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### Construction Aids

- Snap Mode
  You will probably work most of the time with normal snap mode (a graphics window function) enabled.
  Its advantage over the bare cursor mode (cursor as cross hairs) is that you can catch desired objects, when they are lying within the pick circle.
  Using the Intelligent Snap Mode the SISCAD-P user will have the greatest comfort when generating his drawing.

  Figure 33: Activate Snap Mode

- Intelligent Snap Mode

  In this mode you have more help that in the previous one : so-called pick symbols and temporary auxiliary lines.
  Intelligent snap mode is activated in the main menu window.

  - Pick Symbols
    Pick symbols greatly enhance the input of points and permit an extremely efficient way of working. The pick symbols always appear when the current command expects a point input and an object (a line or a circle) is touched by the mouse pointer.
    The contents of the blue circle symbolically show what point will be picked upon clicking the corresponding mouse button.
    A later paragraph is dedicated to the description of the pick symbols.

  - Temporary auxiliary lines
    If the cursor is moved either horizontally or vertically after having touched a point, you are offered a blue (horizontal or vertical) auxiliary line going through that point.
    Any point on this line can then be selected.
    Pick symbols will also appear upon touching this line.

    Auxiliary lines are most used in conjunction with the draft mode.

- Description of Pick Symbols
  - Pick Symbols 1
    (The pick point is determined by existing objects)

    Figure 34: Pick symbols 1

    1
      Picking a point
      The point already exists. This would be the case of e.g. the endpoint of a line segment, the center of a circle, etc.

    2
      Picking a point on a line

    3
      Picking the halfway point of a line segment

    4
      Picking the end point of a line segment on a line
      - only used when constructing a line segment -

    5
      Picking the end point of a line segment at right angles (perpendicularly)
      - only used when constructing a line segment -

    6
      Picking the intersection point of 2 objects

    7
      Picking a point located at a certain value of center angle on an arc of circle
      The angle parameter always must be an integer multiple of the angular grid defined in draft mode, it's value is defined from the positive X-axis.

    8
      Picking the end point of a line segment tangent to a circle
      - only used when constructing a line segment -

  - Pick Symbols 2
    (The pick point is located on temporary auxiliary lines)

    Figure 35: Pick Symbols 2

    Picking a point ..

    1
      .. vertically, above the last touched point
    2
      .. vertically, below the last touched point
    3
      .. horizontally, to the right of the last touched point
    4
      .. horizontally, to the left of the last touched point
    5
      .. on the temporary auxiliary line with the displayed angle
      The angle of the auxiliary temporary line is determined as the line angle in draft mode (default value 45).

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