03 Thermodynamics In The Engine

03 — Thermodynamics in the Engine

Figure 3.0 — Coupled fabric at bindings 8–10. Illustrated chapter →

Why thermodynamics in a renderer?

Every frame destroys information — noise injection, probes, diffusion steps. The engine tracks that cost like a power meter tracks joules. This is accounting, not a laboratory calorimeter.

The three fabric channels

Created in RayCanvas::createAnalogFieldFabric(), bound at slots 8, 9, 10:

Fabric	Role	Shader channels
Phi (Φ)	Wave / gate potential	Binding 8 fieldPhi
Thermo	Heat + entropy density	Binding 9 fieldThermo
Flow	Advection / momentum	Binding 10 fieldFlow (.gb = gradients)

Cross-coupling: FieldCoupling links all three — electrical activity heats the die; heat affects flow.

Per-texel evolution (CANVAS.comp)

1. Phi — discrete Laplacian wave step + WaveSpeed + propalacticScale forcing
2. Thermo — diffusion with ThermoAlpha, entropy floor, coupling to Phi
3. Flow — gradient magnitude mixed with GateFidelity + Tesla relaxation

Stability clamps:

newPhi   ∈ [-2.0, 2.0]
newThermo ∈ [0.0, 1.5]
newFlow  ∈ [0.0, 1.0]

Control knobs (Options::AnalogFields)

Knob	Effect
TimeScale	Global Δt multiplier
ThermoAlpha	Thermal diffusivity α
WaveSpeed	Phi propagation speed c
GateFidelity	0 = soft analog … 1 = sharp gate
EntropyFloor	Minimum irreversible noise
InjectStrength	Mouse/probe energy injection
PropalacticScale	Large-wavelength forcing on Phi
FieldCoupling	Thermo ↔ Phi ↔ Flow coupling

CFL guard (host, before dispatch)

waveCFL   = (waveSpeed × fieldTimeScale) × effDt / dx
thermoCFL = (thermoAlpha × fieldTimeScale) × effDt / dx²

If CFL > 1, parameters scale down. Hard caps: waveSpeed ∈ [0.01, 2.0], dT ≤ 0.033.

✅ Implemented on classic canvases.
🎭 Body-temperature seeding is normalized simulation flavor, not BIOS temperature.

Next: 04 — Entropy