tweak(particlesys): Decouple Particles render update from logic step

[xezon]

Merge with Rebase

This change decouples the Particles render update from the logic step.

Split into 7 commits for ease of understanding and review.

TODO

• Replicate in Generals
• Add pull ids to commit titles

[greptile-apps]

Greptile Summary

This PR decouples the particle system's render update from the fixed logic step: lifetime management and key-frame advancement stay on the logic step (ParticleSystem::update), while physics integration, colour/alpha accumulation, and transform interpolation are moved to a new render-step path (ParticleSystem::draw(Real timeScale)). Frame-rate-independent damping helpers (scaleDamping, scaleAccelDamping) are introduced so particle trajectories remain consistent at varying render rates.

• ParticleSystemManager::update() is moved from GameClient into GameLogic::update(), and a new draw() is called from W3DDisplay at render time; ParticleSystemManagerDummy gains explicit no-op overrides for both, removing the headless updateHeadless() workaround.
• m_pos/m_lastPos on ParticleSystem are renamed to m_logicalPos/m_lastLogicalPos and m_lastPos on Particle is removed; a PRESERVE_RETAIL_PARTICLES compile flag controls a one-frame key-frame delay to preserve the original visual look.
• BaseType.h gains a full set of RGBColor arithmetic operators consumed by the new draw() colour accumulation.

Confidence Score: 4/5

The core logic/render split is sound; only a harmless duplicate initializer and two pre-existing open questions remain.

The physics decoupling and frame-rate scaling math are solid, and the dummy manager overrides cleanly handle headless mode. A duplicate m_velCoeff.zero() call is the only new defect introduced by the diff. Two previously documented concerns — updateTransform() executing on both paths per frame, and alpha/colour-based particle death not firing in fully headless runs — are carried forward.

Core/GameEngine/Source/GameClient/System/ParticleSys.cpp and Core/GameEngine/Include/GameClient/ParticleSys.h

Important Files Changed

Filename	Overview
Core/GameEngine/Source/GameClient/System/ParticleSys.cpp	Major refactor splitting particle logic into update() (logic step: lifetime/keyframes) and draw() (render step: physics/color/alpha). Introduces scaleDamping/scaleAccelDamping helpers for frame-rate-independent physics. Contains a duplicate m_velCoeff.zero() call introduced by the diff.
Core/GameEngine/Include/GameClient/ParticleSys.h	Adds draw(Real timeScale) methods to Particle, ParticleSystem, and ParticleSystemManager; replaces m_pos/m_lastPos with m_logicalPos/m_lastLogicalPos; introduces VisibilityState and refactored transform helpers; adds isDummy() virtual to ParticleSystemManagerDummy.
Core/Libraries/Include/Lib/BaseType.h	Adds a full set of arithmetic operators for RGBColor. All binary operators correctly return by value.
GeneralsMD/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp	Moves TheParticleSystemManager->update() from GameClient to GameLogic::update(), anchoring particle lifetime management to the logic step.
GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DDisplay.cpp	Switches call from ->update() to ->draw() in the render path, completing the logic/render decoupling.

Sequence Diagram

sequenceDiagram
    participant GL as GameLogic::update()
    participant PSM as ParticleSystemManager
    participant PS as ParticleSystem
    participant P as Particle
    participant W3D as W3DDisplay (render)

    GL->>PSM: setLocalPlayerIndex()
    GL->>PSM: update()
    PSM->>PS: update(localPlayerIndex)
    PS->>PS: updateVisibility()
    PS->>PS: updateLastLogicalPos()
    PS->>PS: updateTransform()
    PS->>PS: updateLogicalPos()
    PS->>PS: generateParticles()
    PS->>P: update()
    Note over P: lifetime decrement / keyframe advance / isInvisible() cull

    W3D->>PSM: draw()
    Note over PSM: timeScale = FramePacer ratio
    PSM->>PS: draw(timeScale)
    PS->>PS: updateWindMotion(timeScale)
    PS->>PS: updateTransform()
    PS->>P: applyForce(gravity)
    PS->>P: draw(timeScale)
    Note over P: velocity/position integration / alpha/colour accumulation / accel reset

Loading

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
Core/GameEngine/Source/GameClient/System/ParticleSys.cpp:1125-1128
Duplicate `m_velCoeff.zero()` call introduced by this diff. The line was already present in the original constructor body; the new `+` hunk added a second identical call immediately before it. The later assignment to `m_velCoeff.x/y/z = 1.0f` means both zeroing calls are effectively dead, but having two consecutive identical statements is misleading noise worth removing.

```suggestion
	m_logicalPos.zero();
	m_lastLogicalPos.zero();
	m_velCoeff.zero();
```

_{Reviews (2): Last reviewed commit: "tweak(particlesys): Decouple Particles r..." | Re-trigger Greptile}

[Caball009]

I presume this PR fixes #2467.

[xezon]

This rename was just a side quest from when looking around particle things.

[xezon]

This function was crafted by prompting Chat Gippy many times. I do not understand exactly why it works but it works.

[xezon]

I moved the lifetime check from the bottom of the update to the very top, because there is no reason to go through all the trouble of updating the particle when the lifetime hits zero anyway. So this is a very minor performance improvement maybe.

[xezon]

The plane trails do not fade out gracefully. That needs looking into.

[Caball009]

The changes in this PR don't seem remotely retail compatible. Like many other replays, this PR makes GR1 mismatch with headless mode for me. The mismatch happens at frame 14227, but only with headless mode. It looks like the CI replay checker is silently broken.