鸟群算法boids

鸟群算法 Boids

• 简单的Boids算法

   // 计算所有粒子的Boid运动
   for (int i = 0; i < particleCount; i++)
   {
     Vector3 cohesion = Vector3.zero;
     Vector3 alignment = Vector3.zero;
     Vector3 separation = Vector3.zero;
     int neighborCount = 0;
  
     // 计算每个粒子的邻居
     for (int j = 0; j < particleCount; j++)
     {
         if (i != j)
         {
             Vector3 distanceVector = particles[j].position - particles[i].position;
             float distance = distanceVector.magnitude;
             if (distance < neighborRadius)
             {
                 cohesion += particles[j].position;
                 alignment += particles[j].velocity;
                 if (distance < separationDistance)
                 {
                     // 分离力与距离成反比
                     separation -= distanceVector.normalized / (distance + 0.001f);
                 }
                 neighborCount++;
             }
         }
     }
  
     // 计算合力
     Vector3 force = Vector3.zero;
     if (neighborCount > 0)
     {
         // 凝聚力：指向邻居粒子的平均位置
         cohesion = (cohesion / neighborCount - particles[i].position).normalized;
         // 对齐力：与邻居粒子速度方向一致
         alignment = (alignment / neighborCount).normalized;
         // 分离力：远离过近的邻居
         separation = separation.normalized;
  
         // 合并三个规则
         force += cohesion * cohesionWeight;
         force += alignment * alignmentWeight;
         force += separation * separationWeight;
     }
  
     // 添加边界限制
     if (boundaryRadius > 0)
     {
         float distanceToCenter = particles[i].position.magnitude;
         if (distanceToCenter > boundaryRadius)
         {
             // 边界力：将粒子拉回中心
             Vector3 centerDirection = -particles[i].position.normalized;
             float boundaryInfluence = (distanceToCenter - boundaryRadius) / boundaryRadius;
             force += centerDirection * boundaryInfluence * boundaryWeight;
         }
     }
  
     // 计算目标速度
     Vector3 targetVelocity = particles[i].velocity + force;
     // 添加全局流动方向影响
     targetVelocity += flowDirection.normalized * flowWeight;
     // 添加随机扰动
     targetVelocity += new Vector3(
         Random.Range(-randomness, randomness),
         Random.Range(-randomness, randomness),
         Random.Range(-randomness, randomness)
     );
     // 限制最大速度
     if (targetVelocity.magnitude > maxSpeed) {
         targetVelocity = targetVelocity.normalized * maxSpeed;
     }
  
     // 使用平滑因子过渡到目标速度
     particles[i].velocity = Vector3.Lerp(particles[i].velocity, targetVelocity, 1 - smoothingFactor);
   }