Null COMP
Summary
The Null Component serves as a place-holder in a scene. It can be used to transform (translate, rotate, scale) Components attached to it.
A Null Component can also be used as a "look at" object to help point other Components like cameras or lights.
The Null Component is also used as an End Affector for constructing chains of bones.
Parameters - Xform Page
The Xform parameter page controls the object component's transform in world space.
Transform Order /xOrd - The menu attached to this parameter allows you to specify the order in which the changes to your Component will take place. Changing the Transform order will change where things go much the same way as going a block and turning east gets you to a different place than turning east and then going a block.
Rotate Order /rOrd - The rotational matrix presented when you click on this option allows you to set the transform order for the Component's rotations. As with transform order (above), changing the order in which the Component's rotations take place will alter the Component's final position.
Translate / Rotation / Scale /t[xyz] /r[xyz] /s[xyz] - The three fields allow you to specify the amount of movement along any of the three axes; the amount, in degrees, of rotation around any of the three axes; and a non-uniform scaling along the three axes. As an alternative to entering the values directly into these fields, you can modify the values by manipulating the Component in the Viewport with the Select & Transform state.
Pivot /p[xyz] - The Pivot point edit fields allow you to define the point about which a Component scales and rotates. Altering the pivot point of a Component produces different results depending on the transformation performed on the Component.
For example, during a scaling operation, if the pivot point of an Component is located at -1, -1, 0 and you wanted to scale the Component by 0.5 (reduce its size by 50%), the Component would scale toward the pivot point and appear to slide down and to the left.
In the example above, rotations performed on an Component with different pivot points produce very different results.
Uniform Scale /scale - This field allows you to change the size of an Component uniformly along the three axes.
Note: Scaling a camera's channels is not generally recommended. However, should you decide to do so, the rendered output will match the Viewport as closely as possible when scales are involved.
Look At /lookat - Allows you to orient your Component by naming the Component you would like it to Look At, or point to. Once you have designated this Component to look at, it will continue to face that Component, even if you move it. This is useful if, for instance, you want a camera to follow another Component's movements. The Look At parameter points the Component in question at the other Component's origin.
Tip: To designate a centre of interest for the camera that doesn't appear in your scene, create a Null Component and disable its display flag. Then Parent the Camera to the newly created Null Component, and tell the camera to look at this Component using the Look At parameter. You can direct the attention of the camera by moving the Null Component with the Select state. If you want to see both the camera and the Null Component, enable the Null Component's display flag, and use the Select state in an additional Viewport by clicking one of the icons in the top-right corner of the TouchDesigner window.
Look At Up Vector /lookup - When specifying a Look At, it is possible to specify an up vector for the lookat. Without using an up vector, it is possible to get poor animation when the lookat Component passes through the Y axis of the target Component.
- Don't Use Up Vector - Use this option if the look at Component does not pass through the Y axis of the target Component.
- Use Up Vector - This precisely defines the rotates on the Component doing the looking. The Up Vector specified should not be parallel to the look at direction. See Up Vector below.
- Use Quaternions - Quaternions are a mathematical representation of a 3D rotation. This method finds the most efficient means of moving from one point to another on a sphere.
Path SOP /pathsop - Names the SOP that functions as the path you want this Component to move along. For instance, you can name an SOP that provides a spline path for the camera to follow.
Production Tip: For Smooth Motion Along a Path - Having a Component follow an animation path is simple. However, when using a NURBS curve as your path, you might notice that the Component speeds up and slows down unexpectedly as it travels along the path. This is usually because the CVs are spaced unevenly. In such a case, use the Resample SOP to redistribute the CVs so that they are evenly spaced along the curve. A caution however - using a Resample SOP can be slow if you have an animating path curve.
An alternative method is to append a Basis SOP to the path curve and change it to a Uniform Curve. This way, your Component will move uniformly down the curve, and there is no need for the Resample SOP and the unnecessary points it generates.
Roll /roll - Using the angle control or the editing field, you can specify a Component's rotation as it animates along the path.
