feat(middle-click): Add in GUI and in-world middle-click pick to set and reset channels (#74)

StructureLib built the missing block name on the server, where only
en_US is loaded, so players on dedicated servers saw English names in
chat. Send the item's lang key and let the client translate it. Stacks
whose name is not a plain key, GT meta items among them, keep the old
server side name.

Players also saw two shapes of the same message: a bracketed name with
rarity color and an item tooltip from two of the survivalPlaceBlocks
branches, a bare yellow name from the stack list branch. All three now
build the name the same way.

dependencies.gradle

@@ -3,7 +3,6 @@
 dependencies {
     api("com.github.GTNewHorizons:GTNHLib:0.11.21:dev")
     implementation("com.github.GTNewHorizons:NotEnoughItems:2.8.110-GTNH:dev")
-
     testImplementation(platform('org.junit:junit-bom:5.9.2'))
     testImplementation('org.junit.jupiter:junit-jupiter')
 	testRuntimeOnly ('org.junit.platform:junit-platform-launcher')

src/main/java/com/gtnewhorizon/structurelib/ChannelPickHandler.java

@@ -0,0 +1,88 @@
+package com.gtnewhorizon.structurelib;
+
+import java.util.Collection;
+import java.util.Map;
+
+import javax.annotation.Nullable;
+
+import net.minecraft.block.Block;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.ChatComponentTranslation;
+import net.minecraft.util.MovingObjectPosition;
+import net.minecraft.world.World;
+
+import com.gtnewhorizon.structurelib.alignment.constructable.ChannelDataAccessor;
+import com.gtnewhorizon.structurelib.net.SetChannelDataMessage;
+
+/**
+ * Handler for middle-click channel picking. When the player holds a hologram projector on the cursor and middle-clicks
+ * a registered indicator item, the corresponding channel is set on the projector. The same applies in world when the
+ * projector is held in hand and a registered indicator block is middle-clicked. Shift+middle-click wipes all channels.
+ * Was made side neutral to support server-side validation at some point if necessary.
+ */
+public final class ChannelPickHandler {
+
+    private ChannelPickHandler() {}
+
+    /**
+     * Handle a middle-click event while holding a hologram projector on the cursor.
+     */
+    public static boolean handleMiddleClick(EntityPlayer player, ItemStack holoStack, @Nullable ItemStack targetStack,
+            final boolean isSneaking) {
+        return handlePick(player, holoStack, targetStack, isSneaking, true);
+    }
+
+    public static boolean handleWorldPick(World world, EntityPlayer player, ItemStack holoStack,
+            @Nullable MovingObjectPosition hit, final boolean isSneaking) {
+        ItemStack targetStack = null;
+
+        if (hit != null) {
+            Block block = world.getBlock(hit.blockX, hit.blockY, hit.blockZ);
+            if (!block.isAir(world, hit.blockX, hit.blockY, hit.blockZ)) {
+                targetStack = block.getPickBlock(hit, world, hit.blockX, hit.blockY, hit.blockZ, player);
+            }
+        }
+
+        // A null target still goes through so that shift+middle-click wipes even when aiming at nothing
+        return handlePick(player, holoStack, targetStack, isSneaking, false);
+    }
+
+    private static boolean handlePick(EntityPlayer player, ItemStack holoStack, @Nullable ItemStack targetStack,
+            final boolean isSneaking, final boolean onCursor) {
+        // Clear channels on shift+middle-click. The "press again to confirm" gesture is gated client-side
+        // (see ChannelWipeConfirmation) before this method is ever called.
+        if (isSneaking) {
+            ChannelDataAccessor.wipeChannelData(holoStack);
+            sendChannelData(player, holoStack, onCursor);
+            player.addChatMessage(new ChatComponentTranslation("structurelib.pickchannel.cleared"));
+            return true;
+        }
+
+        if (targetStack == null) return false; // nothing hovered, cancel silently
+
+        Collection<Map.Entry<String, Integer>> channels = ChannelDescription.iterate(targetStack);
+        if (channels.isEmpty()) {
+            player.addChatMessage(new ChatComponentTranslation("structurelib.pickchannel.nomapping"));
+            return false;
+        }
+
+        // Assuming there's only 1 channel per item for now (same behavior as drag and drop)
+        Map.Entry<String, Integer> first = channels.iterator().next();
+        ChannelDataAccessor.setChannelData(holoStack, first.getKey(), first.getValue());
+        sendChannelData(player, holoStack, onCursor);
+        player.addChatMessage(
+                new ChatComponentTranslation("structurelib.pickchannel.success", first.getKey(), first.getValue()));
+        return true;
+    }
+
+    /**
+     * Player is the one triggering this update, so should already be in-sync.
+     */
+    private static void sendChannelData(EntityPlayer player, ItemStack holoStack, boolean onCursor) {
+        if (!(player instanceof EntityPlayerMP)) {
+            StructureLib.net.sendToServer(new SetChannelDataMessage(holoStack, onCursor));
+        }
+    }
+}

