The three icons at the top of the Edit Face rollout let you specify the method of face selection. From left to right, they are:
Face Icon: Click to select a triangular face beneath the cursor; region selection selects multiple triangular faces within the region.
Polygon Icon: Click to select all coplanar faces (defined by the value in the Planar Threshold spinner) beneath the cursor. Usually, a polygon is the area you see within the visible wire edges. Region selection selects multiple polygons within the region.
Element Icon: Click to select all contiguous faces in an object. Region selection selects the same.
By Vertex: When this box is checked, you can select faces by drawing regions around vertices or by clicking on vertices with the mouse. When you click a vertex, any faces that use that vertex are selected.
Ignore Backfaces: When this is on (the default), selection of faces selects only those faces whose normals are visible in the viewport. When off, selection includes all faces, regardless of the direction of their normals. Note that the state of the Backface Cull setting in the Display branch no longer affects face selection. Thus, if Ignore Backfaces is off, you can select faces even if you can’t see them.
Ignore Visible Edges: This checkbox is only enabled when the polygon face selection method is chosen. When the Ignore Visible Edges checkbox is off (the default), face selection works as it did in R1. That is, no matter what the setting of the Planar Thresh. spinner, when you click a face, the selection will not go beyond the visible edges. When this checkbox is on, face selection ignores the visible edges, using the Planar Thresh. setting as a guide. Generally, if you want to select a “facet” (a coplanar collection of faces), you’d set the Planar Threshold to 1.0. On the other hand, if you’re trying to select a curved surface, you’ll need to increase the value, depending on the amount of curvature.
Planar Threshold: Set this to specify the threshold value that determines which faces are coplaner for Polygon face selection.
ExtrusionExtrudes selected faces outward or inward, based on their normals or an average of their selected normals.
Tessellates (subdivides) the selected faces.
Tessellate: Click this button to tessellate selected faces based on the Edge, Face Center and Tension controls.
Edge/Face-Center: Edge inserts vertices in the middle of each face edge and draws three lines connecting those vertices. As a result, four faces are created out of one face. Face-Center adds a vertex to the center of each face and draws three connecting lines from that vertex to the three original vertices. As a result, three faces are created out of one face.
Tension: Active in Edge mode only. Increases or decreases the Edge tension value. A negative value pulls vertices inward from their plane, resulting in a concave effect. A positive value pulls vertices outward from their plane, resulting in a rounding effect.
Explodes the selected faces into multiple elements or objects based on the angles of its edges.
Angle Thresh: When this is on (the default), selection of faces selects only those faces whose normals are visible in the
Explode Into: Specifies whether the exploded faces become the elements of the current object or seperate objects.
Construction Plane: Aligns the selected faces to the current construction plane. The current plane is specified by the active viewport in the case of the home grid. When using a grid object, the current plane is the active grid object.
Viewport: Aligns selected faces to the 0,0,0 plane of the active viewport. In the case of orthographic viewports, this is the same effect as aligning to the construction grid when the home grid is active. When aligning to a perspective viewport (including camera and spotlight views), the faces are reoriented to be aligned to a plane that is parallel to the camera’s viewing plane. (Perspective viewports have invisible camera planes.) In these cases, the selection of faces is not translated but only rotated.
Detach: Creates a new object by detaching the selected faces under a new name. You're prompted to enter a name for the new object. Detached faces leave a hole in the original object when you move them to a new position.
Collapse: Collapses selected faces by welding their vertices to the vertex in the center.
Make Planar: Forces all selected faces to become coplanar. The plane's normal is the average surface normal of the selected faces.
Build Face: Allows you to build new faces by connecting three existing vertices of the same object. This button puts you into a drawing mode in which you click and drag lines between sets of three vertices to create faces.
Delete: Deletes selected faces.
Hide: Hides selected faces. (The Select Invert command on the 3DS MAX Edit menu is useful for selecting faces to hide. Just select the faces you want to focus on, choose Select Invert, then click the Hide button.)
Unhide All: Unhides any hidden faces.
ID: Cycles through the numbered materials in the multi/sub-object material.
Select by ID: Displays a dialog for you to enter the number corresponding to one of the materials in the multi/sub-object material. Faces with that numbered material assigned to them are selected.
Auto Smooth: Sets the smoothing groups based on the angle between faces. Any two adjacent faces will be put in the same smoothing group if the angle between their normals is less than the threshold angle.
Select by Smooth Group: Displays a dialog that shows the current smoothing groups. Select a group by clicking the corresponding numbered button and clicking OK.
Threshold: Set this to specify the maximum angle between the normals of adjacent faces that determines whether those faces will be put in the same smoothing group.
Flip: Reverses the direction of the surface normals of the selected faces.
Flip Normal Mode: Click this to activiate Flip Normal Mode. While the button is active, the normal of any face you click is flipped.
Tip: The best way to use this function is to first set up your viewport in Smooth+Highlight mode along with Edged Faces. Secondly, if you use the function with default settings, you’ll be able to flip a face away from you, but you won’t be able to flip it back. For best results, turn off the Ignore Backfaces checkbox near the top of the Editable Mesh command panel. This will let you click on any face and flip the direction of its normal, regardless of its current direction.
Show Normals: Check this to display normals in the viewport. Normals are displayed as arrows.
Scale: Set this specify the size of the normals that are displayed in the viewport when Show Normals is selected.
Select By Normals: Click this button to select all faces whose normals are facing toward the active viewport, or facing away from the active viewport, depending on the active option button below this button.
Front Facing: When this option is chosen, and you click Select by Normals, all faces whose normals are toward the active viewport become selected.
Back Facing: When this option is chosen, and you click Select by Normals, all faces whose normals are away from the active viewport become selected.
If you hold down CTRL when you click Select By Normals, the selected faces are added to the currently selected faces. If you hold down ALT, the faces that would be selected are removed from the currently selected faces.
You are now in a mode that awaits your next selection.
The selected face is aligned with either the construction plane or the viewport, depending on which button you chose. All of the other selected faces are moved with it, while maintaining their original relationship with each other.
Since the Face Align functions don’t collapse all the selected faces into a plane, you can use them to align elements within an object. First, select the element, and then align it by selecting one of its faces.