Position /pos - This parameter lets you specify the Position of the Component along the path. The values you can enter for this parameter range from 0 to 1, where 0 equals the starting point and 1 equals the end point of the path. The value slider allows for values as high as 10 for multiple "passes" along the path.
Orient Along Path /pathorient - If this option is selected, the Component will be oriented along the path. The positive Z axis of the Component will be pointing down the path.
Up Vector /up - When orienting a Component, the Up Vector is used to determine where the positive Y axis points.
Auto-Bank Factor /bank - The Auto-Bank Factor rolls the Component based on the curvature of the path at its current position. To turn off auto-banking, set the bank scale to 0.
Parameters - Pre-Xform Page
The Pre-Xform parameter page applies a transform to the object component before the Xform page's parameters are applied.
Matrix CHOP matrixchop - The Matrix CHOP parameter can be used to transform using a 4x4 matrix directly. The 16 elements of the matrix are taking from the first 16 channels of any CHOP. It only uses the first sample of each channel. The matrix data is laid out in such as way that the 13th, 14th and 15th channels contain the translation. That is to say, the matrix data is defined in column major order (the first 4 channels are the first column, the next 4 channels are the 2nd column, etc.) If you are converting from a Table DAT using a DAT to CHOP, you'll want to use a Transpose DAT to get the channels in the correct order.
Parameters - Display Page
The Display parameter page controls the component's material and rendering settings.
Material /material - Selects a MAT to apply to the geometry inside.
Render /render - Whether the Component's geometry is visible in the Render TOP. This parameter works in conjunction (logical AND) with the Component's Render Flag.
Draw Priority /drawpriority - Determines the order in which the Components are drawn. Smaller values get drawn after (on top of) larger values.
Wireframe Color /wcolor - Use the R, G, and B fields to set the Component's color when displayed in wireframe shading mode.
Light Mask /lightmask - Defines which lights will illuminate the geometry in the Component. Accept Pattern Matching as described in the Scripting Guide.
Parameters - Common Page
The Common parameter page sets the component's node viewer, clone relationships, and path variable.
Node View - Determines what is displayed in the node viewer, also known as the Node Viewer. Some options will not be available depending on the Component type (Object Component, Panel Component, Misc.)
- Geometry Viewer - Shows a 3D geometry viewer displaying the geometry inside the component. This option is only available for Object components.
- Control Panel - Displays the Control Panel, only available for Panel Components.
- Operator Viewer - Displays the node viewer from any operator specified in the Operator Viewer parameter below.
Operator Viewer /opviewer - Select which operator's node viewer to use when the Node View parameter is set to Operator Viewer.
Clone /clone - Path to a component used as the Master Clone. If the component specified as Master exists, then this component becomes a clone.
Path Variable /pathvar - Specifies a variable name you can use anywhere inside the component as the path to that component. See Path Variable.
Load On Demand /loadondemand - Loads the component into memory only when required. Good to use for components that are not always used in the project.
External .tox /externaltox - Path to a .tox file on disk which will source the component's content upon start of a .toe. This allows for components to contain networks that can be updated independently of the .toe file. Paths used to locate .tox files should not contain expressions or root variables. Built-in and Environment variables (like $MYDOCUMENTS, $DESKTOP and $HOME) are accepted. If the .tox file can not be found, whatever the .toe file was saved with will be loaded.
Use Backup Copy if External .tox is Missing /savebackup - When this checkbox is enabled, a backup copy of the component specified by the External .tox parameter is saved in the .toe file. This backup copy will be used if the External .tox can not be found. This may happen if the .tox was renamed, deleted, or the .toe file is running on another computer that is missing component media.
Sub-Component to Load /subcompname - When loading from an External .tox file, this option allows you to reach into the .tox and pull out a COMP and make that the top-level COMP, ignoring everything else in the file (except for the contents of that COMP). For example if a .tox file named project1.tox contains project1/geo1, putting geo1 as the Sub-Component to Load, will result in geo1 being loaded in place of the current COMP. If this parameter is blank, it just loads the .tox file normally using the top level COMP in the file.
Re-Init Network /reinitnet - This button will re-load from the external .tox file (if present), followed by re-initializing itself from its master, if it's a clone.
See Also
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