src/main/java/com/gtnewhorizon/structurelib/ChannelWipeConfirmation.java

@@ -0,0 +1,33 @@
+package com.gtnewhorizon.structurelib;
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.util.ChatComponentTranslation;
+
+/**
+ * Client-side-only confirmation gate for "wipe all channels" shift+middle-click gesture.
+ */
+public final class ChannelWipeConfirmation {
+
+    private static final long CONFIRM_WINDOW_MS = 5000;
+    private static long armedAtMs = -1;
+
+    private ChannelWipeConfirmation() {}
+
+    /**
+     * Call this before invoking {@link ChannelPickHandler} whenever the wipe gesture (shift+middle-click) is detected.
+     *
+     * @return true if this is a confirming second press within the window and the wipe should proceed now; false if
+     *         this press only armed the confirmation.
+     */
+    public static boolean confirm(EntityPlayer player) {
+        long now = Minecraft.getSystemTime();
+        if (now - armedAtMs > CONFIRM_WINDOW_MS) {
+            armedAtMs = now;
+            player.addChatMessage(new ChatComponentTranslation("structurelib.pickchannel.confirmwipe"));
+            return false;
+        }
+        armedAtMs = -1;
+        return true;
+    }
+}

src/main/java/com/gtnewhorizon/structurelib/ClientProxy.java

@@ -30,6 +30,7 @@ import net.minecraft.util.IChatComponent;
 import net.minecraft.util.IIcon;
 import net.minecraft.util.Vec3;
 import net.minecraft.world.World;
+import net.minecraftforge.client.event.MouseEvent;
 import net.minecraftforge.client.event.RenderWorldLastEvent;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.common.config.ConfigElement;
@@ -40,6 +41,7 @@ import org.apache.commons.lang3.tuple.Pair;
 import org.lwjgl.opengl.GL11;
 
 import com.gtnewhorizon.structurelib.entity.fx.WeightlessParticleFX;
+import com.gtnewhorizon.structurelib.item.ItemConstructableTrigger;
 import com.gtnewhorizon.structurelib.net.RegistryOrderSyncMessage;
 import com.gtnewhorizon.structurelib.net.SetChannelDataMessage;
 
@@ -53,6 +55,8 @@ import cpw.mods.fml.common.eventhandler.SubscribeEvent;
 import cpw.mods.fml.common.gameevent.TickEvent.ClientTickEvent;
 import cpw.mods.fml.common.gameevent.TickEvent.Phase;
 import cpw.mods.fml.common.network.FMLNetworkEvent;
+import cpw.mods.fml.relauncher.Side;
+import cpw.mods.fml.relauncher.SideOnly;
 
 public class ClientProxy extends CommonProxy {
 
@@ -560,6 +564,35 @@ public class ClientProxy extends CommonProxy {
 
     public static class ForgeEventHandler {
 
+        @SubscribeEvent
+        @SideOnly(Side.CLIENT)
+        public void onMouseEvent(MouseEvent event) {
+            final EntityPlayer player = Minecraft.getMinecraft().thePlayer;
+
+            if (player == null || player.isDead) {
+                return;
+            }
+
+            final ItemStack heldItem = player.getHeldItem();
+
+            if (heldItem == null || !(heldItem.getItem() instanceof ItemConstructableTrigger)) return;
+
+            if (event.button != 2 || !event.buttonstate) return;
+
+            // Sink the middle click as soon as a projector is held, so vanilla pick block does not run
+            event.setCanceled(true);
+
+            final boolean isSneaking = player.isSneaking();
+            if (isSneaking && !ChannelWipeConfirmation.confirm(player)) return;
+
+            ChannelPickHandler.handleWorldPick(
+                    player.worldObj,
+                    player,
+                    heldItem,
+                    Minecraft.getMinecraft().objectMouseOver,
+                    isSneaking);
+        }
+
         @SubscribeEvent
         public void onEntityJoinWorld(EntityJoinWorldEvent e) {
             if (e.world.isRemote && e.entity instanceof EntityClientPlayerMP) {

src/main/java/com/gtnewhorizon/structurelib/CommonProxy.java

@@ -17,6 +17,7 @@ import net.minecraftforge.common.MinecraftForge;
 import com.gtnewhorizon.structurelib.net.ErrorHintParticleMessage;
 import com.gtnewhorizon.structurelib.net.UpdateHintParticleMessage;
 
