1 files changed, 90 insertions, 0 deletions
diff --git a/src/texturePacks/java/moe/nea/firmament/features/texturepack/HeadModelChooser.kt b/src/texturePacks/java/moe/nea/firmament/features/texturepack/HeadModelChooser.kt
new file mode 100644
index 0000000..b5f2bfe
--- /dev/null
+++ b/src/texturePacks/java/moe/nea/firmament/features/texturepack/HeadModelChooser.kt
@@ -0,0 +1,90 @@
+package moe.nea.firmament.features.texturepack
+
+import com.google.gson.JsonObject
+import com.mojang.serialization.MapCodec
+import com.mojang.serialization.codecs.RecordCodecBuilder
+import net.minecraft.client.item.ItemModelManager
+import net.minecraft.client.render.item.ItemRenderState
+import net.minecraft.client.render.item.model.BasicItemModel
+import net.minecraft.client.render.item.model.ItemModel
+import net.minecraft.client.render.item.model.ItemModelTypes
+import net.minecraft.client.render.model.ResolvableModel
+import net.minecraft.client.world.ClientWorld
+import net.minecraft.entity.LivingEntity
+import net.minecraft.item.ItemStack
+import net.minecraft.item.ModelTransformationMode
+import net.minecraft.util.Identifier
+
+object HeadModelChooser {
+	val IS_CHOOSING_HEAD_MODEL = ThreadLocal.withInitial { false }
+
+	interface HasExplicitHeadModelMarker {
+		fun markExplicitHead_Firmament()
+		fun isExplicitHeadModel_Firmament(): Boolean
+		companion object{
+			@JvmStatic
+			fun cast(state: ItemRenderState) = state as HasExplicitHeadModelMarker
+		}
+	}
+
+	data class Baked(val head: ItemModel, val regular: ItemModel) : ItemModel {
+		override fun update(
+			state: ItemRenderState,
+			stack: ItemStack?,
+			resolver: ItemModelManager?,
+			transformationMode: ModelTransformationMode?,
+			world: ClientWorld?,
+			user: LivingEntity?,
+			seed: Int
+		) {
+			val instance =
+				if (IS_CHOOSING_HEAD_MODEL.get()) {
+					HasExplicitHeadModelMarker.cast(state).markExplicitHead_Firmament()
+					head
+				} else {
+					regular
+				}
+			instance.update(state, stack, resolver, transformationMode, world, user, seed)
+		}
+	}
+
+	data class Unbaked(
+		val head: ItemModel.Unbaked,
+		val regular: ItemModel.Unbaked,
+	) : ItemModel.Unbaked {
+		override fun getCodec(): MapCodec<out ItemModel.Unbaked> {
+			return CODEC
+		}
+
+		override fun bake(context: ItemModel.BakeContext): ItemModel {
+			return Baked(
+				head.bake(context),
+				regular.bake(context)
+			)
+		}
+
+		override fun resolve(resolver: ResolvableModel.Resolver) {
+			head.resolve(resolver)
+			regular.resolve(resolver)
+		}
+
+		companion object {
+			@JvmStatic
+			fun fromLegacyJson(jsonObject: JsonObject, unbakedModel: ItemModel.Unbaked): ItemModel.Unbaked {
+				val model = jsonObject["firmament:head_model"] ?: return unbakedModel
+				val modelUrl = model.asJsonPrimitive.asString
+				val headModel = BasicItemModel.Unbaked(Identifier.of(modelUrl), listOf())
+				return Unbaked(headModel, unbakedModel)
+			}
+
+			val CODEC = RecordCodecBuilder.mapCodec {
+				it.group(
+					ItemModelTypes.CODEC.fieldOf("head")
+						.forGetter(Unbaked::head),
+					ItemModelTypes.CODEC.fieldOf("regular")
+						.forGetter(Unbaked::regular),
+				).apply(it, ::Unbaked)
+			}
+		}
+	}
+}