Create or select an object. > Modify panel > Right-click object's entry in the stack display. > Convert To: Editable Patch
Create or select an object. > Right-click the object. > Transform (lower-right) quadrant of the quad menu > Convert To: > Convert to Editable Patch
Editable Patch provides controls for manipulating an object as a patch object and at four sub-object levels: vertex, edge, patch, and element.
Editable Patch objects provide the same functionality as the Edit Patch modifier. Because working with them requires less processing and memory, we recommend you use Editable Patch objects rather than the Edit Patch modifier whenever possible.
When you convert an object to an editable patch or apply an Edit Patch modifier, gmax converts the object's geometry into a collection of separate Bezier patches, each patch made up of a framework of vertices and edges, plus a surface.
The framework of control points and connecting tangents defines the surface. Transforming the components of this framework is the primary technique in patch modeling.
The surface is the Bezier patch surface, whose shape is controlled by the vertices and edges.
The control framework conforms exactly to the surface, making it easy to visualize the results of patch modeling.
The output of the Surface modifier is a patch surface. If you are modeling with splines and are using the Surface modifier to generate a patch surface from the spline cage you can use an Edit Patch modifier for further modeling.
Turn on Show End Result on the Modify panel if you have modifiers above the Editable Patch modifier and want to see the result of all the modifiers in the modifier stack. This function will remain on until you turn it off.
See also
Edit Modifiers and Editable Objects
Procedures
To work at a sub-object level:
In the modifier stack display, choose a selection level: Element, Patch, Edge, or Vertex.
Select the sub-object geometry you want to edit.
To attach an object using Edit Patch:
Select an editable patch object, or an object with the Edit Patch modifier applied.
Click Attach in the Modify panel > Geometry rollout > Topology group.
Turn off Reorient, if necessary.
Select an object to attach.
The object takes on a patch structure and stays in its original location.
The attached object is now part of the editable patch object. The Tessellation settings for the original object affect attached objects as well.
To attach and reorient an object:
Turn on Reorient before attaching the object.
The object is both attached and moved to align with the patch object. The pivot of the attached object matches the pivot of the Edit Patch object.
To detach a patch surface:
Make a patch selection.
If you want to reorient the detached surface, turn on Reorient.
Click Detach.
A Detach dialog appears.
Name the detached surface.
The detached surface remains in place if you chose not to reorient it.
To copy a patch surface:
Make a patch selection.
In the Geometry rollout > Topology group, turn on Copy.
If you want to reorient the copied surface, turn on Reorient.
Click Detach.
A Detach dialog appears.
Name the patch copy.
The copied object remains in place if you chose not to reorient it. It is deselected and assigned a different color.
To delete a patch surface:
Make a patch selection.
Click Delete.
The patch surface disappears.
To subdivide a patch:
Select one or more patches.
Turn on Propagate to maintain surface continuity.
Click Subdivide.
The patch selection is subdivided, increasing the number of patches.
You can repeat this process, subdividing multiple times. Each subdivision increases the number of patches, which become increasingly smaller. The following figure is an example of modeling a highly subdivided surface.
To subdivide an edge:
At Patch (Edge) level, make an edge selection.
A single edge is indicated by its coordinate axis or transform gizmo at the center of the edge. For multiple edges, the axis icon is at the center of the selection set.
Optionally, turn on Propagate to maintain surface continuity.
Click Subdivide.
The edge selection is subdivided. Each new edge is on the boundary of a new, smaller patch.
To add a patch:
At Patch (Edge) level, select an open edge (one that bounds a single patch, and therefore is not shared with another patch).
Click Add Tri or Add Quad.
A new patch is added to the surface.
To unlock interior edges of selected patches:
At Patch (Patch) level, select one or more patches.
Right-click the selection and choose Manual Interior from the pop-up menu.
The check mark moves from Auto Interior, the default, to Manual Interior. Interior edges and their vertices are now unlocked. If you now transform the patch, the interior edges remain static. To transform the interior vertices, see the following procedure.