+import cpw.mods.fml.common.event.FMLInitializationEvent;
 import cpw.mods.fml.common.event.FMLLoadCompleteEvent;
 import cpw.mods.fml.common.event.FMLPreInitializationEvent;
 import cpw.mods.fml.common.eventhandler.SubscribeEvent;
@@ -64,6 +65,8 @@ public class CommonProxy {
 
     public void preInit(FMLPreInitializationEvent e) {}
 
+    public void init(FMLInitializationEvent e) {}
+
     public long getOverworldTime() {
         return MinecraftServer.getServer().getEntityWorld().getTotalWorldTime();
     }

src/main/java/com/gtnewhorizon/structurelib/StructureLib.java

@@ -33,6 +33,7 @@ import com.gtnewhorizon.structurelib.util.XSTR;
 
 import cpw.mods.fml.common.Mod;
 import cpw.mods.fml.common.SidedProxy;
+import cpw.mods.fml.common.event.FMLInitializationEvent;
 import cpw.mods.fml.common.event.FMLInterModComms;
 import cpw.mods.fml.common.event.FMLLoadCompleteEvent;
 import cpw.mods.fml.common.event.FMLPreInitializationEvent;
@@ -128,6 +129,11 @@ public class StructureLib {
         DevelopHelper.onPreInit();
     }
 
+    @Mod.EventHandler
+    public void init(FMLInitializationEvent e) {
+        proxy.init(e);
+    }
+
     @Mod.EventHandler
     public void loadComplete(FMLLoadCompleteEvent e) {
         proxy.loadComplete(e);

src/main/java/com/gtnewhorizon/structurelib/alignment/constructable/ChannelDataAccessor.java

@@ -146,7 +146,12 @@ public class ChannelDataAccessor {
      */
     public static void wipeChannelData(ItemStack masterStack) {
         if (masterStack == null) throw new IllegalArgumentException();
-        if (masterStack.stackTagCompound != null) masterStack.stackTagCompound.removeTag(SECONDARY_HINT_TAG);
+        if (masterStack.stackTagCompound != null) {
+            masterStack.stackTagCompound.removeTag(SECONDARY_HINT_TAG);
+            if (masterStack.stackTagCompound.hasNoTags()) {
+                masterStack.stackTagCompound = null;
+            }
+        }
     }
 
     /**

src/main/java/com/gtnewhorizon/structurelib/core/StructureLibCore.java

@@ -1,5 +1,6 @@
 package com.gtnewhorizon.structurelib.core;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
@@ -7,7 +8,9 @@ import java.util.Set;
 
 import com.gtnewhorizon.gtnhmixins.IEarlyMixinLoader;
 
+import cpw.mods.fml.relauncher.FMLLaunchHandler;
 import cpw.mods.fml.relauncher.IFMLLoadingPlugin;
+import cpw.mods.fml.relauncher.Side;
 
 @IFMLLoadingPlugin.MCVersion("1.7.10")
 public class StructureLibCore implements IFMLLoadingPlugin, IEarlyMixinLoader {
@@ -44,6 +47,11 @@ public class StructureLibCore implements IFMLLoadingPlugin, IEarlyMixinLoader {
 
     @Override
     public List<String> getMixins(Set<String> loadedCoreMods) {
-        return Arrays.asList("blockChangeNotifier.MixinForgeHooks", "blockChangeNotifier.MixinWorld");
+        List<String> mixins = new ArrayList<>(
+                Arrays.asList("blockChangeNotifier.MixinForgeHooks", "blockChangeNotifier.MixinWorld"));
+        if (FMLLaunchHandler.side() == Side.CLIENT) {
+            mixins.add("MixinGuiContainer_PickChannel");
+        }
+        return mixins;
     }
 }

src/main/java/com/gtnewhorizon/structurelib/mixins/early/MixinGuiContainer_PickChannel.java

