diff options
Diffstat (limited to 'libdimension/color.c')
| -rw-r--r-- | libdimension/color.c | 95 |
1 files changed, 88 insertions, 7 deletions
diff --git a/libdimension/color.c b/libdimension/color.c index 6de8d0a..eea005b 100644 --- a/libdimension/color.c +++ b/libdimension/color.c @@ -77,7 +77,7 @@ const dmnsn_color dmnsn_magenta = { }; const dmnsn_color dmnsn_orange = { .R = 1.0, - .G = 0.5, + .G = 0.21404114048223255, .B = 0.0, .trans = 0.0, .filter = 0.0, @@ -97,6 +97,75 @@ const dmnsn_color dmnsn_cyan = { .trans = 0.0, }; +/** Inverse function of sRGB's `C' function, for the reverse conversion. */ +static double +dmnsn_sRGB_C_inv(double CsRGB) +{ + /* + * If C represents R, G, and B, then the Clinear values are now found as + * follows: + * + * { Csrgb/12.92, Csrgb <= 0.04045 + * Clinear = { 1/2.4 + * { ((Csrgb + 0.055)/1.055) , Csrgb > 0.04045 + */ + if (CsRGB == 1.0) { + return 1.0; /* Map 1.0 to 1.0 instead of 0.9999999999999999 */ + } else if (CsRGB <= 0.040449936) { + return CsRGB/12.92; + } else { + return pow((CsRGB + 0.055)/1.055, 2.4); + } +} + +/* Convert from sRGB space */ +dmnsn_color +dmnsn_color_from_sRGB(dmnsn_color color) +{ + dmnsn_color ret = { + .R = dmnsn_sRGB_C_inv(color.R), + .G = dmnsn_sRGB_C_inv(color.G), + .B = dmnsn_sRGB_C_inv(color.B), + .trans = color.trans, + .filter = color.filter, + }; + return ret; +} + +/** sRGB's `C' function. */ +static double +dmnsn_sRGB_C(double Clinear) +{ + /* + * If C represents R, G, and B, then the sRGB values are now found as follows: + * + * { 12.92*Clinear, Clinear <= 0.0031308 + * Csrgb = { 1/2.4 + * { (1.055)*Clinear - 0.055, Clinear > 0.0031308 + */ + if (Clinear == 1.0) { + return 1.0; /* Map 1.0 to 1.0 instead of 0.9999999999999999 */ + } else if (Clinear <= 0.0031308) { + return 12.92*Clinear; + } else { + return 1.055*pow(Clinear, 1.0/2.4) - 0.055; + } +} + +/* Convert to sRGB space */ +dmnsn_color +dmnsn_color_to_sRGB(dmnsn_color color) +{ + dmnsn_color ret = { + .R = dmnsn_sRGB_C(color.R), + .G = dmnsn_sRGB_C(color.G), + .B = dmnsn_sRGB_C(color.B), + .trans = color.trans, + .filter = color.filter, + }; + return ret; +} + /* Greyscale color intensity */ double dmnsn_color_intensity(dmnsn_color color) @@ -111,7 +180,7 @@ dmnsn_color_add(dmnsn_color c1, dmnsn_color c2) { dmnsn_color ret = dmnsn_new_color(c1.R + c2.R, c1.G + c2.G, c1.B + c2.B); - /* Switch back into absolute filter and transmittance space */ + /* Switch into absolute filter and transmittance space */ double n1 = dmnsn_color_intensity(c1), n2 = dmnsn_color_intensity(c2); double f1 = c1.filter*c1.trans, f2 = c2.filter*c2.trans; double t1 = c1.trans - f1, t2 = c2.trans - f2; @@ -142,13 +211,25 @@ dmnsn_color_mul(double n, dmnsn_color color) dmnsn_color dmnsn_color_gradient(dmnsn_color c1, dmnsn_color c2, double n) { - return dmnsn_new_color5( + dmnsn_color ret = dmnsn_new_color( n*(c2.R - c1.R) + c1.R, n*(c2.G - c1.G) + c1.G, - n*(c2.B - c1.B) + c1.B, - n*(c2.trans - c1.trans) + c1.trans, - n*(c2.filter - c1.filter) + c1.filter + n*(c2.B - c1.B) + c1.B ); + + /* Switch into absolute filter and transmittance space */ + double f1 = c1.filter*c1.trans, f2 = c2.filter*c2.trans; + double t1 = c1.trans - f1, t2 = c2.trans - f2; + double f = n*(f2 - f1) + f1; + double t = n*(t2 - t1) + t1; + + /* Switch back */ + ret.trans = f + t; + ret.filter = 0.0; + if (ret.trans >= dmnsn_epsilon) + ret.filter = f/ret.trans; + + return ret; } /* Filters `light' through `filter' */ @@ -165,7 +246,7 @@ dmnsn_filter_light(dmnsn_color light, dmnsn_color filter) ); dmnsn_color ret = dmnsn_color_add(transmitted, filtered); - /* Switch back into absolute filter and transmittance space */ + /* Switch into absolute filter and transmittance space */ double lf = light.filter*light.trans, ff = filter.filter*filter.trans; double lt = light.trans - lf, ft = filter.trans - ff; double f = lf*(dmnsn_color_intensity(filtered) + ft) + lt*ff; |