Ayam: Interactive Actions (Modeling)

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## 3. Interactive Actions (Modeling)

Before invoking any modeling action you should select one or more objects using the main window or using the pick action!

Every action can be started with a key press (a shortcut) when the focus is in a view window or by pressing the associated button in the tool window. Using a shortcut starts that action in the current view only, the other views are not affected. Starting an action from the tool window will cause the action to be started in all view windows simultaneously.

To break an action, the `<Esc>` key may be used.

The default action for all views, which is also in effect after use of the `<Esc>` key, is `"None"` or `"Pick"` (depending on the preference setting `"Modeling/DefaultAction"`) See section Selecting Objects within a View for more information about picking objects.

Note that the modeling actions are not available in perspective views.

If an action is in effect for a view, the views title will be changed appropriately.

A modelling action is performed by clicking into the view to mark a point in space or to pick a vertex, then dragging the mouse.

You may undo/redo the effects of an action using `<Ctrl+z>` and `<Ctrl+y>` (see section The Undo System for more information).

Grids are available to restrict the modeling actions to certain points and help in exact modeling.

Also note that you may use the middle and rightmost mouse button to zoom and move the view while modeling actions are active.

For actions that modify the camera of a view please see section View Window Shortcuts and Actions.

## 3.1 Moving Objects or Selected Points

Using the modeling action `"Move"` (shortcut: `<m>`) you may move selected objects or the selected (tagged) points of the selected objects.

Note that the objects/points will be moved in the XY-plane for Front-views, the ZY-plane for Side-views, and the XZ-plane for Top-views only, no matter how the view is rotated.

## 3.2 Rotating Objects or Selected Points

Using the modeling action `"Rotate"` (shortcut: `<r>`) you may rotate objects or the selected (tagged) points of the selected objects.

Note that if multiple objects are selected, each object is rotated around the center of its own local coordinate system. The axis of rotation is always parallel to the Z-axis in Front-views, the Y-axis in Top-views, and the X-axis in Side-views.

## 3.3 Rotating Objects or Selected Points around a Point

Using the modeling action `"Rotate about"` (shortcut: `<a>`) you may rotate objects or the selected (tagged) points of the selected objects around a specified point in space. The action requires a point to be specified using a single click after the action has been started. The point will then be marked by a little red cross. If you want to rotate about a different point, you need to restart the action (press `<a>` again).

After the first click, the action works the same way as the Rotate action, except that it rotates around the specified point. This also works with multiple selected objects. Note that this action does not only change the Rotate_X(_Y,_Z) properties of the selected objects, but also the Translate_X(_Y,_Z) properties.

To avoid degenerated coordinates due to roundoff errors it is highly suggested to use grids with this action.

## 3.4 Scaling Objects or Selected Points

There are several different actions available to scale objects or the selected (tagged) points of the selected objects.

The modeling action `"Scale 3D"` (shortcut: `<S>`, note the big S!) scales all three axes of the selected objects or the selected (tagged) points of the selected objects by the same factor.

The modeling action `"Scale 2D"` (shortcut: `<s>`) scales just two axes of the selected objects or the selected (tagged) points of the selected objects. Those axes are XY in a Front-view, ZY in a Side-view, and XZ in a Top-view.

The modeling actions `"Scale X"` (shortcut: `<x>`), `"Scale Y"` (shortcut: `<y>`), and `"Scale Z"` (shortcut: `<z>`) scale only one axis of the selected objects or the selected (tagged) points of the selected objects.

The modeling action `"Stretch 2D"` (shortcut: `<Alt+s>`) works much like `"Scale 2D"` but the scale factor for each axis may be different. Never start this action by a click near one of the axes to be changed, as this will cause very big scale factors for the other axis. Try it first with a centered box by starting from one of the vertices, then try it once starting on the X-axis.

## 3.5 Selecting Points

The modeling action `"Select Points"` (shortcut: `<t>`; tag points) may be applied to a NURBS curve, NURBS patch or objects that support single point editing only. Objects draw the selectable points using small rectangular handles. Selected points will be drawn in dark red.

The selected points may be modified using the modeling actions Move, Rotate, and Scale as discussed above. Selected points always take precedence for those modeling actions.

After the pick (the selection of a point), the picked point will be added to the list of selected points for the selected object. If the selected point is already in that list it will be removed from the list instead. Note that the list of selected points will not be deleted from the object until a de-select is performed using the shortcut `<D>`.

Note that the list of selected points is not copied, if the object is copied using the clipboard. Undo and redo will destroy the list of selected points too!

However, it is perfectly legal to select some points, move them using the move action, then switch to single point editing, edit some other or even one of the selected points, switch back to the selection action, add other points to the selection or delete some points from the selection, switch to rotate, rotate the selected points and so on.

