Override held item render

src/main/java/vazkii/quark/content/experimental/module/VariantSelectorModule.java

@@ -15,6 +15,7 @@
 import net.minecraft.client.KeyMapping;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.gui.screens.Screen;
+import net.minecraft.client.player.AbstractClientPlayer;
 import net.minecraft.client.renderer.GameRenderer;
 import net.minecraft.core.BlockPos;
 import net.minecraft.network.chat.Component;
@@ -81,6 +82,7 @@ public class VariantSelectorModule extends QuarkModule {
 	@Config public static boolean showSimpleHud = false;
 	@Config public static boolean showHud = true;
 	@Config public static boolean enableGreenTint = true;
+	@Config public static boolean overrideHeldItemRender = true;
 
 	@Config
 	public static BlockSuffixConfig variants = new BlockSuffixConfig(
@@ -268,6 +270,24 @@ public static BlockState modifyBlockPlacementState(BlockState state, BlockPlaceC
 
 		return state;
 	}
+
+	@OnlyIn(Dist.CLIENT)
+	public static ItemStack modifyHeldItemStack(AbstractClientPlayer player, ItemStack stack) {
+		if(!staticEnabled || !overrideHeldItemRender)
+			return stack;
+
+		Minecraft mc = Minecraft.getInstance();
+		if(player == mc.player && stack.getItem() instanceof BlockItem bi) {
+			Block block = bi.getBlock();
+			if(clientVariant != null && !clientVariant.isEmpty()) {
+				Block variant = variants.getBlockForVariant(block, clientVariant);
+				if(variant != null && variant != block)
+					return new ItemStack(variant);
+			}
+		}
+
+		return stack;
+	}
 
 	@SubscribeEvent
 	@OnlyIn(Dist.CLIENT)

src/main/java/vazkii/quark/mixin/client/ItemInHandRendererMixin.java

@@ -0,0 +1,21 @@
+package vazkii.quark.mixin.client;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyVariable;
+
+import net.minecraft.client.player.AbstractClientPlayer;
+import net.minecraft.client.renderer.ItemInHandRenderer;
+import net.minecraft.world.item.ItemStack;
+import vazkii.quark.content.experimental.module.VariantSelectorModule;
+
+@Mixin(ItemInHandRenderer.class)
+public class ItemInHandRendererMixin {
+
+	@ModifyVariable(method = "renderArmWithItem", at = @At("HEAD"), argsOnly = true)
+	private ItemStack renderArmWithItem(ItemStack stack, AbstractClientPlayer player) {
+		return VariantSelectorModule.modifyHeldItemStack(player, stack);
+	}
+
+
+}

src/main/resources/quark.mixins.json

@@ -100,6 +100,7 @@
     "client.RenderBuffersMixin",
     "client.ScreenMixin",
     "client.ThrownTridentRendererMixin",
+    "client.ItemInHandRendererMixin",
     "client.accessor.AccessorBlockColors",
     "client.accessor.AccessorItemColors",
     "client.accessor.AccessorLocalPlayer",