The Bulge tool combines the Transform scale tool with a Radial Falloff and produces a swelling effect on the target object or surface. The tool is applied similar to how any normal scaling transform is applied, but produces a falloff that smoothly fades the affect of the scale across the object or surface.
Usage
The Bugle tool is found in the 'Deform' subtab of the modeling toolbox. It can also be found in the menu bar under "Edit > Deform > Bulge". LMB+clicking the tools button will activate the tool. Next, clicking in the 3D viewport will enable the tool's interactive editing mode. On first click, the bulge tool will create an automatic falloff. The center of this Falloff is placed at the intersection of the mouse pointer and the Work Plane and the size of it is determined by the bounding box of the target element relative to the center point. In some cases, this might not be the desired behavior, so when the tool is active it is also possible to manually position the Falloff. This is done by RMB+clicking and dragging in the 3D viewport.
At first activation the radial falloff is auto-fit to the current geometry and the Stretch tool is activated at the center of the mesh. Using the Stretch handles causes an apparent bulging of the object. You can easily define a custom area of the mesh for applying the bulge by using the right mouse button to drag out the radial falloff region. The left mouse button will apply the stretch tool.
Transform--
Scale: Users may used the X,Y and Z input fields to apply specific scaling values. When adjusting an object interactively in the viewport, the 'Scale' input fields will display the current scale factor applied, providing useful user feedback.
Absolute Handle: The 'Absolute Handle' toggle applies an additional function to the tool handles allowing users to scale the handle itself without affecting the transform amount. In some cases this provides finer control over very large or very small adjustments.
Negative Scale: The 'Negative Scale' toggle enables/disables MODO's ability to interactively apply negative scale values when manipulating the tool handles in the viewport. When disabled, users can always input negative values in any of the input fields directly.
Pivot: Disabled for the 'Bulge' tool.
Gimbal: Disabled for the 'Bulge' tool.
Child Compensate: (Only in Items Mode) The 'Child Compensate' toggle when disabled will pass along the transform value to any child items of the current selection, when enabled, the child items will ignore any transform values.
Slip UVs: (Only in Component Modes) UV values are generally fixed to specific vertices, subsequently further edits to the geometry may warp, deform or otherwise distort the UV values in undesirable ways requiring users to adjust the map or redo it altogether. To avoid this undesirable result, users can enable the 'Slip UVs' function so as to not disturb any existing UV mapping applied to the geometry.
 'Slip UVs' function disabled, note texture warping. |  'Slip UVs' function enabled, texture remains even. |
Morph: (Only in Component Modes) The Morph option determines how MODO treats stored Morph information when applying transforms to geometry (Move, Rotate, Scale, etc.). In previous versions of MODO, in order to transform a Morph along with its base, it needed to be selected in the Vertex Map list. If it wasn't, relative Morph map data when recalled would produce distorted, undesirable results. If users were unaware of the requirements, it was easy to accidentally mess up a model. To remedy this problem, there are now three options controlling how the Morph Map vertex data is dealt with when applying any transforms--
None- Unselected Morph data is not affected, though selected (visible) Morphs can still be transformed independent of their source.
Transform- With this option selected, Morph data is transformed along with base mesh.
Keep Positions- With this option Selected, Morph data is converted into a Absolute Morph Map and all vertices retain their pre-transformed positions.
Snapping--
Please reference the 'Snapping' Section of the documentation.
Radial Falloff--
Center X/Y/Z: Defines the Center of influence, where the strength of the Falloff will be greatest (100%). The strength of the falloff will attenuate toward the outer bounds of the Spherical volume, the area outside the volume receives no tool influence.
Size X/Y/Z: Defines the radius of a perfect circle from the 'Center' and determines the outer area of the Falloff where there is no affect.
Auto Size: Users can select this option to automatically size the Falloff's 'Center' and 'Size' values to match the bounding box of the current selection.
Shape Preset: The strength of the Falloff's influence can be controlled along the extent using a 'Shape Preset'-
Linear- Attenuation of Falloff occurs evenly across its range.
Ease-In- Strength of Falloff is greater toward the 'Start' position.
Ease-Out- Strength of Falloff is greater toward the 'End' position.
Smooth- Strength of Falloff is greater toward the center of the Falloff.
Custom- Users can use the 'In'/'Out' options to fine tune strength of Falloff.
In/Out: The 'In' value determines the strength of the Falloff nearer to the 'Start' position, where the 'Out' value determines the strength on nearer the 'End' side of the Falloff.
Mix Mode: In instances where there are multiple falloffs applied to a transform (using the 'Add' option of the Falloff menu), the mix mode defines how each Falloff interacts with the other.
