PhysX的BroadPhase（碰撞检测的粗略阶段），具体是用AABB（轴向包围盒）来做碰撞检测
具体算法有两种：SAP（Single Pruning Box，单个剪枝盒）和MBP（Multi Pruning Box，多个剪枝盒）
SAP（Single Pruning Box，单个剪枝盒）
当场景中有大量的物体（大世界有百万级别）时，即使它们已按AABB的三个轴向xyz做了排序，一个动态物体在移动过程与它们进行AABB判断也是一个很耗时操作
TG_EndPhysics的卡顿与BpSAP.UpdateWork直接相关
MBP（Multi Pruning Box，多个剪枝盒）
为了解决与物体判断AABB的次数，可以使用MBP来将整个场景划分成多个块，这样动态物体只用与当前所在块中的物体进行AABB判断，大大减少BroadPhase（碰撞检测的粗略阶段）的耗时
全局Default Broadphase Settings
注1：勾上Use MBPOn Client，并设置MBPBounds和MBPNum Subdivs的数值
注2：MBPBounds的Min、Max缺省为0，表示区域为整个场景
注3：MBPNum Subdivs为2，即将MBPBounds划分成2x2，一共4个块
该配置会保存在DefaultEngine.ini中
[/Script/Engine.PhysicsSettings] DefaultBroadphaseSettings=(bUseMBPOnClient=True,bUseMBPOnServer=False,bUseMBPOuterBounds=False,MBPBounds=(Min=(X=0.000000,Y=0.000000,Z=0.000000),Max=(X=0.000000,Y=0.000000,Z=0.000000),IsValid=0),MBPOuterBounds=(Min=(X=0.000000,Y=0.000000,Z=0.000000),Max=(X=0.000000,Y=0.000000,Z=0.000000),IsValid=0),MBPNumSubdivs=2)
在地图中可以覆写全局Default Broadphase Settings
具体代码详见：UnrealEngine\Engine\Source\Runtime\Engine\Private\PhysicsEngine\PhysScene_PhysX.cpp
void FPhysScene_PhysX::InitPhysScene(const AWorldSettings* Settings)
相关CVar变量
| p.ForceMbpClient | Forces all created scenes to use MBP on client builds |
| p.ForceMbpServer | Forces all created scenes to use MBP on server builds |
| p.ForceNoKKPairs | Disables kinematic-kinematic pairs. This is required when using APEX destruction to correctly generate chunk pairs - when not using destruction this speeds up the broadphase by early rejecting KK pairs. |
| p.ForceNoKSPairs | Disables kinematic-static pairs. This makes converting from static to dynamic a little slower - but provides better broadphase performance because we early reject those pairs. |
| p.OverrideMbpNumSubdivisionsClient | Override for number of subdivisions to perform when building MBP regions on a client, note regions are only generated when a scene is created - this will not update the scene if it's already running (0 = No override, 1>16 - Override number) |
| p.OverrideMbpNumSubdivisionsServer | Override for number of subdivisions to perform when building MBP regions on a server, note regions are only generated when a scene is created - this will not update the scene if it's already running (0 = No override, 1>16 - Override number) |
参考
Dive Into PhysX Broad Phase In UE4
标签：pairs,BroadPhase,0.000000,when,碰撞检测,UE4,MBP,PhysX From： https://www.cnblogs.com/kekec/p/18114295