Split some textures into sprite sheets

- Split buttons.png into individual textures.
 - Split corners_xyz.png into the following:

   - borders_xyz.png: A nine-sliced texture of the computer borders.
   - pocket_bottom_xyz.png: A horizontally 3-sliced texture of the
     bottom part of a pocket computer.
   - sidebar_xyz.png: A vertically 3-sliced texture of the computer
     sidebar.

While not splitting the sliced textures into smaller ones may seem a
little odd, it's consistent with what vanilla does in 1.20.2, and I
think will make editing them easier than juggling 9 textures.

I do want to make this more data-driven in the future, but that will
have to wait until the changes in 1.20.2.

This also adds a tools/update-resources.py program, which performs this
transformation on a given resource pack.

projects/common/src/client/java/dan200/computercraft/client/ClientRegistry.java

@@ -21,6 +21,7 @@
 import dan200.computercraft.shared.computer.inventory.ViewComputerMenu;
 import dan200.computercraft.shared.media.items.DiskItem;
 import dan200.computercraft.shared.media.items.TreasureDiskItem;
+import net.minecraft.client.Minecraft;
 import net.minecraft.client.color.item.ItemColor;
 import net.minecraft.client.gui.screens.MenuScreens;
 import net.minecraft.client.multiplayer.ClientLevel;
@@ -30,6 +31,7 @@
 import net.minecraft.client.renderer.item.ClampedItemPropertyFunction;
 import net.minecraft.client.renderer.item.ItemProperties;
 import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.resources.PreparableReloadListener;
 import net.minecraft.server.packs.resources.ResourceProvider;
 import net.minecraft.world.entity.LivingEntity;
 import net.minecraft.world.item.Item;
@@ -107,6 +109,10 @@ private static void registerItemProperty(String name, ClampedItemPropertyFunctio
         for (var item : items) ItemProperties.register(item.get(), id, getter);
     }
 
+    public static void registerReloadListeners(Consumer<PreparableReloadListener> register, Minecraft minecraft) {
+        register.accept(GuiSprites.initialise(minecraft.getTextureManager()));
+    }
+
     private static final String[] EXTRA_MODELS = new String[]{
         "block/turtle_colour",
         "block/turtle_elf_overlay",

projects/common/src/client/java/dan200/computercraft/client/gui/ComputerScreen.java

@@ -5,15 +5,18 @@
 package dan200.computercraft.client.gui;
 
 import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.blaze3d.vertex.Tesselator;
 import dan200.computercraft.client.gui.widgets.ComputerSidebar;
 import dan200.computercraft.client.gui.widgets.TerminalWidget;
 import dan200.computercraft.client.render.ComputerBorderRenderer;
+import dan200.computercraft.client.render.RenderTypes;
+import dan200.computercraft.client.render.SpriteRenderer;
 import dan200.computercraft.shared.computer.inventory.AbstractComputerMenu;
+import net.minecraft.client.renderer.MultiBufferSource;
 import net.minecraft.network.chat.Component;
 import net.minecraft.world.entity.player.Inventory;
 
 import static dan200.computercraft.client.render.ComputerBorderRenderer.BORDER;
-import static dan200.computercraft.client.render.RenderTypes.FULL_BRIGHT_LIGHTMAP;
 
 /**
  * A GUI for computers which renders the terminal (and border), but with no UI elements.
@@ -39,10 +42,16 @@ protected TerminalWidget createTerminal() {
     public void renderBg(PoseStack stack, float partialTicks, int mouseX, int mouseY) {
         // Draw a border around the terminal
         var terminal = getTerminal();
+        var buffers = MultiBufferSource.immediate(Tesselator.getInstance().getBuilder());
+
+        var spriteRenderer = SpriteRenderer.createForGui(stack, buffers.getBuffer(RenderTypes.GUI_SPRITES));
+        var computerTextures = GuiSprites.getComputerTextures(family);
+
         ComputerBorderRenderer.render(
-            stack.last().pose(), ComputerBorderRenderer.getTexture(family), terminal.getX(), terminal.getY(),
-            FULL_BRIGHT_LIGHTMAP, terminal.getWidth(), terminal.getHeight()
+            spriteRenderer, computerTextures,
+            terminal.getX(), terminal.getY(), terminal.getWidth(), terminal.getHeight(), false
         );
-        ComputerSidebar.renderBackground(stack, leftPos, topPos + sidebarYOffset);
+        ComputerSidebar.renderBackground(spriteRenderer, computerTextures, leftPos, topPos + sidebarYOffset);
+        buffers.endBatch();
     }
 }

