custom models: envmap support (#3777)

Custom models and model replacements now support environment mapping.

Also fixed some cases in Jak 3 where tfrags had missing textures
(defaulting to texture 0 from tpage 0, which in Jak 3 is the default eye
texture) and replaced them with more suitable alternatives.

Fixes #3776 


https://github.com/user-attachments/assets/7c11b0de-b254-40cb-9719-11238dfb3d43


![image](https://github.com/user-attachments/assets/4cc60b55-4965-4cb8-b29d-096560e7b3aa)


![image](https://github.com/user-attachments/assets/cb46d0d1-57d7-482c-b235-15d0e633f62c)

common/util/gltf_util.cpp

@@ -1,5 +1,7 @@
 #include "gltf_util.h"
 
+#include "image_resize.h"
+
 #include "common/log/log.h"
 
 namespace gltf_util {
@@ -424,6 +426,64 @@ int texture_pool_add_texture(TexturePool* pool, const tinygltf::Image& tex, int
   return idx;
 }
 
+int texture_pool_add_envmap_control_texture(TexturePool* pool,
+                                            const tinygltf::Model& model,
+                                            int rgb_image_id,
+                                            int mr_image_id,
+                                            bool wrap_w,
+                                            bool wrap_h) {
+  const auto& existing = pool->envmap_textures_by_gltf_id.find({rgb_image_id, mr_image_id});
+  if (existing != pool->envmap_textures_by_gltf_id.end()) {
+    lg::info("Reusing envmap textures");
+    return existing->second;
+  }
+  const auto& rgb_tex = model.images.at(rgb_image_id);
+  const auto& mr_tex = model.images.at(mr_image_id);
+  lg::info("new envmap texture {} {}", rgb_tex.name, mr_tex.name);
+  ASSERT(rgb_tex.bits == 8);
+  ASSERT(rgb_tex.component == 4);
+  ASSERT(rgb_tex.pixel_type == TINYGLTF_TEXTURE_TYPE_UNSIGNED_BYTE);
+
+  ASSERT(mr_tex.bits == 8);
+  ASSERT(mr_tex.pixel_type == TINYGLTF_TEXTURE_TYPE_UNSIGNED_BYTE);
+  ASSERT(mr_tex.component == 4);
+
+  std::vector<u8> resized_mr_tex;
+  const u8* mr_src;
+  if (rgb_tex.width == mr_tex.width && rgb_tex.height == mr_tex.height) {
+    mr_src = mr_tex.image.data();
+  } else {
+    resized_mr_tex.resize(rgb_tex.width * rgb_tex.height * 4);
+    resize_rgba_image(resized_mr_tex.data(), rgb_tex.width, rgb_tex.height, mr_tex.image.data(),
+                      mr_tex.width, mr_tex.height, wrap_w, wrap_h);
+    mr_src = resized_mr_tex.data();
+  }
+
+  size_t idx = pool->textures_by_idx.size();
+  pool->envmap_textures_by_gltf_id[{rgb_image_id, mr_image_id}] = idx;
+  auto& tt = pool->textures_by_idx.emplace_back();
+  tt.w = rgb_tex.width;
+  tt.h = rgb_tex.height;
+  tt.debug_name = rgb_tex.name;
+  tt.debug_tpage_name = "custom-level";
+  tt.load_to_pool = false;
+  tt.combo_id = 0;  // doesn't matter, not a pool tex
+  tt.data.resize(tt.w * tt.h);
+  ASSERT(rgb_tex.image.size() >= tt.data.size());
+  memcpy(tt.data.data(), rgb_tex.image.data(), tt.data.size() * 4);
+
+  // adjust alpha from metallic channel
+  for (size_t i = 0; i < tt.data.size(); i++) {
+    u32 rgb = tt.data[i];
+    u32 metal = mr_src[4 * i + 2] / 4;
+    rgb &= 0xff'ff'ff;
+    rgb |= (metal << 24);
+    tt.data[i] = rgb;
+  }
+
+  return idx;
+}
+
 math::Matrix4f affine_translation(const math::Vector3f& translation) {
   math::Matrix4f result = math::Matrix4f::identity();
   result(0, 3) = translation[0];
@@ -607,6 +667,19 @@ void setup_draw_mode_from_sampler(const tinygltf::Sampler& sampler, DrawMode* mo
   }
 }
 
+EnvmapSettings envmap_settings_from_gltf(const tinygltf::Material& mat) {
+  EnvmapSettings settings;
+
+  ASSERT(mat.extensions.contains("KHR_materials_specular"));
+  const auto& specular_extension = mat.extensions.at("KHR_materials_specular");
+  ASSERT(specular_extension.Has("specularColorTexture"));
+
+  auto& texture = specular_extension.Get("specularColorTexture");
+  ASSERT(texture.Has("index"));
+  settings.texture_idx = texture.Get("index").Get<int>();
+  return settings;
+}
+
 std::optional<int> find_single_skin(const tinygltf::Model& model,
                                     const std::vector<NodeWithTransform>& all_nodes) {
   std::optional<int> skin_index;