Mihail Lupu, currently Lead 3D Character Artist at Gameloft, isn't a full-time software developer, but he builds tools in his spare time, usually after running into a workflow problem in his own character work and looking for a better way to solve it.

Over time, this has grown into a small collection of tools for 3ds Max, which we've featured before. His latest release is retoPoly, a native modifier for manual retopology. The idea came from wanting to keep more of the retopology process directly inside 3ds Max while preserving the workflow he likes most about it: the modifier stack.

retoPoly lets artists draw and tweak topology directly over high-res geometry, with tools for creating contours, editing edge flow, bridging, patching, guides, brushes, masking, and live conforming. Since it works as a modifier, the topology stays editable in the stack, and you can keep working with modifiers like Symmetry, TurboSmooth, etc. without having to collapse the mesh.

How retoPoly Started

I developed retoPoly myself for Autodesk 3ds Max. The project originally started as a personal tool and an experiment around my own retopology workflow. I wanted to explore a different way of doing manual retopology directly inside 3ds Max, while keeping the topology editable as part of the modifier stack.

As I continued working on it, the experiment gradually grew into a much more complete tool. More operations were added, the interaction became more visual, and eventually I realized that the same workflow could also be useful to other 3ds Max artists who prefer having direct control over their topology.

One of the main technical challenges during development was keeping the workflow interactive while the topology remained projected onto one or more high-resolution reference meshes and editable inside the modifier. I wanted the modifier to stay responsive and predictable even as the topology became more complex and more editing operations were added.

Another important part of the development was making the different tools feel like parts of the same workflow rather than isolated commands. I spent a lot of time refining the viewport interaction, previews, and UI so that most operations could be understood visually without constantly referring to documentation.

retoPoly eventually became a native manual retopology modifier built around that idea: the topology remains editable, the artist keeps control over the edge flow, and the whole process stays inside the regular 3ds Max workflow. The plug-in is mainly intended for 3D Artists, Environment Artists, Archviz Artists, Game Artists, Animators, etc.

Creating Topology with Draw and Contour

Two of the tools I use for establishing new topology are Draw and Contour, but they approach the problem in different ways. With Draw, I can extend topology directly from an existing open border by drawing over the reference surface. The tool detects the border section I am working from and generates a new projected row of quads following the stroke.

Draw can also work from guides. I can sketch an open or closed guide directly over the High Poly surface and then build topology progressively from it. Each generated row can become the starting point for the next one, which makes it possible to establish the main flow of a region before worrying about smaller adjustments. It can also use an existing hole border as a guide and generate connected quad rings from it.

Contour is useful when I want to describe the shape through a series of cross-sections. I draw contour rings over the surface, and RetoPoly creates quad bands between consecutive rings. Before committing the result, I can modify the segment count, rotate or reposition the contour, and adjust the topology connecting the two rings. Contour can also continue from an existing open border, so it can become part of the topology that has already been created. 

I tend to think of Draw as a more directional way of constructing topology, while Contour is useful for forms that can be described efficiently through successive rings.

Building Larger Areas with Stripe and Patch

For larger areas, I added tools such as Stripe and Patch, where the idea is to describe the overall topology structure first rather than constructing individual polygons one by one. Stripe creates a multi-row quad strip from a stroke drawn over the reference surface. After drawing it, I can modify the shape using editable knots and control properties such as the number of subdivisions, the number of segments across the strip, its width, and taper. It can also start directly from an existing open border, which makes it useful for quickly extending a larger section of an existing mesh.

Patch works differently. It builds a structured projected grid using guides, existing topology borders, or combinations of the two. For example, I can establish important boundaries first and then use Patch to generate the topology between them. The guides and patch resolution remain adjustable before the operation is committed. There is also a corner-patch workflow with curved editable guides, which is useful when the region does not fit a simple rectangular layout.

Other tools complement this type of construction. Bridge can generate projected quad rows between open borders, while Fill Hole can create a quad grid inside an existing boundary. The general idea is that I can switch between several construction methods depending on the shape I am working on instead of forcing every area through the same retopology operation. 

Edit Flow and Topology Refinement

Once the main topology is in place, a large part of the work becomes editing and redirecting it. This is where Edit Flow became one of the more extensive parts of retoPoly. Rather than making it a single-purpose operation, I developed Edit Flow as a more general topology editing mode. It can extend open topology, create polygons from open vertices, bridge edges, work with loops, connect vertices or edges, inset faces, collapse edges, and clean-remove topology. I can also move individual vertices directly over the High Poly surface without leaving the tool.

This makes it possible to create a larger structure using Draw, Contour, Stripe, or Patch and then stay in Edit Flow for many of the smaller decisions that follow.

Around Edit Flow, there are several more specialized tools. The Transform Brush can move, rotate, scale, or relax groups of vertices directly over the reference surface. Relax helps redistribute vertices, while Conform can project edited areas back onto the High Poly.

Straighten and Edge Length help control spacing and alignment. Fast Loop can insert or remove continuous loops, while Cut provides another way of changing the topology structure.

I also added Flow, which can rebuild a touched quad region as a projected rail grid aligned with a brush stroke, and Guide Flow, which can reshape interior topology according to a guide while preserving open borders. Those two are more like experimental topology tools.

These tools are useful at different scales: some establish large topology structures, while others are intended for progressively refining the result.

Modifier-Based Workflow and Who retoPoly Is For

One of the aspects that became increasingly important while developing retoPoly was keeping everything compatible with the normal 3ds Max modifier-stack workflow. Because retoPoly is itself a modifier, I can continue editing the authored low-resolution topology while other modifiers above it generate the final result. For example, with Symmetry and TurboSmooth above retoPoly, Show Cage lets me see the original control topology while 3ds Max displays the subdivided result at the same time. This makes it much easier to judge the final surface without having to collapse the stack.

The same philosophy extends to smaller workflow features. 

retoPoly includes tools for moving topology precisely to the world-space X, Y, or Z zero plane, which is useful when preparing symmetry seams. It also has operation-scoped Auto Weld, so welding is limited to geometry involved in the current operation rather than affecting unrelated vertices.

The Mask system can freeze parts of the topology so they are protected from destructive editing operations. I also added a Topology Inspector, which can identify things such as isolated vertices, boundary or loose edges, degenerate faces, triangles, quads and N-gons, together with cleanup and repair functionality.

All committed geometry operations participate in the normal 3ds Max Undo/Redo system. The plug-in does not try to decide what the topology should look like. The topology itself is still designed by the artist. retoPoly is essentially the workflow I developed for making that process more interactive and more integrated with the way I already work inside 3ds Max.

Purchase retoPoly here.

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