98 lines
2.9 KiB
C#
98 lines
2.9 KiB
C#
using System.Collections.Generic;
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using UnityEngine;
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namespace XericUI.BubbleLayout
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{
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/// <summary>
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/// 2D 物理力解算器 —— 使用半隐式欧拉积分进行速度/位置更新
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/// </summary>
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public static class BubblePhysicsSolver
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{
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/// <summary>
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/// 对气泡元素列表执行一步物理积分，使用每元素自身的 mass 值
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/// </summary>
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/// <param name="items">气泡元素列表</param>
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/// <param name="deltaTime">时间步长</param>
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/// <param name="damping">速度阻尼系数 (0=无阻尼, 1=完全停止)</param>
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public static void Integrate(List<BubbleItemData> items, float deltaTime, float damping = 0.9f)
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{
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for (int i = 0; i < items.Count; i++)
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{
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var item = items[i];
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// 保存上一帧状态
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item.prevVelocity = item.velocity;
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item.prevForce = item.force;
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// 半隐式欧拉积分: 力 → 加速度 → 速度 → 位置
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float itemMass = Mathf.Max(item.mass, 0.001f);
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Vector2 acceleration = item.force / itemMass;
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// v_new = v_old * damping + a * dt
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item.velocity = item.velocity * (1f - damping) + acceleration * deltaTime;
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// 动量 = m * v
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item.momentum = item.velocity * itemMass;
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// p_new = p_old + v_new * dt
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item.position += item.velocity * deltaTime;
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// 角动量积分
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item.rotation += item.angularMomentum * deltaTime;
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// 清除本帧力（力只持续一帧，需要每帧重新施加）
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item.force = Vector2.zero;
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}
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}
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/// <summary>
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/// 计算两个位置之间的排斥力（用于气泡排挤）
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/// </summary>
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/// <param name="posA">元素A中心位置</param>
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/// <param name="sizeA">元素A尺寸</param>
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/// <param name="posB">元素B中心位置</param>
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/// <param name="sizeB">元素B尺寸</param>
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/// <param name="stiffness">排斥刚度</param>
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/// <returns>施加在A上的排斥力</returns>
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public static Vector2 CalculateRepulsionForce(
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Vector2 posA, Vector2 sizeA,
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Vector2 posB, Vector2 sizeB,
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float stiffness = 1f)
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{
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Vector2 delta = posA - posB;
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Vector2 halfSizes = (sizeA + sizeB) * 0.5f;
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// 计算X方向重叠量
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float overlapX = halfSizes.x - Mathf.Abs(delta.x);
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// 计算Y方向重叠量
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float overlapY = halfSizes.y - Mathf.Abs(delta.y);
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// 仅在重叠时产生力
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if (overlapX <= 0f || overlapY <= 0f)
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return Vector2.zero;
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// 选择最小重叠方向进行排斥
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Vector2 force;
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if (overlapX < overlapY)
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{
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float sign = delta.x > 0f ? 1f : -1f;
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force = new Vector2(sign * overlapX * stiffness, 0f);
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}
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else if (overlapY < overlapX)
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{
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float sign = delta.y > 0f ? 1f : -1f;
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force = new Vector2(0f, sign * overlapY * stiffness);
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}
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else
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{
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// 重叠相等时双向排斥
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float signX = delta.x > 0f ? 1f : -1f;
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float signY = delta.y > 0f ? 1f : -1f;
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force = new Vector2(signX * overlapX * stiffness * 0.5f, signY * overlapY * stiffness * 0.5f);
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}
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return force;
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}
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}
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}
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