@@ -0,0 +1,64 @@
+package com.gtnewhorizon.structurelib.mixins.early;
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.gui.GuiScreen;
+import net.minecraft.client.gui.inventory.GuiContainer;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.inventory.Slot;
+import net.minecraft.item.ItemStack;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Invoker;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import com.gtnewhorizon.structurelib.ChannelPickHandler;
+import com.gtnewhorizon.structurelib.ChannelWipeConfirmation;
+import com.gtnewhorizon.structurelib.StructureLib;
+import com.gtnewhorizon.structurelib.item.ItemConstructableTrigger;
+
+import codechicken.nei.NEIClientConfig;
+import codechicken.nei.guihook.GuiContainerManager;
+import cpw.mods.fml.common.Loader;
+
+@Mixin(value = GuiContainer.class, priority = 100)
+public abstract class MixinGuiContainer_PickChannel {
+
+    @Inject(method = "mouseClicked(III)V", at = @At("HEAD"), cancellable = true)
+    private void slib$onMouseClicked(int mouseX, int mouseY, int mouseButton, CallbackInfo ci) {
+        if (mouseButton != 2) return;
+
+        EntityPlayer player = Minecraft.getMinecraft().thePlayer;
+        if (player == null) return;
+
+        ItemStack cursorStack = player.inventory.getItemStack();
+        if (cursorStack == null || !(cursorStack.getItem() instanceof ItemConstructableTrigger)) return;
+
+        // Sink middle click as soon as projector is picked up
+        ci.cancel();
+
+        ItemStack hoveredStack = null;
+        try {
+            Slot slot = slib$invokeGetSlotAtPosition(mouseX, mouseY);
+            if (slot != null) {
+                hoveredStack = slot.getStack();
+            }
+
+            // try NEI
+            if (hoveredStack == null && Loader.isModLoaded("NotEnoughItems") && !NEIClientConfig.isHidden()) {
+                hoveredStack = GuiContainerManager.getStackMouseOver((GuiContainer) (Object) this);
+            }
+        } catch (Exception e) {
+            StructureLib.LOGGER.error("Error while resolving hovered slot for channel pick", e);
+        }
+
+        boolean isSneaking = GuiScreen.isShiftKeyDown();
+        if (isSneaking && !ChannelWipeConfirmation.confirm(player)) return;
+
+        ChannelPickHandler.handleMiddleClick(player, cursorStack, hoveredStack, isSneaking);
+    }
+
+    @Invoker("getSlotAtPosition")
+    protected abstract Slot slib$invokeGetSlotAtPosition(int x, int y);
+}

src/main/java/com/gtnewhorizon/structurelib/net/SetChannelDataMessage.java

@@ -23,15 +23,22 @@ import io.netty.buffer.ByteBuf;
 public class SetChannelDataMessage implements IMessage {
 
     private final List<Map.Entry<String, Integer>> data = new ArrayList<>();
+    private boolean onCursor;
 
     public SetChannelDataMessage() {}
 
     public SetChannelDataMessage(ItemStack trigger) {
+        this(trigger, false);
+    }
+
+    public SetChannelDataMessage(ItemStack trigger, final boolean onCursor) {
+        this.onCursor = onCursor;
         ChannelDataAccessor.iterateChannelData(trigger).forEach(data::add);
     }
 
     @Override
     public void fromBytes(ByteBuf buf) {
+        onCursor = buf.readBoolean();
         data.clear();
         int size = ByteBufUtils.readVarShort(buf);
         for (int i = 0; i < size; i++) {
@@ -41,6 +48,7 @@ public class SetChannelDataMessage implements IMessage {
 
     @Override
     public void toBytes(ByteBuf buf) {
+        buf.writeBoolean(onCursor);
         ByteBufUtils.writeVarShort(buf, data.size());
         for (Entry<String, Integer> e : data) {
             ByteBufUtils.writeUTF8String(buf, e.getKey());
@@ -53,11 +61,11 @@ public class SetChannelDataMessage implements IMessage {
         @Override
         public IMessage onMessage(SetChannelDataMessage message, MessageContext ctx) {
             EntityPlayerMP player = ctx.getServerHandler().playerEntity;
-            ItemStack heldItem = player.getHeldItem();
+            ItemStack target = message.onCursor ? player.inventory.getItemStack() : player.getHeldItem();
-            if (heldItem != null && heldItem.getItem() instanceof ItemConstructableTrigger) {
+            if (target != null && target.getItem() instanceof ItemConstructableTrigger) {
-                ChannelDataAccessor.wipeChannelData(heldItem);
+                ChannelDataAccessor.wipeChannelData(target);
                 for (Entry<String, Integer> e : message.data) {
-                    ChannelDataAccessor.setChannelData(heldItem, e.getKey(), e.getValue());
+                    ChannelDataAccessor.setChannelData(target, e.getKey(), e.getValue());
                 }
                 // since this is a set all channel request from the client, we would assume client already know
                 // what this would look like on the client, so no sync
@@ -65,7 +73,7 @@ public class SetChannelDataMessage implements IMessage {
                 StructureLib.LOGGER.warn(
                         "{} trying to set channel data on {}, which is not a hologram projector!",
                         player.getUniqueID(),
-                        heldItem);
+                        target);
             }
             return null;
         }

src/main/java/com/gtnewhorizon/structurelib/structure/IStructureDefinition.java

@@ -67,7 +67,7 @@ public interface IStructureDefinition<T> {
      * @throws java.util.NoSuchElementException if the given structure piece is not found and the moon phase perfectly
      *                                          matches
      */
-    IStructureElement<? super T>[] getStructureFor(String name);
+    IStructureElement<T>[] getStructureFor(String name);
 
     boolean isContainedInStructure(String name, int offsetA, int offsetB, int offsetC);
 
