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You can use subnets to simplify complex networks by creating a hierarchy. You can put multiple objects inside a subnet and use it like an object. You can also nest subnets inside subnets.
The left menu chooses the order in which transforms are applied (for example, scale, then rotate, then translate). This can change the position and orientation of the object, in the same way that going a block and turning east takes you to a different place than turning east and then going a block.
The right menu chooses the order in which to rotate around the X, Y, and Z axes. Certain orders can make character joint transforms easier to use, depending on the character.
Translation along XYZ axes.
Degrees rotation about XYZ axes.
Non-uniform scaling about XYZ axes.
Local origin of the object. See also setting the pivot point .
Scale the object uniformly along all three axes.
This menu contains options for manipulating the pre-transform values. The pre-transform is an internal transform that is applied prior to the regular transform parameters. This allows you to change the frame of reference for the translate, rotate, scale parameter values below without changing the overall transform.
This reverts the translate, rotate, scale parameters to their default values while maintaining the same overall transform.
This sets the translate parameter to (0, 0, 0) while maintaining the same overall transform.
This sets the rotate parameter to (0, 0, 0) while maintaining the same overall transform.
This sets the scale parameter to (1, 1, 1) while maintaining the same overall transform.
This removes the pre-transform by setting the translate, rotate, and scale parameters in order to maintain the same overall transform. Note that if there were shears in the pre-transform, it can not be completely removed.
This completely removes the pre-transform without changing any parameters. This will change the overall transform of the object if there are any non-default values in the translate, rotate, and scale parameters.
Keep Position When Parenting
When the object is re-parented, maintain its current world position by changing the object’s transform parameters.
When the object is being transformed, maintain the current world transforms of its children by changing their transform parameters.
Enable Constraints Network on the object.
Path to a CHOP Constraints Network. See also creating constraints.
You can you use the Constraints drop down button to activate one of the Constraints Shelf Tool. If you do so, the first pick session is filled automatically by nodes selected in the parameter panel.
Labels for the four inputs to the subnetwork. These labels appear when you press on the input connections. This is useful to document the purpose of each input.
Whether or not this object is displayed in the viewport and rendered. Turn on the checkbox to have Houdini use this parameter, then set the value to 0 to hide the object in the viewport and not render it, or 1 to show and render the object. If the checkbox is off, Houdini ignores the value.
The object inside the subnet from which to get the subnet’s output transform, or one of the inputs to use as the parent.
The local transform of the subnet is currently always the transform computed from its transform parameters. So it may be inconsistent with its world transform when this is set to a child object.
Space separated list of objects inside the subnet to display. Use
* to make all objects visible (the default). You can use wildcards and bundle references to specify objects.
This parameter lets you:
Quickly filter the visible objects based on an existing naming convention, for example
Control visibility of objects inside a locked digital asset where the display flags are not available.
Otherwise, in a normal subnet you can simply go into the subnet and set the display flag on objects.
Viewport Selecting Enabled
Object is capable of being picked in the viewport.
Script to run when the object is picked in the viewport. See select scripts .
Cache Object Transform
Caches object transforms once Houdini calculates them. This is especially useful for objects whose world space position is expensive to calculate (such as Sticky objects), and objects at the end of long parenting chains (such as Bones). This option is turned on by default for Sticky and Bone objects.
See the OBJ Caching section of the Houdini Preferences window for how to control the size of the object transform cache.
The following examples include this node.
This example actually includes eight examples of ways that you can use voronoi fracturing in Houdini. In particular, it shows how you can use the Voronoi Fracture Solver and the Voronoi Fracture Configure Object nodes in your fracture simulations. Turn on the display flags for these examples one at a time to play the animation and dive down into each example to examine the setup.
No geometry is animated in this file. All animation is achieved by animating the textures
Flames are grids so that UV textures can easily be applied, they are then warped around a metaball using a magnet SOP. The flames are then assigned to either a yellow or blue Flames texture. The Flames' opacity mask wrap is set to Decal to prevent the texture from repeating and showing a single pixel ring at the top of the flame geometry. I'm also using a mask file named
flameOpacMap.jpg to enhance the flames' shape at the top. The noise offset has been animated over
$T with an greater emphasis on the Y axis so that the flames look like they are rising. This is the same reason the Noise jitter is larger for the Y axis as well.
The coals are spheres that have been copy stamped onto a deformed grid. Using Attribute Create surface nodes I am able to override and copy stamp the lava texture’s parameters at the SOP level so that local variables, such as
$BBY, can be used to animate the texture. This way the texture’s crust and its crust values can be used only to form the tops of the coals. This reserves the lava aspect of the texture to be used on the bottoms of the coals. The lava intensity (
Kd attribute) is then stamped and animated to create the look of embers on the bottom of coals glowing.
This example demonstrates how to create a simple parent-child agent setup.