3D Scene Rotation

Controlling the System Camera. Rotating (Spinning) and Moving a Camera

Initially after opening the 3D window, the system camera is located at the distance providing visibility of all elements of the 3D scene (that is, all 3D constructions and 3D Bodies present in the model). To view the 3D scene, you can rotate (spin) and/or move it arbitrarily, zoom in and out, change the orientation and view direction, as well as scale the image in the 3D window.

As the user watches the 3D window in the process of spinning (rotating) and moving the system camera, one feels as if the 3D scene itself is moving, rather than the camera. Therefore, when describing 3D model handling in the future, we will frequently refer to the process of rotating (spinning) and moving the system camera as the 3D scene rotation.

Rotating the 3D Scene

When working with a 3D model, the most commonly used is the free rotation mode; therefore it is preset in the 3D window by default. The camera can be panned, rotated, zoomed in/out using the mouse and the keyboard.

Notice that under "zooming in/out the camera" we mean changing the focal length of its objective lens. The camera itself, however, stays still.  This process is similar to the function of a real camera.

The most common way of rotating the camera is dragging the mouse with the depressed within the 3D window.

You can use additional commands described in the Manage 2D View chapter for controlling the 3D scene as well.

Center of camera rotation

Rotating the image in the 3D window with the default system camera active is achieved by moving the camera around the scene center. If necessary, the center of rotation can be changed via the Set Center Of Rotation command:

The command can also be called from the contextual menu.

After the call, the current camera rotation center appears on the screen as a crosshair. Following options become available in the Parameters window:

Intersection point

Solid center

X, Y and Z coordinates of a selected center of rotation are displayed below.

Upon selecting the option, you need to click on an operation in the 3D scene. The crosshair representing the rotation center will relocate to a center of mass of the body created by a selected operation.

The option allows to select an arbitrary point as the center of rotation. Upon selecting the option, click on arbitrary location in the 3D scene. A ray parallel to the view direction will be cast from the selected location through the 3D scene. If this ray intersects with some 3D object, the intersection point becomes the center of rotation. If this ray does not intersect any of 3D objects, the center of rotation remains unchanged.

It is possible to define arbitrary center of rotation without calling the Set Center of Rotation command. This can be done by pressing without releasing for some time at any object within 3D scene. The crosshair will appear at the specified point. This represents the position of the new temporary center of rotation. After finishing the rotation (when mouse button is released) center of rotation returns to the original position.

 

The Reset center of rotation command is used for clearing the custom center of rotation and reverting to the default one:

Fixed view direction
Is enabled via the Fix command.

The command can also be called from the contextual menu.

Enabling this mode makes rotation of the 3D scene impossible. However, you still can pan and zoom. This setting is saved in the active document and remains enabled upon opening the document in other sessions.

To disable this mode select one of the system camera rotation modes.

System camera rotation modes

There are the following system camera rotation modes:

•Free rotation.

•Rotation about one of the axes of the coordinate system located at the center of rotation.
Axes orientation may be defined either by the global coordinate system, or by the screen coordinate system.

•Panoramic Rotation.

 

Free camera rotation mode:

The command can also be called from the contextual menu.

This mode id set by default. It allows to rotate 3D camera in any direction around a center of rotation.

 

Rotation around X axis mode:

The command can also be called from the contextual menu.

At the center of the rotation is an imaginary coordinate system, relative to the X-axis of which the rotation occurs. The orientation of the axes of this coordinate system coincides either with the direction of the axes of the global coordinate system, or with screen coordinate system, depending on the status of the screen coordinate system mode (see below).

 

Rotation around Y axis mode:

The command can also be called from the contextual menu.

At the center of the rotation is an imaginary coordinate system, relative to the Y-axis of which the rotation occurs. The orientation of the axes of this coordinate system coincides either with the direction of the axes of the global coordinate system, or with screen coordinate system, depending on the status of the screen coordinate system mode (see below).

 

Rotation around Z axis mode:

The command can also be called from the contextual menu.

At the center of the rotation is an imaginary coordinate system, relative to the Z-axis of which the rotation occurs. The orientation of the axes of this coordinate system coincides either with the direction of the axes of the global coordinate system, or with screen coordinate system, depending on the status of the screen coordinate system mode (see below).

 

Orientation of the coordinate axes for three aforementioned rotation modes is defined by condition of the Screen coordinate system mode:

The command can also be called from the contextual menu.

When this command is active, rotation occurs in the screen coordinate system, when off - the orientation of the rotation coordinates coincides with the global coordinate system. Screen coordinate system is formed by two axes laying in the screen plane (one vertical, one horizontal) and an axis coinciding with the view direction.

 

Panorama mode:

The command can also be called from the contextual menu.

In this mode the Z axis cannot lean left/right. You can still lean it back/forward though. The projection of Z axis onto a screen plane always remains vertical. The mode of the panoramic rotation can be useful when working with the models of buildings, furniture, interiors etc.

Automatic Rotation

The command can be called in one of the following ways:

The command can also be called from the contextual menu.

Automatic rotation can be applied in any of the rotation modes mentioned above.

To define rotation parameters, depress and, while holding it, drag the mouse in the rotation direction. After that, release . In that way, you define the direction and angular rotation velocity.

The automatic rotation mode is switched off by a repeated call of the same command.

Auto-Resize

The command can be called in one of the following ways:

The command can also be called from the contextual menu.

It switches on/off the mode where each regeneration of the model leads to 3D window automatically reframing in such way that it fits all existing 3D objects.

Rotate Normal to Selected Element

The command can be called in one of the following ways:

The command is also available in the View Toolbar in 3D window, including the drawing on active workplane mode. The command can be called not only in the standby mode, but also, when working with other commands. In the latter case, the status of the active command will be saved, and the system will return to it, upon exiting the Rotate Normal... command.

When drawing on active workplane, the command makes view direction normal to such workplane.

When not drawing on active workplane, upon calling the command, you have to select a flat object, so the following automenu option is active:

Move the cursor over a desired object and press . In result, the view direction will become normal to the selected object. Upon setting the desired view direction, exit the command by pressing or <Esc>, or using the following automenu option

If a flat object is selected in advance prior to calling the command, then the command instantly makes the view direction normal to such object, so then you only have to exit the command.

3D scene rotation via the contextual menu

3D scene rotation commands are also available in the contextual menu invoked by clicking on an empty space in the 3D scene in command standby mode.

An icon of a currently active mode is highlighted in menus.