Orientation

Goal: Start a session, find the tools and their settings, and know which object is which.

Words

• Source object: the original shape you're copying, usually dense and messy (a sculpt). Any visible mesh that isn't the active object counts as a source [4].
• Target (retopology object): the new, clean, low mesh you're drawing. It snaps onto the source's surface.
• You need at least one source, or the tools do nothing.

Where things live

• Start a session: in Object Mode, Add > Mesh. Two entries sit at the bottom: "Retopology at Cursor" and "Retopology from Active". "From Active" puts the new object at the active object's position and rotation, which is usually what you want. "At Cursor" puts it at the 3D cursor, aligned to the world [1] [3]. In F3 search, the operator is "RF: New target from Active".
• Tools: the toolbar on the left of the 3D View, in Edit Mode, on the target: PolyPen, PolyStrips, Strokes, Contours, Patches, Tweak, Relax [2].
• Tool options: the bar across the top of the 3D View while a Retopoflow tool is active, plus N > Tool, plus the Properties Editor's Tool tab [4]. The far right of the header has a "General Options" dropdown: overlay colour and offset, vertex size, and how much other objects fade.
• Pie menu: W while a Retopoflow tool is active switches tools and shows common settings [4].
• If the new mesh seems to poke through the source: lower the retopology overlay offset in the header [4] [1].

Before you draw

• Hide everything that isn't the thing you're copying. Hidden objects aren't sources.
• Save the file, and save again every few minutes.
• You can narrow the sources in the Snapping menu: a specific object or collection, or only selected objects [4].

Time target: novice 10 min, competent 3 min, fluent 1 min.

PolyStrips: the skeleton

Goal: Draw the main flow lines of the form (ridges, lips, and the edges where the shadow turns) as strips of quads.

Concept

• PolyStrips draws a strip of quads along a path you drag on the source [12].
• The width is the brush size you see when you hold Ctrl. It isn't fitted for you, so choose it on purpose.
• For a toon look, only forms that change the silhouette or move the shadow band need geometry. A rock's skeleton is a few long strips, not a net.
• A strip can start or stop on an existing face and attach to it. You can also draw alongside an existing edge.

Clicks and keys

1. Make a target ("Retopology from Active") on your sculpt. Enter Edit Mode if you aren't in it already. Pick PolyStrips.
2. Hold Ctrl to see the brush circle. Shift F, or [ and ], changes its size.
3. Ctrl + left-drag along the top ridge. A strip appears.
4. Straight after drawing, Ctrl Scroll changes the number of segments and Shift Scroll changes the width. The same sliders are in Blender's Adjust Last Operation panel.
5. Draw a second strip along a lip, starting on the end of the first. It attaches, and takes its width from the face it snaps to.
6. Curve handles are on by default. Drag a control point to bend the strip, or a handle to rotate it. Alt C toggles them. Hover over a control point and press V to switch between smooth and corner. Alt + left-drag on a control point changes the width there [13].
7. To select part of a strip: click one face, then Ctrl Shift + click another [12].

Exercise: add a Cube, give it a few cuts, and push some vertices around to make a lumpy slab. Use it as a source. Draw one strip along its top edge and one down a side. Then, on a real sculpt, draw three strips only: the top ridge and the two lips.

Common mistakes

• Forgetting Ctrl: a plain left-drag only selects or tweaks.
• Strips so wide that two of them cover the same area.
• A strip for a bump that doesn't change the outline or the shadow. Skip it.

Time target: novice 30 min, competent 10 min, fluent 4 min.

Strokes: fill between lines

Goal: Turn the gaps between the skeleton strips into clean patches of quads.

Concept

• The manual calls Strokes "an incredibly versatile tool for quickly sketching out patches of quads and filling holes" [14].
• It reads your selection and your stroke and picks a fill type for you. You don't need to memorise the names.
• Selected edges plus a new stroke extrude into a patch of evenly spaced quads.
• The count method decides how many quads you get: Fixed, Brush, Average (square quads matching the width of the selected edges) or Length.

Clicks and keys

1. Pick Strokes. Deselect all. Ctrl + left-drag on the source to draw a free line of vertices (an Edge Strip).
2. Keep that line selected. Draw a second stroke, roughly parallel to it, with Ctrl + left-drag. The space between fills with a grid of quads (an Equals Strip).
3. After either, Ctrl Scroll changes the number of vertices or loops.
4. To bridge two separate pieces: select the edges on one side, start the stroke on a vertex of the selection, and end it on a vertex of the other piece (an I Strip). Alt Scroll slides the bridge along the loop.
5. To fill a hole between strips: select one border, then stroke to the opposite border. The sides merge to nearby vertices, so holes close without overlapping.
6. A stroke that ends where it started makes a Loop. In the redo panel, Circle makes it round.
7. Settings worth knowing: Count Method, Extrapolation (Flat or Adapt, for T strips), Smoothing (0 gives straight lines) and Spacing [14].

Exercise: on the slab from the last step, fill the top between two PolyStrips. Select one strip's inner edge and stroke along the other. Use Ctrl Scroll to find the fewest loops that still follow the form. Then fill every gap between the three strips on your sculpt.

