Render destination snapshots with Ponder

README.md

@@ -26,9 +26,9 @@ right-clicking with an empty hand. Sneak-right-click with an empty hand to take
 the book back and restore the vanilla lectern. Breaking a Book Stand drops both
 the stored book and a vanilla lectern.
 
-Version 0.1.4 establishes a Ponder-backed destination-preview boundary and an
-animated loading view. Transmitting a destination snapshot and rendering its
-actual blocks as the rotating scene is the next preview iteration.
+Bound Linking Books request a small, server-validated snapshot around their
+destination and render its blocks as a rotating Ponder scene on the left page.
+The snapshot is visual only; the server independently validates every link.
 
 ## Requirements
 

docs/PORTING.md

@@ -51,7 +51,7 @@ the symbol grammar is introduced.
 - [x] Book-screen foundation with server-authoritative naming, binding, and
   explicit link activation.
 - [x] Ponder dependency and isolated destination-preview level boundary.
-- [ ] Server-provided destination snapshots rendered as rotating Ponder scenes.
+- [x] Server-provided destination snapshots rendered as rotating Ponder scenes.
 - [x] Book Stand floating names synchronized from the stored book stack.
 - [x] Open the stored book screen from a Book Stand with server-validated linking.
 - [ ] Automated in-game tests for binding, persistence, and travel.
@@ -110,6 +110,10 @@ revalidates the stand position, interaction distance, stored item, and target.
 Version 0.1.12 replaces the Linking Book screen's convenience text draws with
 explicit no-shadow rendering for clearer dark ink on the parchment texture.
 
+Version 0.1.13 requests a bounded, server-validated 9-by-7-by-9 block snapshot
+from the held book or nearby Book Stand and renders it as a clipped, rotating
+Ponder world section on the Linking Book's left page.
+
 The preview code is separated behind a renderer interface and uses an isolated
 Ponder level. The first iteration supplies the animated loading boundary; the
 next iteration will add server-authoritative snapshot transport and populate

gradle.properties

@@ -33,7 +33,7 @@ mod_name=Rivencraft
 # The license of the mod. Review your options at https://choosealicense.com/. All Rights Reserved is the default.
 mod_license=LGPL-3.0-or-later
 # The mod version. See https://semver.org/
-mod_version=0.1.12
+mod_version=0.1.13
 # The group ID for the mod. It is only important when publishing as an artifact to a Maven repository.
 # This should match the base package used for the mod sources.
 # See https://maven.apache.org/guides/mini/guide-naming-conventions.html

src/main/java/net/dnorberg/rivencraft/client/ClientEvents.java

@@ -24,4 +24,5 @@ public final class ClientEvents {
         NeoForge.EVENT_BUS.addListener(ClientBookInteractionHandler::onRightClickItem);
         NeoForge.EVENT_BUS.addListener(ClientBookInteractionHandler::onRightClickBlock);
     }
+
 }

src/main/java/net/dnorberg/rivencraft/client/ClientLinkPreviewHandler.java

@@ -0,0 +1,19 @@
+package net.dnorberg.rivencraft.client;
+
+import net.dnorberg.rivencraft.client.screen.LinkingBookScreen;
+import net.dnorberg.rivencraft.network.LinkPreviewPayload;
+import net.minecraft.client.Minecraft;
+import net.neoforged.neoforge.network.handling.IPayloadContext;
+
+public final class ClientLinkPreviewHandler {
+    private ClientLinkPreviewHandler() {
+    }
+
+    public static void handle(LinkPreviewPayload payload, IPayloadContext context) {
+        context.enqueueWork(() -> {
+            if (Minecraft.getInstance().screen instanceof LinkingBookScreen screen) {
+                screen.acceptPreview(payload);
+            }
+        });
+    }
+}

src/main/java/net/dnorberg/rivencraft/client/preview/DestinationPreviewRenderer.java

@@ -1,8 +1,11 @@
 package net.dnorberg.rivencraft.client.preview;
 
 import net.minecraft.client.gui.GuiGraphics;
+import net.dnorberg.rivencraft.network.LinkPreviewPayload;
 
 public interface DestinationPreviewRenderer extends AutoCloseable {
+    void accept(LinkPreviewPayload payload);
+
     void tick();
 
     void render(GuiGraphics graphics, int left, int top, int width, int height, float partialTick);

src/main/java/net/dnorberg/rivencraft/client/preview/PonderDestinationPreviewRenderer.java

@@ -1,10 +1,27 @@
 package net.dnorberg.rivencraft.client.preview;
 