projects/common/src/client/java/dan200/computercraft/client/gui/GuiSprites.java

@@ -0,0 +1,127 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.client.gui;
+
+import dan200.computercraft.api.ComputerCraftAPI;
+import dan200.computercraft.client.render.ComputerBorderRenderer;
+import dan200.computercraft.data.client.ClientDataProviders;
+import dan200.computercraft.shared.computer.core.ComputerFamily;
+import net.minecraft.client.renderer.texture.TextureAtlasSprite;
+import net.minecraft.client.renderer.texture.TextureManager;
+import net.minecraft.client.resources.TextureAtlasHolder;
+import net.minecraft.resources.ResourceLocation;
+
+import javax.annotation.Nullable;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+/**
+ * Sprite sheet for all GUI texutres in the mod.
+ */
+public final class GuiSprites extends TextureAtlasHolder {
+    public static final ResourceLocation SPRITE_SHEET = new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui");
+    public static final ResourceLocation TEXTURE = SPRITE_SHEET.withPath(x -> "textures/atlas/" + x + ".png");
+
+    public static final ButtonTextures TURNED_OFF = button("turned_off");
+    public static final ButtonTextures TURNED_ON = button("turned_on");
+    public static final ButtonTextures TERMINATE = button("terminate");
+
+    public static final ComputerTextures COMPUTER_NORMAL = computer("normal", true, true);
+    public static final ComputerTextures COMPUTER_ADVANCED = computer("advanced", true, true);
+    public static final ComputerTextures COMPUTER_COMMAND = computer("command", false, true);
+    public static final ComputerTextures COMPUTER_COLOUR = computer("colour", true, false);
+
+    private static ButtonTextures button(String name) {
+        return new ButtonTextures(
+            new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/buttons/" + name),
+            new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/buttons/" + name + "_hover")
+        );
+    }
+
+    private static ComputerTextures computer(String name, boolean pocket, boolean sidebar) {
+        return new ComputerTextures(
+            new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/border_" + name),
+            pocket ? new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/pocket_bottom_" + name) : null,
+            sidebar ? new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/sidebar_" + name) : null
+        );
+    }
+
+    private static @Nullable GuiSprites instance;
+
+    private GuiSprites(TextureManager textureManager) {
+        super(textureManager, TEXTURE, SPRITE_SHEET);
+    }
+
+    /**
+     * Initialise the singleton {@link GuiSprites} instance.
+     *
+     * @param textureManager The current texture manager.
+     * @return The singleton {@link GuiSprites} instance, to register as resource reload listener.
+     */
+    public static GuiSprites initialise(TextureManager textureManager) {
+        if (instance != null) throw new IllegalStateException("GuiSprites has already been initialised");
+        return instance = new GuiSprites(textureManager);
+    }
+
+    /**
+     * Lookup a texture on the atlas.
+     *
+     * @param texture The texture to find.
+     * @return The sprite on the atlas.
+     */
+    public static TextureAtlasSprite get(ResourceLocation texture) {
+        if (instance == null) throw new IllegalStateException("GuiSprites has not been initialised");
+        return instance.getSprite(texture);
+    }
+
+    /**
+     * Get the appropriate textures to use for a particular computer family.
+     *
+     * @param family The computer family.
+     * @return The family-specific textures.
+     */
+    public static ComputerTextures getComputerTextures(ComputerFamily family) {
+        return switch (family) {
+            case NORMAL -> COMPUTER_NORMAL;
+            case ADVANCED -> COMPUTER_ADVANCED;
+            case COMMAND -> COMPUTER_COMMAND;
+        };
+    }
+
+    /**
+     * A set of sprites for a button, with both a normal and "active" state.
+     *
+     * @param normal The normal texture for the button.
+     * @param active The texture for the button when it is active (hovered or focused).
+     */
+    public record ButtonTextures(ResourceLocation normal, ResourceLocation active) {
+        public TextureAtlasSprite get(boolean active) {
+            return GuiSprites.get(active ? this.active : normal);
+        }
+
+        public Stream<ResourceLocation> textures() {
+            return Stream.of(normal, active);
+        }
+    }
+
+    /**
+     * Set the set of sprites for a computer family.
+     *
+     * @param border       The texture for the computer's border.
+     * @param pocketBottom The texture for the bottom of a pocket computer.
+     * @param sidebar      The texture for the computer sidebar.
+     * @see ComputerBorderRenderer
+     * @see ClientDataProviders
+     */
+    public record ComputerTextures(
+        ResourceLocation border,
+        @Nullable ResourceLocation pocketBottom,
+        @Nullable ResourceLocation sidebar
+    ) {
+        public Stream<ResourceLocation> textures() {
+            return Stream.of(border, pocketBottom, sidebar).filter(Objects::nonNull);
+        }
+    }
+}

projects/common/src/client/java/dan200/computercraft/client/gui/TurtleScreen.java

@@ -6,13 +6,16 @@
 
 import com.mojang.blaze3d.systems.RenderSystem;
 import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.blaze3d.vertex.Tesselator;
 import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.client.gui.widgets.ComputerSidebar;
 import dan200.computercraft.client.gui.widgets.TerminalWidget;
-import dan200.computercraft.client.render.ComputerBorderRenderer;
+import dan200.computercraft.client.render.RenderTypes;
+import dan200.computercraft.client.render.SpriteRenderer;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
 import dan200.computercraft.shared.computer.inventory.AbstractComputerMenu;
 import dan200.computercraft.shared.turtle.inventory.TurtleMenu;
+import net.minecraft.client.renderer.MultiBufferSource;
 import net.minecraft.network.chat.Component;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.player.Inventory;
@@ -60,7 +63,10 @@ protected void renderBg(PoseStack transform, float partialTicks, int mouseX, int
             );
         }
 
-        RenderSystem.setShaderTexture(0, advanced ? ComputerBorderRenderer.BACKGROUND_ADVANCED : ComputerBorderRenderer.BACKGROUND_NORMAL);
-        ComputerSidebar.renderBackground(transform, leftPos, topPos + sidebarYOffset);
+        // Render sidebar
+        var buffers = MultiBufferSource.immediate(Tesselator.getInstance().getBuilder());
+        var spriteRenderer = SpriteRenderer.createForGui(transform, buffers.getBuffer(RenderTypes.GUI_SPRITES));
+        ComputerSidebar.renderBackground(spriteRenderer, GuiSprites.getComputerTextures(family), leftPos, topPos + sidebarYOffset);
+        buffers.endBatch();
     }
 }

projects/common/src/client/java/dan200/computercraft/client/gui/widgets/ComputerSidebar.java

@@ -4,16 +4,13 @@
 
 package dan200.computercraft.client.gui.widgets;
 
-import com.mojang.blaze3d.vertex.PoseStack;
-import dan200.computercraft.api.ComputerCraftAPI;
+import dan200.computercraft.client.gui.GuiSprites;
 import dan200.computercraft.client.gui.widgets.DynamicImageButton.HintedMessage;
-import dan200.computercraft.client.render.ComputerBorderRenderer;
+import dan200.computercraft.client.render.SpriteRenderer;
 import dan200.computercraft.shared.computer.core.InputHandler;
 import dan200.computercraft.shared.computer.inventory.AbstractComputerMenu;
 import net.minecraft.client.gui.components.AbstractWidget;
-import net.minecraft.client.gui.screens.Screen;
 import net.minecraft.network.chat.Component;
-import net.minecraft.resources.ResourceLocation;
 
 import java.util.function.BooleanSupplier;
 import java.util.function.Consumer;
@@ -22,22 +19,18 @@
  * Registers buttons to interact with a computer.
  */
 public final class ComputerSidebar {
-    private static final ResourceLocation TEXTURE = new ResourceLocation(ComputerCraftAPI.MOD_ID, "textures/gui/buttons.png");
-
-    private static final int TEX_SIZE = 64;
-
     private static final int ICON_WIDTH = 12;
     private static final int ICON_HEIGHT = 12;
     private static final int ICON_MARGIN = 2;
 
