1/// @ref gtc_color_space
2/// @file glm/gtc/color_space.inl
3
4namespace glm{
5namespace detail
6{
7	template<length_t L, typename T, qualifier Q>
8	struct compute_rgbToSrgb
9	{
10		GLM_FUNC_QUALIFIER static vec<L, T, Q> call(vec<L, T, Q> const& ColorRGB, T GammaCorrection)
11		{
12			vec<L, T, Q> const ClampedColor(clamp(ColorRGB, static_cast<T>(0), static_cast<T>(1)));
13
14			return mix(
15				pow(ClampedColor, vec<L, T, Q>(GammaCorrection)) * static_cast<T>(1.055) - static_cast<T>(0.055),
16				ClampedColor * static_cast<T>(12.92),
17				lessThan(ClampedColor, vec<L, T, Q>(static_cast<T>(0.0031308))));
18		}
19	};
20
21	template<typename T, qualifier Q>
22	struct compute_rgbToSrgb<4, T, Q>
23	{
24		GLM_FUNC_QUALIFIER static vec<4, T, Q> call(vec<4, T, Q> const& ColorRGB, T GammaCorrection)
25		{
26			return vec<4, T, Q>(compute_rgbToSrgb<3, T, Q>::call(vec<3, T, Q>(ColorRGB), GammaCorrection), ColorRGB.w);
27		}
28	};
29
30	template<length_t L, typename T, qualifier Q>
31	struct compute_srgbToRgb
32	{
33		GLM_FUNC_QUALIFIER static vec<L, T, Q> call(vec<L, T, Q> const& ColorSRGB, T Gamma)
34		{
35			return mix(
36				pow((ColorSRGB + static_cast<T>(0.055)) * static_cast<T>(0.94786729857819905213270142180095), vec<L, T, Q>(Gamma)),
37				ColorSRGB * static_cast<T>(0.07739938080495356037151702786378),
38				lessThanEqual(ColorSRGB, vec<L, T, Q>(static_cast<T>(0.04045))));
39		}
40	};
41
42	template<typename T, qualifier Q>
43	struct compute_srgbToRgb<4, T, Q>
44	{
45		GLM_FUNC_QUALIFIER static vec<4, T, Q> call(vec<4, T, Q> const& ColorSRGB, T Gamma)
46		{
47			return vec<4, T, Q>(compute_srgbToRgb<3, T, Q>::call(vec<3, T, Q>(ColorSRGB), Gamma), ColorSRGB.w);
48		}
49	};
50}//namespace detail
51
52	template<length_t L, typename T, qualifier Q>
53	GLM_FUNC_QUALIFIER vec<L, T, Q> convertLinearToSRGB(vec<L, T, Q> const& ColorLinear)
54	{
55		return detail::compute_rgbToSrgb<L, T, Q>::call(ColorLinear, static_cast<T>(0.41666));
56	}
57
58	// Based on Ian Taylor http://chilliant.blogspot.fr/2012/08/srgb-approximations-for-hlsl.html
59	template<>
60	GLM_FUNC_QUALIFIER vec<3, float, lowp> convertLinearToSRGB(vec<3, float, lowp> const& ColorLinear)
61	{
62		vec<3, float, lowp> S1 = sqrt(ColorLinear);
63		vec<3, float, lowp> S2 = sqrt(S1);
64		vec<3, float, lowp> S3 = sqrt(S2);
65		return 0.662002687f * S1 + 0.684122060f * S2 - 0.323583601f * S3 - 0.0225411470f * ColorLinear;
66	}
67
68	template<length_t L, typename T, qualifier Q>
69	GLM_FUNC_QUALIFIER vec<L, T, Q> convertLinearToSRGB(vec<L, T, Q> const& ColorLinear, T Gamma)
70	{
71		return detail::compute_rgbToSrgb<L, T, Q>::call(ColorLinear, static_cast<T>(1) / Gamma);
72	}
73
74	template<length_t L, typename T, qualifier Q>
75	GLM_FUNC_QUALIFIER vec<L, T, Q> convertSRGBToLinear(vec<L, T, Q> const& ColorSRGB)
76	{
77		return detail::compute_srgbToRgb<L, T, Q>::call(ColorSRGB, static_cast<T>(2.4));
78	}
79
80	template<length_t L, typename T, qualifier Q>
81	GLM_FUNC_QUALIFIER vec<L, T, Q> convertSRGBToLinear(vec<L, T, Q> const& ColorSRGB, T Gamma)
82	{
83		return detail::compute_srgbToRgb<L, T, Q>::call(ColorSRGB, Gamma);
84	}
85}//namespace glm
86