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Action:
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Adds a curve constraint that is a straight line in the parametric space of the deformable model and returns its tag.
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Filename:
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adm/ds_scm/dsscm.cxx
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APIs:
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api_dm_get_attrib_dm2acis
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Syntax:
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(ds:add-str-cstrn owner target=1 behavior
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start-point stop-point [integral-degree=10])
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Arg Types:
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owner
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entity
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target
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integer
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behavior
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string
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start-point
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par-pos
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stop-point
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par-pos
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integral-degree
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integer
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Returns:
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integer
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Description:
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Adds a curve constraint to the
target deformable model of the
owner along a straight line segment within the domain of the deformable surface. The line runs from
start-point to
stop-point.
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The
target argument specifies which deformable model to use in a patch hierarchy. Valid values for
target are:
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1
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= active deformable model
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2
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= root deformable model
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-1
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= active deformable model and offspring
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-2
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= root deformable model and offspring
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Otherwise, the
target is the deformable model whose tag identifier equals
target.
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For deformable curves only the
u values of the input
par-pos objects are used. The
u and
v values in
start-point and
stop-point are scaled to range from 0.0 to 1.0.
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integral-degree specifies the accuracy of numerical integration used within each element. (A polynomial function of degree
integral_degree will be integrated exactly.) Increasing the
integral-degree increases the computation cost and reduces the error.
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behavior specifies whether the position and/or the tangent of the deformable model across the curve is constrained along the length of the curve. The valid string values for
behavior are:
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For curve constraints allowed behaviors include:
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-
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"pos_tan" or
"pt"
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-
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"pos_cur" or
"pc" (turns on "tangent")
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owner ACIS face or edge on which the deformable model lives.
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target specifies which deformable model to use in a patch hierarchy.
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start-point is the starting point of a line.
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stop-point is the ending point of a line.
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behavior specifies whether the position, the tangent, and/or the curvature of the deformable model across the curve is constrained along the length of the curve.
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integral-degree specifies the accuracy of numerical integration used within each element.
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Limitations:
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This Scheme extensions will not always work correctly if the target argument is not already the active deformable model. A target deformable model can be made active by calling a query Scheme extensions on it, such as
ds:get-tag-summary or
ds:get-alpha. This should be used immediately before calling the extension.
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Example:
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; ds:add-str-cstrn
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; Add to a square test face a straight crv-cstrn
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; and use it.
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; Build a test square spline face.
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; (6x6 control points, x and y side length = 36)
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(define dsmodel1 (ds:test-face 6 6 36 36 0))
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;; dsmodel1
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; Don't display entity / ds test face exists
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(define erase (entity:erase dsmodel1))
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;; erase
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; Render the loads and constraints.
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(ds:set-draw-state dsmodel1 1
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(+ ds-draw-cstrns ds-draw-loads))
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;; ()
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; toggle off the default edge crv-cstrns
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(ds:toggle-cstrn dsmodel1 1)
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;; 0
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(ds:toggle-cstrn dsmodel1 2)
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;; 0
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(ds:toggle-cstrn dsmodel1 3)
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;; 6
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(ds:toggle-cstrn dsmodel1 4)
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;; 6
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; Add in corner constraints
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(ds:add-pt-cstrn dsmodel1 1 "position"
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(par-pos 1 0))
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;; 7
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(ds:add-pt-cstrn dsmodel1 1 "position"
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(par-pos 1 1))
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;; 8
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(ds:add-pt-cstrn dsmodel1 1 "position"
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(par-pos 0 1))
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;; 9
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; Add straight constraint across square's corner
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(ds:add-str-cstrn dsmodel1 1 "position"
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(par-pos 0 0.4) (par-pos 0.4 0))
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;; 10
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; Add a pt-cstrn at the center and track it
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(define cc1 (ds:add-pt-cstrn dsmodel1
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1 "position" (par-pos 0.5 0.5)))
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;; cc1
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(ds:set-pt-xyz dsmodel1 cc1 0
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(position 18 18 20))
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;; 8
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; OUTPUT Original
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; Compute a new deformable model position
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(ds:solve dsmodel1 1 1)
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;; ()
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; The dsmodel1 deforms to interpolate
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; all the point and the curve constraints
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; OUTPUT Result
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Figure 4-13. ds:add-str-cstrn
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