-    private static final int ICON_TEX_Y_DIFF = 14;
-
     private static final int CORNERS_BORDER = 3;
     private static final int FULL_BORDER = CORNERS_BORDER + ICON_MARGIN;
 
     private static final int BUTTONS = 2;
     private static final int HEIGHT = (ICON_HEIGHT + ICON_MARGIN * 2) * BUTTONS + CORNERS_BORDER * 2;
 
+    private static final int TEX_HEIGHT = 14;
+
     private ComputerSidebar() {
     }
 
@@ -51,16 +44,18 @@ public static void addButtons(BooleanSupplier isOn, InputHandler input, Consumer
             Component.translatable("gui.computercraft.tooltip.turn_off.key")
         );
         add.accept(new DynamicImageButton(
-            x, y, ICON_WIDTH, ICON_HEIGHT, () -> isOn.getAsBoolean() ? 15 : 1, 1, ICON_TEX_Y_DIFF,
-            TEXTURE, TEX_SIZE, TEX_SIZE, b -> toggleComputer(isOn, input),
+            x, y, ICON_WIDTH, ICON_HEIGHT,
+            h -> isOn.getAsBoolean() ? GuiSprites.TURNED_ON.get(h) : GuiSprites.TURNED_OFF.get(h),
+            b -> toggleComputer(isOn, input),
             () -> isOn.getAsBoolean() ? turnOff : turnOn
         ));
 
         y += ICON_HEIGHT + ICON_MARGIN * 2;
 
         add.accept(new DynamicImageButton(
-            x, y, ICON_WIDTH, ICON_HEIGHT, 29, 1, ICON_TEX_Y_DIFF,
-            TEXTURE, TEX_SIZE, TEX_SIZE, b -> input.queueEvent("terminate"),
+            x, y, ICON_WIDTH, ICON_HEIGHT,
+            GuiSprites.TERMINATE::get,
+            b -> input.queueEvent("terminate"),
             new HintedMessage(
                 Component.translatable("gui.computercraft.tooltip.terminate"),
                 Component.translatable("gui.computercraft.tooltip.terminate.key")
@@ -68,22 +63,12 @@ public static void addButtons(BooleanSupplier isOn, InputHandler input, Consumer
         ));
     }
 
-    public static void renderBackground(PoseStack transform, int x, int y) {
-        Screen.blit(transform,
-            x, y, 0, 102, AbstractComputerMenu.SIDEBAR_WIDTH, FULL_BORDER,
-            ComputerBorderRenderer.TEX_SIZE, ComputerBorderRenderer.TEX_SIZE
-        );
+    public static void renderBackground(SpriteRenderer renderer, GuiSprites.ComputerTextures textures, int x, int y) {
+        var texture = textures.sidebar();
+        if (texture == null) throw new NullPointerException(textures + " has no sidebar texture");
+        var sprite = GuiSprites.get(texture);
 
-        Screen.blit(transform,
-            x, y + FULL_BORDER, AbstractComputerMenu.SIDEBAR_WIDTH, HEIGHT - FULL_BORDER * 2,
-            0, 107, AbstractComputerMenu.SIDEBAR_WIDTH, 4,
-            ComputerBorderRenderer.TEX_SIZE, ComputerBorderRenderer.TEX_SIZE
-        );
-
-        Screen.blit(transform,
-            x, y + HEIGHT - FULL_BORDER, 0, 111, AbstractComputerMenu.SIDEBAR_WIDTH, FULL_BORDER,
-            ComputerBorderRenderer.TEX_SIZE, ComputerBorderRenderer.TEX_SIZE
-        );
+        renderer.blitVerticalSliced(sprite, x, y, AbstractComputerMenu.SIDEBAR_WIDTH, HEIGHT, FULL_BORDER, FULL_BORDER, TEX_HEIGHT);
     }
 
     private static void toggleComputer(BooleanSupplier isOn, InputHandler input) {

projects/common/src/client/java/dan200/computercraft/client/gui/widgets/DynamicImageButton.java

@@ -6,14 +6,14 @@
 
 import com.mojang.blaze3d.systems.RenderSystem;
 import com.mojang.blaze3d.vertex.PoseStack;
+import it.unimi.dsi.fastutil.booleans.Boolean2ObjectFunction;
 import net.minecraft.ChatFormatting;
 import net.minecraft.client.gui.components.Button;
 import net.minecraft.client.gui.components.Tooltip;
+import net.minecraft.client.renderer.texture.TextureAtlasSprite;
 import net.minecraft.network.chat.Component;
-import net.minecraft.resources.ResourceLocation;
 
 import javax.annotation.Nullable;
-import java.util.function.IntSupplier;
 import java.util.function.Supplier;
 
 /**
@@ -21,50 +21,33 @@
  * dynamically.
  */
 public class DynamicImageButton extends Button {
-    private final ResourceLocation texture;
-    private final IntSupplier xTexStart;
-    private final int yTexStart;
-    private final int yDiffTex;
-    private final int textureWidth;
-    private final int textureHeight;
+    private final Boolean2ObjectFunction<TextureAtlasSprite> texture;
     private final Supplier<HintedMessage> message;
 
     public DynamicImageButton(
-        int x, int y, int width, int height, int xTexStart, int yTexStart, int yDiffTex,
-        ResourceLocation texture, int textureWidth, int textureHeight,
-        OnPress onPress, HintedMessage message
+        int x, int y, int width, int height, Boolean2ObjectFunction<TextureAtlasSprite> texture, OnPress onPress,
+        HintedMessage message
     ) {
-        this(
-            x, y, width, height, () -> xTexStart, yTexStart, yDiffTex,
-            texture, textureWidth, textureHeight,
-            onPress, () -> message
-        );
+        this(x, y, width, height, texture, onPress, () -> message);
     }
 
     public DynamicImageButton(
-        int x, int y, int width, int height, IntSupplier xTexStart, int yTexStart, int yDiffTex,
-        ResourceLocation texture, int textureWidth, int textureHeight,
+        int x, int y, int width, int height,
+        Boolean2ObjectFunction<TextureAtlasSprite> texture,
         OnPress onPress, Supplier<HintedMessage> message
     ) {
         super(x, y, width, height, Component.empty(), onPress, DEFAULT_NARRATION);
-        this.textureWidth = textureWidth;
-        this.textureHeight = textureHeight;
-        this.xTexStart = xTexStart;
-        this.yTexStart = yTexStart;
-        this.yDiffTex = yDiffTex;
         this.texture = texture;
         this.message = message;
     }
 