Common mistakes

• Drawing the second stroke far from parallel, so the fill twists. Redraw it closer to the first.
• Using Average with no edges selected: it falls back to the brush size.
• Too many loops. Count down with Ctrl Scroll until it hurts, then add one back.

Time target: novice 40 min, competent 15 min, fluent 6 min.

Relax and Tweak: clean up

Goal: Even out the quads and fix lumpy spots without redoing anything.

Concept

• Both are brushes that only affect the geometry under the brush.
• Relax evens out spacing and angles while staying on the source surface. It isn't a plain smooth [9].
• Tweak pushes vertices around. The default brush is Nudge; Alt toggles loop mode in Nudge [10] [11].
• You can reach both from any other Retopoflow tool without switching.

Clicks and keys

1. From any Retopoflow tool, hold Shift and left-drag over vertices: Relax.
2. Hold Ctrl Shift and left-drag: Tweak.
3. In the Relax or Tweak tool itself, left-drag applies the brush. Select with Shift + click, box select with B, or lasso with Ctrl + right-drag [10].
4. Brush size is F, strength Shift F, falloff Ctrl F.
5. Masking: Boundary (Exclude, Slide, Include) keeps the outer edge from drifting. Selected (Exclude, Only, All) limits the brush to or away from the selection.
6. Pin vertices you like: select them and use Pin Selected in the tool settings (Shift P); unpin with Alt P [9] [11]. Pins only show in vertex select mode.
7. For a whole selected loop, use the Relax operator (Shift R) or Even (Shift Alt R) in Edit Mode [6] [11].

Exercise: on your sculpt's new mesh, drag a few vertices out of place with Tweak on purpose, then Shift-drag Relax over the area and watch the quads recover. Then pin a sharp corner and Relax across it. It shouldn't move.

Common mistakes

• Relaxing sharp corners flat. Pin them, or mask Corners.
• Turning up Iterations, when Strength is the setting to try first [9].
• Expecting a plain click to select inside the brush tools.

Time target: novice 20 min, competent 8 min, fluent 3 min.

Caps and fills: closing the top and bottom

Goal: Close the open holes at the top and bottom of the mesh.

Concept

• F is an auto fill: it tries to fill the selected boundary with quads [6] [5].
• The Patches tool also fills when you press Enter or Ctrl + click.
• Check your version: in Retopoflow 4.2.2 the toolbar's Patches tool is the older "legacy" one, because the newer one is switched off in the code [3]. The manual describes the newer tool, so check its exact settings (Solution, Offset, step width) by eye. F, Enter and Ctrl + click should work in both.

Clicks and keys

1. Select the edges of the hole. Loop select is Alt + click, or double-click on an edge [4].
2. Tap F. A filled patch appears.
3. If it looks wrong, open the Adjust Last Operation panel. The Solution and Offset sliders (and Ctrl Scroll and Shift Scroll while the preview is up) cycle through other fills [5].
4. For holes with sharp corners, toggle which vertices count as corners with Ctrl + click on a selected boundary vertex [5].
5. Plain Blender fallback: select the boundary loop, then Edge > Grid Fill. It needs an even number of edges around the loop; if the count is odd, add or remove a vertex first.
6. If a hole won't fill cleanly, F with the loop selected makes a single n-gon [5].

Exercise: take the slab from earlier with its top and bottom open. Close the top with F and leave the bottom open. Then redo the top with Grid Fill and compare the face counts in the Statistics overlay.

Common mistakes

• Selecting only part of the boundary loop.
• Fighting for an all-quad bottom that nobody will see.
• Forgetting that Grid Fill needs an even edge count around the loop.

Time target: novice 15 min, competent 5 min, fluent 2 min.

PolyPen: fix corners and single faces

Goal: Place or fix vertices one at a time where the other tools get it wrong.

Concept

• PolyPen gives vertex-by-vertex control, built for low-poly game models [15].
• Insert Method decides what a click makes. Tri / Quad is the precise default: a vertex, then an edge, then a triangle, then a quad.
• It also works as a knife, cutting into existing faces.
• It expects vertex and edge selection, not face selection.

Clicks and keys

1. Pick PolyPen. Deselect all. Ctrl + click on the source: one vertex.
2. Keep it selected. Ctrl + click again: an edge. Again: a triangle. Again: the fourth corner makes it a quad.
3. To bridge two edges with a quad: select one edge, then Ctrl + click on the second edge.
4. To cut: deselect all, Ctrl + click on an edge, then Ctrl + click on another edge of the same piece. Partial loops and quad junctions are toggles in the tool options (Knife Loop Cuts, Knife Junctions).
5. Drag any vertex, without Ctrl, to tweak it. Hold Shift while dragging to move in small steps [11].
6. Set Insert Method to Quad for one-click quads.

Exercise: on the slab, delete one corner quad and rebuild it with PolyPen in Tri / Quad mode.

Common mistakes

• Clicking without Ctrl: that only selects.
• Insert Method left on Edge or Vertex, so faces never appear.

Time target: novice 15 min, competent 5 min, fluent 2 min.

