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Move half-curvature change routine into engine

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This routine is implemented in a very representation-specific way, so
the engine seems like the best place for it.
This commit is contained in:
Aaron Fenyes 2025-04-15 23:44:35 -07:00
parent e1952d7d52
commit 4654bf06bf
2 changed files with 38 additions and 31 deletions
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35
app-proto/src/assembly.rs
View file

@ -8,6 +8,7 @@ use web_sys::{console, wasm_bindgen::JsValue}; /* DEBUG */
use crate::{ use crate::{
engine::{ engine::{
Q, Q,
change_half_curvature,
local_unif_to_std, local_unif_to_std,
realize_gram, realize_gram,
sphere, sphere,
@ -401,37 +402,9 @@ impl Assembly {
let representation = self_for_effect.elements.with_untracked( let representation = self_for_effect.elements.with_untracked(
|elts| elts[subject].representation |elts| elts[subject].representation
); );
representation.update(|rep| { representation.update(
// set the sphere's half-curvature to the desired value |rep| change_half_curvature(rep, half_curv)
rep[3] = half_curv; );
// restore normalization by contracting toward the curvature
// axis
const SIZE_THRESHOLD: f64 = 1e-9;
let half_q_lt = -2.0 * half_curv * rep[4];
let half_q_lt_sq = half_q_lt * half_q_lt;
let mut spatial = rep.fixed_rows_mut::<3>(0);
let q_sp = spatial.norm_squared();
if q_sp < SIZE_THRESHOLD && half_q_lt_sq < SIZE_THRESHOLD {
spatial.copy_from_slice(
&[0.0, 0.0, (1.0 - 2.0 * half_q_lt).sqrt()]
);
} else {
let scaling = half_q_lt + (q_sp + half_q_lt_sq).sqrt();
spatial.scale_mut(1.0 / scaling);
rep[4] /= scaling;
}
/* DEBUG */
// verify normalization
let rep_for_debug = rep.clone();
console::log_1(&JsValue::from(
format!(
"Sphere self-product after curvature change: {}",
rep_for_debug.dot(&(&*Q * &rep_for_debug))
)
));
});
self_for_effect.realize(); self_for_effect.realize();
} }
}); });

34
app-proto/src/engine.rs
View file

@ -35,6 +35,40 @@ pub fn sphere_with_offset(dir_x: f64, dir_y: f64, dir_z: f64, off: f64, curv: f6
]) ])
} }
// given a sphere's representation vector, change the sphere's half-curvature to
// `half-curv` and then restore normalization by contracting the representation
// vector toward the curvature axis
pub fn change_half_curvature(rep: &mut DVector<f64>, half_curv: f64) {
// set the sphere's half-curvature to the desired value
rep[3] = half_curv;
// restore normalization by contracting toward the curvature axis
const SIZE_THRESHOLD: f64 = 1e-9;
let half_q_lt = -2.0 * half_curv * rep[4];
let half_q_lt_sq = half_q_lt * half_q_lt;
let mut spatial = rep.fixed_rows_mut::<3>(0);
let q_sp = spatial.norm_squared();
if q_sp < SIZE_THRESHOLD && half_q_lt_sq < SIZE_THRESHOLD {
spatial.copy_from_slice(
&[0.0, 0.0, (1.0 - 2.0 * half_q_lt).sqrt()]
);
} else {
let scaling = half_q_lt + (q_sp + half_q_lt_sq).sqrt();
spatial.scale_mut(1.0 / scaling);
rep[4] /= scaling;
}
/* DEBUG */
// verify normalization
let rep_for_debug = rep.clone();
console::log_1(&JsValue::from(
format!(
"Sphere self-product after curvature change: {}",
rep_for_debug.dot(&(&*Q * &rep_for_debug))
)
));
}
// --- partial matrices --- // --- partial matrices ---
pub struct MatrixEntry { pub struct MatrixEntry {