You may also add a bigger number of points to the selection using a click and drag operation. All points that are inside the rectangular region defined by the click and drag will be added to the selection.

## 3.6 Editing Points

To edit the points of an object three actions (`"Edit"`, `"Edit Weights"`, and `"Direct Point Edit"`) are available. All those actions may be applied to objects that support single point editing only. Objects mark themselves editable by drawing the editable points using small rectangular handles if one of the single point editing action is activated and the object is selected.

- The modeling action `"Edit"` (shortcut: `<e>`) works much like the move action, but it moves single points instead of objects. In contrast to the move action, you need to pick on the handle of the point you want to move. Furthermore, it is not possible to move points of multiple selected objects, only the first selected object is considered.

  If a NURBS curve has multiple points, this action modifies all points that make up the multiple point.

- The modeling action `"Edit Weights"` (shortcut: `<w>`) changes the w coordinate of a single point by dragging the mouse left or right. The weights may be reset for all points using the shortcut: `<W>`. Furthermore, it is not possible to edit the weights of multiple selected objects, only the first selected object is considered.

  If a NURBS curve has multiple points, this action modifies all points that make up the multiple point.

- The modeling action `"Direct Point Edit"` (shortcut: `<p>`) opens a small window where you may change the coordinates of the selected point directly by entering numbers. Note that the w coordinate setting will be ignored if the picked point does not have weight information (is not homogenous). Using the small menu on top of the coordinate window you may determine whether editing takes place in local object or global world space.

  If a NURBS curve has multiple points, this action modifies all points that make up the multiple point.

  Notice that since Ayam 1.4 the direct point editing dialog may stay open all the time. Furthermore, it is not necessary that the original object stays selected, you may select other objects to e.g. infer new point coordinates from their properties and apply them to the original object. However, certain actions like deleting objects, will also delete the reference to the selected points. In this case you will have to select the object and then a point to edit again. Furthermore notice that the coordinate values displayed in the direct point editing window will not update when the point is modified by another modeling action. Simply click on the point again in a view where the direct point editing action is active, to update the coordinate values in the direct point editing dialog. This modelling action also may only be applied to a single selected object.

## 3.7 Inserting or Deleting Points

The modeling action `"Insert Point"` (shortcut: `<i>`) may be applied to NURBS and interpolating curves (objects of type NCurve and ICurve) only. A new control point will be inserted in the curve right after the picked point. The new point will be inserted in the middle between the selected point and the next point, changing the shape of the curve. (It is also possible to insert control points into certain types of NURBS curves without changing their shape using knot insertion; see the insert knot tool The Insert Knot Tool.)

The modeling action `"Delete Point"` (shortcut: `<d>`) may be applied to NURBS and interpolating curves (objects of type NCurve and ICurve) only. The selected control point will be deleted from the curve. Deleting points from a curve with knot type custom may currently lead to an incorrect knot sequence, please check and correct the new sequence manually.

## 3.8 Miscellaneous Actions

This section documents some special modeling actions.

- The modeling action `"FindU"` (shortcut: `<u>`) may be applied to NURBS curves (objects of type NCurve) only. This action may be used to get the corresponding parametric value u from a point on a curve. Pick a point on the curve (not a control point!). If this is done, the appropriate value for u is calculated, stored in the global variable u, and additionally written to the console. A small cross is drawn at the position of the picked point. Remember to exactly pick a point on the curve or nearby, otherwise the calculation may fail and no value will be written to the console.
- The modeling action `"Split Curve"` (shortcut `<c>`) may be applied to NURBS curves (objects of type NCurve) only. Using this action you may split a NURBS curve into two new curves at a point on the curve that may be specified by picking a point on the curve. Remember to exactly pick a point on the curve or nearby otherwise the calculation of the parametric value for the split will fail. The selected curve will be changed by this action, and a new curve will be created. It is currently not possible to undo the changes of a split!

## 3.9 Editing in Local Space

Normally, all editing takes place in world space and the input plane of all modelling actions is constrained to the world XY-, ZY-, or XZ-plane (depending on the type of view used).

However, if a view is aligned and switched to local, you can also edit in local object space. This means you can e.g. edit a two-dimensional parameter curve of a skin object where both objects (curve and skin) are rotated and scaled arbitrarily and make sure that the curve remains two-dimensional all the time.

All you need to do is to first select the curve and then press `"Ctrl+a"` to align the view and then `"Ctrl+l"` to make it local. In practice, this means that the input plane of an aligned local view will match the XY-, ZY-, or XZ-plane of the local object space, depending on the type of the view (`"Front"`, `"Side"`, or `"Top"`).

Furthermore, grids will also act as if defined in local object space. Note that in contrast to their normal behaviour, grids can also be scaled differently in X-window and Y-window coordinates in aligned local views (if the local object space is deformed this way).

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