imglib: add jpg/png loading using stb_image

common/imglib.cc

@@ -4,6 +4,9 @@
 #include <common/entdata.h>
 #include <common/json.hh>
 
+#define STB_IMAGE_IMPLEMENTATION
+#include "../3rdparty/stb_image.h"
+
 /*
 ============================================================================
 PALETTE
@@ -404,6 +407,42 @@ breakOut:;
     return tex; // mxd
 }
 
+std::optional<texture> load_stb(
+    const std::string_view &name, const fs::data &file, bool meta_only, const gamedef_t *game)
+{
+    int x, y, channels_in_file;
+    stbi_uc *rgba_data = stbi_load_from_memory(file->data(), file->size(), &x, &y, &channels_in_file, 4);
+
+    if (!rgba_data) {
+        logging::funcprint("stbi error: {}\n", stbi_failure_reason());
+        return {};
+    }
+
+    texture tex;
+    tex.meta.extension = ext::STB;
+    tex.meta.name = name;
+    tex.meta.width = tex.width = x;
+    tex.meta.height = tex.height = y;
+
+    if (!meta_only) {
+        int num_pixels = x * y;
+        if (num_pixels < 0) {
+            return {};
+        }
+
+        tex.pixels.resize(num_pixels);
+
+        qvec4b *out = tex.pixels.data();
+        for (int i = 0; i < num_pixels; ++i) {
+            out[i] = {rgba_data[4 * i], rgba_data[4 * i + 1], rgba_data[4 * i + 2], rgba_data[4 * i + 3]};
+        }
+    }
+
+    stbi_image_free(rgba_data);
+
+    return tex;
+}
+
 // texture cache
 std::unordered_map<std::string, texture, case_insensitive_hash, case_insensitive_equal> textures;
 

include/common/imglib.hh

@@ -31,7 +31,11 @@ enum class ext
 {
     TGA,
     WAL,
-    MIP
+    MIP,
+    /**
+     * Anything loadable by stb_image.h
+     */
+    STB
 };
 
 extern std::vector<qvec3b> palette;
@@ -66,6 +70,7 @@ struct texture
     // the width/height of the metadata.
     uint32_t width = 0, height = 0;
 
+    // RGBA order
     std::vector<qvec4b> pixels;
 
     // the scale required to map a pixel from the
@@ -95,14 +100,18 @@ std::optional<texture> load_tga(
 std::optional<texture> load_mip(
     const std::string_view &name, const fs::data &file, bool meta_only, const gamedef_t *game);
 
+// stb_image.h loaders
+std::optional<texture> load_stb(
+    const std::string_view &name, const fs::data &file, bool meta_only, const gamedef_t *game);
+
 // list of supported extensions and their loaders
 constexpr struct
 {
     const char *suffix;
     ext id;
     decltype(load_wal) *loader;
-} extension_list[] = {
-    {".tga", ext::TGA, load_tga}, {".wal", ext::WAL, load_wal}, {".mip", ext::MIP, load_mip}, {"", ext::MIP, load_mip}};
+} extension_list[] = {{".png", ext::STB, load_stb}, {".jpg", ext::STB, load_stb}, {".tga", ext::TGA, load_tga},
+    {".wal", ext::WAL, load_wal}, {".mip", ext::MIP, load_mip}, {"", ext::MIP, load_mip}};
 
 // Attempt to load a texture from the specified name.
 std::tuple<std::optional<texture>, fs::resolve_result, fs::data> load_texture(