42 lines
1.7 KiB
C#
42 lines
1.7 KiB
C#
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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using System;
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using CultMath;
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using static CultMath.math;
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using float2 = CultMath.float2;
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// A free-floating body in a zone: a floating item or a mine. Zone-scoped and never reused within a zone;
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// runtime state only, never saved.
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public readonly struct FloatingBodyId : IEquatable<FloatingBodyId>
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{
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public readonly uint Value;
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public FloatingBodyId(uint value) => Value = value;
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public bool Equals(FloatingBodyId other) => Value == other.Value;
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public override bool Equals(object obj) => obj is FloatingBodyId other && Equals(other);
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public override int GetHashCode() => (int) Value;
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public override string ToString() => Value.ToString();
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}
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// The one drift integrator of every free body in a zone. A launch velocity decays on its own drag; the zone's
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// force accumulates into a separate drift velocity that has its own drag, so a body settles to
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// force * gravity / drag. Engine-free: the caller supplies dt and the zone force at the body's position.
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public struct KinematicBody
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{
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public float2 Position;
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// The launch velocity, decaying.
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public float2 Velocity;
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public float2 Drift;
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// What a presenter draws ahead with.
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public float2 TotalVelocity => Velocity + Drift;
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public void Step(float dt, float2 force, GameplaySettings s)
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{
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Velocity *= exp(-s.FloatingBodyLaunchDrag * dt);
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Drift += force * s.FloatingBodyGravity * dt;
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Drift *= exp(-s.FloatingBodyDrag * dt);
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Position += (Velocity + Drift) * dt;
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}
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}
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