Houdini 16.5 Cloth

Setting up the cloth simulation

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After a Cloth Object and a character Collision Object have been created, the cloth sim set-up can be completed using a variety of constraints. For example, pants typically need to be constrained to the body around the waist. You may also want the collar and the sleeves of a shirt to stay close to their original positions on the character.

The constraint types for cloth can be hard or soft. The hard version of the constraint overrides the cloth position and velocities with an exact trajectory. The soft version of a constraint generates forces that will try to make the cloth match goal positions and velocities.

Attach cloth constraint

The Cloth Attach Constraint shelf tool allows you to attach Cloth Objects to other (non-coth) simulation objects that contain geometry. Its main purpose is to bind cloth garments to Deforming Colliders. The corresponding shelf tool makes it easy to set the Cloth Attach Constraint DOP properly. It allows you to select specific points on the cloth object and constrain them to the nearest point on the Deforming Collider at the initialization start frame for the Cloth Simulation DOP object.

One unique feature of the Cloth Attach Constraint DOP is that the goal target uses primitives and not points. At the start of the simulation, a nearest location lookup is performed on the cloth constrain points to that of the specified goal primitives to determine the goal position. This means that there is no need to insert specific points on the Deforming Colliders that correlate to the cloth constraint points to avoid unwanted cloth pinching and bunching.

Stitch cloth constraint

The stitch constraint can be used to attach two pieces of cloth together. The hard version of this constraint will result in a merged piece of cloth that acts as a single sheet, which even has bend forces around the seam. The soft version will simply try to keep the points on both ends close together, without generating a bend force.

Cloth

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