     @Override
     public void renderWidget(PoseStack stack, int mouseX, int mouseY, float partialTicks) {
-        RenderSystem.setShaderTexture(0, texture);
+        var texture = this.texture.get(isHoveredOrFocused());
+        RenderSystem.setShaderTexture(0, texture.atlasLocation());
         RenderSystem.disableDepthTest();
 
-        var yTex = yTexStart;
-        if (isHoveredOrFocused()) yTex += yDiffTex;
-
-        blit(stack, getX(), getY(), xTexStart.getAsInt(), yTex, width, height, textureWidth, textureHeight);
+        blit(stack, getX(), getY(), 0, width, height, texture);
         RenderSystem.enableDepthTest();
     }
 

projects/common/src/client/java/dan200/computercraft/client/render/ComputerBorderRenderer.java

@@ -4,25 +4,17 @@
 
 package dan200.computercraft.client.render;
 
-import com.mojang.blaze3d.vertex.Tesselator;
-import com.mojang.blaze3d.vertex.VertexConsumer;
-import dan200.computercraft.api.ComputerCraftAPI;
-import dan200.computercraft.shared.computer.core.ComputerFamily;
-import net.minecraft.client.renderer.MultiBufferSource;
-import net.minecraft.client.renderer.RenderType;
-import net.minecraft.resources.ResourceLocation;
-import org.joml.Matrix4f;
+import dan200.computercraft.client.gui.GuiSprites;
+import net.minecraft.client.renderer.texture.TextureAtlasSprite;
+
+import static dan200.computercraft.client.render.SpriteRenderer.u;
+import static dan200.computercraft.client.render.SpriteRenderer.v;
 
 /**
  * Renders the borders of computers, either for a GUI ({@link dan200.computercraft.client.gui.ComputerScreen}) or
  * {@linkplain PocketItemRenderer in-hand pocket computers}.
  */
-public class ComputerBorderRenderer {
-    public static final ResourceLocation BACKGROUND_NORMAL = new ResourceLocation(ComputerCraftAPI.MOD_ID, "textures/gui/corners_normal.png");
-    public static final ResourceLocation BACKGROUND_ADVANCED = new ResourceLocation(ComputerCraftAPI.MOD_ID, "textures/gui/corners_advanced.png");
-    public static final ResourceLocation BACKGROUND_COMMAND = new ResourceLocation(ComputerCraftAPI.MOD_ID, "textures/gui/corners_command.png");
-    public static final ResourceLocation BACKGROUND_COLOUR = new ResourceLocation(ComputerCraftAPI.MOD_ID, "textures/gui/corners_colour.png");
-
+public final class ComputerBorderRenderer {
     /**
      * The margin between the terminal and its border.
      */
@@ -33,100 +25,51 @@ public class ComputerBorderRenderer {
      */
     public static final int BORDER = 12;
 
-    private static final int CORNER_TOP_Y = 28;
-    private static final int CORNER_BOTTOM_Y = CORNER_TOP_Y + BORDER;
-    private static final int CORNER_LEFT_X = BORDER;
-    private static final int CORNER_RIGHT_X = CORNER_LEFT_X + BORDER;
-    private static final int BORDER_RIGHT_X = 36;
-    private static final int LIGHT_BORDER_Y = 56;
-    private static final int LIGHT_CORNER_Y = 80;
-
     public static final int LIGHT_HEIGHT = 8;
 
-    public static final int TEX_SIZE = 256;
-    private static final float TEX_SCALE = 1 / (float) TEX_SIZE;
+    private static final int TEX_SIZE = 36;
 
-    private final Matrix4f transform;
-    private final VertexConsumer builder;
-    private final int light;
-    private final int z;
-    private final float r, g, b;
-
-    public ComputerBorderRenderer(Matrix4f transform, VertexConsumer builder, int z, int light, float r, float g, float b) {
-        this.transform = transform;
-        this.builder = builder;
-        this.z = z;
-        this.light = light;
-        this.r = r;
-        this.g = g;
-        this.b = b;
+    private ComputerBorderRenderer() {
     }
 
-    public static ResourceLocation getTexture(ComputerFamily family) {
-        return switch (family) {
-            case NORMAL -> BACKGROUND_NORMAL;
-            case ADVANCED -> BACKGROUND_ADVANCED;
-            case COMMAND -> BACKGROUND_COMMAND;
-        };
-    }
-
-    public static RenderType getRenderType(ResourceLocation location) {
-        // See note in RenderTypes about why we use text rather than anything intuitive.
-        return RenderType.text(location);
-    }
-
-    public static void render(Matrix4f transform, ResourceLocation location, int x, int y, int light, int width, int height) {
-        var source = MultiBufferSource.immediate(Tesselator.getInstance().getBuilder());
-        render(transform, source.getBuffer(getRenderType(location)), x, y, 1, light, width, height, false, 1, 1, 1);
-        source.endBatch();
-    }
-
-    public static void render(Matrix4f transform, VertexConsumer buffer, int x, int y, int z, int light, int width, int height, boolean withLight, float r, float g, float b) {
-        new ComputerBorderRenderer(transform, buffer, z, light, r, g, b).doRender(x, y, width, height, withLight);
-    }
-
-    public void doRender(int x, int y, int width, int height, boolean withLight) {
+    public static void render(SpriteRenderer renderer, GuiSprites.ComputerTextures textures, int x, int y, int width, int height, boolean withLight) {
         var endX = x + width;
         var endY = y + height;
 
-        // Vertical bars
-        renderLine(x - BORDER, y, 0, CORNER_TOP_Y, BORDER, endY - y);
-        renderLine(endX, y, BORDER_RIGHT_X, CORNER_TOP_Y, BORDER, endY - y);
+        var border = GuiSprites.get(textures.border());
 
