Box blue algorithm

Author: mnerv

CMakeLists.txt

@@ -75,6 +75,40 @@ else()
 endif()
 source_group(TREE "${CMAKE_CURRENT_LIST_DIR}" FILES ${TARGET_SOURCE_FILES})
 
+# Box blur
+project(boxblur)
+set(TARGET_SOURCE_FILES
+    "boxblur.cpp"
+)
+add_executable(${PROJECT_NAME} ${TARGET_SOURCE_FILES})
+target_include_directories(${PROJECT_NAME} PRIVATE
+    "${PROJECT_SOURCE_DIR}"
+)
+target_link_libraries(${PROJECT_NAME}
+    stb
+    glm::glm
+    asio::asio
+    Threads::Threads
+    image
+)
+target_compile_features(${PROJECT_NAME} PRIVATE cxx_std_20)
+if (NOT MSVC)
+    target_compile_options(${PROJECT_NAME} PRIVATE
+        "-Wall"
+        "-Wextra"
+        "-Wconversion"
+        "-Wpedantic"
+        "-Wshadow"
+        "-Werror"
+    )
+else()
+    target_compile_options(${PROJECT_NAME} PRIVATE
+        "/W4"
+        "/WX"
+    )
+endif()
+source_group(TREE "${CMAKE_CURRENT_LIST_DIR}" FILES ${TARGET_SOURCE_FILES})
+
 # Gaussian blur
 project(gaussian)
 set(TARGET_SOURCE_FILES

boxblur.cpp

@@ -0,0 +1,58 @@
+/**
+ * @file   gaussian.cpp
+ * @author mononerv ([email protected])
+ * @brief  Box blur
+ *         https://en.wikipedia.org/wiki/Box_blur
+ * @date   2022-10-14
+ *
+ * @copyright Copyright (c) 2022 mononerv
+ */
+#include <random>
+#include <filesystem>
+#include <cmath>
+#include <iostream>
+
+#include "image.hpp"
+
+auto box_blur(nrv::image const& img) -> nrv::image {
+    nrv::image output{img.width(), img.height(), img.channels()};
+    nrv::render_img(img, [&](glm::ivec2 const& pos, glm::vec4 const&) {
+        auto sum_at = [&](glm::ivec2 const& offset) {
+            return img.get_pixel_rgba(pos.x + offset.x, pos.y + offset.y);
+        };
+
+        std::int32_t const blur_width  = 1;
+        std::int32_t const blur_height = 1;
+        auto sum = glm::vec4{0.0f};
+        auto denom = 0.0f;
+        for (std::int32_t i = -blur_height; i <= blur_height; ++i) {
+            for (std::int32_t j = -blur_width; j <= blur_width; ++j) {
+                sum += sum_at({j, i});
+                denom += 1.0f;
+            }
+        }
+
+        output.set_pixel(pos.x, pos.y, sum / denom);
+    });
+    return output;
+}
+
+auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
+    if (argc < 2) {
+        std::cout << "No file given\n";
+        std::cout << "usage: " << argv[0] << " {filename}\n";
+        return 1;
+    }
+
+    std::filesystem::path filename = argv[1];
+    if (!std::filesystem::exists(filename)) {
+        std::cout << "Not a valid file\n";
+        return 1;
+    }
+
+    nrv::image image{filename};
+    auto out = box_blur(image);
+    nrv::write_png("box_blur_out.png", out);
+
+    return 0;
+}