MartB
/
glc002-firmware
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fix math for XY colors

main
MartB 2022-04-04 03:04:22 +02:00
parent 2a6a6e8697
commit 7d845f5ce8
1 changed files with 49 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
sampleLightCtrl.c
View File

@ -30,7 +30,6 @@
#include "zcl_include.h" #include "zcl_include.h"
#include "sampleLight.h" #include "sampleLight.h"
#include "sampleLightCtrl.h" #include "sampleLightCtrl.h"
#include <math.h>
/********************************************************************** /**********************************************************************
* LOCAL CONSTANTS * LOCAL CONSTANTS
@ -345,34 +344,72 @@ static float ENFORCE_BOUNDS_FLOAT(float lowerBound, float num, float upperBound)
: num; : num;
} }
/*
A horrible power function for floats
*/
static float fpow(float x, float y) {
float result = 1;
for(int i = 0; i < y; ++i)
{
result *= x;
}
return result;
}
float LINEAR_TO_SRGB_GAMMA_CORRECTION(const float part) float LINEAR_TO_SRGB_GAMMA_CORRECTION(const float part)
{ {
return part <= 0.0031308 ? 12.92 * part : 1.055 * pow(part, 1.0 / 2.4) - 0.055; return part <= 0.0031308f ? 12.92f * part : 1.055f * fpow(part, 1.0f / 2.4f) - 0.055f;
} }
#define MAX(x,y) ((x) > (y) ? (x) : (y))
#define MIN(x,y) ((x) < (y) ? (x) : (y))
#define roundu8(a) (u8) (a+0.5)
void hwLight_colorUpdate_XY2RGB(u16 xI, u16 yI, u8 level) void hwLight_colorUpdate_XY2RGB(u16 xI, u16 yI, u8 level)
{ {
float x = xI / 65536.f; float x = xI / (float)ZCL_COLOR_ATTR_XY_MAX;
float y = yI / 65536.f; float y = yI / (float)ZCL_COLOR_ATTR_XY_MAX;
// This does not locate the closest point in the gamma spectrum of the lamps. possible #todo // This does not locate the closest point in the gamma spectrum of the lamps. possible #todo
const float z = 1 - x - y; const float z = 1 - x - y;
const float Y = level / ZCL_LEVEL_ATTR_MAX_LEVEL; // This is luminance, but used as brightness const float Y = level / (float)ZCL_LEVEL_ATTR_MAX_LEVEL; // This is luminance, but used as brightness
const float X = ((Y) / y) * x; const float X = ((Y) / y) * x;
const float Z = ((Y) / y) * z; const float Z = ((Y) / y) * z;
// D65 BT.709 conversion https://en.wikipedia.org/wiki/SRGB // D65 BT.709 conversion https://en.wikipedia.org/wiki/SRGB
float r = X * 1.656492 - Y * 0.354851 - Z * 0.255038; float r = X * 1.656492f - Y * 0.354851f - Z * 0.255038f;
float g = -X * 0.707196 + Y * 1.655397 + Z * 0.036152; float g = -X * 0.707196f + Y * 1.655397f + Z * 0.036152f;
float b = X * 0.051713 - Y * 0.121364 + Z * 1.011530; float b = X * 0.051713f - Y * 0.121364f + Z * 1.011530f;
// Normalize to maximum component being 1.0
float maxComponent = MAX(MAX(r, g), b);
if (maxComponent > 1.0) {
r /= maxComponent;
g /= maxComponent;
b /= maxComponent;
}
// Apply LINEAR => SRGB Gamma correction
r = LINEAR_TO_SRGB_GAMMA_CORRECTION(r);
g = LINEAR_TO_SRGB_GAMMA_CORRECTION(g);
b = LINEAR_TO_SRGB_GAMMA_CORRECTION(b);
// Normalize again to avoid out of range
maxComponent = MAX(MAX(r, g), b);
if (maxComponent > 1.0) {
r /= maxComponent;
g /= maxComponent;
b /= maxComponent;
}
// Enforce the lower and upper bounds // Enforce the lower and upper bounds
r = ENFORCE_BOUNDS_FLOAT(0.0, r * 255, 255.0); r = ENFORCE_BOUNDS_FLOAT(0.0f, r * 255, 255.0f);
g = ENFORCE_BOUNDS_FLOAT(0.0, g * 255, 255.0); g = ENFORCE_BOUNDS_FLOAT(0.0f, g * 255, 255.0f);
b = ENFORCE_BOUNDS_FLOAT(0.0, b * 255, 255.0); b = ENFORCE_BOUNDS_FLOAT(0.0f, b * 255, 255.0f);
hwLight_colorUpdate_RGB((u8)r, (u8)g, (u8)b); hwLight_colorUpdate_RGB(roundu8(r), roundu8(g), roundu8(b));
} }
/********************************************************************* /*********************************************************************