Circle and Polygon
These two tools are grouped together because they are basically the same. Both create multi-segmented polygons; a higher number of segments is a better approximation to a circle. The difference basically lies in the appearance of the faces that result when you use Push/Pull.
1. Start in top view and activate Circle (Draw / Circle).
Draw a circle in the red-green plane by clicking the center point and then a point on the circumference. You could also click and drag from the center to the circumference.
Note that the preview color of the circle tells you what plane you are working in. When you place a circle in the red-green plane, the circle is perpendicular to the blue axis, so its preview color is blue.
- When the circle is defined, it is filled in.
Like with all 2D drawing tools, you can draw a circle in any of the three planes. Orbit so that you are facing the red-blue plane and draw another circle. This time the preview color is green.
4. Do the same in the green-blue plane. The preview color is red.
You can also create circles on existing faces. Start a new file, and create a rectangle. Push/Pull it up to create a box. Activate Circle. The circle preview is horizontal anywhere you place the mouse, as long as it is not along a face.
6. Move the cursor to face, and the circle aligns to it.
You can also draw a circle on a face that is not aligned to it. Move the cursor so that the circle is horizontal again, and press Shift to lock the orientation. Then move along a face or edge - the circle remains flat.
- This is how you would draw something like this: a horizontal circle that intersects a vertical face.
Now for more on the inner workings of this tool. Undo the horizontal circle if you created it.
Now for more on the inner workings of this tool. Undo the horizontal circle if you created it.
Draw a diagonal line on one of the faces - when the line turns magenta that means its endpoints are equidistant from the corner.
10. Push the triangular portion of the face inward until it cuts all the way through. Create a circle on the side face.
If you look closely at the circle, you'll see that it's not actually round, it's actually comprised of many short segments.
Because the circle divided the vertical side into two faces, you can use Push/Pull on the circular portion to pull out a cylinder.
Even though the circle is a series of lines, the cylinder face appears smooth and round. It is actually comprised of a series of flat faces, but looks and acts as one, curved face.
The next circle will be concentric with the front face of the cylinder. To pick up the Center inference, first hover over one of the endpoints, then move the cursor around the center until the green dot appears.
- Start to draw a concentric circle on this face, but do not click the second point to complete it.
14. Before the circle is complete, you can choose to specify a radius or a different number of segments. Type "8s" to change the sides to 8. You need the "s" because a number alone will be interpreted as a dimension.
If you change segmentation this way, the segment number stays active for future circles, until the number is changed again. The same applies for Polygon.
You can also change the number of sides after the circle is completed. However, if the circle is located on an existing face (such as in this example), the circle will sometimes be created on top of (not within) the face.
Note: You can also use the VCB to set the circle radius - simply type in the radius and press Enter.
Complete the circle (which is actually an octagon) and Push/Pull this inner circle back to the vertical face of the box.
If not already displayed, show the Entity Info window (Window / Entity Info). With nothing selected, and no faces highlighted, the window should be blank.
17. Activate Select and select the circle shown. The Entity Info window displays the radius, number of segments, and length of the circle. (If the length does not appear, click the down arrow at the top of the window and select Show Details.)
|
I Entity Info | |
|
Cirde |
* |
|
\ Layer: LayerO |
~3 |
|
\ Radius: 1' 7' | |
|
Segments: | 24 | |
|
Length: | - 9' 11 3/3' |
- |
|
r l-7den Cast Shadows | |
Once a circle has been extruded, you can still change its radius. (Before extruding you can also change its segmentation.)
TIP: You could also have displayed this by right-clicking on the circle and selecting Entity Info from the menu.
- 18. Assign a slightly smaller radius - remember to specify your units. (For 1'- 4" you could type 1'4.)
- 19. The hollow cylinder now has a inward draft angle.
20. Now draw a small circle on the sloped face (leave room for another circle next to it). Note that it has eight sides - this is the last segmentation value you used. Also note that the circle automatically aligns
itself to this face. Because the circle isn't aligned with any of the three standard planes, it is given the default edge color.
21. Activate Polygon (Draw / Polygon).
Polygons are drawn just like circles - center then radius.
Before drawing the polygon, pick up the center point of the last circle you made, and move in the red or green direction along the diagonal face.
23. Align the polygon center to this point. Create a polygon with approximately the same radius as the circle.
By default, the polygon should have six sides, unless this was already changed. Open the polygon's Entity Info and change the number of segments to 8, to match the circle. (If you're a perfectionist, you can also use the Entity Info to assign the exact same radii to the circle and polygon.)
Polygon
Layer: LayerO Radius
Segments :|1
Note: The "8s" method would also work for polygons. But once you Push/Pull a polygon (or circle), you can no longer change its segmentation.
- You should now have two adjacent octagons.
To see how these are different, Push/Pull them both. (Remember, you can Push/Pull one face, then double-click the second face to extrude it the same distance.) The circular face appears smooth, while the polygonal face is faceted.
In actuality, these objects are the same, only their appearance is different. Circular faces are faceted as well, but their edges are smoothed and hidden. To see the edges of the circular faces, select View / Hidden Geometry.
Hide the edges again. Another difference in these faces is how they are selected. Activate Select, and click one of the polygonal facets. Each of these faces can be selected separately.
- 28. Select the circular face - it is selected as one face.
- 29. Undo as many times as needed to erase the two cylinders on the diagonal face.
30. Activate Circle. You can change the number of segments before placing the first point by simply typing the number (no "s" needed). Enter 12, and the value appears next to Sides in the VCB.
31. Locate the center at the midpoint of the edge shown (do not click yet). Depending on how you move the cursor, you can align the circle with either adjacent face. Click when the circle preview is vertical. Make the circle vertical, and orient the radius straight up (or straight across) so that the box edge contains two segment endpoints.
Because two of the segment endpoints lie on the edge, the edge divides the circle in half. Select the top part of the circle and delete it. You are left with an arc that has bold lines, indicating that it is not considered properly aligned with the face.
Note: If you had placed the circle so that its segments overlapped the edge, the circle would not have been divided.
To resolve the arc to the face, simply use Line to connect its endpoints. (You could also use Line to recreate any of the arc's segments.) The arc becomes thin-lined.
- Push/Pull the arc face outward. Because this arc was created from a circle, its extruded face is smooth.
Right-click on the arc shown and select Convert to Polygon.
Right-click on the arc shown and select Convert to Polygon.
- Note: If you get the context menu for one of the faces, try right-clicking again on the arc edge so that the edge is highlighted. Then the menu should look like the one shown above.
Push/Pull the arc face out again, pressing Ctrl/Option (this is like starting a new extrusion, instead of continuing the old one). This time the extrusion is faceted.
- 37. Now Select the arc shown. It is a half-circle you converted into a polygon, but it is still one object.
- 38. Right-click on this arc and select Explode Curve. This breaks the curve into its individual segments.
- You can now select any segment of this curve and delete it.
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