playcanvas
Version:
Open-source WebGL/WebGPU 3D engine for the web
112 lines (111 loc) • 2.92 kB
JavaScript
import { math } from "../../../core/math/math.js";
import { INTERPOLATION_CUBIC, INTERPOLATION_LINEAR, INTERPOLATION_STEP } from "../constants.js";
class AnimCache {
constructor() {
this._left = Infinity;
this._right = -Infinity;
this._len = 0;
this._recip = 0;
this._p0 = 0;
this._p1 = 0;
this._t = 0;
this._hermite = {
// hermite weights, calculated on demand
valid: false,
p0: 0,
m0: 0,
p1: 0,
m1: 0
};
}
update(time, input) {
if (time < this._left || time >= this._right) {
const len = input.length;
if (!len) {
this._left = -Infinity;
this._right = Infinity;
this._len = 0;
this._recip = 0;
this._p0 = this._p1 = 0;
} else {
if (time < input[0]) {
this._left = -Infinity;
this._right = input[0];
this._len = 0;
this._recip = 0;
this._p0 = this._p1 = 0;
} else if (time >= input[len - 1]) {
this._left = input[len - 1];
this._right = Infinity;
this._len = 0;
this._recip = 0;
this._p0 = this._p1 = len - 1;
} else {
const index = this._findKey(time, input);
this._left = input[index];
this._right = input[index + 1];
this._len = this._right - this._left;
const diff = 1 / this._len;
this._recip = isFinite(diff) ? diff : 0;
this._p0 = index;
this._p1 = index + 1;
}
}
}
this._t = this._recip === 0 ? 0 : (time - this._left) * this._recip;
this._hermite.valid = false;
}
_findKey(time, input) {
let index = 0;
while (time >= input[index + 1]) {
index++;
}
return index;
}
// evaluate the output anim data at the current time
eval(result, interpolation, output) {
const data = output._data;
const comp = output._components;
const idx0 = this._p0 * comp;
if (interpolation === INTERPOLATION_STEP) {
for (let i = 0; i < comp; ++i) {
result[i] = data[idx0 + i];
}
} else {
const t = this._t;
const idx1 = this._p1 * comp;
switch (interpolation) {
case INTERPOLATION_LINEAR:
for (let i = 0; i < comp; ++i) {
result[i] = math.lerp(data[idx0 + i], data[idx1 + i], t);
}
break;
case INTERPOLATION_CUBIC: {
const hermite = this._hermite;
if (!hermite.valid) {
const t2 = t * t;
const twot = t + t;
const omt = 1 - t;
const omt2 = omt * omt;
hermite.valid = true;
hermite.p0 = (1 + twot) * omt2;
hermite.m0 = t * omt2;
hermite.p1 = t2 * (3 - twot);
hermite.m1 = t2 * (t - 1);
}
const p0 = (this._p0 * 3 + 1) * comp;
const m0 = (this._p0 * 3 + 2) * comp;
const p1 = (this._p1 * 3 + 1) * comp;
const m1 = (this._p1 * 3 + 0) * comp;
for (let i = 0; i < comp; ++i) {
result[i] = hermite.p0 * data[p0 + i] + hermite.m0 * data[m0 + i] * this._len + hermite.p1 * data[p1 + i] + hermite.m1 * data[m1 + i] * this._len;
}
break;
}
}
}
}
}
export {
AnimCache
};