Add abstract brush class and cardinal average

Add FuncBlur (i.e. with inverse distance function)
Add ListBlur to average a list of points
Use configure_file instead of file(COPY) bc it uses relative paths.
- Also it is more declarative.
Rename cpp to cc
Update README
Update TODO

7 files changed, 105 insertions, 11 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ee0c65a..b2facc6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,11 +4,7 @@ project(noise VERSION 0.0 LANGUAGES CXX)
 
 find_package(SFML COMPONENTS graphics REQUIRED)
 
-add_executable(noise noise.cpp)
+add_executable(noise noise.cc brush.cc)
 target_link_libraries(noise sfml-graphics)
 target_compile_features(noise PRIVATE cxx_std_17)
-file(COPY_FILE
-    ${CMAKE_CURRENT_SOURCE_DIR}/OpenSans-Regular.ttf
-    ${CMAKE_CURRENT_BINARY_DIR}/OpenSans.ttf
-  ONLY_IF_DIFFERENT
-)
+configure_file(OpenSans-Regular.ttf OpenSans.ttf COPYONLY)
diff --git a/README.md b/README.md
index 6d021ae..0056553 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,9 @@
 Texture generation.
 
 ## Requirements
-- SFML
+- CMake >= 3.8
+- SFML >= 2
+- C++ compiler with C++17 support
 
 ## Build instructions
 ```
diff --git a/TODO.md b/TODO.md
index 7d97ad6..c9f92f6 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,4 +1,4 @@
 Todo list
 =========
 - Split app and functions into files.
-- Add brush class - virtual getColor(int i, int j).
+- CMake check for filesystem vs. experimental/filesystem.
diff --git a/brush.cc b/brush.cc
new file mode 100644
index 0000000..cb9a5b9
--- /dev/null
+++ b/brush.cc
@@ -0,0 +1,46 @@
+#include "brush.h"
+
+namespace {
+static bool in_range(const sf::Vector2u& size, const sf::Vector2u& v) {
+        return v.x < size.x && v.y < size.y;
+}
+}  // namespace
+
+sf::Color FuncBlur::getColor(const sf::Image& im, unsigned i,
+                                                                                                                 unsigned j) const {
+        int radius = 3;
+        float sum = 0.0;
+        sf::Uint16 r = 0, g = 0, b = 0, a = 0;
+        for (int di = -radius; di <= radius; ++di) {
+                for (int dj = -radius; dj <= radius; ++dj) {
+                        sf::Vector2u v(i + di, j + dj);
+                        if (in_range(im.getSize(), v)) {
+                                sf::Color c = im.getPixel(v.x, v.y);
+        float w = weight(di, dj);
+                                r += c.r * w;
+                                g += c.g * w;
+                                b += c.b * w;
+                                a += c.a * w;
+                                sum += w;
+                        }
+                }
+        }
+  return sf::Color(r / sum, g / sum, b / sum, a / sum);
+}
+sf::Color ListBlur::getColor(const sf::Image& im, unsigned i,
+                                                                                                                 unsigned j) const {
+        float sum = 0.0;
+        sf::Uint16 r = 0, g = 0, b = 0, a = 0;
+        for (const Info& in : weights) {
+                sf::Vector2u v(i + in.di, j + in.dj);
+                if (in_range(im.getSize(), v)) {
+                        sf::Color c = im.getPixel(v.x, v.y);
+                        r += c.r * in.weight;
+                        g += c.g * in.weight;
+                        b += c.b * in.weight;
+                        a += c.a * in.weight;
+                        sum += in.weight;
+                }
+        }
+        return sf::Color(r / sum, g / sum, b / sum, a / sum);
+}
diff --git a/brush.h b/brush.h
new file mode 100644
index 0000000..62a06b4
--- /dev/null
+++ b/brush.h
@@ -0,0 +1,38 @@
+#include <vector>
+
+#include <SFML/Graphics.hpp>
+
+#ifndef NOISE_BRUSH_H_
+#define NOISE_BRUSH_H_
+
+class BlurBrush {
+  virtual sf::Color getColor(const sf::Image &im, unsigned i, unsigned j) const = 0;
+  public:
+  sf::Color operator()(const sf::Image &im, unsigned i, unsigned j) const {
+    return getColor(im, i, j);
+  }
+};
+
+
+class FuncBlur : public BlurBrush {
+  sf::Color getColor(const sf::Image &im, unsigned i, unsigned j) const;
+  virtual float weight (int di, int dj) const = 0;
+};
+
+
+class ListBlur : public BlurBrush {
+  sf::Color getColor(const sf::Image &im, unsigned i, unsigned j) const;
+  public:
+  struct Info {
+    int di, dj;
+    float weight;
+    Info (int di_, int dj_, float w): di(di_), dj(dj_), weight(w) {}
+  };
+
+  ListBlur(const std::vector<Info> &w) : weights(w) {}
+
+  private:
+  std::vector<Info> weights;
+};
+
+#endif // NOISE_BRUSH_H_
diff --git a/brushes.h b/brushes.h
new file mode 100644
index 0000000..7018a55
--- /dev/null
+++ b/brushes.h
@@ -0,0 +1,10 @@
+#include "brush.h"
+
+#ifndef NOISE_BRUSHES_H_
+#define NOISE_BRUSHES_H_
+
+namespace brushes {
+  ListBlur CardinalAverage({{0, 0, 1}, {1, 0, 1}, {0, 1, 1}, {-1, 0, 1}, {0, -1, 1}});
+}
+
+#endif // NOISE_BRUSHES_H_
\ No newline at end of file
diff --git a/noise.cpp b/noise.cc
index 2b2279d..b5651e8 100644
--- a/noise.cpp
+++ b/noise.cc
@@ -6,6 +6,8 @@
 
 #include <SFML/Graphics.hpp>
 
+#include "brushes.h"
+
 namespace fs = std::filesystem;
 
 namespace {
@@ -19,7 +21,7 @@ sf::Color random_color() {
                 engine.seed(std::random_device{}());
                 seeded = true;
         }
-#define COLOR_MODE 4
+#define COLOR_MODE 2
 #if (COLOR_MODE == 1)
         sf::Color c = sf::Color(color_dist(engine));
         c.a = 255;
@@ -103,14 +105,14 @@ void noise(sf::Image& im, int mode) {
                 im3.create(im.getSize().x * 2, im.getSize().y * 2);
                 for (unsigned i = 0; i < im2.getSize().x; ++i) {
                         for (unsigned j = 0; j < im2.getSize().y; ++j) {
-                                im3.setPixel(i, j, avg_card(im2, i, j));
+                                im3.setPixel(i, j, brushes::CardinalAverage(im2, i, j));
                         }
                 }
         } else if (mode == 2) {
                 im3.create(im.getSize().x, im.getSize().y);
                 for (unsigned i = 0; i < im.getSize().x; ++i) {
                         for (unsigned j = 0; j < im.getSize().y; ++j) {
-                                im3.setPixel(i, j, avg_card(im, i, j));
+                                im3.setPixel(i, j, brushes::CardinalAverage(im, i, j));
                         }
                 }
         } else if (mode == 3) {