Freaks City

Intrinsic Attributes for Packed Geometry Packed geometry in Houdini exposes several intrinsic attributes that control transform behavior. When creating a Grid and Sphere, then using a Copy node to replicate spheres onto the grid with Pack Geometry Before Copying enabled, moving points via an Edit node stores transform data in the intrinsic:pack ...

Houdini’s Grain solver operates on Position-Based Dynamics (PBD) principles, which decouple collision resolution from velocity integration. Instead of calculating forces and accelerating particles, the solver directly modifies particle coordinates to satisfy spatial constraints, then reconstructs velocities from the resulting positional delta. ...

Bounding Box Based Rotation vector bbox_low, bbox_high; getbbox(bbox_low, bbox_high); float spin_limit = 4; matrix3 base_mtx = ident(); float spin_factor = fit(@P.y, bbox_low.y, bbox_high.y, 0, 1); rotate(base_mtx, spin_factor * spin_limit, {0, 1, 0}); @P *= base_mtx; Custom Parameter UI Definition #pragma label oper_mode "Operation" ...

Deformation Gradient The deformation gradient F serves as a fundamental tensor in continuum mechanics, capturing the local deformation of material points. It provides a complete description of stretch, shear, and rigid body rotation within an infinitesimal neighborhood around each material point. Mathematical Definition: The mapping relationshi ...

When simulating projectile impacts, calculating the angle between incoming trajectory and surface orientation determines whether the object adheres to the surface or rebounds. By comparing the normalized dot product against a configurable threshold, we can trigger a reflection sequence. vector trajectory = @v; vector surf_normal = normalize(@hi ...