From 6cd04636c133a6a103a35d8c35bcad844233a487 Mon Sep 17 00:00:00 2001
From: Bart Beumer <bart@4beumer.nl>
Date: Tue, 11 Nov 2025 19:56:39 +0000
Subject: [PATCH] WIP add color

---
 applications/http-mandelbrot/src/main.cpp |  16 ++-
 bmrshared/include/bmrshared/color.hpp     | 138 ++++++++++++++++++++++
 2 files changed, 150 insertions(+), 4 deletions(-)
 create mode 100644 bmrshared/include/bmrshared/color.hpp

diff --git a/applications/http-mandelbrot/src/main.cpp b/applications/http-mandelbrot/src/main.cpp
index db06ae3..86a8fb2 100644
--- a/applications/http-mandelbrot/src/main.cpp
+++ b/applications/http-mandelbrot/src/main.cpp
@@ -10,6 +10,7 @@
 #include <bmrshared/request_handler_interface.hpp>
 #include <bmrshared/directory_request_handler.hpp>
 #include <bmrshared/request_response.hpp>
+#include <bmrshared/color.hpp>
 #include <boost/asio/signal_set.hpp>
 #include <boost/gil/image.hpp>
 #include <boost/gil/image_view.hpp>
@@ -155,16 +156,23 @@ void fractal(
                     constexpr int max_iterations = 255;
 
 
-                    boost::gil::gray8_image_t image(pixel_width,pixel_height);
+                    boost::gil::rgb8_image_t image(pixel_width,pixel_height);
                     auto view = boost::gil::view(image);
-                    boost::gil::fill_pixels(view, boost::gil::gray8_pixel_t(0));
+                    boost::gil::fill_pixels(view, boost::gil::rgb8_pixel_t(0));
 
                     auto painter = [&](int x, int y, int num_iter) -> void
                     {
                         if(x >= 0 && y >= 0 && x < pixel_width && y < pixel_height)
                         {
+                            bmrshared::color c({.h=(num_iter*5)%360,.s=(0.5+(num_iter/200.0)), .v=1.0});
+                            auto crgb = c.rgb();
+                            uint8_t r = crgb.r * 255;
+                            uint8_t g = crgb.g * 255;
+                            uint8_t b = crgb.b * 255;
+
+
                             const auto iter = view.at({x, y});
-                            boost::gil::color_convert(boost::gil::gray8_pixel_t(num_iter), *iter);
+                            boost::gil::color_convert(boost::gil::rgb8_pixel_t(r,g,b), *iter);
                         }
                     };
 
@@ -245,7 +253,7 @@ int main(int argc, char **argv)
     
     
     std::vector<std::jthread> threads;
-    while(threads.size() < 16)
+    while(threads.size() < 4)
     {
         threads.emplace_back([&ioc]{ioc.run();});
     }
diff --git a/bmrshared/include/bmrshared/color.hpp b/bmrshared/include/bmrshared/color.hpp
new file mode 100644
index 0000000..82df346
--- /dev/null
+++ b/bmrshared/include/bmrshared/color.hpp
@@ -0,0 +1,138 @@
+// GNU Lesser General Public License v3.0
+// Copyright (c) 2023 Bart Beumer <bart@4beumer.nl>
+//
+// This program is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License v3.0 as published by
+// the Free Software Foundation.
+//
+#pragma once
+#include <cmath>
+#include <optional>
+#include <utility>
+
+
+namespace bmrshared
+{
+class color
+{
+public:
+    struct color_hsv
+    {
+        double h;
+        double s;
+        double v;
+    };
+
+    struct color_rgb
+    {
+        double r;
+        double g;
+        double b;
+    };
+
+    color() = delete;
+    ~color() = default;
+    constexpr color(const color&) = default;
+    constexpr color(color&&) = default;
+    constexpr color& operator=(const color&) = default;
+    constexpr color& operator=(color&&) = default;
+
+    constexpr color(const color_hsv& c)
+        : m_rgb()
+        , m_hsv(c)
+    {}
+
+    constexpr color(const color_rgb& c)
+        : m_rgb(c)
+        , m_hsv()
+    {}
+
+    constexpr const color_rgb& rgb() const
+    {
+        if (!m_rgb)
+        {
+            m_rgb = calculate_rgb(*m_hsv);
+        }
+        return *m_rgb;
+    }
+
+    constexpr const color_hsv& hsv() const
+    {
+        if (!m_hsv)
+        {
+            m_hsv = calculate_hsv(*m_rgb);
+        }
+        return *m_hsv;
+    }
+
+private:
+    static constexpr color_hsv calculate_hsv(const color_rgb& c)
+    {
+        color_hsv r{.h = 0.0, .s = 0.0, .v = 0.0};
+        double min = std::min(c.r, std::min(c.g,c.b));
+        r.v = std::max(c.r, std::max(c.g,c.b));
+        double delta = r.v - min;
+        r.s = (r.v <= 0.0) ? 0.0 : (delta / r.v);
+        if (r.s <= 0.0)
+        {
+            r.h = 0.0;
+        }
+        else
+        {
+            if (c.r == r.v)
+            {
+                r.h = (c.g - c.b) / delta;
+            }
+            else if (c.g == r.v)
+            {
+                r.h = 2.0 + (c.b - c.r) / delta;
+            }
+            else if (c.b == r.v)
+            {
+                r.h = 4.0 + (c.r - c.g) / delta;
+            }
+            r.h*=60.0;
+            if (r.h < 0.0)
+            {
+                r.h +=360.0;
+            }
+        }
+        return r;
+	}
+
+    static constexpr color_rgb calculate_rgb(const color_hsv& in)
+    {
+        double C = in.s * in.v;
+        double X = C*(1-std::fabs(std::fmod(in.h/60.0, 2)-1));
+        double m = in.v-C;
+
+        color_rgb result{.r = 0.0, .g = 0.0, .b = 0.0};
+        if(in.h >= 0.0 && in.h < 60.0){
+            result = {.r = C, .g = X, .b = 0.0};
+        }
+        else if(in.h >= 60.0 && in.h < 120.0){
+            result = {.r = X, .g = C, . b = 0.0};
+        }
+        else if(in.h >= 120.0 && in.h < 180.0){
+            result = {.r = 0.0, .g = C, .b = X};
+        }
+        else if(in.h >= 180.0 && in.h < 240.0){
+            result = {.r = 0.0, .g = X, .b = C};
+        }
+        else if(in.h >= 240.0 && in.h < 300.0){
+            result = {.r = X, .g = 0.0, .b = C};
+        }
+        else{
+            result = {.r = C, .g = 0.0, .b = X};
+        }
+        result.r+=m;
+        result.g+=m;
+        result.b+=m;
+        
+        return result;
+    }
+
+    mutable std::optional<color_rgb> m_rgb;
+    mutable std::optional<color_hsv> m_hsv;
+};
+}