99 lines
2.9 KiB
C#
99 lines
2.9 KiB
C#
using UnityEngine;
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struct ConfettiPiece
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{
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public void Init(
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Vector3 position,
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Vector3 velocity,
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float deltaTime,
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Quaternion orientation, //Z軸方向に
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float halfZSize,
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float normalBendRatio)
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{
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this.normalBendRatio = normalBendRatio;
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this.orientation = orientation;
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this.position = position;
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var forward = orientation * new Vector3(0f, 0f, 1f);
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var t = forward * halfZSize;
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var dp = velocity * deltaTime;
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prevPosition0 = position - t;
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prevPosition1 = position + t;
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prevPosition0 -= dp;
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prevPosition1 -= dp;
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}
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public void Update(
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float deltaTime,
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ref Vector3 wind,
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ref Vector3 gravity,
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float resistance,
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float halfZSize)
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{
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var forward = orientation * new Vector3(0f, 0f, 1f);
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var t = forward * halfZSize;
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var p0 = position - t;
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var p1 = position + t;
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// 相対的な風ベクトルを出す
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var v0 = (p0 - prevPosition0) / deltaTime;
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var v1 = (p1 - prevPosition1) / deltaTime;
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var relativeWind0 = wind - v0;
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var relativeWind1 = wind - v1;
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// 頂点ごとの法線を生成
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var n = orientation * new Vector3(0f, 1f, 0f);
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// 曲げる
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t = forward * normalBendRatio;
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var n0 = n + t;
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var n1 = n - t;
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// 正規化。n1はn0と同じ長さなので長さを計算して使い回す
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n0.Normalize();
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n1.Normalize();
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// 風ベクトルの法線方向成分を、加速度とする
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var dot0 = Vector3.Dot(n0, relativeWind0);
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var dot1 = Vector3.Dot(n1, relativeWind1);
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if (dot0 < 0)
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{
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n0 = -n0;
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dot0 = -dot0;
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}
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if (dot1 < 0)
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{
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n1 = -n1;
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dot1 = -dot1;
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}
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var accel0 = n0 * (dot0 * resistance);
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var accel1 = n1 * (dot1 * resistance);
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// 重力を追加
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accel0 += gravity;
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accel1 += gravity;
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// 独立に積分
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var dt2 = deltaTime * deltaTime;
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var dp0 = p0 - prevPosition0 + (accel0 * dt2);
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var dp1 = p1 - prevPosition1 + (accel1 * dt2);
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var nextP0 = p0 + dp0;
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var nextP1 = p1 + dp1;
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prevPosition0 = p0;
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prevPosition1 = p1;
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p0 = nextP0;
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p1 = nextP1;
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// 拘束
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var newForward = (p1 - p0).normalized;
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position = (p0 + p1) * 0.5f;
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// 姿勢更新
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// forward -> newForwardに向くような、回転軸右ベクタの回転を作用させる
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var dq = Quaternion.FromToRotation(forward, newForward);
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orientation = dq * orientation; // dqは時間的に後の回転だから、ベクタから遠い方、つまり前から乗算
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orientation.Normalize();
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}
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public void GetTransform(
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ref Matrix4x4 matrix,
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float ZSize,
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float XSize)
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{
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matrix.SetTRS(position, orientation, new Vector3(XSize, 1f, ZSize));
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}
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public Vector3 position;
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Vector3 prevPosition0;
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Vector3 prevPosition1;
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Quaternion orientation;
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float normalBendRatio;
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} |