模拟点被弹簧连接着的行为。
Spring会给每个点指定一个质量，并在点上模拟力的效果（重力，风，纹紊乱）。每个点会像弹簧那样，试图返回到其原始位置处。
You can:
使用节点上的Fix Point参数，配合一个点组，使网格特定的点停留在固定位置处。
使用力选项卡中的参数，给点运用方向力，阻力，紊乱力。
连接一个Force SOP到第三输入端，可以让你使用变形球吸引，或排斥粒子。
Tip
阻力值越大，或质量越小，步频消亡会越快。
Note
S平日们好 SOP可以用于模拟很多效果，但是对于复杂精致的模拟，可使用刚体，布料，或线动力学。
Note
如果输入的数据中，有点法线属性，但没有点速度属性，Spring 节点会使用点的法线作为初始点的速度。如果你像点上添加速度属性，点法线会被忽略。
Parameters
State
| StartTime | Time at which the simulation resets. | ||||
| Preroll Time | Number of initial frames skipped. | ||||
| Time Inc | Time per iteration. | ||||
| Accurate Moves | Particles move more accurately. | ||||
| Attractor Use | How the attractor points affect particles
|
Forces
| External Force | Force of gravity on points. |
| Wind | Wind force acting on points. |
| Turbulence | Amplitude of turbulence along axes. |
| Turb Period | Inverse variance of turbulence over space. |
| Seed | Seed for random turbulence generator. |
Nodes
| Fixed Points | Group of points not to be moved by this operation. | ||||
| Fixed Points go to Source Positions | Fixed Points are put to their positions in the Source. | ||||
| Copy Groups from Source | All Source groups are copied at each frame. Useful if the Fixed Points group contents are animated. | ||||
| Add Mass Attribute | Causes point mass to be calculated. | ||||
| Mass | Relative mass of each point. | ||||
| Add Drag Attribute | Causes drag coefficient to be calculated. | ||||
| Drag | Drag of each point. | ||||
| Spring Behavior | How the springs will behave
| ||||
| Spring Constant | Stiffness of the spring | ||||
| Initial Tension | Initial spring tension before deformations. |
Limits
| + Limit Plane, – Limit Plane | Points die or bounce off limit planes on contact. /limitposx … /limitposz, /limitnegx … |
| Hit Behavior | Whether particles die or bounce on limit planes. |
| Gain Tangent | Energy loss tangent to the collision. |
| Gain Normal | Energy loss perpendicular to the collision. |
Inputs
| Spring Source | The points to simulate, for example a polygon sphere or mesh. |
| Collision Object | (Optional) Geometry for the points to collide with. When the points hit this geometry, they can stick or bounce. If the collision object is deforming, collision detection may fail, causing some points to leak through the collision geometry. |
| Force | (Optional) A Force SOP, which uses a metaball to create a field which attracts or repels the points. |