+import com.mojang.blaze3d.systems.RenderSystem;
 import net.createmod.ponder.api.level.PonderLevel;
+import net.createmod.ponder.api.element.PonderSceneElement;
+import net.createmod.ponder.api.scene.Selection;
+import net.createmod.ponder.foundation.SelectionImpl;
+import net.createmod.ponder.foundation.element.WorldSectionElementImpl;
+import net.createmod.catnip.gui.UIRenderHelper;
+import net.createmod.catnip.render.DefaultSuperRenderTypeBuffer;
+import net.createmod.catnip.render.SuperRenderTypeBuffer;
+import net.dnorberg.rivencraft.network.LinkPreviewPayload;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.gui.GuiGraphics;
+import net.minecraft.client.renderer.RenderType;
 import net.minecraft.core.BlockPos;
 import net.minecraft.network.chat.Component;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
+import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.blaze3d.vertex.VertexSorting;
+import com.mojang.math.Axis;
+import org.joml.Matrix4f;
+import org.joml.Vector3f;
 
 /**
  * Initial Ponder-backed preview boundary.
@@ -14,12 +31,27 @@ import net.minecraft.network.chat.Component;
  * state rather than reading arbitrary remote chunks from the client.</p>
  */
 public final class PonderDestinationPreviewRenderer implements DestinationPreviewRenderer {
+    private static final Vector3f DIFFUSE_LIGHT_0 = new Vector3f(0.4F, -1.0F, 0.7F).normalize();
+    private static final Vector3f DIFFUSE_LIGHT_1 = new Vector3f(-0.4F, -0.5F, 0.7F).normalize();
     private final PonderLevel previewLevel;
+    private final Selection selection;
+    private final PonderSceneElement section;
     private int ticks;
+    private boolean loaded;
 
     public PonderDestinationPreviewRenderer() {
         Minecraft minecraft = Minecraft.getInstance();
         previewLevel = new PonderLevel(BlockPos.ZERO, minecraft.level);
+        selection = SelectionImpl.of(new BoundingBox(0, 0, 0, 8, 6, 8));
+        section = new WorldSectionElementImpl(selection);
+    }
+
+    @Override
+    public void accept(LinkPreviewPayload payload) {
+        selection.forEach(pos -> previewLevel.setBlock(pos, Blocks.AIR.defaultBlockState(), 2));
+        payload.blocks().forEach(block -> previewLevel.setBlock(block.pos(), block.state(), 2));
+        ((net.createmod.ponder.api.element.WorldSectionElement)section).queueRedraw();
+        loaded = true;
     }
 
     @Override
@@ -33,6 +65,11 @@ public final class PonderDestinationPreviewRenderer implements DestinationPrevie
         graphics.fill(left, top, left + width, top + height, 0xFF080C18);
         graphics.renderOutline(left, top, width, height, 0xFF7B6AA8);
 
+        if (loaded) {
+            renderSnapshot(graphics, left, top, width, height, partialTick);
+            return;
+        }
+
         double angle = (ticks + partialTick) * 0.04;
         int centerX = left + width / 2;
         int centerY = top + height / 2;
@@ -47,4 +84,38 @@ public final class PonderDestinationPreviewRenderer implements DestinationPrevie
                 0xFFB8C5E0
         );
     }
+
+    private void renderSnapshot(GuiGraphics graphics, int left, int top, int width, int height, float partialTick) {
+        graphics.enableScissor(left + 1, top + 1, left + width - 1, top + height - 1);
+        RenderSystem.enableBlend();
+        RenderSystem.enableDepthTest();
+        RenderSystem.backupProjectionMatrix();
+        RenderSystem.setupLevelDiffuseLighting(DIFFUSE_LIGHT_0, DIFFUSE_LIGHT_1);
+
+        Matrix4f projection = new Matrix4f(RenderSystem.getProjectionMatrix());
+        projection.translate(0.0F, 0.0F, 800.0F);
+        RenderSystem.setProjectionMatrix(projection, VertexSorting.DISTANCE_TO_ORIGIN);
+
+        PoseStack poseStack = graphics.pose();
+        poseStack.pushPose();
+        poseStack.translate(0.0F, 0.0F, -800.0F);
+        poseStack.translate(left + width / 2.0F, top + height / 2.0F + 8.0F, 200.0F);
+        poseStack.mulPose(Axis.XP.rotationDegrees(-28.0F));
+        poseStack.mulPose(Axis.YP.rotationDegrees((ticks + partialTick) * 0.6F));
+        UIRenderHelper.flipForGuiRender(poseStack);
+        poseStack.scale(10.0F, 10.0F, 10.0F);
+        poseStack.translate(-4.5F, -1.5F, -4.5F);
+
+        SuperRenderTypeBuffer buffer = DefaultSuperRenderTypeBuffer.getInstance();
+        section.renderFirst(previewLevel, buffer, graphics, partialTick);
+        for (RenderType type : RenderType.chunkBufferLayers()) {
+            section.renderLayer(previewLevel, buffer, type, graphics, partialTick);
+        }
+        section.renderLast(previewLevel, buffer, graphics, partialTick);
+        buffer.draw();
+
+        poseStack.popPose();
+        RenderSystem.restoreProjectionMatrix();
+        graphics.disableScissor();
+    }
 }

