fx_sdf

Signed distance fields for effect shaders — the primitives an effect is shaped out of, the boolean and smooth-boolean operators that combine them, and the domain operators that repeat, round and hollow them.

#include "@builtin::deprecated.deprecatedParticles.fx.fx_sdf"

Pure math — no bindings. A Surface-domain shader and a .computeShader see different generated frameworks and can share a function only when it touches neither, so a shield's material and the compute pass that fills its volume measure one distance.

Every primitive is centred on the origin and takes the sample point in its own space, so a caller places one by transforming p rather than by passing a centre. Every one returns the signed distance to the surface: negative inside, positive outside, zero on it.

Primitives

Function	Surface
fx_sd_sphere(p, r)	radius r about the origin
fx_sd_box(p, b)	half-extents b
fx_sd_round_box(p, b, r)	half-extents b with edges rounded by r; the solid still reaches b
fx_sd_torus(p, major, minor)	ring of radius major in XZ, tube radius minor
fx_sd_plane(p, n, h)	plane through -h * n with normal n
fx_sd_capsule(p, a, b, r)	radius r around the segment a→b
fx_sd_cylinder(p, h, r)	radius r, half-height h, axis Y

Operators

fx_op_union is min, fx_op_intersect is max, and fx_op_subtract(a, b) carves b out of a.

fx_op_smooth_union, fx_op_smooth_intersect and fx_op_smooth_subtract take a fillet width k and weld the surfaces over it. A smooth union is never greater than min(a, b) and never less than min(a, b) - k / 4, so it reaches its hard counterpart as k approaches zero.

fx_op_round grows the field outwards, fx_op_onion hollows it into a shell, and fx_op_blend morphs one field into another.

Domain operators

These transform the point rather than the distance, so a primitive evaluated at the result is the one that repeats or stretches: fx_op_elongate stretches along each axis, fx_op_repeat folds the point into one cell of an infinite grid, fx_op_mirror folds it into the positive octant.