match vanilla arrow/trident orientation incl. arrow impact shake, add projectile test scenes

src/main/java/eu/mhsl/minecraft/pixelpics/render/entity/cem/CemBaker.java

@@ -134,6 +134,9 @@ public final class CemBaker implements EntityBaker<EntityState> {
             place = Affine.translation(s.x(), s.y(), s.z())
                     .mul(Affine.scale(extra))
                     .mul(Affine.rotY(yawSign * Math.toRadians(s.bodyYaw())));
+            // Projectiles (verified against ArrowRenderer/ThrownTridentRenderer 26.3): T0 = rotY(-90)[·rotZ(90)],
+            // pitchAxis = -X, so rotY(yaw)·rotAxis(-X, pitch)·T0 == vanilla rotY(yRot-90)·rotZ(xRot[+90]) with the
+            // raw projectile rotation (yaw atan2(dx,dz), pitch positive up); origin = entity position, no offset.
             if (info != null && info.pitchAxis() != null && s.pitch() != 0) {
                 double[] a = info.pitchAxis();
                 place = place.mul(Affine.rotAxis(a[0], a[1], a[2], Math.toRadians(s.pitch())));

src/main/java/eu/mhsl/minecraft/pixelpics/render/snapshot/EntitySnapshotBuilder.java

@@ -19,6 +19,7 @@ import java.util.function.DoubleSupplier;
 import org.bukkit.Keyed;
 import org.bukkit.Location;
 import org.bukkit.Material;
+import org.bukkit.entity.AbstractArrow;
 import org.bukkit.entity.AbstractHorse;
 import org.bukkit.entity.Ageable;
 import org.bukkit.entity.ArmorStand;
@@ -47,6 +48,7 @@ import org.bukkit.entity.Shulker;
 import org.bukkit.entity.Slime;
 import org.bukkit.entity.Snowman;
 import org.bukkit.entity.TraderLlama;
+import org.bukkit.entity.Trident;
 import org.bukkit.entity.TropicalFish;
 import org.bukkit.entity.Villager;
 import org.bukkit.entity.Wolf;
@@ -304,7 +306,7 @@ public final class EntitySnapshotBuilder {
                 bodyEquip,
                 equipment,
                 invisible,
-                loc.getPitch(),
+                loc.getPitch() + arrowShake(e),
                 bodyDye,
                 tint2,
                 e.isInsideVehicle(),
@@ -406,6 +408,36 @@ public final class EntitySnapshotBuilder {
         }
     }
 
+    /** Per NMS entity class: its public {@code shakeTime} field (AbstractArrow), or null. */
+    private static final ClassValue<java.lang.reflect.Field> SHAKE_FIELD = new ClassValue<>() {
+        @Override
+        protected java.lang.reflect.Field computeValue(Class<?> c) {
+            try {
+                return c.getField("shakeTime");
+            } catch (NoSuchFieldException ex) {
+                return null;
+            }
+        }
+    };
+
+    /**
+     * Vanilla impact wobble of a freshly stuck arrow (ArrowModel#setupAnim, partialTick 0): the model root turns
+     * by {@code -sin(3·shake)·shake} degrees about its z axis — the same axis as the pitch, so it is added to it.
+     * {@code shakeTime} (7 → 0 ticks after hitting a block) has no API; read from the server entity. Tridents
+     * ignore it (ThrownTridentRenderer has no shake).
+     */
+    private static float arrowShake(Entity e) {
+        if (!(e instanceof AbstractArrow) || e instanceof Trident) return 0;
+        try {
+            Object handle = e.getClass().getMethod("getHandle").invoke(e);
+            java.lang.reflect.Field f = SHAKE_FIELD.get(handle.getClass());
+            int shake = f == null ? 0 : f.getInt(handle);
+            return shake <= 0 ? 0 : (float) (-Math.sin(shake * 3.0) * shake);
+        } catch (ReflectiveOperationException | RuntimeException ex) {
+            return 0;
+        }
+    }
+
     /** Per entity class: its {@code getVariant()} / {@code getWeatheringState()} getter, or null. */
     private static final ClassValue<java.lang.reflect.Method> VARIANT_GETTER = new ClassValue<>() {
         @Override