Curve BSpline Curve
You can create bspline curve by several construction types. Click View, Geom Curve to toggle the display of individual curve.
To create a bspline curve:
In the BSpline Curve dialog, we define two types b-spline curves: Piecewise and Natural. Piecewise b-spline curve is a polygon chained by points, so it's C0 continuity. Natural b-spline curve looks more smooth than Piecewise curve, its degree is usually set as 3.
In the dialog, select the type of you want to create the bspline curve:
- Interpolate Pnts. Create a bspline curve by interpolating the selected points. If you just want to create piecewise b-spline curve (one degree, similar as polygon), check "Piecewise". "Closed" will close the bspline curve. If lots of unsort points are area selected into the listbox, "Sort Points" would sort them. You can also sketch bspline curves on any plane when Sketch on Plane is checked. If you want to define the start and end points' tangent vector, check Use Tangent. Tangent constraint is only available when "Piecewise" is unchecked.
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a. Interpolation points |
b. Check Closed option. |
c. Check Piecewise |
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a. B-Spline without tangent constraint |
b. With tangent constraint |
- On Surface. Create a bspline curve on the surface by interpolation points locating at the same surface. It will automatically find the surface which the selected points locate at. You can create the point on the surface by using Geometry Tools, Project. If you want to close the bspline curve on the surface, check Closed.
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a. Only interpolation points |
b. Interpolating curve on surface |
- Sketch on Mesh. You can sketch curves directly onto mesh. Check Closed if the curve want to be closed. If you want to create one curve only, uncheck Muli-Curves. When Elastic on All Mesh is checked, the curve will be the convex hull of the sketched results.
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a. Sketch four coner points onto mesh |
b. The final four sketched curves |
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c. Check Elastic on All Mesh and sketch two points |
d. The final sketched curves |
- From Mesh. Select Node, Part, Edge from shell elements. Especially, when you check "ByEdge" and "Prop" options, you can use angle tolerance to select multiple continuious edges by one click on the seed edge.
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a. Raw shell |
b. Curve from Mesh. See check option in figure c. |
c. In gen. sel dialog, check "ByEdge", check "Prop", input "Ang" as 30. |
- Shelll Intersection. Select shells to intersect with each other.
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a. Two shells |
b. Intersection curve of two shells |
- Snap Edge End. Select independent edges to snap with each other. Internally we will project each edge's end to neighbour edge and move the end to the projecting position if the distance is under the given tolerance. If you don't know how to give a proper distance tolerance, you can go to GeomTools->Measure and select the vertex which you want to project and select the destination edge, there is a distance column in Measure dialog.
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a. Raw curves |
b. After snapping, By Extend is checked. |
c. Using Trim->Mutual to trim edges , and delete the small curves |
- Respace. To convert a curve to piecewise (one degree) b-spline curve, Respace will resample points and create a new curve. An advanced option of "Bias" is provided if you want to sample curve non-linearly. To sample points in specified direction, change Direction.
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a. Raw curve |
b. Respace By Number, num = 7. |
c. Respace By Number, num=5 |
- Respace Para. Project or map already spaced curves to unspaced curves. When "Projection" is checked, the points in spaced curve will project to unspaced curve. The unspaced curve will copy the spaced parameter from spaced curves when "Mapping" is checked.
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a. Raw curves. The green curve is a spaced curve. We want to respace the red curve by green curve. |
b. Respace result by Projection using Direction as Default . |
c. Respace result by Projection using Direct as "Y" . |
d. Respace result by Mapping |
- Cur Map to Surf. Map curves to surface.
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a. Raw curves "LSTC" and a cylinder surface. |
b. Map "LSTC" to surface. U scale is 0.6, V scale is 0.2. |
- From Mesh Hole. Search inner or outer hole from shell mesh and create b-spline curves using the holes.
- Plane's Medial Axis. Search inner medial axis from a plannar face.
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a. Raw curves "LSTC" and a cylinder surface. |
b. Map "LSTC" to surface. U scale is 0.6, V scale is 0.2. |
- Adjust Start Pnt. Adjust end point in a closed curve. "Reverse" is an option to reverse close curve's direction.
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a. End point in raw closed curve. |
b. Curve after adjusting the end point |