3D clothing in Blender: sewing and simulating a garment with free software

A 3D garment is made like a real one: you cut pieces of fabric from a pattern, sew them together, and gravity creates the folds. Specialist software is paid, but Blender, which is free, contains everything needed to follow this method: a cloth simulation, virtual seams, collisions with the body, then rendering. This guide presents the free software, explains how the simulation works, then walks through the method from pattern to seam.

Software for creating 3D clothing

Blender is, in this list, the free tool that works in 3D from start to finish. Its cloth simulation is not designed only for fashion: it is also used for flags, curtains, tablecloths and cushions. But with the sewing option and collisions, it reproduces the method of a workshop.

Seamly2D is open source pattern-making software, actively maintained, which builds patterns from size charts or made-to-measure measurements. It works on flat patterns: useful for preparing accurate pieces, which you then reproduce in Blender to give them volume and simulate them.

Marvelous Designer is commercial software dedicated to digital clothing. It works by subscription, with a two-week free trial for new users and a plan for students; the terms are on its website.

How Blender simulates cloth

In the Physics tab of the object properties, the Cloth button adds a Cloth modifier to the mesh. Blender then connects the vertices with four kinds of virtual springs: tension, compression, shear and bending. Each one is set separately in the Physical Properties panel, along with the mass of the vertices (Vertex Mass) and air resistance (Air Viscosity). Presets serve as a starting point: Cotton, Denim, Leather, Rubber and Silk.

• Quality Steps sets the number of calculation steps per frame: the higher it is, the less the cloth passes through obstacles, but the longer the calculation takes.
• The calculation runs on the processor and the result is cached as playback progresses. Play the animation from the first frame, without jumping ahead.
• Applying the modifier freezes the shape of the cloth at the current frame. This is how you keep a drape for a still image: let the cloth fall, then apply.

Mesh density matters: cloth needs enough vertices to fold, but every vertex added slows the simulation down. A regular mesh, without very stretched faces, behaves better.

First step: draping a cloth

Before the garment, a simple exercise builds the right reflexes: a tablecloth on a table.

1. Add a plane above the table and subdivide it in Edit Mode to give it vertices.
2. Add the Cloth physics to it.
3. Select the table and add the Collision physics to it: collision with objects is set on the obstacle, not on the cloth.
4. Start playback with Space: the tablecloth falls and settles over the table.

For a curtain hanging from its rail, you need to pin the top of the cloth. Create a vertex group containing the top row, then choose it as the Pin Group in the Shape panel. The weight of each vertex in the group sets the strength of the pinning: painted in Weight Paint, it allows a smooth transition between the part that is held and the part that hangs free.

From pattern to seam: creating a garment

For a T-shirt or a dress, you reproduce the workshop method: flat pieces, sewn around the body. In Blender, seams are sewing springs: edges that belong to no face and that, during the simulation, pull together the vertices they connect.

1. Prepare the body. A character in a rest pose, arms apart, makes the work easier: the guide to the T-pose explains why. Add the Collision physics to it and set its outer margin (Thickness, Outer) so that the cloth settles just above the skin.
2. Draw the pieces flat. Start from a plane and, in Edit Mode, give it the shape of the front, then do the same for the back, as on a pattern. You can trace the outlines of a pattern prepared in Seamly2D. Keep a regular vertex density.
3. Place the pieces in front of and behind the body, a few centimetres away, without ever touching it: the manual warns that cloth that starts inside an obstacle makes the simulation unstable.
4. Join them into a single object with Ctrl+J: seams only connect vertices of the same mesh.
5. Draw the seams. In Edit Mode, select two borders that must meet, for example the sides of the front and the back, and run Edge, Bridge Edge Loops. Then select the faces that were created and delete them with Delete, Only Faces, which keeps the edges. What remains are edges without faces between the two borders, which is exactly what you need. Repeat for the shoulders and the sleeves.
6. Turn on sewing. Add the Cloth physics to the object, then in the Shape panel tick Sewing and set Max Sewing Force. Do not leave it at zero: zero means no limit, and the manual points out that extreme forces at the start, when the borders are still far apart, make the simulation unstable.
7. Keep the pieces from falling before they are sewn. Turn off the scene gravity (scene properties, Gravity) while sewing, then turn it back on to let the garment settle.
8. Turn on the collisions of the cloth with itself (Self Collisions): a garment seen up close must not pass through itself.
9. Start playback. The borders come together and the garment closes around the body. When the shape suits you, apply the Cloth modifier, then weld the sewn borders in Edit Mode with Mesh, Clean Up, Merge by Distance.

The Shrinking setting in the same panel shrinks the cloth by a given factor, or enlarges it with a negative value: handy for adjusting a garment that is too wide without redrawing the pieces.

A garment on an animated character

If the character moves, the garment has to follow. The body carries an armature, described in the Blender rigging guide, and its Collision physics must come after the Armature modifier in the stack, so that the cloth sees the body in its pose at the current frame.

• Pin what must hold: a belt, a collar, the top of a skirt, with a Pin Group whose vertices follow the body.
• Dynamic Mesh, in the Shape panel, recalculates the rest shape at every frame: useful for a heavily deformed, cartoon-style character.
• Bake the simulation from the Cache panel, over the frame range you need. The manual recommends it before rendering: the result is fixed and no longer varies from one playback to the next.
• Keep the same subdivision level in the viewport and at render time: the cache is calculated for a given level.

For the principles of animation itself, key poses and interpolation, see the guide to animation in Blender.

Finishing: thickness and folds

• Thickness. The simulation works on a surface with no thickness. Add a Solidify modifier after the Cloth modifier to give the cloth a real edge, and a subdivision to smooth it.
• Folds. In Sculpt Mode, the Cloth brush simulates the cloth under the cursor: handy for adding a fold or pulling an area taut by hand. The manual advises a small brush size, which is much faster to calculate. The 3D sculpting guide introduces Sculpt Mode.

Rendering cloth

Convincing cloth depends as much on the material as on the shape. In the Principled BSDF:

• A high roughness for cotton or wool, lower for silk or satin.
• Sheen simulates the very fine fibres of the surface: on cloth, it adds a soft, velvet-like highlight near the edges. It is set by its weight, roughness and tint.
• Thin Wall treats the surface as a wall with no thickness, suited to a fine sheer fabric or to cloth modelled as a single layer of faces.
• A weave texture used as a normal map gives the grain of the fabric. The guide to free 3D textures shows where to find them under a free licence, and the guide to Blender textures how to apply them.

Common mistakes

• The cloth passes through the body: Collision physics missing or placed before the armature, collision distance too small, or movement too fast for the chosen quality.
• The simulation explodes from the first frame: pieces that start inside the body, or Max Sewing Force left at zero.
• The garment falls to the floor before it is sewn: gravity active during sewing.
• The cloth folds like cardboard: mesh not dense enough, or preset too stiff.
• The animation changes from one playback to the next: simulation not baked, or a cache that needs clearing after a change to the cloth.