         // Top bar
-        renderLine(x, y - BORDER, 0, 0, endX - x, BORDER);
-        renderCorner(x - BORDER, y - BORDER, CORNER_LEFT_X, CORNER_TOP_Y);
-        renderCorner(endX, y - BORDER, CORNER_RIGHT_X, CORNER_TOP_Y);
+        blitBorder(renderer, border, x - BORDER, y - BORDER, 0, 0, BORDER, BORDER);
+        blitBorder(renderer, border, x, y - BORDER, BORDER, 0, width, BORDER);
+        blitBorder(renderer, border, endX, y - BORDER, BORDER * 2, 0, BORDER, BORDER);
+
+        // Vertical bars
+        blitBorder(renderer, border, x - BORDER, y, 0, BORDER, BORDER, height);
+        blitBorder(renderer, border, endX, y, BORDER * 2, BORDER, BORDER, height);
 
         // Bottom bar. We allow for drawing a stretched version, which allows for additional elements (such as the
         // pocket computer's lights).
         if (withLight) {
-            renderTexture(x, endY, 0, LIGHT_BORDER_Y, endX - x, BORDER + LIGHT_HEIGHT, BORDER, BORDER + LIGHT_HEIGHT);
-            renderTexture(x - BORDER, endY, CORNER_LEFT_X, LIGHT_CORNER_Y, BORDER, BORDER + LIGHT_HEIGHT);
-            renderTexture(endX, endY, CORNER_RIGHT_X, LIGHT_CORNER_Y, BORDER, BORDER + LIGHT_HEIGHT);
+            var pocketBottomTexture = textures.pocketBottom();
+            if (pocketBottomTexture == null) throw new NullPointerException(textures + " has no pocket texture");
+            var pocketBottom = GuiSprites.get(pocketBottomTexture);
+
+            renderer.blitHorizontalSliced(
+                pocketBottom, x - BORDER, endY, width + BORDER * 2, BORDER + LIGHT_HEIGHT,
+                BORDER, BORDER, BORDER * 3
+            );
         } else {
-            renderLine(x, endY, 0, BORDER, endX - x, BORDER);
-            renderCorner(x - BORDER, endY, CORNER_LEFT_X, CORNER_BOTTOM_Y);
-            renderCorner(endX, endY, CORNER_RIGHT_X, CORNER_BOTTOM_Y);
+            blitBorder(renderer, border, x - BORDER, endY, 0, BORDER * 2, BORDER, BORDER);
+            blitBorder(renderer, border, x, endY, BORDER, BORDER * 2, width, BORDER);
+            blitBorder(renderer, border, endX, endY, BORDER * 2, BORDER * 2, BORDER, BORDER);
         }
     }
 
-    private void renderCorner(int x, int y, int u, int v) {
-        renderTexture(x, y, u, v, BORDER, BORDER, BORDER, BORDER);
-    }
-
-    private void renderLine(int x, int y, int u, int v, int width, int height) {
-        renderTexture(x, y, u, v, width, height, BORDER, BORDER);
-    }
-
-    private void renderTexture(int x, int y, int u, int v, int width, int height) {
-        renderTexture(x, y, u, v, width, height, width, height);
-    }
-
-    private void renderTexture(int x, int y, int u, int v, int width, int height, int textureWidth, int textureHeight) {
-        builder.vertex(transform, x, y + height, z).color(r, g, b, 1.0f).uv(u * TEX_SCALE, (v + textureHeight) * TEX_SCALE).uv2(light).endVertex();
-        builder.vertex(transform, x + width, y + height, z).color(r, g, b, 1.0f).uv((u + textureWidth) * TEX_SCALE, (v + textureHeight) * TEX_SCALE).uv2(light).endVertex();
-        builder.vertex(transform, x + width, y, z).color(r, g, b, 1.0f).uv((u + textureWidth) * TEX_SCALE, v * TEX_SCALE).uv2(light).endVertex();
-        builder.vertex(transform, x, y, z).color(r, g, b, 1.0f).uv(u * TEX_SCALE, v * TEX_SCALE).uv2(light).endVertex();
+    private static void blitBorder(SpriteRenderer renderer, TextureAtlasSprite sprite, int x, int y, int u, int v, int width, int height) {
+        renderer.blit(
+            x, y, width, height,
+            u(sprite, u, TEX_SIZE), v(sprite, v, TEX_SIZE),
+            u(sprite, u + BORDER, TEX_SIZE), v(sprite, v + BORDER, TEX_SIZE)
+        );
     }
 }

projects/common/src/client/java/dan200/computercraft/client/render/PocketItemRenderer.java

@@ -6,6 +6,7 @@
 
 import com.mojang.blaze3d.vertex.PoseStack;
 import com.mojang.math.Axis;
+import dan200.computercraft.client.gui.GuiSprites;
 import dan200.computercraft.client.pocket.ClientPocketComputers;
 import dan200.computercraft.client.render.text.FixedWidthFontRenderer;
 import dan200.computercraft.core.util.Colour;
@@ -72,13 +73,14 @@ protected void renderItem(PoseStack transform, MultiBufferSource bufferSource, I
     }
 
     private static void renderFrame(Matrix4f transform, MultiBufferSource render, ComputerFamily family, int colour, int light, int width, int height) {
-        var texture = colour != -1 ? ComputerBorderRenderer.BACKGROUND_COLOUR : ComputerBorderRenderer.getTexture(family);
+        var texture = colour != -1 ? GuiSprites.COMPUTER_COLOUR : GuiSprites.getComputerTextures(family);
 
-        var r = ((colour >>> 16) & 0xFF) / 255.0f;
-        var g = ((colour >>> 8) & 0xFF) / 255.0f;
-        var b = (colour & 0xFF) / 255.0f;
+        var r = (colour >>> 16) & 0xFF;
+        var g = (colour >>> 8) & 0xFF;
+        var b = colour & 0xFF;
 
