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GridTool Documentation
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GridTool: A Tool for Structured and Unstructured Grid Generation

Points/Curves

This panel contains several buttons, input-fields and a positioner, and they are used to create/modify/delete points and curves. In GridTool, a curve is represented by a link-list of points. These points are either on a surface (surface points) or somewhere in space (XYZ points). For surface points, in addition to the x, y, z, the surface number and its parametric coordinates, u and v are stored in the data base. Curves can be created together as a family. For example, all curves associated with a wing could be created together as a "wing" family. The family name for curves is selected from the "Patches" panel which will be discussed later. To start a new curve, press the "Next Curve" button. To create a new point for a curve, the "Next Point" button should be pressed, and this newly created point becomes the active point. Since every operation is done in one step, the new point will be placed where the last point was, and then the user can move the new point, (the active point), to any location. The active point can be moved to an existing point on a curve by placing the cursor over the desired curve point and hitting the hot key "m". Similarly, the active point can be moved to an existing point on the active surface by placing the cursor over the surface point and hitting the hot key "t". Also, the active point can be moved to any location on the active surface by either: (1) typing the parametric coordinates in the "U & V" input box, (2) moving the "U & V" positioner, (3) moving the "U & V" sliders. In order to move the active point in space, first the point should be converted to an "XYZ" point by pressing "On Surface" button. Once the active point is an XYZ point, the "x", "y", and "z" sliders can beused to move the point to anywhere in the space. It is also possible to change the coordinate by typing the values in the input field boxes. A point can be inserted ahead of the active point on a curve by pressing the "Insert Point" button. The new point becomes the active, and if the two neighboring points are on the same surface, then the inserted point will also be on the same surface. The point or the active curve can be deleted by pressing the "Delete Point" or the "Delete Curve" buttons, respectively. A point or a curve can become active by placing the cursor over it and hitting the hot key "p" or "c", respectively.

Image of the Points and Curves Panel

Distribution

This panel is used to distribute points on the active curve. The distribution is determined either from curvature (optimum) and spacing at the curve ends. For optimimum spacing, the weight controls the spacing. For a zero weight, the distribution will be similar to the distribution for the active curve. For weight equal to one, the distribution is determined by the curvatue. For weight between zero and one, the distribution is linear combintation of the current distribution and curvature distribution. Points can be distributed based on the spacing on either or both ends. The method is based on techniques develop by Vinokur and implemented in GRIDGEN [13].

FAQ

How do I create a curve?
To start a new curve, press the "Next Curve" button.
How do I add a point to an existing curves?
To create a new point for a curve, the "Next Point" button should be pressed, and this newly created point becomes the active point. Since every operation is done in one step, the new point will be placed where the last point was, and then the user can move the new point, (the active point), to any location.
The active point can be moved to an existing point on a curve by placing the cursor over the desired curve point and hitting the hot key "m". Similarly, the active point can be moved to a display path on the active surface by placing the cursor over the display path and hitting the hot key hot key "t". Also, the active point can be moved to any location on the active surface by either: (1) typing the parametric coordinates in the "U & V" input box, (2) moving the "U & V" positioner, (3) moving the "U & V" sliders. In order to move the active point in space, first the point should be converted to an "XYZ" point by pressing "On Surface" button. Once the active point is an XYZ point, the "x", "y", and "z" sliders can beused to move the point to anywhere in the space. It is also possible to change the coordinate by typing the values in the input field boxes.
How do I make a point active?
Place the cursor over the point, and hit the hotkey p.
How do I delete/project a point?
Make the point active, then push the delete/project point from Points/Curves panel
How do I insert a point?
A point can be inserted ahead of the active point on a curve by pressing the "Insert Point" button. The new point becomes the active, and if the two neighboring points are on the same surface, then the inserted point will also be on the same surface.
How do I convert a surface point to an XYZ point?
In order to move the active point in space, first the point should be converted to an "XYZ" point by pressing "On Surface" button. Once the active point is an XYZ point, the "x", "y", and "z" sliders can be used to move the point to anywhere in the space. It is also possible to change the coordinate by typing the values in the input field boxes.
How do I change the coordinates of an existing point?
Also, the active point can be moved to any location on the active surface by either: (1) typing the parametric coordinates in the "U & V" input box, (2) moving the "U & V" positioner, (3) moving the "U & V" sliders. In order to move the active point in space, first the point should be converted to an "XYZ" point by pressing "On Surface" button. Once the active point is an XYZ point, the "x", "y", and "z" sliders can beused to move the point to anywhere in the space. It is also possible to change the coordinate by typing the values in the input field boxes.
How do I split a curve?
  1. Make the curve active
  2. Make the point at which the curve will split active
  3. Push the split curve button
How do I combine two curves?
  1. Make the first curve active
  2. Push the combine button on the upper left of the Points/Curves
  3. Make the second curve active
  4. Push Combine Curves
How do I copy/project/smooth/delete a curve?
  1. Make the curve active
  2. Push the copy/project/smooth/delete button on the Points/Curves
How do I delete a family of curves?
  1. Type in the family name Family input-field in the Patches panel
  2. Push the Delete Family in the Patches Panel
How do extract edges of an existing surface?
  1. Turn the desired surfaces on
  2. Push the Auto Edge button
How do I collapse the endpoints of curves that are close?
  1. Activate the point to which the nearby points (to within the gap size) should be collapsed
  2. Input the Gap size the input-field
  3. Push the Collapse Points
How do I delete unused curves?
Push the Unused Curves button.
How do I turn on/off curves?
Push the All Curves button.
How do I enrich points on an existing curve?
  1. Make the curve active
  2. Enter desired number of points between each existing points (e.g. -2, will put 2 points between each existing points)
  3. Push the Enrich button
How do I redistribute points on an existing curve?
  1. Make the curve active
  2. Activate the Distribute Panel from Points/Curves Panel
  3. Enter desired number of points for the curve
  4. Enter the end spacings (-1 for default)
  5. Push the Distribute button
How can I tell if I have defined the same curve (or patch) twice?
Place the cursor over the curve (or patch) in question, and hit the c key ( f for patches). If there is more than one curve (or patch) at that location, different curve (or patch) numbers will appear in the Curve Number (or Patch Number ) buffer in the Points/Curves menu (or the Patches menu for patches).
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Comments and Questions
Last Updated: Sep 17, 2002