HeatColor()

CRGB HeatColor

(

uint8_t

temperature

)

Approximates a "black body radiation" spectrum for a given "heat" level.

This is useful for animations of "fire". Heat is specified as an arbitrary scale from 0 (cool) to 255 (hot). This is NOT a chromatically correct "black body radiation" spectrum, but it's surprisingly close, and it's fast and small.

Definition at line 543 of file colorutils.cpp.

{
    CRGB heatcolor;
 
    // Scale 'heat' down from 0-255 to 0-191,
    // which can then be easily divided into three
    // equal 'thirds' of 64 units each.
    uint8_t t192 = scale8_video( temperature, 191);
 
    // calculate a value that ramps up from
    // zero to 255 in each 'third' of the scale.
    uint8_t heatramp = t192 & 0x3F; // 0..63
    heatramp <<= 2; // scale up to 0..252
 
    // now figure out which third of the spectrum we're in:
    if( t192 & 0x80) {
        // we're in the hottest third
        heatcolor.r = 255; // full red
        heatcolor.g = 255; // full green
        heatcolor.b = heatramp; // ramp up blue
 
    } else if( t192 & 0x40 ) {
        // we're in the middle third
        heatcolor.r = 255; // full red
        heatcolor.g = heatramp; // ramp up green
        heatcolor.b = 0; // no blue
 
    } else {
        // we're in the coolest third
        heatcolor.r = heatramp; // ramp up red
        heatcolor.g = 0; // no green
        heatcolor.b = 0; // no blue
    }
 
    return heatcolor;
}

References scale8_video().

Referenced by Fire2012().

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