Add subset of GLSL-Color-Spaces library (HCY)

plugins/editor/CMakeLists.txt

@@ -59,6 +59,10 @@ if(APPLE)
 endif()
 
 # dependencies
+add_library(sfizz_colorspaces INTERFACE)
+add_library(sfizz::colorspaces ALIAS sfizz_colorspaces)
+target_include_directories(sfizz_colorspaces INTERFACE "external/color-spaces")
+
 if(WIN32)
     #
 elseif(APPLE)
@@ -69,7 +73,7 @@ else()
     target_include_directories(sfizz_editor PRIVATE ${sfizz-gio_INCLUDE_DIRS})
     target_link_libraries(sfizz_editor PRIVATE ${sfizz-gio_LIBRARIES})
 endif()
-target_link_libraries(sfizz_editor PRIVATE sfizz::bit_array sfizz::filesystem)
+target_link_libraries(sfizz_editor PRIVATE sfizz::colorspaces sfizz::bit_array sfizz::filesystem)
 
 # layout tool
 if(NOT CMAKE_CROSSCOMPILING)

plugins/editor/external/color-spaces/ColorSpaces.h

@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: MIT
+/*
+GLSL Color Space Utility Functions
+(c) 2015 tobspr
+
+Porting a subset to C++
+(c) 2020 Jean Pierre Cimalando
+
+-------------------------------------------------------------------------------
+
+The MIT License (MIT)
+
+Copyright (c) 2015
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+-------------------------------------------------------------------------------
+
+Most formulars / matrices are from:
+https://en.wikipedia.org/wiki/SRGB
+
+Some are from:
+http://www.chilliant.com/rgb2hsv.html
+https://www.fourcc.org/fccyvrgb.php
+*/
+
+#pragma once
+#include <array>
+#include <algorithm>
+#include <cmath>
+
+namespace ColorSpaces {
+
+template <std::size_t N> using vec = std::array<float, N>;
+using vec3 = vec<3>;
+using vec4 = vec<4>;
+
+template <class T>
+T clamp(T x, T lo, T hi)
+{
+    return std::max(lo, std::min(hi, x));
+}
+
+template <std::size_t N>
+vec<N> saturate(vec<N> x)
+{
+    for (std::size_t i = 0; i < N; ++i)
+        x[i] = clamp(x[i], 0.0f, 1.0f);
+    return x;
+}
+
+float dot(vec3 a, vec3 b)
+{
+    return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
+}
+
+// Constants
+static constexpr float HCV_EPSILON = 1e-10;
+static constexpr float HCY_EPSILON = 1e-10;
+
+// Converts a value from linear RGB to HCV (Hue, Chroma, Value)
+vec3 rgb_to_hcv(vec3 rgb)
+{
+    // Based on work by Sam Hocevar and Emil Persson
+    vec4 P = (rgb[1] < rgb[2]) ? vec4{{rgb[2], rgb[1], -1.0, 2.0/3.0}} : vec4{{rgb[1], rgb[2], 0.0, -1.0/3.0}};
+    vec4 Q = (rgb[0] < P[0]) ? vec4{{P[0], P[1], P[3], rgb[0]}} : vec4{{rgb[0], P[1], P[2], P[0]}};
+    float C = Q[0] - std::min(Q[3], Q[1]);
+    float H = std::abs((Q[3] - Q[1]) / (6 * C + HCV_EPSILON) + Q[2]);
+    return vec3{{H, C, Q[0]}};
+}
+
+// Converts from pure Hue to linear RGB
+vec3 hue_to_rgb(float hue)
+{
+    float R = std::fabs(hue * 6 - 3) - 1;
+    float G = 2 - std::fabs(hue * 6 - 2);
+    float B = 2 - std::fabs(hue * 6 - 4);
+    return saturate(vec3{{R,G,B}});
+}
+
+// Converts from HCY to linear RGB
+vec3 hcy_to_rgb(vec3 hcy)
+{
+    const vec3 HCYwts{{0.299, 0.587, 0.114}};
+    vec3 RGB = hue_to_rgb(hcy[0]);
+    float Z = dot(RGB, HCYwts);
+    if (hcy[2] < Z) {
+        hcy[1] *= hcy[2] / Z;
+    } else if (Z < 1) {
+        hcy[1] *= (1 - hcy[2]) / (1 - Z);
+    }
+    return vec3{{(RGB[0] - Z)  * hcy[1] + hcy[2],
+                 (RGB[1] - Z)  * hcy[1] + hcy[2],
+                 (RGB[2] - Z)  * hcy[1] + hcy[2]}};
+}
+
+// Converts from rgb to hcy (Hue, Chroma, Luminance)
+vec3 rgb_to_hcy(vec3 rgb)
+{
+    const vec3 HCYwts = vec3{{0.299, 0.587, 0.114}};
+    // Corrected by David Schaeffer
+    vec3 HCV = rgb_to_hcv(rgb);
+    float Y = dot(rgb, HCYwts);
+    float Z = dot(hue_to_rgb(HCV[0]), HCYwts);
+    if (Y < Z) {
+      HCV[1] *= Z / (HCY_EPSILON + Y);
+    } else {
+      HCV[1] *= (1 - Z) / (HCY_EPSILON + 1 - Y);
+    }
+    return vec3{{HCV[0], HCV[1], Y}};
+}
+
+} // namespace ColorSpaces

plugins/editor/external/color-spaces/LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+