Learning › geometry › Polyface Clip
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Examples of PolyfaceClip methods

Cut Fill

red and green meshes >
>
Compute "over and under" mesh parts
(red is meshA, green is meshB)		 const cutFill = PolyfaceClip.computeCutFill(meshA, meshB);
cutFill.meshAOverB > `
cutFill.meshBOverA > `

Unit Test

  • source: core\geometry\src\test\clipping\PolyfaceClip.test.ts
  • test name: "CutFill"
  • output: core\geometry\src\test\output\PolyfaceClip\CutFill.imjs

Section Cut

grey: closed volume mesh
green: section plane		 >
extract linework of section cut const section = PolyfaceClip.sectionPolyfaceClipPlane(facets, clipPlane);
This produces an array of LineString3d >
Clip the facet set and produce facets on the cut plane
insideClip is a boolean controlling which side of the cut is kept. ` const clippedPolyface = PolyfaceClip.clipPolyfaceClipPlaneWithClosureFace(facets, clipPlane, insideClip, true);'
Lower and upper parts >

Unit Test:

  • source: core\geometry\src\test\clipping\PolyfaceClip.test.ts
  • test name: "ClosedSection"
  • output: core\geometry\src\test\output\PolyfaceClip\ClosedSection.imjs

Clipping with ConvexClipPlaneSet or UnionOfConvexClipPlaneSet

gray box is a closed volume mesh
Red shape is to be swept vertically		 >
Create SweepContour as intermediate step to UnionOfConvexClipPlaneSets for the clipping. const contour = SweepContour.createForPolygon([Point3d.create(xA, yA), Point3d.create(xB, yA), Point3d.create(xA, yB), Point3d.create(xA, yA)])!;
Get the clipper out of the SweepContour const clipper = contourP0.sweepToUnionOfConvexClipPlaneSets()!;
Create a ClipBuilders object for use in the clip const clipBuilders = ClippedPolyfaceBuilders.create(true, true, true);
Do the clip PolyfaceClip.clipPolyfaceInsideOutside(facets, clipper, clipBuilders);
Extract the inside part insidePart = clipBuilders.claimPolyface(0, true);
>
Extract the outside part insidePart = clipBuilders.claimPolyface(1, true);
>

Unit Test:

  • source: core\geometry\src\test\clipping\PolyfaceClip.test.ts
  • test name: "BoxClosureNonConvex"
  • output: core\geometry\src\test\output\PolyfaceClip\BoxClosureNonConvex.imjs

Last Updated: 12 February, 2024