-        ComputerBorderRenderer.render(transform, render.getBuffer(ComputerBorderRenderer.getRenderType(texture)), 0, 0, 0, light, width, height, true, r, g, b);
+        var spriteRenderer = new SpriteRenderer(transform, render.getBuffer(RenderTypes.GUI_SPRITES), 0, light, r, g, b);
+        ComputerBorderRenderer.render(spriteRenderer, texture, 0, 0, width, height, true);
     }
 
     private static void renderLight(PoseStack transform, MultiBufferSource render, int colour, int width, int height) {

projects/common/src/client/java/dan200/computercraft/client/render/RenderTypes.java

@@ -7,6 +7,7 @@
 import com.mojang.blaze3d.vertex.DefaultVertexFormat;
 import com.mojang.blaze3d.vertex.VertexFormat;
 import dan200.computercraft.api.ComputerCraftAPI;
+import dan200.computercraft.client.gui.GuiSprites;
 import dan200.computercraft.client.render.monitor.MonitorTextureBufferShader;
 import dan200.computercraft.client.render.text.FixedWidthFontRenderer;
 import net.minecraft.client.renderer.GameRenderer;
@@ -53,6 +54,11 @@ public class RenderTypes {
      */
     public static final RenderType PRINTOUT_BACKGROUND = RenderType.text(new ResourceLocation("computercraft", "textures/gui/printout.png"));
 
+    /**
+     * Render type for {@linkplain GuiSprites GUI sprites}.
+     */
+    public static final RenderType GUI_SPRITES = RenderType.text(GuiSprites.TEXTURE);
+
     public static MonitorTextureBufferShader getMonitorTextureBufferShader() {
         if (monitorTboShader == null) throw new NullPointerException("MonitorTboShader has not been registered");
         return monitorTboShader;

projects/common/src/client/java/dan200/computercraft/client/render/SpriteRenderer.java

@@ -0,0 +1,131 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.client.render;
+
+import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.blaze3d.vertex.VertexConsumer;
+import net.minecraft.client.gui.GuiComponent;
+import net.minecraft.client.renderer.texture.TextureAtlasSprite;
+import org.joml.Matrix4f;
+
+/**
+ * A {@link GuiComponent}-equivalent which is suitable for both rendering in to a GUI and in-world (as part of an entity
+ * renderer).
+ * <p>
+ * This batches all render calls together, though requires that all {@link TextureAtlasSprite}s are on the same sprite
+ * sheet.
+ */
+public class SpriteRenderer {
+    private final Matrix4f transform;
+    private final VertexConsumer builder;
+    private final int light;
+    private final int z;
+    private final int r, g, b;
+
+    public SpriteRenderer(Matrix4f transform, VertexConsumer builder, int z, int light, int r, int g, int b) {
+        this.transform = transform;
+        this.builder = builder;
+        this.z = z;
+        this.light = light;
+        this.r = r;
+        this.g = g;
+        this.b = b;
+    }
+
+    public static SpriteRenderer createForGui(PoseStack stack, VertexConsumer builder) {
+        return new SpriteRenderer(stack.last().pose(), builder, 0, RenderTypes.FULL_BRIGHT_LIGHTMAP, 255, 255, 255);
+    }
+
+    /**
+     * Render a single sprite.
+     *
+     * @param sprite The texture to draw.
+     * @param x      The x position of the rectangle we'll draw.
+     * @param y      The x position of the rectangle we'll draw.
+     * @param width  The width of the rectangle we'll draw.
+     * @param height The height of the rectangle we'll draw.
+     */
+    public void blit(TextureAtlasSprite sprite, int x, int y, int width, int height) {
+        blit(x, y, width, height, sprite.getU0(), sprite.getV0(), sprite.getU1(), sprite.getV1());
+    }
+
+    /**
+     * Render a horizontal 3-sliced texture (i.e. split into left, middle and right). Unlike {@link GuiComponent#blitNineSliced},
+     * the middle texture is stretched rather than repeated.
+     *
+     * @param sprite       The texture to draw.
+     * @param x            The x position of the rectangle we'll draw.
+     * @param y            The x position of the rectangle we'll draw.
+     * @param width        The width of the rectangle we'll draw.
+     * @param height       The height of the rectangle we'll draw.
+     * @param leftBorder   The width of the left border.
+     * @param rightBorder  The width of the right border.
+     * @param textureWidth The width of the whole texture.
+     */
+    public void blitHorizontalSliced(TextureAtlasSprite sprite, int x, int y, int width, int height, int leftBorder, int rightBorder, int textureWidth) {
+        // TODO(1.20.2)/TODO(1.21.0): Drive this from mcmeta files, like vanilla does.
+        if (width < leftBorder + rightBorder) throw new IllegalArgumentException("width is less than two borders");
+
+        var centerStart = SpriteRenderer.u(sprite, leftBorder, textureWidth);
+        var centerEnd = SpriteRenderer.u(sprite, textureWidth - rightBorder, textureWidth);
+
+        blit(x, y, leftBorder, height, sprite.getU0(), sprite.getV0(), centerStart, sprite.getV1());
+        blit(x + leftBorder, y, width - leftBorder - rightBorder, height, centerStart, sprite.getV0(), centerEnd, sprite.getV1());
+        blit(x + width - rightBorder, y, rightBorder, height, centerEnd, sprite.getV0(), sprite.getU1(), sprite.getV1());
+    }
+
+    /**
+     * Render a vertical 3-sliced texture (i.e. split into top, middle and bottom). Unlike {@link GuiComponent#blitNineSliced},
+     * the middle texture is stretched rather than repeated.
+     *
+     * @param sprite        The texture to draw.
+     * @param x             The x position of the rectangle we'll draw.
+     * @param y             The x position of the rectangle we'll draw.
+     * @param width         The width of the rectangle we'll draw.
+     * @param height        The height of the rectangle we'll draw.
+     * @param topBorder     The height of the top border.
+     * @param bottomBorder  The height of the bottom border.
+     * @param textureHeight The height of the whole texture.
+     */
+    public void blitVerticalSliced(TextureAtlasSprite sprite, int x, int y, int width, int height, int topBorder, int bottomBorder, int textureHeight) {
+        // TODO(1.20.2)/TODO(1.21.0): Drive this from mcmeta files, like vanilla does.
+        if (width < topBorder + bottomBorder) throw new IllegalArgumentException("height is less than two borders");
+
+        var centerStart = SpriteRenderer.v(sprite, topBorder, textureHeight);
+        var centerEnd = SpriteRenderer.v(sprite, textureHeight - bottomBorder, textureHeight);
+
+        blit(x, y, width, topBorder, sprite.getU0(), sprite.getV0(), sprite.getU1(), centerStart);
+        blit(x, y + topBorder, width, height - topBorder - bottomBorder, sprite.getU0(), centerStart, sprite.getU1(), centerEnd);
+        blit(x, y + height - bottomBorder, width, bottomBorder, sprite.getU0(), centerEnd, sprite.getU1(), sprite.getV1());
+    }
+
+    /**
+     * The low-level blit function, used to render a portion of the sprite sheet. Unlike other functions, this takes uvs rather than a single sprite.
+     *
+     * @param x      The x position of the rectangle we'll draw.
+     * @param y      The x position of the rectangle we'll draw.
+     * @param width  The width of the rectangle we'll draw.
+     * @param height The height of the rectangle we'll draw.
+     * @param u0     The first U coordinate.
+     * @param v0     The first V coordinate.
+     * @param u1     The second U coordinate.
+     * @param v1     The second V coordinate.
+     */
+    public void blit(
+        int x, int y, int width, int height, float u0, float v0, float u1, float v1) {
+        builder.vertex(transform, x, y + height, z).color(r, g, b, 255).uv(u0, v1).uv2(light).endVertex();
+        builder.vertex(transform, x + width, y + height, z).color(r, g, b, 255).uv(u1, v1).uv2(light).endVertex();
+        builder.vertex(transform, x + width, y, z).color(r, g, b, 255).uv(u1, v0).uv2(light).endVertex();
+        builder.vertex(transform, x, y, z).color(r, g, b, 255).uv(u0, v0).uv2(light).endVertex();
+    }
+
+    public static float u(TextureAtlasSprite sprite, int x, int width) {
+        return sprite.getU((double) x / width * 16);
+    }
+
+    public static float v(TextureAtlasSprite sprite, int y, int height) {
+        return sprite.getV((double) y / height * 16);
+    }
+}

