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Action:
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Creates a new pattern by applying a random keep filter to an existing pattern.
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Filename:
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kern/kern_scm/pattern_scm.cxx
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APIs:
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api_random_keep_pattern
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Syntax:
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(pattern:random-keep pat fraction [merge=#t])
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Arg Types:
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pat
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pattern
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fraction
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real
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merge
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boolean
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Returns:
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pattern
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Description:
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Applies a periodic keep filter to an existing pattern, merging with any existing filter or, optionally (with
merge=#f), replacing it.
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pat specifies a pattern.
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fraction determines the fraction of pattern elements that are kept.
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If
merge is specified as false (#f), the existing pattern is replaced. The default value is true (#t).
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Example:
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; pattern:random-keep
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; make a prism
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(define height 1)
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;; height
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(define maj_rad 1)
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;; maj_rad
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(define min_rad 0.5)
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;; min_rad
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(define num_sides 3)
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;; num_sides
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(define prism
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(solid:prism height maj_rad min_rad num_sides))
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;; prism
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; position the prism
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(define origin (position 1 2 3))
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;; origin
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(define transform (entity:transform prism
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(transform:axes
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origin (gvector 1 0 0) (gvector 0 1 0))))
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;; transform
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; make a pattern
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(define x-vec (gvector 4 0 0))
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;; x-vec
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(define num_x 12)
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;; num_x
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(define y-vec (gvector 0 4 0))
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;; y-vec
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(define num_y 12)
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;; num_y
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(define pat (pattern:linear x-vec num_x y-vec num_y))
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;; pat
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; modify the pattern
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(define keep_fraction 0.5)
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;; keep_fraction
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(set! pat (pattern:random-keep pat keep_fraction))
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;; #[pattern
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;; trans-vec:"DOMAIN(X*VEC(4,0,0)+X2*VEC
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;; (0,4,0),0,11,0,11)"
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;; x-vec:
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"null_law"
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;; y-vec:
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"null_law"
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;; z-vec:
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"null_law"
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;; scale:
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"null_law"
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;; keep:
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"null_law"
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;; [list]]
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; apply the pattern to the prism
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(define body (entity:pattern prism pat))
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;; body
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