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Create panel > Shapes button > NURBS Curves > Point Curve button
Tab panels > Shapes tab > NURBS Point Curve
Tab panels > Modeling tab > NURBS Point Curve
Points lie on the curve they define.
Point curves are NURBS curves whose points are constrained to lie on the curve.
A point curve can be the basis of a full NURBS model.
When you create a point curve, you can draw it in three dimensions. There are two ways to do this:
With the CTRL key method, further mouse movement lifts the latest point off the construction plane. There are two ways to use CTRL:
Click-drag. If you hold down CTRL and also hold down the mouse button, you can drag to change the height of the point. The point's location is set when you release the mouse button.
This method is probably more intuitive.
Click-click. If you CTRL+click and then release the mouse button, the height changes as you drag the mouse. Clicking the mouse a second time sets the point's location.
This method is less prone to repetitive stress injury.
While you are offsetting the point, a red dotted line is drawn between the original point on the construction plane and the actual point offset from the plane. You can move the mouse into an inactive viewport, in which case the software sets the height of the point using the point's Z-axis in the inactive viewport. This lets you set the height of the point with accuracy.
Snaps also work when you change the height of a point. For example, if you turn on Point snapping, you can set a point to have the same height as another point by snapping to that other point in an inactive viewport.
To create a NURBS point curve:
Go to the Create panel.
Turn on Shapes, and choose NURBS Curves from the drop-down list.
Turn on Point Curve.
In a viewport, click and drag to create the first point, as well as the first curve segment. Release the mouse button to add the second point. Each subsequent location you click adds a new point to the curve. Right-click to end curve creation.
Note: If you begin the curve by clicking without dragging, this also creates the curve's first point. However, if you release the mouse button more than five pixels away from where you initially pressed it, this creates an additional point.
While you are creating a point curve, you can press BACKSPACE to remove the last point you created, and then previous points in reverse order.
If Draw In All Viewports is on, you can draw in any viewport, creating a 3D curve.
To lift a point off the construction plane, use the CTRL key as described earlier in this topic under "Drawing Three-Dimensional Curves."
As with splines, if you click over the curve's initial point, a Close Curve dialog is displayed. This dialog asks whether you want the curve to be closed. Click No to keep the curve open or Yes to close the curve. (You can also close a curve when you edit it at the Curve sub-object level.) When a closed curve is displayed at the Curve sub-object level, the initial point is displayed as a green circle, and a green tick mark indicates the curve's direction.
Adjust the curve's creation parameters.
(Optional.) To add a new NURBS curve sub-object, you can turn off the Start New Shape check box, and then repeat the preceding steps.
The creation parameters are the same for both point curves and CV curves.
Lets you turn on and off the renderability of the curve, specify its thickness in the rendered scene, and apply mapping coordinates.
Render parameters can be animated. For example, you can animate the number of sides.
Viewport—Turn on and set viewport thickness, sides, and angles. Enabled when both Display Render Mesh and Use Viewport Settings are checked.
Renderer—Turn on and set renderer thickness, sides, and angles.
Thickness—Set this to specify the diameter of the viewport or rendered spline. (Spinner value: float, 0.0 to 1.0E30)
A curve and the same curve rendered with thickness
Sides—Sets the number of sides for the spline mesh in the viewports or renderer. For example, a value of 4 will give you a square cross section.
Angle—Adjust the rotational position of the cross-section in the viewports or renderer. For example, if you have a square cross section you can use Angle to position a "flat" side down.
Renderable—When on, the shape is rendered using the specified parameters.
Generate Mapping Coords—Turn this on to apply mapping coordinates. The U coordinate wraps once around the thickness of the spline; the V coordinate is mapped once along the length of the spline. Tiling is achieved using the tiling parameters in the material itself.
Display Render Mesh—Displays the mesh generated by the spline.
Use Viewport Settings—Displays the mesh generated by the Viewport settings.
The Keyboard Entry rollout lets you create a NURBS curve by typing. Use the TAB key to move between the controls in this rollout. To click a button from the keyboard, press ENTER while the button is active.
X, Y, and Z—Let you enter the coordinates of the next point to add.
Add Point—Adds the point to the curve.
Close—Ends creation of the curve and creates a segment between the last point and the initial point to close the curve.
Finish—Ends creation of the curve, leaving it open.
The controls in this group box change the accuracy and type of curve approximation used to generate and display the curve.
Draw In All Viewports—Lets you use any viewport while you are drawing the curve. This is one way to create a 3D curve. When off, you must finish drawing the curve in the viewport where you began it. Default=on.
While Draw In All Viewports is on, you can also use snaps in any viewport.
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