projects/common/src/client/java/dan200/computercraft/data/client/ClientDataProviders.java

@@ -4,8 +4,10 @@
 
 package dan200.computercraft.data.client;
 
+import dan200.computercraft.client.gui.GuiSprites;
 import dan200.computercraft.data.DataProviders;
 import dan200.computercraft.shared.turtle.inventory.UpgradeSlot;
+import net.minecraft.client.renderer.texture.atlas.SpriteSource;
 import net.minecraft.client.renderer.texture.atlas.SpriteSources;
 import net.minecraft.client.renderer.texture.atlas.sources.SingleFile;
 import net.minecraft.resources.ResourceLocation;
@@ -13,6 +15,7 @@
 
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Stream;
 
 /**
  * A version of {@link DataProviders} which relies on client-side classes.
@@ -29,6 +32,17 @@ public static void add(DataProviders.GeneratorSink generator) {
                 new SingleFile(UpgradeSlot.LEFT_UPGRADE, Optional.empty()),
                 new SingleFile(UpgradeSlot.RIGHT_UPGRADE, Optional.empty())
             ));
+            out.accept(GuiSprites.SPRITE_SHEET, Stream.of(
+                // Buttons
+                GuiSprites.TURNED_OFF.textures(),
+                GuiSprites.TURNED_ON.textures(),
+                GuiSprites.TERMINATE.textures(),
+                // Computers
+                GuiSprites.COMPUTER_NORMAL.textures(),
+                GuiSprites.COMPUTER_ADVANCED.textures(),
+                GuiSprites.COMPUTER_COMMAND.textures(),
+                GuiSprites.COMPUTER_COLOUR.textures()
+            ).flatMap(x -> x).<SpriteSource>map(x -> new SingleFile(x, Optional.empty())).toList());
         });
     }
 }

projects/fabric/src/client/java/dan200/computercraft/mixin/client/MinecraftMixin.java

@@ -5,16 +5,25 @@
 package dan200.computercraft.mixin.client;
 
 import dan200.computercraft.client.ClientHooks;
+import dan200.computercraft.client.ClientRegistry;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.gui.screens.Screen;
+import net.minecraft.client.main.GameConfig;
 import net.minecraft.client.multiplayer.ClientLevel;
+import net.minecraft.server.packs.resources.ReloadableResourceManager;
+import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 @Mixin(Minecraft.class)
 class MinecraftMixin {
+    @Shadow
+    @Final
+    private ReloadableResourceManager resourceManager;
+
     @Inject(method = "clearLevel(Lnet/minecraft/client/gui/screens/Screen;)V", at = @At("HEAD"))
     @SuppressWarnings("UnusedMethod")
     private void clearLevel(Screen screen, CallbackInfo ci) {
@@ -26,4 +35,16 @@ private void clearLevel(Screen screen, CallbackInfo ci) {
     private void setLevel(ClientLevel screen, CallbackInfo ci) {
         ClientHooks.onWorldUnload();
     }
+
+    @Inject(
+        method = "<init>(Lnet/minecraft/client/main/GameConfig;)V",
+        at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/client/ResourceLoadStateTracker;startReload(Lnet/minecraft/client/ResourceLoadStateTracker$ReloadReason;Ljava/util/List;)V",
+            ordinal = 0
+        )
+    )
+    public void beforeInitialResourceReload(GameConfig gameConfig, CallbackInfo ci) {
+        ClientRegistry.registerReloadListeners(resourceManager::registerReloadListener, (Minecraft) (Object) this);
+    }
 }

projects/fabric/src/generated/resources/assets/computercraft/atlases/gui.json

@@ -0,0 +1,20 @@
+{
+  "sources": [
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_off"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_off_hover"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_on"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_on_hover"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/terminate"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/terminate_hover"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_normal"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/pocket_bottom_normal"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/sidebar_normal"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_advanced"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/pocket_bottom_advanced"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/sidebar_advanced"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_command"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/sidebar_command"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_colour"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/pocket_bottom_colour"}
+  ]
+}

projects/forge/src/client/java/dan200/computercraft/client/ForgeClientRegistry.java