src/main/java/net/dnorberg/rivencraft/client/screen/LinkingBookScreen.java

@@ -7,6 +7,8 @@ import net.dnorberg.rivencraft.network.BindLinkingBookPayload;
 import net.dnorberg.rivencraft.network.ModNetworking;
 import net.dnorberg.rivencraft.network.UseLinkingBookPayload;
 import net.dnorberg.rivencraft.network.UseBookStandPayload;
+import net.dnorberg.rivencraft.network.RequestLinkPreviewPayload;
+import net.dnorberg.rivencraft.network.LinkPreviewPayload;
 import net.dnorberg.rivencraft.registry.ModDataComponents;
 import net.minecraft.client.gui.GuiGraphics;
 import net.minecraft.client.gui.components.Button;
@@ -77,6 +79,11 @@ public final class LinkingBookScreen extends Screen {
                     .build());
         } else {
             preview = new PonderDestinationPreviewRenderer();
+            PacketDistributor.sendToServer(new RequestLinkPreviewPayload(
+                    bookStandPos != null,
+                    bookStandPos == null && hand == InteractionHand.OFF_HAND,
+                    bookStandPos == null ? BlockPos.ZERO : bookStandPos
+            ));
         }
     }
 
@@ -143,6 +150,12 @@ public final class LinkingBookScreen extends Screen {
         }
     }
 
+    public void acceptPreview(LinkPreviewPayload payload) {
+        if (preview != null) {
+            preview.accept(payload);
+        }
+    }
+
     private void bind() {
         String name = titleInput.getValue().strip();
         if (!name.isEmpty()) {

src/main/java/net/dnorberg/rivencraft/network/LinkPreviewPayload.java

@@ -0,0 +1,47 @@
+package net.dnorberg.rivencraft.network;
+
+import java.util.ArrayList;
+import java.util.List;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.state.BlockState;
+
+public record LinkPreviewPayload(List<SnapshotBlock> blocks) implements CustomPacketPayload {
+    private static final int MAX_BLOCKS = 9 * 7 * 9;
+    public static final Type<LinkPreviewPayload> TYPE = new Type<>(
+            ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID, "link_preview")
+    );
+    public static final StreamCodec<RegistryFriendlyByteBuf, LinkPreviewPayload> STREAM_CODEC = StreamCodec.of(
+            (buffer, payload) -> {
+                buffer.writeVarInt(payload.blocks.size());
+                for (SnapshotBlock block : payload.blocks) {
+                    buffer.writeBlockPos(block.pos);
+                    buffer.writeVarInt(Block.getId(block.state));
+                }
+            },
+            buffer -> {
+                int size = buffer.readVarInt();
+                if (size < 0 || size > MAX_BLOCKS) {
+                    throw new IllegalArgumentException("Invalid link preview size: " + size);
+                }
+                List<SnapshotBlock> blocks = new ArrayList<>(size);
+                for (int i = 0; i < size; i++) {
+                    blocks.add(new SnapshotBlock(buffer.readBlockPos(), Block.stateById(buffer.readVarInt())));
+                }
+                return new LinkPreviewPayload(List.copyOf(blocks));
+            }
+    );
+
+    @Override
+    public Type<? extends CustomPacketPayload> type() {
+        return TYPE;
+    }
+
+    public record SnapshotBlock(BlockPos pos, BlockState state) {
+    }
+}

src/main/java/net/dnorberg/rivencraft/network/ModNetworking.java

@@ -2,12 +2,15 @@ package net.dnorberg.rivencraft.network;
 
 import net.dnorberg.rivencraft.book.LinkTarget;
 import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
+import net.dnorberg.rivencraft.client.ClientLinkPreviewHandler;
 import net.dnorberg.rivencraft.item.LinkingBookItem;
 import net.dnorberg.rivencraft.registry.ModDataComponents;
 import net.dnorberg.rivencraft.registry.ModItems;
 import net.minecraft.core.component.DataComponents;
+import net.minecraft.core.BlockPos;
 import net.minecraft.network.chat.Component;
 import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.level.ServerLevel;
 import net.minecraft.sounds.SoundEvents;
 import net.minecraft.sounds.SoundSource;
 import net.minecraft.world.InteractionHand;
@@ -16,6 +19,9 @@ import net.minecraft.world.phys.Vec3;
 import net.neoforged.neoforge.network.event.RegisterPayloadHandlersEvent;
 import net.neoforged.neoforge.network.handling.IPayloadContext;
 import net.neoforged.neoforge.network.registration.PayloadRegistrar;
+import net.neoforged.neoforge.network.PacketDistributor;
+import java.util.ArrayList;
+import java.util.List;
 
