Add flappy bird

examples/flappy_bird/image_loader.cpp

@@ -0,0 +1,72 @@
+#include <paradiso/rgba.hpp>
+#include <paradiso/sprite.hpp>
+
+#include <fstream>
+#include <iostream>
+#include <optional>
+#include <unordered_map>
+
+// STB image loading
+#define STB_IMAGE_IMPLEMENTATION
+#include "lib/stb_image.h"
+
+#include "image_loader.hpp"
+
+std::unordered_map<std::string, paradiso::Bitmap> image_loader::image_cache =
+    std::unordered_map<std::string, paradiso::Bitmap>();
+
+paradiso::Bitmap image_loader::load(const std::string& filename) {
+    if (image_cache.find(filename) == image_cache.end()) {
+        std::string path = ASSET_PATH + filename;
+        std::cout << "Loading " << path << std::endl;
+        auto data = readBMP(path);
+        image_cache[filename] = data;
+    }
+    return image_cache[filename];
+}
+
+paradiso::Bitmap image_loader::readBMP(std::string& filename) {
+    // Load with stb_image
+    stbi_set_flip_vertically_on_load(true); // flip y axis for OpenGL
+    int width, height, channels;
+    unsigned char* image =
+        stbi_load(filename.c_str(), &width, &height, &channels, 4);
+    int size = width * height;
+
+    if (!image)
+        throw std::runtime_error("Error loading image");
+
+    // Convert to Vector of RGBA
+    std::vector<paradiso::RGBA> rgba = std::vector<paradiso::RGBA>(size);
+    for (int i = 0; i < size; i++) {
+        // get rgba values
+        int pos = i * 4;
+        int r = image[pos + 0];
+        int g = image[pos + 1];
+        int b = image[pos + 2];
+        int a = image[pos + 3];
+
+        // bug in from_rgba. it expects bgra, not rgba
+        auto val = paradiso::RGBA::from_rgba(b, g, r, a);
+        rgba[i] = val;
+    }
+
+    // rotate image by 90 degrees CW
+    std::vector<paradiso::RGBA> rotated = std::vector<paradiso::RGBA>(size);
+    for (int x = 0; x < width; x++) {
+        for (int y = 0; y < height; y++) {
+
+            int pos = y * width + x;
+            int pos_rotated = x * height + (height - y - 1);
+            rotated[pos_rotated] = rgba[pos];
+        }
+    }
+
+    // free image
+    stbi_image_free(image);
+
+    return paradiso::Bitmap::from_data(
+        paradiso::Size{static_cast<unsigned int>(height),
+                       static_cast<unsigned int>(width)},
+        rotated);
+}