@@ -356,7 +356,7 @@ public interface IStructureDefinition<T> {
      * @return true if iteration completed successfully.
      * @param <T> type of context object.
      */
-    static <T> boolean iterate(T object, ItemStack trigger, IStructureElement<? super T>[] elements, World world,
+    static <T> boolean iterate(T object, ItemStack trigger, IStructureElement<T>[] elements, World world,
             ExtendedFacing extendedFacing, int basePositionX, int basePositionY, int basePositionZ, int basePositionA,
             int basePositionB, int basePositionC, boolean hintsOnly, Boolean checkBlocksIfNotNullForceCheckAllIfTrue) {
         if (!world.isRemote && hintsOnly) {

src/main/java/com/gtnewhorizon/structurelib/structure/IStructureElement.java

@@ -28,9 +28,6 @@ import com.gtnewhorizon.structurelib.util.ItemStackPredicate.NBTMode;
 /**
  * Use StructureUtility to instantiate. These are the building blocks for your {@link IStructureDefinition}. It
  * represents what a particular element can be and how this particular element should be autoplaced.
- *
- * @param <T> Type of the context object. {@link IStructureElement} is contravariant over T, so parameters and fields of
- *            type {@link IStructureElement} should be declared as {@code IStructureElement<? super T>}
  */
 public interface IStructureElement<T> {
 
@@ -216,7 +213,7 @@ public interface IStructureElement<T> {
      * Forget the messed up class dependency graph for now. this is just so convenient.
      */
     default IStructureElementNoPlacement<T> noPlacement() {
-        return new IStructureElementNoPlacement<>() {
+        return new IStructureElementNoPlacement<T>() {
 
             @Override
             public boolean check(T t, World world, int x, int y, int z) {

src/main/java/com/gtnewhorizon/structurelib/structure/IStructureElementChain.java

@@ -21,11 +21,11 @@ import com.google.common.collect.Iterables;
  */
 public interface IStructureElementChain<T> extends IStructureElement<T> {
 
-    IStructureElement<? super T>[] fallbacks();
+    IStructureElement<T>[] fallbacks();
 
     @Override
     default boolean check(T t, World world, int x, int y, int z) {
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             if (fallback.check(t, world, x, y, z)) {
                 return true;
             }
@@ -35,7 +35,7 @@ public interface IStructureElementChain<T> extends IStructureElement<T> {
 
     @Override
     default boolean couldBeValid(T t, World world, int x, int y, int z, ItemStack trigger) {
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             if (fallback.couldBeValid(t, world, x, y, z, trigger)) {
                 return true;
             }
@@ -45,7 +45,7 @@ public interface IStructureElementChain<T> extends IStructureElement<T> {
 
     @Override
     default boolean spawnHint(T t, World world, int x, int y, int z, ItemStack trigger) {
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             if (fallback.spawnHint(t, world, x, y, z, trigger)) {
                 return true;
             }
@@ -55,7 +55,7 @@ public interface IStructureElementChain<T> extends IStructureElement<T> {
 
     @Override
     default boolean placeBlock(T t, World world, int x, int y, int z, ItemStack trigger) {
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             if (fallback.placeBlock(t, world, x, y, z, trigger)) {
                 return true;
             }
@@ -67,7 +67,7 @@ public interface IStructureElementChain<T> extends IStructureElement<T> {
     @Override
     default List<String> getDescription(T context) {
         Set<String> descriptions = new LinkedHashSet<>();
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             List<String> desc = fallback.getDescription(context);
             if (desc != null) {
                 descriptions.addAll(desc);
@@ -82,7 +82,7 @@ public interface IStructureElementChain<T> extends IStructureElement<T> {
             AutoPlaceEnvironment env) {
         Predicate<ItemStack> predicate = null;
         List<Iterable<ItemStack>> is = new ArrayList<>();
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             BlocksToPlace e = fallback.getBlocksToPlace(t, world, x, y, z, trigger, env);
             if (e == null) continue;
             if (predicate == null) predicate = e.getPredicate();
@@ -99,7 +99,7 @@ public interface IStructureElementChain<T> extends IStructureElement<T> {
             EntityPlayerMP actor, Consumer<IChatComponent> chatter) {
         boolean allContinue = true;
         List<IChatComponent> bufferedNoise = new ArrayList<>();
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             PlaceResult result = fallback.survivalPlaceBlock(t, world, x, y, z, trigger, s, actor, bufferedNoise::add);
             switch (result) {
                 case REJECT_CONTINUE:
@@ -124,7 +124,7 @@ public interface IStructureElementChain<T> extends IStructureElement<T> {
             AutoPlaceEnvironment env) {
         boolean allContinue = true;
         List<IChatComponent> bufferedNoise = new ArrayList<>();
-        for (IStructureElement<? super T> fallback : fallbacks()) {
+        for (IStructureElement<T> fallback : fallbacks()) {
             PlaceResult result = fallback
                     .survivalPlaceBlock(t, world, x, y, z, trigger, env.withChatter(bufferedNoise::add));
             switch (result) {

