props

AnimationDirector.js

@@ -4001,7 +4001,12 @@
     const explicit = model.display?.[context];
     const data = explicit || (slot === 'left' ? model.display?.thirdperson_righthand : null) || {};
     const rotation = v3(data.rotation), translation = v3(data.translation), scale = v3(data.scale, 1);
-    if (slot === 'left' && !explicit) { translation[0] *= -1; rotation[1] *= -1; rotation[2] *= -1; }
+    // Minecraft mirrors the selected display transform for left-hand rendering.
+    if (slot === 'left') {
+      translation[0] = -translation[0] || 0;
+      rotation[1] = -rotation[1] || 0;
+      rotation[2] = -rotation[2] || 0;
+    }
     return { rotation, translation, scale };
   }
 
@@ -4223,8 +4228,6 @@
           centered.add(new THREE.Mesh(geometry, material));
         }
       }
-      // GeckoLib -> Blockbench coordinate conversion mirrors model X, including attached items.
-      root.scale.x = -1;
       return root;
     } catch (error) { disposePropMesh(root); throw error; }
   }

test/item-props.test.js

@@ -77,8 +77,11 @@ test('left-hand and floor transforms follow Minecraft display contexts', () => {
   assert.deepEqual(Array.from(left.translation),[-1,2,3]);
   assert.deepEqual(Array.from(h.propDisplayTransform(model,'floor').scale),[.5,.5,.5]);
   const handheld = h.propDisplayTransform(h.manualPropModel('handheld'),'left');
-  assert.deepEqual(Array.from(handheld.rotation),[0,90,-55]);
+  assert.deepEqual(Array.from(handheld.rotation),[0,-90,55]);
   assert.deepEqual(Array.from(handheld.translation),[0,4,0.5]);
+  const explicit = h.propDisplayTransform({display:{thirdperson_lefthand:{rotation:[5,35,-20],translation:[2,3,4]}}},'left');
+  assert.deepEqual(Array.from(explicit.rotation),[5,-35,20]);
+  assert.deepEqual(Array.from(explicit.translation),[-2,3,4]);
 });
 
 test('3D JSON models keep elements, UVs, rotations and texture aliases', () => {