.. _program_listing_file__tmp_ws_src_color_util_color_util_include_color_util_blend.hpp:

Program Listing for File blend.hpp
==================================

|exhale_lsh| :ref:`Return to documentation for file <file__tmp_ws_src_color_util_color_util_include_color_util_blend.hpp>` (``/tmp/ws/src/color_util/color_util/include/color_util/blend.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   /*
    * Software License Agreement (BSD License)
    *
    *  Copyright (c) 2020, Locus Robotics
    *  Copyright (c) 2023, Metro Robots
    *  All rights reserved.
    *
    *  Redistribution and use in source and binary forms, with or without
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    *  are met:
    *
    *   * Redistributions of source code must retain the above copyright
    *     notice, this list of conditions and the following disclaimer.
    *   * Redistributions in binary form must reproduce the above
    *     copyright notice, this list of conditions and the following
    *     disclaimer in the documentation and/or other materials provided
    *     with the distribution.
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    *     contributors may be used to endorse or promote products derived
    *     from this software without specific prior written permission.
    *
    *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    *  COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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    *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    *  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    *  POSSIBILITY OF SUCH DAMAGE.
    */
   
   /* Author: David V. Lu!! */
   
   #pragma once
   
   #include <color_util/types.hpp>
   #include <algorithm>
   
   namespace color_util
   {
   template <typename rgba>
   inline rgba rgbaBlend(const rgba& color_a, const rgba& color_b, double ratio)
   {
     ratio = std::min(ratio, 1.0);
     ratio = std::max(ratio, 0.0);
   
     double i_ratio = 1.0 - ratio;
   
     rgba color;
     color.r = color_a.r * i_ratio + color_b.r * ratio;
     color.g = color_a.g * i_ratio + color_b.g * ratio;
     color.b = color_a.b * i_ratio + color_b.b * ratio;
     color.a = color_a.a * i_ratio + color_b.a * ratio;
     return color;
   }
   
   template <typename hsva>
   inline hsva hueBlend(const hsva& color_a, const hsva& color_b, double ratio)
   {
     ratio = std::min(ratio, 1.0);
     ratio = std::max(ratio, 0.0);
   
     double i_ratio = 1.0 - ratio;
   
     hsva color;
     color.h = color_a.h * i_ratio + color_b.h * ratio;
     color.s = color_a.s * i_ratio + color_b.s * ratio;
     color.v = color_a.v * i_ratio + color_b.v * ratio;
     color.a = color_a.a * i_ratio + color_b.a * ratio;
     return color;
   }
   
   inline color_util::ColorHSVA hueBlendPlus(const color_util::ColorHSVA& color_a, const color_util::ColorHSVA& color_b,
                                             double ratio)
   {
     ratio = std::min(ratio, 1.0);
     ratio = std::max(ratio, 0.0);
   
     double i_ratio = 1.0 - ratio;
   
     // Direct interpolation for saturation/value/alpha
     color_util::ColorHSVA color;
     color.s = color_a.s * i_ratio + color_b.s * ratio;
     color.v = color_a.v * i_ratio + color_b.v * ratio;
     color.a = color_a.a * i_ratio + color_b.a * ratio;
   
     // Hue interpolation
     double start_h, end_h, diff;
     if (color_a.h > color_b.h)
     {
       start_h = color_b.h;
       end_h = color_a.h;
       ratio = i_ratio;
     }
     else
     {
       start_h = color_a.h;
       end_h = color_b.h;
     }
     diff = end_h - start_h;
   
     // If the hue difference is greater than 0.5, interpolate the other way around
     if (diff > 0.5)  // 180deg
     {
       start_h = start_h + 1;  // 360deg
       double ipart;
       color.h = modf(start_h + ratio * (end_h - start_h), &ipart);  // 360deg
     }
     else
     {
       color.h = start_h + ratio * diff;
     }
     return color;
   }
   
   }  // namespace color_util