src/main/java/com/gtnewhorizon/structurelib/structure/IStructureNavigate.java

@@ -10,36 +10,36 @@ import net.minecraft.world.World;
 /**
  * Use StructureUtility to instantiate
  */
-interface IStructureNavigate extends IStructureElement<Object> {
+interface IStructureNavigate<T> extends IStructureElement<T> {
 
     @Override
-    default boolean check(Object t, World world, int x, int y, int z) {
+    default boolean check(T t, World world, int x, int y, int z) {
         return true;
     }
 
     @Override
-    default boolean couldBeValid(Object t, World world, int x, int y, int z, ItemStack trigger) {
+    default boolean couldBeValid(T t, World world, int x, int y, int z, ItemStack trigger) {
         return true;
     }
 
     @Override
-    default boolean spawnHint(Object t, World world, int x, int y, int z, ItemStack trigger) {
+    default boolean spawnHint(T t, World world, int x, int y, int z, ItemStack trigger) {
         return true;
     }
 
     @Override
-    default boolean placeBlock(Object t, World world, int x, int y, int z, ItemStack trigger) {
+    default boolean placeBlock(T t, World world, int x, int y, int z, ItemStack trigger) {
         return true;
     }
 
     @Override
-    default PlaceResult survivalPlaceBlock(Object t, World world, int x, int y, int z, ItemStack trigger, IItemSource s,
+    default PlaceResult survivalPlaceBlock(T t, World world, int x, int y, int z, ItemStack trigger, IItemSource s,
             EntityPlayerMP actor, Consumer<IChatComponent> chatter) {
         return PlaceResult.SKIP;
     }
 
     @Override
-    default PlaceResult survivalPlaceBlock(Object t, World world, int x, int y, int z, ItemStack trigger,
+    default PlaceResult survivalPlaceBlock(T t, World world, int x, int y, int z, ItemStack trigger,
             AutoPlaceEnvironment env) {
         return PlaceResult.SKIP;
     }

src/main/java/com/gtnewhorizon/structurelib/structure/IStructureWalker.java

@@ -21,42 +21,40 @@ public interface IStructureWalker<T> {
      * @param c       The relative C position of the element in structure-local coordinates (pre transform)
      * @return False to stop iterating, true to continue.
      */
-    boolean visit(IStructureElement<? super T> element, World world, int x, int y, int z, int a, int b, int c);
+    boolean visit(IStructureElement<T> element, World world, int x, int y, int z, int a, int b, int c);
 
-    default boolean blockNotLoaded(IStructureElement<? super T> element, World world, int x, int y, int z, int a, int b,
+    default boolean blockNotLoaded(IStructureElement<T> element, World world, int x, int y, int z, int a, int b,
             int c) {
         return false;
     }
 
     static <T> IStructureWalker<T> ignoreBlockUnloaded(IStructureWalker<T> walker) {
-        return new IStructureWalker<>() {
+        return new IStructureWalker<T>() {
 
             @Override
-            public boolean visit(IStructureElement<? super T> element, World world, int x, int y, int z, int a, int b,
+            public boolean visit(IStructureElement<T> element, World world, int x, int y, int z, int a, int b, int c) {
-                    int c) {
                 return walker.visit(element, world, x, y, z, a, b, c);
             }
 
             @Override
-            public boolean blockNotLoaded(IStructureElement<? super T> element, World world, int x, int y, int z, int a,
+            public boolean blockNotLoaded(IStructureElement<T> element, World world, int x, int y, int z, int a, int b,
-                    int b, int c) {
+                    int c) {
                 return walker.visit(element, world, x, y, z, a, b, c);
             }
         };
     }
 
     static <T> IStructureWalker<T> skipBlockUnloaded(IStructureWalker<T> walker) {
-        return new IStructureWalker<>() {
+        return new IStructureWalker<T>() {
 
             @Override
-            public boolean visit(IStructureElement<? super T> element, World world, int x, int y, int z, int a, int b,
+            public boolean visit(IStructureElement<T> element, World world, int x, int y, int z, int a, int b, int c) {
-                    int c) {
                 return walker.visit(element, world, x, y, z, a, b, c);
             }
 
