From cd309c04f2597f4029655f2aca797b677371bd95 Mon Sep 17 00:00:00 2001
From: Simon Hardt <simon.hardt@stud.hs-kempten.de>
Date: Thu, 3 Mar 2022 22:24:30 +0100
Subject: [PATCH] add: Circle

---
 frame/src/Vector.hpp              | 11 +++++++---
 frame/src/main.cpp                | 10 ++++-----
 frame/src/render/RenderTarget.cpp | 36 ++++++++++++++++++++++++++++---
 frame/src/render/RenderTarget.hpp |  4 ++++
 4 files changed, 50 insertions(+), 11 deletions(-)

diff --git a/frame/src/Vector.hpp b/frame/src/Vector.hpp
index 15d1173..a07d0b6 100644
--- a/frame/src/Vector.hpp
+++ b/frame/src/Vector.hpp
@@ -1,8 +1,8 @@
 #pragma once
-#include <iostream>
-
 #include "Size.hpp"
 
+#include <iostream>
+
 namespace frame
 {
     struct Vector
@@ -56,7 +56,12 @@ namespace frame
 
     inline std::ostream& operator<<(std::ostream& os, Vector const& v)
     {
-        return os << "x: "<< v.x << " y: " << v.y;
+        return os << "x: " << v.x << " y: " << v.y;
+    }
+
+    inline Vector operator+(Vector const& a, Vector const& b)
+    {
+        return {a.x + b.x, a.y + b.y};
     }
 
 } // namespace frame
diff --git a/frame/src/main.cpp b/frame/src/main.cpp
index edd52be..5e59351 100644
--- a/frame/src/main.cpp
+++ b/frame/src/main.cpp
@@ -1,20 +1,19 @@
-#include <cmath>
 #include <chrono>
+#include <cmath>
 #include <iostream>
 #include <thread>
 #include <vector>
 
+
 using namespace std::chrono_literals;
 
 #include "display/EPD_7in5_V2.hpp"
 #include "render/RenderTarget.hpp"
 
-
 int main()
 {
     constexpr double pi = 3.14159;
 
-
     frame::display::EPD_7in5_V2 display{};
 
     display.Init();
@@ -25,7 +24,6 @@ int main()
 
     frame::Vector const center = (display.getSize() / 2);
 
-
     target.DrawPixel({10, 10}, frame::BLACK);
     target.DrawLine({10, 12}, {100, 12}, frame::BLACK);
 
@@ -33,7 +31,7 @@ int main()
     {
         auto end = center;
 
-	double const x = std::cos(i * pi / 180.f) * 200.f;
+        double const x = std::cos(i * pi / 180.f) * 200.f;
         double const y = std::sin(i * pi / 180.f) * 200.f;
 
         end.x += (int)x;
@@ -42,6 +40,8 @@ int main()
         target.DrawLine(center, end);
     }
 
+    target.DrawCircle(center, 210);
+
     display.Display(target.getImage());
 
     std::this_thread::sleep_for(10s);
diff --git a/frame/src/render/RenderTarget.cpp b/frame/src/render/RenderTarget.cpp
index 3483591..09af0d6 100644
--- a/frame/src/render/RenderTarget.cpp
+++ b/frame/src/render/RenderTarget.cpp
@@ -55,8 +55,7 @@ namespace frame::render
                 {
                     pos.x += rX;
                     pos.y += rY;
-                }
-                else
+                } else
                 {
                     pos.y += rX;
                     pos.x += rY;
@@ -65,11 +64,42 @@ namespace frame::render
                 E += 2 * deltaY - 2 * deltaX;
             }
 
-            if(pos.x < 0 || pos.y < 0 || pos.x >= image.getWidth() || pos.y >= image.getHeight())
+            if(pos.x < 0 || pos.y < 0 || pos.x >= image.getWidth()
+               || pos.y >= image.getHeight())
                 break;
 
             DrawPixel(pos, color);
         }
     }
 
+    void RenderTarget::DrawCircle(Vector const& center,
+                                  int32_t radius,
+                                  Color color)
+    {
+        int32_t const r_2 = radius * radius;
+        Vector pos{0, -radius};
+
+        pos.x += 1;
+        float E =
+            pos.x * pos.x + ((float)pos.y - 0.5f) * ((float)pos.y - 0.5f) - r_2;
+
+        while(pos.x <= radius / std::sqrt(2.f))
+        {
+            if(E < 0)
+            {
+                pos.x += 1;
+
+                E += 3;
+            } else
+            {
+                pos.x += 1;
+                pos.y -= 1;
+
+                E -= 2 * (-radius) + 5;
+            }
+
+            DrawPixel(center + pos, color);
+        }
+    }
+
 } // namespace frame::render
diff --git a/frame/src/render/RenderTarget.hpp b/frame/src/render/RenderTarget.hpp
index bae9a8d..1ed53d5 100644
--- a/frame/src/render/RenderTarget.hpp
+++ b/frame/src/render/RenderTarget.hpp
@@ -20,6 +20,10 @@ namespace frame::render
                       Vector const& end,
                       Color color = BLACK);
 
+        void DrawCircle(Vector const& center,
+                        int32_t radius,
+                        Color color = BLACK);
+
         Image const& getImage()
         {
             return image;