Start with no recipes and unlock them as you discover spells

src/main/java/com/minelittlepony/unicopia/container/SpellbookScreen.java

@@ -3,6 +3,7 @@ package com.minelittlepony.unicopia.container;
 import com.minelittlepony.common.client.gui.IViewRoot;
 import com.minelittlepony.common.client.gui.ScrollContainer;
 import com.minelittlepony.common.client.gui.element.Button;
+import com.minelittlepony.common.client.gui.element.Label;
 import com.minelittlepony.common.client.gui.sprite.TextureSprite;
 import com.minelittlepony.unicopia.ability.magic.spell.crafting.SpellbookRecipe;
 import com.minelittlepony.unicopia.ability.magic.spell.trait.Trait;
@@ -15,6 +16,8 @@ import com.mojang.blaze3d.platform.GlStateManager;
 import com.mojang.blaze3d.systems.RenderSystem;
 
 import net.minecraft.client.gui.screen.ingame.HandledScreen;
+import net.minecraft.client.gui.screen.recipebook.RecipeBookProvider;
+import net.minecraft.client.gui.screen.recipebook.RecipeBookWidget;
 import net.minecraft.client.render.GameRenderer;
 import net.minecraft.client.util.math.MatrixStack;
 import net.minecraft.entity.player.PlayerInventory;
@@ -23,10 +26,12 @@ import net.minecraft.text.Text;
 import net.minecraft.text.TranslatableText;
 import net.minecraft.util.Identifier;
 
-public class SpellbookScreen extends HandledScreen<SpellbookScreenHandler> {
+public class SpellbookScreen extends HandledScreen<SpellbookScreenHandler> implements RecipeBookProvider {
     public static final Identifier TEXTURE = new Identifier("unicopia", "textures/gui/container/book.png");
     public static final Identifier SLOT = new Identifier("unicopia", "textures/gui/container/slot.png");
 
+    private final RecipeBookWidget recipeBook = new RecipeBookWidget();
+
     private final ScrollContainer container = new ScrollContainer() {
         {
             backgroundColor = 0xFFf9efd3;
@@ -89,6 +94,18 @@ public class SpellbookScreen extends HandledScreen<SpellbookScreenHandler> {
         addDrawableChild(new PageButton(x + 350, y + 187, 1));
         addDrawableChild(new PageButton(x + 300, y + 187, -1));
         container.init(this::initPageContent);
+        addDrawable(container);
+        ((IViewRoot)this).getChildElements().add(container);
+    }
+
+    @Override
+    public void refreshRecipeBook() {
+        container.init(this::initPageContent);
+    }
+
+    @Override
+    public RecipeBookWidget getRecipeBookWidget() {
+        return recipeBook;
     }
 
     @Override
@@ -147,8 +164,6 @@ public class SpellbookScreen extends HandledScreen<SpellbookScreenHandler> {
     private void initPageContent() {
         container.getContentPadding().setVertical(10);
         container.getContentPadding().bottom = 30;
-        addDrawable(container);
-        ((IViewRoot)this).getChildElements().add(container);
 
         switch (SpellbookPage.getCurrent()) {
             case DISCOVERIES: {
@@ -173,6 +188,7 @@ public class SpellbookScreen extends HandledScreen<SpellbookScreenHandler> {
             case RECIPES:
                 int top = 0;
                 for (SpellbookRecipe recipe : this.client.world.getRecipeManager().listAllOfType(URecipes.SPELLBOOK)) {
+                    if (client.player.getRecipeBook().contains(recipe)) {
                         IngredientTree tree = new IngredientTree(0, top,
                                 container.width - container.scrollbar.getBounds().width + 2,
                                 20);
@@ -180,6 +196,10 @@ public class SpellbookScreen extends HandledScreen<SpellbookScreenHandler> {
                         top += tree.build(container);
                     }
                 }
+                if (top == 0) {
+                    container.addButton(new Label(container.width / 2, 0).setCentered()).getStyle().setText("gui.unicopia.spellbook.page.recipes.empty");
+                }
+        }
     }
 
     @Override

src/main/java/com/minelittlepony/unicopia/container/SpellbookScreenHandler.java

@@ -7,7 +7,6 @@ import com.minelittlepony.unicopia.EquinePredicates;
 import com.minelittlepony.unicopia.USounds;
 import com.minelittlepony.unicopia.ability.magic.spell.trait.SpellTraits;
 import com.minelittlepony.unicopia.entity.player.Pony;
-import com.minelittlepony.unicopia.item.UItems;
 import com.minelittlepony.unicopia.item.URecipes;
 import com.minelittlepony.unicopia.util.InventoryUtil;
 import com.mojang.datafixers.util.Pair;
@@ -132,6 +131,10 @@ public class SpellbookScreenHandler extends ScreenHandler {
         onContentChanged(input);
     }
 
+    public int getOutputSlotId() {
+        return outputSlot.id;
+    }
+
     @Override
     public boolean canUse(PlayerEntity player) {
         return EquinePredicates.IS_CASTER.test(player);
@@ -139,6 +142,7 @@ public class SpellbookScreenHandler extends ScreenHandler {
 
     @Override
     public void onContentChanged(Inventory inventory) {
+        super.onContentChanged(inventory);
         context.run((world, pos) -> {
             if (!world.isClient && !gemSlot.getStack().isEmpty()) {
                 outputSlot.setStack(
@@ -410,7 +414,7 @@ public class SpellbookScreenHandler extends ScreenHandler {
         }
     }
 
-    public static class ResultSlot extends CraftingResultSlot implements SpellbookSlot {
+    public class ResultSlot extends CraftingResultSlot implements SpellbookSlot {
         private final PlayerEntity player;
         private final SpellbookInventory input;
 
@@ -423,11 +427,6 @@ public class SpellbookScreenHandler extends ScreenHandler {
             this.ring = params[2];
         }
 
-        @Override
-        public boolean canInsert(ItemStack stack) {
-            return stack.getItem() == UItems.GEMSTONE;
-        }
-
         @Override
         public void setStack(ItemStack stack) {
             super.setStack(stack);

src/main/resources/assets/unicopia/lang/en_us.json

@@ -298,6 +298,7 @@
   "gui.unicopia.spellbook.page.inventory": "Inventory",
   "gui.unicopia.spellbook.page.discoveries": "Discoveries",
   "gui.unicopia.spellbook.page.recipes": "Recipes",
+  "gui.unicopia.spellbook.page.recipes.empty": "0 Recipes Unlocked",
 
   "gui.unicopia.action.spells_cleared": "Removed all spells",
   "gui.unicopia.action.no_spells_cleared": "You have no active spells",