To transform interior vertices:
At Patch (Patch) level, select one or more patches.
Right-click the selection and choose Manual Interior from the pop-up menu.
The check mark moves from Auto Interior, the default, to Manual Interior.
Switch to Vertex level.
The interior vertices appear as yellow squares.
With the Vectors filter turned on, transform the interior vertices of the selected patches.
To anchor a patch:
By default, the welding process shifts the geometry of both patches to a common center. You can anchor one patch so that the other patch moves to its location when the weld occurs.
At the Patch (Patch) level, before you begin the weld, select the patch you want anchored.
Return to Vertex level and weld the vertices.
When the weld occurs, the anchor patch remains fixed while the other patch moves to make the weld.
To create a new element, do one of the following:
SHIFT-drag one or more patches.
SHIFT-extrude one or more patches.
SHIFT-extrude one or more edges.
SHIFT-drag an element.
Interface
The Selection rollout provides buttons for selecting the sub-object level, working with named selections, display and filter settings, and displays information about selected entities.
Editable Patch has four levels of sub-object editing: Vertex, Edge, Patch, and Element. The selection you make at each level appears in the viewport as a component of the patch object. Each level maintains its own sub-object selection. When you return to a level, the selection reappears.
Clicking a button here is the same as selecting a sub-object type in the Modifier Stack rollout. Click the button again to turn it off and return to object selection level.
Vertex: Selects a vertex control point and its vector handles on a patch object. At this level, vertices can be welded and deleted.
A Transform gizmo or axis tripod appears at each selected vertex.
Vector handles appear as small green squares around the vertex. Also, with certain objects you may see interior vertices represented as yellow squares.
Edge: Selects a bounding edge of the patch object. At this level, edges can be subdivided, and new patches added to open edges.
A Transform gizmo or axis tripod appears in the middle of a single selected edge. For multiple selected edges, the icon is at the selection center.
Patch: Selects an entire patch. At this level, a patch can be detached, deleted, or its surface subdivided. When a patch is subdivided, the surface is broken into smaller patches, each with its own vertices and edges.
Element: Select and edit an entire element. An element has contiguous faces.
Tip: You can highlight selected patches in a shaded display by turning on Shade Selected Faces in the Viewport Properties dialog. Right-click over the viewport name and choose Configure in the menu to display the Viewport Properties dialog.
Named Selections group
Copy: Places a named selection into the copy buffer.
Paste: Pastes a named selection from the copy buffer.
Filter group
When either check box is turned off, you can't select those elements. Thus, for example, you can disable vectors and click a patch object without moving a vector by mistake.
Vertices: When on, you can select and move vertices.
Vectors: When on, you can select and move vectors (handles on the control points).
Lock Handles: Affects only Corner vertices. Locks the tangent vectors together so that when you move one, you move them all. Applies only to the Vertex sub-object level.
By Vertex: When you click a vertex, any edges or patches that use that vertex, depending on the current sub-object level, are selected. This also works with Region Select.
Note: When By Vertex is on, you can select sub-objects only by clicking a vertex, or by region selection.
Ignore Backfacing: When on, selection of sub-objects selects only those sub-objects whose normals are visible in the viewport. When off (the default), selection includes all sub-objects, regardless of the direction of their normals. Use this on a complex patch model where you want to select only visible patches.
Note: The state of the Backface Cull setting in the Display panel does not affect sub-object selection. Thus, if Ignore Backfacing is off, you can still select sub-objects, even if you can't see them.
Select Open Edges: Selects all edges, in sub-object edge, that are used by only one patch. You can use this to troubleshoot a surface; open edges will be highlighted.
Selection Information: At the bottom of the Selection rollout is a text display giving information about the current selection. If 0 or more than one sub-object is selected, the text gives the number and type selected. If one sub-object is selected, the text gives the identification number and type of the selected item.
Geometry rollout
The Geometry rollout provides functions for editing a patch object and its sub-objects. For specific information on controls found in all groups except Tessellation, select any of the links below: