Add armor retexturing for skyblock items

docs/Texture Pack Format.md

@@ -143,3 +143,17 @@ specify one of these other matchers and one color preserving property.
 }
 ```
 
+## Armor textures
+
+You can re-*texture* armors, but not re-*model* them with firmament. 
+
+To do so, simply place the layer 1 and layer 2 armor
+texture files at `assets/firmskyblock/textures/models/armor/{skyblock_id}_layer_1.png` and
+`assets/firmskyblock/textures/models/armor/{skyblock_id}_layer_2.png` respectively.
+
+If you want to re-texture a leather
+armor you can use `assets/firmskyblock/textures/models/armor/{skyblock_id}_layer_1_overlay.png` and
+`assets/firmskyblock/textures/models/armor/{skyblock_id}_layer_2_overlay.png` instead. Doing this will cancel out the
+regular leather colors. If you want the leather colors to be applied, supply the normal non-`_overlay` variant, and
+also supply a blank `_overlay` variant. You can also put non-color-affected parts into the `_overlay` variant.
+

src/main/java/moe/nea/firmament/mixins/ArmorTexturePatch.java

@@ -0,0 +1,68 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Linnea Gräf <nea@nea.moe>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package moe.nea.firmament.mixins;
+
+
+import com.llamalad7.mixinextras.injector.v2.WrapWithCondition;
+import com.llamalad7.mixinextras.sugar.Local;
+import moe.nea.firmament.features.texturepack.CustomSkyBlockTextures;
+import net.minecraft.client.render.VertexConsumer;
+import net.minecraft.client.render.VertexConsumerProvider;
+import net.minecraft.client.render.entity.feature.ArmorFeatureRenderer;
+import net.minecraft.client.render.entity.model.BipedEntityModel;
+import net.minecraft.client.util.math.MatrixStack;
+import net.minecraft.entity.EquipmentSlot;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.item.ArmorItem;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.Identifier;
+import org.jetbrains.annotations.Nullable;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Unique;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+@Mixin(ArmorFeatureRenderer.class)
+public abstract class ArmorTexturePatch<T extends LivingEntity, M extends BipedEntityModel<T>, A extends BipedEntityModel<T>> {
+    @Unique
+    private ItemStack lastRenderedArmorItem;
+
+    @Unique
+    private boolean foundCustomTexture;
+
+    @WrapWithCondition(method = "renderArmorParts", at = @At(value = "INVOKE", target = "Lnet/minecraft/client/render/entity/model/BipedEntityModel;render(Lnet/minecraft/client/util/math/MatrixStack;Lnet/minecraft/client/render/VertexConsumer;IIFFFF)V"))
+    private boolean preventRenderingLeatherArmorColor(BipedEntityModel instance, MatrixStack matrixStack,
+                                                      VertexConsumer vertexConsumer, int light, int uv,
+                                                      float r, float g, float b, float a,
+                                                      @Local(argsOnly = true) @Nullable String overlay) {
+        if (overlay != null) return true;
+        if (foundCustomTexture) return true;
+        var customOverlayTexture = CustomSkyBlockTextures.INSTANCE.getArmorTexture(this.lastRenderedArmorItem, false, "overlay");
+        return customOverlayTexture == null;
+    }
+
+    @Inject(method = "renderArmor", at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;getItem()Lnet/minecraft/item/Item;"))
+    private void onBeforeRenderArmor(MatrixStack matrices, VertexConsumerProvider vertexConsumers,
+                                     T entity, EquipmentSlot armorSlot, int light, A model, CallbackInfo ci,
+                                     @Local ItemStack itemStack) {
+        this.lastRenderedArmorItem = itemStack;
+    }
+
+    @Inject(method = "getArmorTexture", at = @At("HEAD"), cancellable = true)
+    private void onGetTexture(ArmorItem item, boolean secondLayer, String overlay, CallbackInfoReturnable<Identifier> cir) {
+        if (this.lastRenderedArmorItem == null) return;
+        var armorTexture = CustomSkyBlockTextures.INSTANCE.getArmorTexture(this.lastRenderedArmorItem, secondLayer, overlay);
+        if (armorTexture != null) {
+            cir.setReturnValue(armorTexture);
+            this.foundCustomTexture = true;
+        } else {
+            this.foundCustomTexture = false;
+        }
+    }
+}

src/main/kotlin/moe/nea/firmament/features/texturepack/CustomSkyBlockTextures.kt

@@ -14,6 +14,7 @@ import net.minecraft.block.SkullBlock
 import net.minecraft.client.MinecraftClient
 import net.minecraft.client.render.RenderLayer
 import net.minecraft.client.util.ModelIdentifier
+import net.minecraft.item.ItemStack
 import net.minecraft.util.Identifier
 import moe.nea.firmament.events.CustomItemModelEvent
 import moe.nea.firmament.events.TickEvent
@@ -70,6 +71,23 @@ object CustomSkyBlockTextures : FirmamentFeature {
         return Identifier("firmskyblock", "textures/placedskull/$id.png")
     }
 
+    fun getArmorTexture(
+        itemStack: ItemStack, secondLayer: Boolean,
+        overlay: String?
+    ): Identifier? {
+        val modelIdentifier = CustomItemModelEvent.getModelIdentifier(itemStack) ?: return null
+        // Vanilla scheme: "textures/models/armor/" + var10000 + "_layer_" + (secondLayer ? 2 : 1) + (overlay == null ? "" : "_" + overlay) + ".png";
+        val overlayPart = if (overlay != null) "_$overlay" else ""
+        val identifier = Identifier(
+            modelIdentifier.namespace,
+            "textures/models/armor/${modelIdentifier.path}_layer_${if (secondLayer) 2 else 1}$overlayPart.png"
+        )
+        if (MC.resourceManager.getResource(identifier).isPresent) {
+            return identifier
+        }
+        return null
+    }
+
     fun modifySkullTexture(
         type: SkullBlock.SkullType?,
         profile: GameProfile?,