Editing Autodesk 3ds Max (section)

== Modeling techniques ==
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=== Polygon modeling ===
{{main|Polygon modeling}}
Polygon modeling is more common with game design than any other modeling technique as the very specific control over individual polygons allows for extreme optimization. Usually, the modeler begins with one of the 3ds max primitives, and using such tools as [[bevel]] and [[extrude]], adds detail to and refines the model. Versions 4 and up feature the Editable Polygon object, which simplifies most mesh editing operations, and provides subdivision smoothing at customizable levels (see [[NURMS]]).

Version 7 introduced the ''edit poly'' modifier, which allows the use of the tools available in the editable polygon object to be used higher in the modifier stack (i.e., on top of other modifications).

NURBS in 3ds Max is a legacy feature. None of the features have been updated since version 4 and have been ignored by the development teams over the past decade. For example, the updated path deform and the updated normalize spline modifiers in version 2018 do not work on NURBS curves anymore as they did in previous versions.

<!--HERE A GENERAL DESCRIPTION OF NURBS, WHICH IS NOT SPECIFIC TO 3DSMAX ONLY-->

=== NURBS (Non-Uniform Rational Based-Splines) ===
An alternative to polygons, it gives a smoothed out surface that eliminates the straight edges of a polygon model. [[NURBS]] is a mathematically exact representation of freeform surfaces like those used for car bodies and ship hulls, which can be exactly reproduced at any resolution whenever needed. With NURBS, a smooth sphere can be created with only one face.

The non-uniform property of NURBS brings up an important point. Because they are generated mathematically, NURBS objects have a parameter space in addition to the 3D geometric space in which they are displayed. Specifically, an array of values called knots specifies the extent of influence of each control vertex (CV) on the curve or surface. Knots are invisible in 3D space and can't be manipulated directly, but occasionally their behavior affects the visible appearance of the NURBS object. Parameter space is one-dimensional for curves, which have only a single U dimension topologically, even though they exist geometrically in 3D space. Surfaces have two dimensions in parameter space, called U and V.<ref>[http://www.rw-designer.com/NURBS "NURBS Curves and Surfaces"], November 22, 2013</ref>

NURBS curves and surfaces have the important properties of not changing under the standard geometric affine transformations (Transforms), or under perspective projections. The CVs have local control of the object: moving a CV or changing its weight does not affect any part of the object beyond the neighboring CVs. (This property can be overridden by using the Soft Selection controls). Also, the control lattice that connects CVs surrounds the surface. This is known as the convex hull property.<ref>{{cite web |url=https://math.stackexchange.com/q/118937 |title=Why is the Convex Hull property so important |date=November 22, 2013 |work=Stack Exchange }}</ref>

=== Surface tool/editable patch object ===
''Surface tool'' was originally a 3rd party plugin, but Kinetix acquired and included this feature since version 3.0.{{Citation needed|date=June 2008}} The surface tool is for creating common 3ds Max splines, and then applying a modifier called "surface." This modifier makes a surface from every three or four vertices in a grid. It is often seen as an alternative to "mesh" or "nurbs" modeling, as it enables a user to interpolate curved sections with straight geometry (for example a hole through a box shape). Although the surface tool is a useful way to generate parametrically accurate geometry, it lacks the "surface properties" found in the similar Edit Patch modifier, which enables a user to maintain the original parametric geometry whilst being able to adjust "smoothing groups" between faces.{{Citation needed|date=June 2008}}