             @Override
-            public boolean blockNotLoaded(IStructureElement<? super T> element, World world, int x, int y, int z, int a,
+            public boolean blockNotLoaded(IStructureElement<T> element, World world, int x, int y, int z, int a, int b,
-                    int b, int c) {
+                    int c) {
                 return true;
             }
         };

src/main/java/com/gtnewhorizon/structurelib/structure/LazyStructureElement.java

@@ -13,14 +13,14 @@ import net.minecraft.world.World;
 
 class LazyStructureElement<T> implements IStructureElementDeferred<T> {
 
-    private Function<? super T, ? extends IStructureElement<? super T>> to;
+    private Function<T, IStructureElement<T>> to;
-    private IStructureElement<? super T> elem;
+    private IStructureElement<T> elem;
 
-    public LazyStructureElement(Function<? super T, ? extends IStructureElement<? super T>> to) {
+    public LazyStructureElement(Function<T, IStructureElement<T>> to) {
         this.to = to;
     }
 
-    private IStructureElement<? super T> get(T t) {
+    private IStructureElement<T> get(T t) {
         if (to != null) {
             elem = to.apply(t);
             to = null;

src/main/java/com/gtnewhorizon/structurelib/structure/StructureDefinition.java

@@ -16,17 +16,17 @@ import com.gtnewhorizon.structurelib.util.Vec3Impl;
 
 public class StructureDefinition<T> implements IStructureDefinition<T> {
 
-    private final Map<Character, IStructureElement<? super T>> elements;
+    private final Map<Character, IStructureElement<T>> elements;
     private final Map<String, String> shapes;
-    private final Map<String, IStructureElement<? super T>[]> structures;
+    private final Map<String, IStructureElement<T>[]> structures;
     private final Map<String, Set<Vec3Impl>> occupiedSpaces;
 
     public static <B> Builder<B> builder() {
         return new Builder<>();
     }
 
-    private StructureDefinition(Map<Character, IStructureElement<? super T>> elements, Map<String, String> shapes,
+    private StructureDefinition(Map<Character, IStructureElement<T>> elements, Map<String, String> shapes,
-            Map<String, IStructureElement<? super T>[]> structures, Map<String, Set<Vec3Impl>> occupiedSpaces) {
+            Map<String, IStructureElement<T>[]> structures, Map<String, Set<Vec3Impl>> occupiedSpaces) {
         this.elements = elements;
         this.shapes = shapes;
         this.structures = structures;
@@ -40,7 +40,7 @@ public class StructureDefinition<T> implements IStructureDefinition<T> {
         private static final char C = '\uC000';
         private char d = '\uD000';
         private final Map<Vec3Impl, Character> navigates;
-        private final Map<Character, IStructureElement<? super T>> elements;
+        private final Map<Character, IStructureElement<T>> elements;
         private final Map<String, String> shapes;
         private final Map<String, Set<Vec3Impl>> occupiedSpaces;
 
@@ -51,7 +51,7 @@ public class StructureDefinition<T> implements IStructureDefinition<T> {
             occupiedSpaces = new HashMap<>();
         }
 
-        public Map<Character, IStructureElement<? super T>> getElements() {
+        public Map<Character, IStructureElement<T>> getElements() {
             return elements;
         }
 
@@ -181,18 +181,18 @@ public class StructureDefinition<T> implements IStructureDefinition<T> {
          * @deprecated use the unboxed version
          */
         @Deprecated
-        public Builder<T> addElement(Character name, IStructureElement<? super T> structurePiece) {
+        public Builder<T> addElement(Character name, IStructureElement<T> structurePiece) {
             elements.putIfAbsent(name, structurePiece);
             return this;
         }
 
-        public Builder<T> addElement(char name, IStructureElement<? super T> structurePiece) {
+        public Builder<T> addElement(char name, IStructureElement<T> structurePiece) {
             elements.putIfAbsent(name, structurePiece);
             return this;
         }
 
         public IStructureDefinition<T> build() {
-            Map<String, IStructureElement<? super T>[]> structures = compileStructureMap();
+            Map<String, IStructureElement<T>[]> structures = compileStructureMap();
             return new StructureDefinition<>(
                     new HashMap<>(elements),
                     new HashMap<>(shapes),
@@ -201,7 +201,7 @@ public class StructureDefinition<T> implements IStructureDefinition<T> {
         }
 
         @SuppressWarnings("unchecked")
-        private Map<String, IStructureElement<? super T>[]> compileElementSetMap() {
+        private Map<String, IStructureElement<T>[]> compileElementSetMap() {
             Set<Integer> missing = findMissing();
             if (missing.isEmpty()) {
                 return shapes.entrySet().stream().collect(
@@ -217,7 +217,7 @@ public class StructureDefinition<T> implements IStructureDefinition<T> {
         }
 
