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Normalize deformed assembly by contracting

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Uniformly contract spatial and curvature components. This preserves the
centers of spheres, but alters their curvatures. It should preserve
planes entirely.
This commit is contained in:
Aaron Fenyes 2025-02-03 15:56:52 -08:00
parent 817a446fad
commit fa1e54f171
1 changed files with 20 additions and 4 deletions
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24
app-proto/src/assembly.rs
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@ -371,8 +371,8 @@ impl Assembly {
}
}
// step each element along the mass shell geodesic that matches its
// velocity in the deformation found above
// step the assembly along the deformation, and then project each
// element back onto its mass shall
/* KLUDGE */
// since our test assemblies only include spheres, we assume that every
// element is on the 1 mass shell
@ -380,9 +380,25 @@ impl Assembly {
elt.representation.update_silent(|rep| {
match elt.column_index {
Some(column_index) => {
// apply the deformation linearly
let rep_next = &*rep + motion_proj.column(column_index);
let normalizer = rep_next.dot(&(&*Q * &rep_next));
rep.set_column(0, &(rep_next / normalizer));
// project back onto the mass shell by contracting
// toward the last coordinate axis
let q_sp = rep_next.fixed_rows::<3>(0).norm_squared();
let half_q_lt = -2.0 * rep_next[3] * rep_next[4];
let half_q_lt_sq = half_q_lt * half_q_lt;
let scaling = half_q_lt + (q_sp + half_q_lt_sq).sqrt();
rep.fixed_rows_mut::<4>(0).copy_from(
&(rep_next.fixed_rows::<4>(0) / scaling)
);
rep[4] = rep_next[4];
/* DEBUG */
// report self-product before and after projection
console::log_1(&JsValue::from(
format!("Self-product of element representation\n After step: {}\n Scaling: {}\n After scaling: {}", rep_next.dot(&(&*Q * &rep_next)), scaling, rep.dot(&(&*Q * &*rep)))
));
},
None => {
console::log_1(&JsValue::from(