xy_mapping: properly redo the xy -> rgb conversion
parent
0f797f3611
commit
abca39b3fe
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@ -338,78 +338,73 @@ void hwLight_colorUpdate_RGB(u8 R, u8 G, u8 B)
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pwmSetDuty(WARM_LIGHT_PWM_CHANNEL, 0);
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}
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static float ENFORCE_BOUNDS_FLOAT(float lowerBound, float num, float upperBound)
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static u8 ENFORCE_BOUNDS_U8(u8 lowerBound, s16 num, u8 upperBound)
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{
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return num < lowerBound ? lowerBound : num > upperBound ? upperBound
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: num;
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return num < lowerBound ? lowerBound : num > upperBound ? upperBound : num;
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}
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/*
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A horrible power function for floats
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iLog, pow and root functions, taken from
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http://rosettacode.org/wiki/Nth_root#C
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*/
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static float fpow(float x, float y) {
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float result = 1;
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for(int i = 0; i < y; ++i)
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{
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result *= x;
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}
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float _fpow(float x, int e) {
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int i;
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float r = 1;
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for (i = 0; i < e; i++) {
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r *= x;
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}
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return r;
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}
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return result;
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float _fsqrt(float x, int n) {
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float d, r = 1;
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if (!x) {
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return 0;
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}
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if (n < 1 || (x < 0 && !(n&1))) {
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return 0.0 / 0.0; /* NaN */
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}
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do {
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d = (x / _fpow(r, n - 1) - r) / n;
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r += d;
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}
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while (d >= 0.000010f * 10 || d <= -0.000010f * 10);
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return r;
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}
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float LINEAR_TO_SRGB_GAMMA_CORRECTION(const float part)
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{
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return part <= 0.0031308f ? 12.92f * part : 1.055f * fpow(part, 1.0f / 2.4f) - 0.055f;
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// Optimization for embedded devices without math libraries: a ^ (m / n) == nth_root(a) ^ m
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return part <= 0.0031308f ? 12.92f * part : 1.055f * _fpow(_fsqrt(part, 12), 5) - 0.055f;
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}
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#define MAX(x,y) ((x) > (y) ? (x) : (y))
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#define MIN(x,y) ((x) < (y) ? (x) : (y))
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#define roundu8(a) (u8) (a+0.5)
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#define round(a) (s16) (a+0.5)
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void hwLight_colorUpdate_XY2RGB(u16 xI, u16 yI, u8 level)
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{
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float x = xI / (float)ZCL_COLOR_ATTR_XY_MAX;
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float y = yI / (float)ZCL_COLOR_ATTR_XY_MAX;
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float x = xI / 65535.0f;
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float y = yI / 65535.0f;
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// This does not locate the closest point in the gamma spectrum of the lamps. possible #todo
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const float z = 1 - x - y;
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const float Y = level / (float)ZCL_LEVEL_ATTR_MAX_LEVEL; // This is luminance, but used as brightness
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const float X = ((Y) / y) * x;
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const float Z = ((Y) / y) * z;
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// D65 BT.709 conversion https://en.wikipedia.org/wiki/SRGB
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float r = X * 1.656492f - Y * 0.354851f - Z * 0.255038f;
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float g = -X * 0.707196f + Y * 1.655397f + Z * 0.036152f;
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float b = X * 0.051713f - Y * 0.121364f + Z * 1.011530f;
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// Normalize to maximum component being 1.0
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float maxComponent = MAX(MAX(r, g), b);
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if (maxComponent > 1.0) {
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r /= maxComponent;
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g /= maxComponent;
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b /= maxComponent;
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}
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const float z = 1.f - x - y;
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const float Y = (level / (float)ZCL_LEVEL_ATTR_MAX_LEVEL); // This is luminance, but used as brightness
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const float X = (Y / y) * x;
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const float Z = (Y / y) * z;
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// SRGB http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
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float r = X * 3.2404542f - Y * -1.5371385f - Z * 0.4985314f;
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float g = -X * 0.9692660f + Y * 1.8760108f + Z * 0.0415560f;
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float b = X * 0.0556434f - Y * 0.2040259f + Z * 1.0572252f;
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// Apply LINEAR => SRGB Gamma correction
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r = LINEAR_TO_SRGB_GAMMA_CORRECTION(r);
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g = LINEAR_TO_SRGB_GAMMA_CORRECTION(g);
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b = LINEAR_TO_SRGB_GAMMA_CORRECTION(b);
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// Normalize again to avoid out of range
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maxComponent = MAX(MAX(r, g), b);
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if (maxComponent > 1.0) {
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r /= maxComponent;
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g /= maxComponent;
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b /= maxComponent;
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}
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// Enforce the lower and upper bounds
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r = ENFORCE_BOUNDS_FLOAT(0.0f, r * 255, 255.0f);
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g = ENFORCE_BOUNDS_FLOAT(0.0f, g * 255, 255.0f);
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b = ENFORCE_BOUNDS_FLOAT(0.0f, b * 255, 255.0f);
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hwLight_colorUpdate_RGB(roundu8(r), roundu8(g), roundu8(b));
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hwLight_colorUpdate_RGB(ENFORCE_BOUNDS_U8(0, round(r * 255), 255), ENFORCE_BOUNDS_U8(0, round(g * 255), 255), ENFORCE_BOUNDS_U8(0, round(b * 255) , 255));
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}
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/*********************************************************************
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