PhysX物理引擎 on 👨🏼‍🌾

PhysX物理引擎（4）Character Controller

Mon, 04 Dec 2023 00:00:00 +0000

本文主要介绍PhysX角色控制器相关的内部机制和使用方法。

PhysX物理引擎系列记录了在实际项目中使用Nvdia PhysX 3.4物理引擎（Code, Doc）的一些经验，有不少对官方资料的补充。

Warm-up

Character Controller (a.k.a CCT) is a special physical object handling player movement. In PhysX, CCT is not a Rigidbody, which means it does not integrate seamlessly in collision system. However, there is a kinematic actor underlying in CCT, and you can attach custom data via PxController::getActor()->userData.

PhysX物理引擎（3）Rigidbody Dynamics

Mon, 04 Sep 2023 00:00:00 +0000

本文主要介绍PhysX刚体动力学相关的内部机制和使用方法。

PhysX物理引擎系列记录了在实际项目中使用Nvdia PhysX 3.4物理引擎（Code, Doc）的一些经验，有不少对官方资料的补充。

Warm-up

Let’s start with some key concepts:

Both Kinematic and Dynamic rigidbodies are represented as PxRigidDynamic in PhysX. You can switch between them at runtime using PxRigidBody::setRigidBodyFlag(PxRigidBodyFlag::eKINEMATIC, true).
Kinematic and Static actors remain stationary unless explicitly moved in code.
Moving Static actors can result in incorrect collision behavior with dynamic actors.
When moving Kinematic actors, always use PxRigidDynamic::setKinematicTarget each frame instead of PxRigidActor::setGlobalPose to ensure correct collision detection with dynamic actors.

This post focuses on dynamic rigidbody movement, covering topics such as force and torque, gravity, sleeping, and more.

PhysX物理引擎（2）Collision

Fri, 11 Aug 2023 00:00:00 +0000

本文主要介绍PhysX碰撞检测的一些内部机制和使用方法。

PhysX物理引擎系列记录了在实际项目中使用Nvdia PhysX 3.4物理引擎（Code, Doc）的一些经验，有不少对官方资料的补充。

Warm-up

Static, Kinematic & Dynamic

Static colliders are non-movable. In fact, they are not rigidbody, just PxRigidStatic.
Kinematic and dynamic rigidbody are both PxRigidDynamic, and can switch to each other at runtime by setRigidBodyFlag(PxRigidBodyFlag::eKINEMATIC, true/false). The biggest difference is that kinematic rigidbody behaves like infinite mass, and will not move by external force. Instead, you call MovePosition on it.
Dynamic rigidbody is the only type we can AddForce to, which has mass, center of mass, and inertia tensor to simulate a natural movement with Newton’s laws of motion.

classDiagram

PxRigidActor <-- PxRigidStatic
PxRigidActor <-- PxRigidBody
PxRigidBody <-- PxRigidDynamic
PxRigidActor *.. PxShape

class PxRigidBody {
    PxRigidBodyFlag
}
class PxShape {
    PxShapeFlag
}

We cannot make a rigidbody without a shape. Shapes are tangible, with a real size.

PhysX零值Crash

Tue, 13 Jun 2023 00:00:00 +0000

本文是PhysX物理引擎系列的特别篇，记录了影响近一周的物理引擎底层概率性Crash的定位过程和修复方法，具有很高的实践参考价值。“有多高？”“三四层楼那么高啦！”

发现问题

运维同事发现体验服和某区在新版本上线一小段时间后，会出现概率不高但持续出现的进程Crash。这里先简单说明一下：我们会在一台机器上部署多个GameServer实例，每个GameServer实例进程同时进行着多场不同的Match，如果某一场Match出现了业务层Crash，并不会影响其他Match。但如果是C++物理库内出现Crash，则会同时中止其他正常运行的Match，对玩家的影响较大。

PhysX物理引擎（1）Scene Query

Fri, 26 May 2023 00:00:00 +0000

本文主要介绍PhysX场景查询的一些内部机制和使用方法。

PhysX物理引擎系列记录了在实际项目中使用Nvdia PhysX 3.4物理引擎（Code, Doc）的一些经验，有不少对官方资料的补充。

Warm-up

A Scene in PhysX engine is a container of objects in a hierachical manner.

---
title: Scene Hierachy
---
classDiagram
direction LR

class world
class scene {
    Flags
    Gravity
    ...
}
class actor {
    ActorFlags
    Name
    GlobalPose
    ...
}
class shape {
    Flags
    GeometryType
    LocalPose
    QueryFilterData
    SimulationFilterData
    ...
}
class geometry {
    ...
}
class material {
    friction
    restitution
    damping
}

world "1"*.. "N"scene
scene "1"*.. "N"actor
actor "1"*.. "N"shape
shape o--geometry
shape o--material

There are only position and rotation in GlobalPose and LocalPose, no “scale”. Scale only reflects on geometry’s actual size.