new blocks grow out of the previous block and glide into place

- new jump blocks spawn as a small block display inside the previous block and
  interpolate position and scale to their target over 8 ticks
- the real block (plus light and particles) is placed when the display arrives,
  the display is removed afterwards

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/main/java/eu/mhsl/minecraft/endlessjumper/generator/BlockTransition.java

@@ -0,0 +1,49 @@
+package eu.mhsl.minecraft.endlessjumper.generator;
+
+import net.minestom.server.coordinate.Pos;
+import net.minestom.server.coordinate.Vec;
+import net.minestom.server.entity.Entity;
+import net.minestom.server.entity.EntityType;
+import net.minestom.server.entity.metadata.display.BlockDisplayMeta;
+import net.minestom.server.instance.Instance;
+import net.minestom.server.instance.block.Block;
+import net.minestom.server.timer.TaskSchedule;
+
+/**
+ * Lässt einen neuen Block als Block-Display aus dem vorherigen Block „herauswachsen“ und
+ * zu seiner Zielposition gleiten. Erst bei Ankunft wird der echte Block gesetzt.
+ */
+public class BlockTransition {
+    private static final int DURATION_TICKS = 8;
+    private static final double START_SCALE = 0.3;
+
+    public static void animate(Instance world, Pos from, Pos to, Block block, Runnable onArrival) {
+        Entity display = new Entity(EntityType.BLOCK_DISPLAY);
+        display.setNoGravity(true);
+        display.editEntityMeta(BlockDisplayMeta.class, meta -> {
+            meta.setBlockState(block);
+            meta.setPosRotInterpolationDuration(DURATION_TICKS);
+            meta.setTransformationInterpolationDuration(DURATION_TICKS);
+            // klein und mittig im Ursprungsblock starten
+            meta.setScale(new Vec(START_SCALE));
+            meta.setTranslation(new Vec((1 - START_SCALE) / 2));
+        });
+
+        display.setInstance(world, from).thenRun(() -> {
+            // einen Moment warten, damit der Client das Display kennt, bevor die Interpolation startet
+            display.scheduler().buildTask(() -> {
+                display.editEntityMeta(BlockDisplayMeta.class, meta -> {
+                    meta.setTransformationInterpolationStartDelta(0);
+                    meta.setScale(Vec.ONE);
+                    meta.setTranslation(Vec.ZERO);
+                });
+                display.teleport(to);
+            }).delay(TaskSchedule.tick(2)).schedule();
+
+            display.scheduler().buildTask(() -> {
+                onArrival.run();
+                display.remove();
+            }).delay(TaskSchedule.tick(DURATION_TICKS + 3)).schedule();
+        });
+    }
+}

src/main/java/eu/mhsl/minecraft/endlessjumper/generator/JumpGenerator.java

@@ -48,8 +48,15 @@ public class JumpGenerator {
 
         Random r = new Random();
         int index = this.blocks.size();
-        Pos target = blocks.get(blocks.size()-1).add(this.nextOffset(index, r));
+        Pos previous = blocks.get(blocks.size()-1);
-        this.world.setBlock(target, isHundredth ? Block.DIAMOND_BLOCK : isTenth ? Block.GOLD_BLOCK : BlockPalette.getRandom(index, r));
+        Pos target = previous.add(this.nextOffset(index, r));
+        Block block = isHundredth ? Block.DIAMOND_BLOCK : isTenth ? Block.GOLD_BLOCK : BlockPalette.getRandom(index, r);
+        BlockTransition.animate(this.world, previous, target, block, () -> {
+            this.world.setBlock(target, block);
+            this.world.setBlock(target.add(0, 1, 0), Block.LIGHT);
+            this.player.sendPacket(new ParticlePacket(Particle.CRIT, target, target.add(0.5), 1, 10));
+            this.player.sendPacket(new ParticlePacket(Particle.FALLING_NECTAR, target, target.add(0.5), 0.3f, 10));
+        });
 
         if(standingTenth) {
             Pos current = this.blocks.get(this.blocks.size()-this.preview-1);
@@ -64,10 +71,7 @@ public class JumpGenerator {
             this.player.playSound(Sound.sound(SoundEvent.UI_TOAST_CHALLENGE_COMPLETE, Sound.Source.MASTER, 0.4f, 1f));
             this.player.showTitle(Title.title(Component.text(reachedStage.name(), TextColor.color(255, 170, 0)), Component.text("")));
         }
-        this.world.setBlock(target.add(0, 1 ,0), Block.LIGHT);
         this.blocks.add(target);
-        this.player.sendPacket(new ParticlePacket(Particle.CRIT, target, target.add(0.5), 1, 10));
-        this.player.sendPacket(new ParticlePacket(Particle.FALLING_NECTAR, target, target.add(0.5),0.3f, 10));
         this.combo++;
     }