David Kruger
8df9031d27
``` ~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js ```
34 lines
1.2 KiB
JavaScript
34 lines
1.2 KiB
JavaScript
"use strict";
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exports.__esModule = true;
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exports["default"] = stepper;
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// stepper is used a lot. Saves allocation to return the same array wrapper.
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// This is fine and danger-free against mutations because the callsite
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// immediately destructures it and gets the numbers inside without passing the
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// array reference around.
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var reusedTuple = [0, 0];
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function stepper(secondPerFrame, x, v, destX, k, b, precision) {
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// Spring stiffness, in kg / s^2
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// for animations, destX is really spring length (spring at rest). initial
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// position is considered as the stretched/compressed position of a spring
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var Fspring = -k * (x - destX); // Damping, in kg / s
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var Fdamper = -b * v; // usually we put mass here, but for animation purposes, specifying mass is a
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// bit redundant. you could simply adjust k and b accordingly
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// let a = (Fspring + Fdamper) / mass;
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var a = Fspring + Fdamper;
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var newV = v + a * secondPerFrame;
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var newX = x + newV * secondPerFrame;
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if (Math.abs(newV) < precision && Math.abs(newX - destX) < precision) {
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reusedTuple[0] = destX;
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reusedTuple[1] = 0;
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return reusedTuple;
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}
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reusedTuple[0] = newX;
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reusedTuple[1] = newV;
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return reusedTuple;
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} |