Colliders

Other objects that press into a mesh: a hand, a chair, a prop, another character. A mesh always collides with itself; colliders are for everything else.

Adding a collider

Press Add Collider with the other objects selected to add them all, or with nothing else selected to add an empty entry and pick one (the panel asks you to). An entry is an Object or a Collection. A collection adds every mesh in it, but never the mesh it is set on. So several characters can share one: set each of them up with the same collection as its collider, and they press into each other. For the meshes that make up one character, such as a body and a separate head, use Several meshes as one instead.

How firm a collider is

• Firmness % (0 to 100) is how firm the collider is. At the same Dent, a firm collider (100%) presses the flesh in twice as far as a soft one (0%). How far it presses in also follows how far the collider reaches into the mesh.
• Use Its Own Firmness: a collider that is set up itself (another character, or a prop you set up) presses with the Firmness it is set up with, ticked on every collider you add. Its Firmness, and its regions' where they cover it: a character whose knee region is firm presses in harder with the knee than with the thigh, into another character as into itself. The panel shows what it presses with, such as Uses Hand's own Firmness (0%) and its 1 region, and the list says F own. Untick it to give the whole collider the one Firmness typed here instead. A collider that is not set up always takes the number here. A firm part next to a soft one gives a firmer side to the dent and the bulge, blended rather than a sharp edge; the lower the Bulge Width, the sharper. Changing one of its Firmness regions, or the vertex group one reads, puts the frames of every character it presses out of date.

Another character as a collider

A set-up character presses as it is without its own deformation. So two characters can be each other's colliders: bake them in either order, or with Bake All, and re-baking one never puts the other out of date.

Showing and hiding colliders

• Hide a collider with the eye, not by disabling it. A collider disabled in viewports (the monitor icon), or in a collection that is disabled or excluded, is not worked out by Blender, so its place is unknown. The panel says so (… is turned off in the viewport …), and a bake refuses rather than guessing. As a member of a Collection entry, an object disabled in viewports does still work, as long as that collection is not disabled itself.
• Bake with colliders shown as they will render. A collider whose subdivision differs between the viewport and the render is a different surface in the render, and those frames are refused there, as for the character itself (see step 1 of Your first shot).

How deep a collider presses

• Dent sets how far the flesh gives. At the default Dent (15%), a collider pressed deep can show through the skin: a ball pressed 2 cm into a thigh dents it about 6 mm. For a firm press, raise Dent, to 50% or more; a soft cushion takes 70%.
• A thin collider needs more Dent to read, since it reaches only a little way into the flesh.
• A collider sunk deeper than it is thick is missed: a part wholly under the skin, such as the thin tip of a coil pushed right in, passes through untouched. Keep each part's press shallower than it is thick.

Exact Collider Edges

On by default, under the list, shown once there is a collider. Without it, where the edge of a collider moves over the flesh, a spot at the edge can sink for one frame and come back the next, with a bulge round it: a pop. A ball rolled over a cushion shows it at the ball's trailing edge.

Exact Collider Edges stops those pops. Everything else comes out the same.

• Only colliders. The mesh's own parts pressing into each other, and the meshes of a group set up as one, are not affected. With no collider the setting does nothing, so it is not shown.
• It works on every frame, Bake This Frame and Live included. With Smooth Pops as well, this removes the edge pops and Smooth Pops evens out what jumps remain.

Turning it on or off changes the result of a mesh with colliders, so frames baked one way are refused the other way until you bake again. Both stay in the cache, as with any setting. Frames baked for a mesh with colliders by a version of Fleshy without this setting were baked with it off: they read as out of date until you bake again, or untick it to play them as they are.