Contours: tubes

Goal: Wrap loops around cylindrical forms: limbs, tails, necks, horns, poles.

Concept

• You draw strokes across the form, perpendicular to its length. Each stroke becomes a ring [7].
• Spans is how many vertices a new ring has. Cuts is how many loops sit between two rings.
• Method: Walk (the best, but slower on dense meshes), SDF or Fast. Start with the default.
• Tweak Loops is on by default: dragging an edge slides a whole loop.

Clicks and keys

1. Pick Contours. Deselect all.
2. Ctrl + left-drag across the tube near one end. A ring appears.
3. Straight away, Ctrl Scroll changes the number of vertices in the ring.
4. With the ring selected, drag a second stroke across the tube further along. It connects with a tube section.
5. Ctrl Scroll changes the loops in between. Shift Scroll or Alt T twists a ring.
6. Click and drag an edge to slide a loop along the form.

Exercise: add a Cylinder with a few cuts, bend it with Simple Deform or by moving vertices, and apply it so it's a plain mesh. Use it as a source. Draw 4 rings along it. Try 6 and 8 spans and count the faces.

Common mistakes

• Drawing strokes at an angle, which twists the ring.
• Too many spans.

Time target: novice 30 min, competent 10 min, fluent 4 min.

Mirror: half a creature

Goal: Model one half and get the other half for free.

Concept

• Retopoflow 4 uses Blender's real Mirror modifier; there's no separate symmetry mode [8].
• A Mirror section in the tool settings toggles axes, changes the modifier's properties, or applies it.
• Display modes: None, Applied (shows the mirrored side as real-looking geometry, which is confusing), Wire, Solid.
• Blender's own Edit Mode symmetry isn't supported [8].

Clicks and keys

1. Put the target's origin on the symmetry plane (standard Blender practice).
2. Open the Mirror section in the tool settings and turn on the axis, usually X.
3. Pick a display mode. Wire is the least confusing.
4. Draw across the symmetry line. It works in PolyPen, Contours and PolyStrips.
5. If you can't see the mirrored half in Edit Mode, turn on the modifier's On Cage button (the triangle icon) [2] [8].
6. When the half is done, apply the mirror from the same section.

Exercise: mirror a half-cylinder and draw a strip across the centre line.

Common mistakes

• Working on the "fake" side with Applied display: edits appear backwards [8].
• Forgetting to apply.

Time target: novice 15 min, competent 5 min, fluent 2 min.

Curve handles and helper ops

Goal: Know the extras that save time. Learn them last, one per session.

• Curve handles (Alt C): drag a selection as if it were a curve. On by default in PolyStrips and Strokes [13].
• Mesh Cleanup: in the tool settings or the W pie. It snaps to the source, merges doubles, fixes normals, fills holes, and can triangulate [6].
• Even (Shift Alt R) and Relax (Shift R) as operators for selected loops [11].
• Twist Loops (Alt T) and Rotate Topology (Alt R) realign a grid fill [6].
• Diamond Bevel (Ctrl Alt B): a crease-like junction on selected edges [6] [11].
• Adjust Loop Count: resamples a strip's count.

Exercise: try one helper per session on a mesh you've already made.

Time target: novice 10 min per helper, competent 3 min, fluent under a minute.

The whole flow: sculpt to game mesh

Goal: See the steps above as one flow, from a sculpt to a mesh you can export.

1. Sculpt the form, or a blockout. Keep it to big planes.
2. Make the target: Add > Mesh > Retopology from Active. Hide everything else. Save.
3. Skeleton: a few PolyStrips along the ridges and lips.
4. Fill: Strokes between them.
5. Tidy: Relax, Tweak and pins.
6. Caps: F on the top; leave the bottom open if it's buried.
7. Check the budget in the Statistics overlay. A 5 m toon rock might start at about 300 to 600 triangles; treat that as a value to test, not a rule. Far over? Remove loops.
8. Game mesh rules:
   • No Subdivision Surface modifier on the game mesh. If a result looks soft and soapy, check for this modifier first.
   • Mark Sharp on the edges that should stay crisp, then Shade Auto Smooth (Blender; in 5.x the menu may read "Shade Smooth by Angle").
   • Optional: a Bevel modifier with 1 segment plus Weighted Normal, for a soft highlight along edges (Blender).
9. Export the way your engine expects.

When not to retopologise (reasoned advice, not from the manual): hats, props and clothes. Box-model them directly at game density. Retopology is for shapes you sculpted first: rocks, cliffs, creatures.

Capstone: one rock from scratch

Goal: Retopologise one sculpted rock or cliff, start to finish, using only these lessons.

Steps: orientation, skeleton (3 to 5 PolyStrips), Strokes fill, Relax and Tweak, a top cap with F, the bottom as you choose, a Statistics check, Mark Sharp, Shade Auto Smooth, and no Subdivision.

Time target: novice 2 hours, competent 45 minutes, fluent 20 minutes. On a first-ever try, any of these is a pass.

Compare: if you've retopologised this sculpt before, put the old result next to the new one, count the faces, and see what you left out.