stored in
attributes attached to the bodies. If token
is nonzero, the data is stored on the model as attributes and identified
by token. Existing attributes identified by the same token are replaced.
-
The body-list supplies a list
of bodies that participate in the computation.
-
The view argument supplies
a view object.
-
If the unfaceted argument
is #t the body will not be faceted. If it is #f (the default), the body
will be re-faceted prior to hidden line computation and display.
; ihl:compute
; Compute and draw hidden lines for a view.
(define block1
(solid:block (position -10 -25 -35)
(position 10 25 35)))
;; block1
(define cyl1
(solid:cylinder (position 0 0 -20)
(position 0 0 20) 30))
;; cyl1
(define combo (bool:unite block1 cyl1))
;; combo
(define ihldata1 (ihl:compute 1 combo #f))
;; ihldata1
(ihl:draw ihldata1)
;; #[ihl-data 40248e60] |
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ihl:display
- Action
-
Computes and displays hidden line drawings.
Filename-
scm/scmext/ihl/ihl_scm.cpp
APIs-
api_ihl_compute
Syntax-
(ihl:display body-list [unfaceted=#f])
Arg Types-
Returns-
unspecified
Description
This extension computes and displays the interactive hidden line data for
the list of bodies. The default views are the views defined in the current
viewport. The hidden line data is not attached to the bodies. If no bodies
are specified, all bodies in the currently active part are processed.
- Arguments
-
The body-list supplies a list
of bodies that participate in the computation.
If the unfaceted argument
is #t the body will not be re-faceted. If it is #f (the default), the
body will be re-faceted prior to hidden line computation and display.
; ihl:display
; Display the hidden lines for the current view.
(define block1
(solid:block (position -10 -25 -35)
(position 10 25 35)))
;; block1
(define cyl1
(solid:cylinder (position 0 0 -20)
(position 0 0 20) 30))
;; cyl1
(define unite (bool:unite cyl1 block1))
;; unite
(ihl:display cyl1 #f)
;; () |
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ihl:draw
- Action
-
Draws interactive hidden line data.
Filename-
scm/scmext/ihl/ihl_scm.cpp
APIs-
None
Syntax-
(ihl:draw ihl-data [view=active] [clear])
Arg Types-
Returns-
ihl-data
Description
This extension draws ihl-data returned from the ihl:compute
or ihl:retrieve extensions.
- Arguments
-
The optional view specifies
the view to print. Prior to the image being written out to a file, the
eye, target, and projection mode of the specified (or, active if none
is specified) view are internally changed by the system to agree with
those of the view in the context of which ihl-data was generated.
-
If the optional clear is #t,
the screen is cleared before drawing. If clear
is not specified or is #f, the screen is not cleared before drawing.
; ihl:draw
; Compute and draw hidden lines for a view.
(define block1
(solid:block (position -10 -25 -35)
(position 10 25 35)))
;; block1
(define cyl1
(solid:cylinder (position 0 0 -20)
(position 0 0 20) 30))
;; cyl1
(define combo (bool:unite block1 cyl1))
;; combo
(define ihldata1 (ihl:compute 1 combo))
;; ihldata1
(ihl:draw ihldata1)
;; #[ihl-data 40248f40] |
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ihl:postscript
- Action
-
Prints an interactive hidden line image to a PostScript file.
Filename-
scm/scmext/ihl/ihl_scm.cpp
APIs-
None
Syntax-
(ihl:postscript ihl-data [filename=plotfile.ps]
[color=#f] [x-size=195.9 y-size=259.4]
[view=active])
Arg Types-
Returns-
string
Description
ihl-data specifies IHL data from ihl:compute
or ihl:retrieve. This extension returns
the filename.
- Arguments
-
The optional filename specifies
the filename where images are sent. The default filename
is plotfile.ps.
-
The optional color is a logical
flag (#t or #f) that indicates whether the color is to be sent to the
file.
-
The optional x-size and y-size specify the dimensions, in millimeters,
of a rectangle into which the printed image of the viewport is to fit
as tightly as possible without distortion. The default is x-size
= 195.9mm (7.75 in) by y-size
= 259.4mm (10.25 in).
-
The optional view specifies
the view to print. Prior to the image being written out to the file, the
eye, target, and projection mode of the specified (or, active, if none
is specified) view are internally changed by the system to agree with
those of the view in the context of which ihl-data was generated.
; ihl:postscript
; Create a cylinder.
(define cyl1
(solid:cylinder (position -20 -25 -15)
(position 25 35 20) 17.5))
;; cyl1
; Render the cylinder with ihl
(ihl:postscript (ihl:compute cyl1))
;; "plotfile.ps" |
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ihl:retrieve
- Action
-
Retrieves interactive hidden line data from attributes attached to
the bodies.
Filename-
scm/scmext/ihl/ihl_scm.cpp
APIs-
api_ihl_retrieve
Syntax-
(ihl:retrieve body-list [token=0])
Arg Types-
Returns-
ihl-data
Description
This extension retrieves the data stored in IHL attributes with a matching
view token and returns the list of hidden line segments as an ihl-data
object. All data returned is a copy of the data stored in attributes on
the body.
- Arguments
-
The optional token is an integer
index to a view; the default is 0. When token
is 0, no action is taken. A nonzero token
retrieves interactive hidden line data from attributes corresponding to
the views attached to the bodies.
; ihl:retrieve
; Compute the hidden lines for two different views,
; storing the data in attributes attached to the
; body. Then retrieve and display each view.
(define view1 (view:dl))
;; view1
(define view2 (view:dl))
;; view2
(view:set-eye (position 100 0 100) view2)
;; #[position 0 0 500]
(define block1 (solid:block (position -10 -25 -35)
(position 10 25 35)))
;; block1
(define cyl1
(solid:cylinder (position 0 0 -20)
(position 0 0 20) 30))
;; cyl1
(define combo (bool:unite cyl1 block1))
;; combo
(define ihldata1 (ihl:compute 1 combo view1))
;; ihldata1
(define ihldata2 (ihl:compute 2 combo view2))
;; ihldata2
(define ihldata3 (ihl:retrieve 1 combo))
;; ihldata3
(ihl:draw ihldata3 view1)
;; #[ihl-data 40227c20]
(define ihldata4 (ihl:retrieve 2 combo))
;; ihldata4
(ihl:draw ihldata4 view2)
;; #[ihl-data 40227e50] |
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