Construction Circle through Node, with One Tangent, Using Radius |
  
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Construction Circle through Node, with One Tangent, Using Radius |
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1. Activate the mode of creating circles passing through node.
2. Select a 2D node for the circle to pass through. A node may be selected in one of the following ways:
•Press 
or <Enter>, while the cursor is within drawing window, in order to select a node nearest to the cursor.
This way of selection works, only if the node is selected before selecting any other elements.
•Move the cursor over the desired node, using object snappings, and press or <Enter>.
•Move the cursor over an intersection of construction lines or a characteristic point of a graphic line, using object snappings, and press or <Enter>. A connected 2D node will be created automatically at the specified point.
•Activate the following automenu option:
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<N> |
Select Node |
If the option is activated via keyboard, then the node nearest to cursor gets selected instantly.
If the option is activated via mouse, then you have to additionally press within drawing window for selecting the nearest node.
3. Select a line for the circle to be tangent to. You can select a construction line (straight, circle or ellipse) or a graphic line (straight, circle or circular arc). A line can be selected in one of the following ways:
•Move the cursor over the desired line, using object snappings, and press or <Enter>. In case of selecting a graphic line, a coinciding construction lines (straight or circle) is created automatically, and the current circle is based on such construction line.
•Activate one of the following automenu options:
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<L> |
Select tangent line |
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<C> |
Select tangent circle |
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<E> |
Select tangent ellipse |
If the option is activated via keyboard, then the construction line of the corresponding type nearest to cursor gets selected instantly.
If the option is activated via mouse, then you have to additionally press within drawing window for selecting the nearest line.
The ellipse selection option is not available after selecting a node, but you still can select an ellipse without using the automenu.
Second and third steps can be performed in any order. If the selection starts with selecting a node, then the first step is mandatory. If the selection starts with selecting a line, then it doesn't matter if the mode of creating circles passing through node is active or not - you may start the construction in the mode of creating circles centered at node as well.
4. Set the desired tangency configuration, if necessary. Use the following automenu option for switching between possible tangency configurations:
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<Z> |
Change construction tangency |
Tangency configurations are also switched automatically, when moving the mouse, depending on which configuration allows the circle to pass closer to the cursor.
If the selected tangent line is an ellipse, the manual switching of tangency configurations is not available.
5. Specify a radius or diameter of the circle in one of the following ways:
•Type a value via keyboard. Values are typed into input boxes of the parameters window. The Radius input box is active by default. In order to switch between Radius and Diameter, press <Tab> or click the desired input box with. You may also input a variable name instead of a numerical value. If the specified value is not possible considering passing of the circle through the previously selected node and tangency with the previously selected line, then the message will appear:
In such case, you should input a different value.
In order to finish the input, press <Enter> or click anywhere within drawing window.
•Place the cursor at an arbitrary point of drawing window without snapping to existing elements and then press or <Enter>. The radius and diameter of the circle will be calculated so, that the circle passes through such point or as close to it as possible.
Regardless of the way of definition, radius and diameter are saved in circle parameters and can be edited later.
Example of creating a circle tangent to a graphic circular arc
Example of creating a circle based on the same elements with different tangency configuration
After creating a circle the command returns to the initial state.