@@ -6,8 +6,10 @@
 
 import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.client.model.turtle.TurtleModelLoader;
+import net.minecraft.client.Minecraft;
 import net.minecraftforge.api.distmarker.Dist;
 import net.minecraftforge.client.event.ModelEvent;
+import net.minecraftforge.client.event.RegisterClientReloadListenersEvent;
 import net.minecraftforge.client.event.RegisterColorHandlersEvent;
 import net.minecraftforge.client.event.RegisterShadersEvent;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
@@ -44,6 +46,11 @@ public static void onItemColours(RegisterColorHandlersEvent.Item event) {
         ClientRegistry.registerItemColours(event::register);
     }
 
+    @SubscribeEvent
+    public static void registerReloadListeners(RegisterClientReloadListenersEvent event) {
+        ClientRegistry.registerReloadListeners(event::registerReloadListener, Minecraft.getInstance());
+    }
+
     @SubscribeEvent
     public static void setupClient(FMLClientSetupEvent event) {
         ClientRegistry.register();

projects/forge/src/generated/resources/assets/computercraft/atlases/gui.json

@@ -0,0 +1,20 @@
+{
+  "sources": [
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_off"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_off_hover"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_on"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/turned_on_hover"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/terminate"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/buttons/terminate_hover"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_normal"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/pocket_bottom_normal"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/sidebar_normal"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_advanced"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/pocket_bottom_advanced"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/sidebar_advanced"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_command"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/sidebar_command"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/border_colour"},
+    {"type": "minecraft:single", "resource": "computercraft:gui/pocket_bottom_colour"}
+  ]
+}

tools/update-resources.py

@@ -0,0 +1,115 @@
+#!/usr/bin/env python3
+
+# SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+#
+# SPDX-License-Identifier: MPL-2.0
+
+
+"""
+Upgrades textures to newer resource pack formats.
+
+Currently implemented transformations:
+ - Split gui/corners_*.png and gui/buttons.png textures into smaller textures.
+"""
+
+from PIL import Image
+import os
+import pathlib
+import argparse
+
+
+def box(x: int, y: int, w: int, h: int):
+    return (x, y, x + w, y + h)
+
+
+def unstitch_buttons(input_file: pathlib.Path):
+    """Unstitch the button texture,"""
+    buttons = Image.open(input_file)
+
+    output_dir = input_file.parent / "buttons"
+    output_dir.mkdir(exist_ok=True)
+
+    buttons.crop(box(1, 1, 12, 12)).save(output_dir / "turned_off.png")
+    buttons.crop(box(1, 15, 12, 12)).save(output_dir / "turned_off_hover.png")
+
+    buttons.crop(box(15, 1, 12, 12)).save(output_dir / "turned_on.png")
+    buttons.crop(box(15, 15, 12, 12)).save(output_dir / "turned_on_hover.png")
+
+    buttons.crop(box(29, 1, 12, 12)).save(output_dir / "terminate.png")
+    buttons.crop(box(29, 15, 12, 12)).save(output_dir / "terminate_hover.png")
+
+
+def unstitch_corners(input_file: pathlib.Path, family: str):
+    """Unstitch the corners texture."""
+
+    input = Image.open(input_file)
+    output_dir = input_file.parent
+
+    border = Image.new("RGBA", (36, 36))
+    # Corners
+    border.paste(input.crop(box(12, 28, 12, 12)), box(00, 00, 12, 12))
+    border.paste(input.crop(box(24, 28, 12, 12)), box(24, 00, 12, 12))
+    border.paste(input.crop(box(12, 40, 12, 12)), box(00, 24, 12, 12))
+    border.paste(input.crop(box(24, 40, 12, 12)), box(24, 24, 12, 12))
+    # Horizontal bars
+    border.paste(input.crop(box(00, 00, 12, 12)), box(12, 00, 12, 12))
+    border.paste(input.crop(box(00, 12, 12, 12)), box(12, 24, 12, 12))
+    # Vertical bars
+    border.paste(input.crop(box(00, 28, 12, 12)), box(00, 12, 12, 12))
+    border.paste(input.crop(box(36, 28, 12, 12)), box(24, 12, 12, 12))
+
+    border.save(output_dir / f"border_{family}.png")
+
+    if family != "command":
+        # Fatter bottom pocket computer border.
+        pocket_computer = Image.new("RGBA", (36, 20))
+        # Middle
+        pocket_computer.paste(input.crop(box(00, 56, 12, 20)), box(12, 0, 12, 20))
+        # Corners
+        pocket_computer.paste(input.crop(box(12, 80, 12, 20)), box(00, 0, 12, 20))
+        pocket_computer.paste(input.crop(box(24, 80, 12, 20)), box(24, 0, 12, 20))
+        pocket_computer.save(output_dir / f"pocket_bottom_{family}.png")
+
+    if family != "colour":
+        # Sidebar
+        sidebar = Image.new("RGBA", (17, 14))
+        sidebar.paste(input.crop(box(0, 102, 17, 14)), box(0, 0, 17, 14))
+        sidebar.save(output_dir / f"sidebar_{family}.png")
+
+
+def main() -> None:
+    spec = argparse.ArgumentParser()
+    spec.add_argument("dir", type=pathlib.Path)
+
+    dir: pathlib.Path = spec.parse_args().dir
+
+    texture_path = dir / "assets" / "computercraft" / "textures"
+
+    transformed: list[pathlib.Path] = []
+
+    buttons_path = texture_path / "gui" / "buttons.png"
+    if buttons_path.exists():
+        unstitch_buttons(buttons_path)
+        transformed.append(buttons_path)
+
+    for family in ("normal", "advanced", "command", "colour"):
+        path = texture_path / "gui" / f"corners_{family}.png"
+        if path.exists():
+            unstitch_corners(path, family)
+            transformed.append(path)
+
+    if len(transformed) == 0:
+        print("No files were transformed")
+        return
+
+    print("The following files may be deleted")
+    for file in transformed:
+        print(f" - {file}")
+
+    if input("Do so now? [y/N]").lower() == "y":
+        for file in transformed:
+            os.remove(file)
+
+
+if __name__ == "__main__":
+    main()