 public final class ModNetworking {
     public static final int MAX_BOOK_TITLE_LENGTH = 32;
@@ -24,10 +30,14 @@ public final class ModNetworking {
     }
 
     public static void register(RegisterPayloadHandlersEvent event) {
-        PayloadRegistrar registrar = event.registrar("1");
+        PayloadRegistrar registrar = event.registrar("2");
         registrar.playToServer(BindLinkingBookPayload.TYPE, BindLinkingBookPayload.STREAM_CODEC, ModNetworking::bindBook);
         registrar.playToServer(UseLinkingBookPayload.TYPE, UseLinkingBookPayload.STREAM_CODEC, ModNetworking::useBook);
         registrar.playToServer(UseBookStandPayload.TYPE, UseBookStandPayload.STREAM_CODEC, ModNetworking::useBookStand);
+        registrar.playToServer(RequestLinkPreviewPayload.TYPE, RequestLinkPreviewPayload.STREAM_CODEC,
+                ModNetworking::requestLinkPreview);
+        registrar.playToClient(LinkPreviewPayload.TYPE, LinkPreviewPayload.STREAM_CODEC,
+                ClientLinkPreviewHandler::handle);
     }
 
     private static void bindBook(BindLinkingBookPayload payload, IPayloadContext context) {
@@ -75,6 +85,44 @@ public final class ModNetworking {
         }
     }
 
+    private static void requestLinkPreview(RequestLinkPreviewPayload payload, IPayloadContext context) {
+        if (!(context.player() instanceof ServerPlayer player)) {
+            return;
+        }
+
+        ItemStack stack;
+        if (payload.fromStand()) {
+            if (player.distanceToSqr(Vec3.atCenterOf(payload.standPos())) > 64.0D
+                    || !(player.level().getBlockEntity(payload.standPos()) instanceof BookStandBlockEntity stand)) {
+                return;
+            }
+            stack = stand.getBook();
+        } else {
+            stack = player.getItemInHand(hand(payload.offhand()));
+        }
+
+        LinkTarget target = stack.is(ModItems.LINKING_BOOK.get())
+                ? stack.get(ModDataComponents.LINK_TARGET.get()) : null;
+        if (target == null) {
+            return;
+        }
+
+        ServerLevel level = player.getServer().getLevel(target.location().dimension());
+        if (level == null) {
+            return;
+        }
+
+        BlockPos origin = target.location().pos();
+        List<LinkPreviewPayload.SnapshotBlock> blocks = new ArrayList<>();
+        for (BlockPos pos : BlockPos.betweenClosed(origin.offset(-4, -2, -4), origin.offset(4, 4, 4))) {
+            var state = level.getBlockState(pos);
+            if (!state.isAir()) {
+                blocks.add(new LinkPreviewPayload.SnapshotBlock(pos.subtract(origin).offset(4, 2, 4), state));
+            }
+        }
+        PacketDistributor.sendToPlayer(player, new LinkPreviewPayload(List.copyOf(blocks)));
+    }
+
     private static InteractionHand hand(boolean offhand) {
         return offhand ? InteractionHand.OFF_HAND : InteractionHand.MAIN_HAND;
     }

src/main/java/net/dnorberg/rivencraft/network/RequestLinkPreviewPayload.java

@@ -0,0 +1,28 @@
+package net.dnorberg.rivencraft.network;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.ByteBufCodecs;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.ResourceLocation;
+
+public record RequestLinkPreviewPayload(boolean fromStand, boolean offhand, BlockPos standPos)
+        implements CustomPacketPayload {
+    public static final Type<RequestLinkPreviewPayload> TYPE = new Type<>(
+            ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID, "request_link_preview")
+    );
+    public static final StreamCodec<RegistryFriendlyByteBuf, RequestLinkPreviewPayload> STREAM_CODEC =
+            StreamCodec.composite(
+                    ByteBufCodecs.BOOL, RequestLinkPreviewPayload::fromStand,
+                    ByteBufCodecs.BOOL, RequestLinkPreviewPayload::offhand,
+                    BlockPos.STREAM_CODEC, RequestLinkPreviewPayload::standPos,
+                    RequestLinkPreviewPayload::new
+            );
+
+    @Override
+    public Type<? extends CustomPacketPayload> type() {
+        return TYPE;
+    }
+}

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

@@ -17,7 +17,7 @@
   "screen.rivencraft.book.bind": "Bind",
   "screen.rivencraft.book.link": "Link",
   "screen.rivencraft.book.unwritten": "This Descriptive Book is unwritten",
-  "screen.rivencraft.book.preview_pending": "Ponder preview loading",
+  "screen.rivencraft.book.preview_pending": "Loading destination...",
   "screen.rivencraft.book.click_to_link": "Click the panel to link",
   "itemGroup.rivencraft": "Rivencraft"
 }