Physical 3D LED Block Campfire

#include <FastLED.h>
#include <SimplexNoise.h>

#define MAX_LOGS 12
#define FACETS_PER_LOG 4
#define VOXELS_PER_FACET 16
#define TOTAL_SURFACE_VOXELS (MAX_LOGS * FACETS_PER_LOG * VOXELS_PER_FACET)

// Central Brain Scene Graph: 3D Facet Voxel Map
struct SurfaceVoxel {
    float x, y, z;        // Absolute world coordinates (cm)
    float nx, ny, nz;     // Surface normal vector
    float coreHeat;       // Log core caloric level [0.0 - 1.0]
    uint8_t logId;
    uint8_t facetIndex;
};

SurfaceVoxel sceneVoxels[TOTAL_SURFACE_VOXELS];
CRGB surfaceFrameBuffer[TOTAL_SURFACE_VOXELS];
SimplexNoise simplex;

// Non-linear Planckian blackbody color radiation curve
CRGB blackbodyToCRGB(float temperatureKelvin, float radiance) {
    // 1800K (Crimson Ember) -> 2400K (Radiant Amber) -> 3200K (Golden White Flame)
    float t = constrain((temperatureKelvin - 1600.0f) / 1600.0f, 0.0f, 1.0f);
    uint8_t r = (uint8_t)(255 * radiance);
    uint8_t g = (uint8_t)(constrain(t * 185.0f, 0.0f, 185.0f) * radiance);
    uint8_t b = (uint8_t)(constrain(pow(t, 2.4f) * 75.0f, 0.0f, 75.0f) * radiance);
    return CRGB(r, g, b);
}

// 60 FPS Volumetric Solver: Samples continuous 3D field across all block surfaces
void computeVolumetricSurfaceFrame(float timeSec) {
    const float riseVelocity = 2.2f;    // Upward convection (cm/s)
    const float spatialScale = 0.075f;  // Turbulence spatial frequency
    
    for (int i = 0; i < TOTAL_SURFACE_VOXELS; i++) {
        SurfaceVoxel& v = sceneVoxels[i];
        
        // Compute upward traveling turbulence coordinate
        float sampleX = v.x * spatialScale;
        float sampleY = (v.y - (timeSec * riseVelocity)) * spatialScale;
        float sampleZ = v.z * spatialScale;
        
        // Multi-octave Simplex fluid noise
        float noise = simplex.noise(sampleX, sampleY, sampleZ);
        noise += 0.5f * simplex.noise(sampleX * 2.2f, sampleY * 2.2f, sampleZ * 2.2f);
        noise = (noise + 1.5f) / 3.0f; // Normalized [0.0, 1.0]
        
        // Height gradient: Lower blocks form glowing ember foundation; upper facets flicker
        float heightFactor = constrain(1.0f - (v.y / 50.0f), 0.18f, 1.0f);
        float thermalEnergy = noise * heightFactor * v.coreHeat;
        
        // Map thermal energy to Planckian blackbody color
        float kelvin = 1600.0f + (thermalEnergy * 1600.0f);
        float brightness = constrain(thermalEnergy * 1.35f, 0.04f, 1.0f);
        
        surfaceFrameBuffer[i] = blackbodyToCRGB(kelvin, brightness);
    }
    
    // Broadcast complete frame over high-speed RS-485 / FastLED bus to all full-surface blocks
    FastLED.show();
}