         @SuppressWarnings("unchecked")
-        private Map<String, IStructureElement<? super T>[]> compileStructureMap() {
+        private Map<String, IStructureElement<T>[]> compileStructureMap() {
             Set<Integer> missing = findMissing();
             if (missing.isEmpty()) {
                 return shapes.entrySet().stream().collect(
@@ -238,7 +238,7 @@ public class StructureDefinition<T> implements IStructureDefinition<T> {
         }
     }
 
-    public Map<Character, IStructureElement<? super T>> getElements() {
+    public Map<Character, IStructureElement<T>> getElements() {
         return elements;
     }
 
@@ -246,13 +246,13 @@ public class StructureDefinition<T> implements IStructureDefinition<T> {
         return shapes;
     }
 
-    public Map<String, IStructureElement<? super T>[]> getStructures() {
+    public Map<String, IStructureElement<T>[]> getStructures() {
         return structures;
     }
 
     @Override
-    public IStructureElement<? super T>[] getStructureFor(String name) {
+    public IStructureElement<T>[] getStructureFor(String name) {
-        IStructureElement<? super T>[] elements = structures.get(name);
+        IStructureElement<T>[] elements = structures.get(name);
         if (elements == null) throw new NoSuchElementException(name);
         return elements;
     }

src/main/java/com/gtnewhorizon/structurelib/structure/SurvivalBuildStructureWalker.java

@@ -37,7 +37,7 @@ class SurvivalBuildStructureWalker<T> implements IStructureWalker<T> {
     }
 
     @Override
-    public boolean visit(IStructureElement<? super T> element, World world, int x, int y, int z, int a, int b, int c) {
+    public boolean visit(IStructureElement<T> element, World world, int x, int y, int z, int a, int b, int c) {
         env.offsetABC[0] = a;
         env.offsetABC[1] = b;
         env.offsetABC[2] = c;

src/main/java/com/gtnewhorizon/structurelib/util/SortedRegistry.java

@@ -0,0 +1,64 @@
+package com.gtnewhorizon.structurelib.util;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NavigableMap;
+import java.util.Spliterator;
+import java.util.TreeMap;
+import java.util.function.Consumer;
+
+public class SortedRegistry<V> implements Iterable<V> {
+
+    private final NavigableMap<String, V> store = new TreeMap<>();
+    /**
+     * Store stuff in an array for faster iteration access than a red black tree
+     */
+    private List<V> baked = Collections.emptyList();
+
+    public void register(String key, V val) {
+        if (key == null || val == null) throw new NullPointerException();
+        V old = store.putIfAbsent(key, val);
+        if (old != null) {
+            throw new IllegalArgumentException("Duplicate key: " + key);
+        }
+        // TODO allow a user to edit the order with a configuration file
+        baked = new ArrayList<>(store.values());
+    }
+
+    public int size() {
+        return store.size();
+    }
+
+    public boolean isEmpty() {
+        return store.isEmpty();
+    }
+
+    public boolean containsKey(String key) {
+        return store.containsKey(key);
+    }
+
+    public boolean containsValue(V value) {
+        return store.containsValue(value);
+    }
+
+    public V get(String key) {
+        return store.get(key);
+    }
+
+    @Override
+    public Iterator<V> iterator() {
+        return baked.iterator();
+    }
+
+    @Override
+    public void forEach(Consumer<? super V> action) {
+        baked.forEach(action);
+    }
+
+    @Override
+    public Spliterator<V> spliterator() {
+        return baked.spliterator();
+    }
+}

src/main/resources/assets/structurelib/lang/en_US.lang

@@ -44,7 +44,11 @@ item.structurelib.constructableTrigger.gui.info=Many multiblocks support some de
 channels.structurelib.show_errors=When set, will highlight parts of the multiblock that is definitely wrong
 
 structurelib.tooltip.channelvalue=§7Value §b%d§r§7 for subchannel §b%s
-structurelib.tooltip.indicator_dnd=Drop into GUI to select this value for this channel
+structurelib.tooltip.indicator_dnd=Drop into GUI or middle-click to select this value for this channel
+structurelib.pickchannel.success=§aSet §b%s§r§a to §b%d§r
+structurelib.pickchannel.cleared=§aAll channels cleared§r
+structurelib.pickchannel.confirmwipe=§6Sneak+Middle-click again to clear all channels
+structurelib.pickchannel.nomapping=§cNo channel mapping found for this item
 
 structurelib.autoplace.built_stat=Built %s blocks
 structurelib.autoplace.complete=§aThis multiblock has completed!