97 lines
2.7 KiB
C#
97 lines
2.7 KiB
C#
// Based on: allenchou.net/2015/04/game-math-precise-control-over-numeric-springing/
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using Godot;
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using System;
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using System.Diagnostics;
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public class SpringDamper
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{
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public float omega = 1;
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public float zeta = 1;
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public SpringDamper(float osc_freq = 1.0f, float osc_red = 0.1f, float osc_red_h = 1.0f)
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{
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Debug.Assert(osc_red > 0.001 && osc_red < 0.999);
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omega = osc_freq * 2 * Mathf.Pi;
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zeta = Mathf.Log(1.0f - osc_red) / (-omega * osc_red_h);
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}
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public (float, float) Calc(float x, float v, float xt, float h)
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{
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float f = 1 + 2 * h * zeta * omega;
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float oo = omega * omega;
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float hoo = oo * h;
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float hhoo = hoo * h;
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float det_inv = 1.0f / (f + hhoo);
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float det_x = f * x + h * v + hhoo * xt;
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float det_v = v + hoo * (xt - x);
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return (det_x * det_inv, det_v * det_inv);
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}
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public (Vector3, Vector3) Calc(Vector3 x, Vector3 v, Vector3 xt, float h)
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{
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float f = 1 + 2 * h * zeta * omega;
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float oo = omega * omega;
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float hoo = oo * h;
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float hhoo = hoo * h;
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float det_inv = 1.0f / (f + hhoo);
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Vector3 det_x = f * x + h * v + hhoo * xt;
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Vector3 det_v = v + hoo * (xt - x);
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return (det_x * det_inv, det_v * det_inv);
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}
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public (Vector3, Vector3) CalcClampedSpeed(Vector3 x, Vector3 v, Vector3 xt, float h, float speedMax)
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{
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var defaultResult = Calc(x, v, xt, h);
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Vector3 x_new = defaultResult.Item1;
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Vector3 vel_new = (x_new - x) / h;
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float speed_new = vel_new.Length();
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if (speed_new > speedMax)
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{
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vel_new = (vel_new / speed_new) * speedMax;
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x_new = x + vel_new * h;
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}
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return (x_new, vel_new);
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}
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public (Vector3, Vector3) CalcClampedSpeedXZ(Vector3 x, Vector3 v, Vector3 xt, float h, float speedMax)
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{
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var result_x = Calc(x.x, v.x, xt.x, h);
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var result_z = Calc(x.z, v.z, xt.z, h);
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Vector3 x_new = x;
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Vector3 v_new = v;
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x_new.x = result_x.Item1;
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v_new.x = result_x.Item2;
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x_new.z = result_z.Item1;
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v_new.z = result_z.Item2;
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Vector3 result_v_xz = new Vector3(
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(result_x.Item1 - x.x) / h,
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0,
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(result_z.Item1 - x.z) / h);
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float speed_new = result_v_xz.Length();
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if (speed_new > speedMax)
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{
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result_v_xz = (result_v_xz) / speed_new * speedMax;
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x_new.x = x.x + result_v_xz.x * h;
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x_new.z = x.z + result_v_xz.z * h;
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}
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v.x = result_v_xz.x;
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v.z = result_v_xz.z;
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return (x_new, v_new);
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}
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} |