3ds Max 2012 Bible - Kelly L. Murdock [161]
Trim and Extend
The Trim button cuts off any extending portion between two overlapping splines. The splines must be part of the same object. To use the Trim feature, select the spline that you want to keep, click the Trim button, and then click the segment to trim. The spline you click is trimmed back to the nearest intersecting point of the selected object. This button works only in Spline subobject mode. The trimming command is dependent on the viewport that is active. When the Perspective or a Camera view is active, this command uses the Top viewport to trim.
Figure 12.33 shows a circle intersected by two ellipse shapes. The Trim button was used to cut the center sections of the ellipse shapes away.
FIGURE 12.33
You can use the Trim button to cut away the excess of a spline.
The Extend button works in the reverse manner compared to the Trim button. The Extend button lengthens the end of a spline until it encounters an intersection. (There must be a spline segment to intersect.) To use the Extend command, click the Extend button and then click the segment to extend. The spline you click is extended. To exit Extend mode, right-click in the viewport or click the Extend button again.
The Infinite Bounds option works for both the Trim and Extend buttons. When enabled, it treats all open splines as if they were infinite for the purpose of locating an intersecting point. The Extend command, like Trim, is dependent on the active viewport.
Close
The Close button completes an open spline and creates a closed spline by attaching a segment between the first and last vertices. You can check which vertex is first by enabling the Show Vertex Numbers in the Selection rollout. This is similar to the Connect feature (accessible in Vertex subobject mode), but the Connect feature can connect the end point of one spline to the end point of another as long as they are part of the same Editable Spline object. The Close feature works only in Spline subobject mode and connects only the end points of each given spline.
Explode
The Explode button performs the Detach command on all subobject splines at once. It separates each segment into a separate spline. You can select to explode all spline objects to separate Splines or Objects. If you select to explode to Objects, then a dialog box appears asking you for a name. Each spline uses the name you enter with a two-digit number appended to distinguish between the different splines.
Tutorial: Spinning a spider's web
Now that you're familiar with the many aspects of editing splines, you'll try to mimic one of the best spline producers in the world—the spider. The spider is an expert at connecting lines together to create an intricate pattern. (Luckily, unlike the spider that depends on its web for food, you won't go hungry if this example fails.)
To create a spider web from splines, follow these steps:
1. Select Create⇒Shapes⇒Circle, and drag in the Front viewport to create a large circle for the perimeter of the web (pretend that the spider is building this web inside a tire swing). Right-click on the circle, and select Convert To⇒Editable Spline to convert the circle shape.
2. Select the Spline subobject in the Modifier Stack (or press the 3 key) to enter Spline subobject mode.
3. Click the Create Line button in the Geometry rollout, and click in the center of the circle and again outside the circle to create a line. Then right-click to end the line. Repeat this step until 12 or so radial lines extend from the center of the circle outward.
4. Select and right-click on the 2D Snaps Toggle in the main toolbar. In the Grid and Snap Settings dialog box, enable the Vertex and Edge/Segment options and close the dialog box. While you're still in Create Line mode, click on the circle's center and create lines in a spiral pattern by clicking on each radial line that you intersect. Right-click to end the line when you finally reach the edge of the circle. Then right-click again to exit Create Line mode.
5. Select the circle shape, and click the