46 lines
1.8 KiB
JavaScript
46 lines
1.8 KiB
JavaScript
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/* ISLE SLINGERS -- physics/aim/index.js (submodule: aim)
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* RC-375D84 S-2 modularization (behavior-neutral split of the original
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* js/core.js monolith). Installs its units into ONE shared physics scope `P`
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* that every physics submodule sees -- the same single-scope semantics the
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* monolith had. Must load before js/physics/index.js (the aggregator that
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* attaches the public ISLE_CORE API). Surface installed: aimVector, trajectory.
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*/
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(function (root, factory) {
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var part = factory();
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if (typeof module !== 'undefined' && module.exports) module.exports = part;
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else (root.ISLE_PHYSICS_PARTS = root.ISLE_PHYSICS_PARTS || []).push(part);
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})(typeof globalThis !== 'undefined' ? globalThis : this, function () {
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'use strict';
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return function (P) {
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P.aimVector = function(g, sling, drag) {
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var dx = sling.x - drag.x, dy = sling.y - drag.y;
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var len = Math.sqrt(dx * dx + dy * dy);
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if (len < P.MIN_PULL) return null;
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var cl = Math.min(len, P.MAX_PULL);
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var v = cl * P.LAUNCH_POWER;
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return { vx: (dx / len) * v, vy: (dy / len) * v, pull: cl };
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}
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// Pure P.trajectory preview: identical integrator + substepping as the live
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// sim (2x 1/120 per output point), so the dotted preview matches the real
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// flight exactly. Gravity + drag only; stops at the ground.
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P.trajectory = function(g, sx, sy, vx, vy, steps) {
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var pts = [];
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var x = sx, y = sy, i, sub;
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for (i = 0; i < steps; i++) {
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for (sub = 0; sub < 2; sub++) {
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var dt = 1 / 120;
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var nvy = vy + P.GRAVITY * dt;
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x += vx * dt;
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y += (vy + nvy) * 0.5 * dt;
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vx *= P.AIR_DRAG;
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vy = nvy;
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}
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if (y > P.WORLD.ground - 18) { pts.push({ x: x, y: P.WORLD.ground - 18, last: true }); break; }
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pts.push({ x: x, y: y, last: false });
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}
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return pts;
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}
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};
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});
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