fix: Use native GLTF material when mappingType is 'uv' to preserve exact original UV mappings and texture orientations

src/components/ModelViewer.tsx

@@ -58,7 +58,7 @@ const MeshMaterialManager = ({ mesh, sceneObj, textureCache }: MeshMaterialManag
       
       activeMat.triplanarUniforms.uTriplanarScale.value = uvScale;
       activeMat.triplanarUniforms.uBlendSharpness.value = 5.0; // Default or from props
-    } else {
+    } else if (mappingType !== 'uv') {
       activeMat = MaterialFactory.getInstance().getStandardUVMaterial(
         baseParams,
         mesh.uuid
@@ -71,6 +71,9 @@ const MeshMaterialManager = ({ mesh, sceneObj, textureCache }: MeshMaterialManag
 
       activeMat.uvUniforms.uMappingMode.value = modeIndex;
       activeMat.updateUVTransform(uvOffset, [uvTiling[0] * uvScale, uvTiling[1] * uvScale], uvRotation * (Math.PI / 180));
+    } else {
+      // Use the native material to preserve exact GLTF UV behavior
+      activeMat = origMat;
     }
 
     // Apply basic props
@@ -117,6 +120,14 @@ const MeshMaterialManager = ({ mesh, sceneObj, textureCache }: MeshMaterialManag
         if (mappingType === 'triplanar') activeMat.triplanarUniforms['t' + type.charAt(0).toUpperCase() + type.slice(1).replace('Map', '')].value = null;
         activeMat.needsUpdate = true;
       }
+
+      // Native UV mapping transforms
+      if (mappingType === 'uv' && activeMat[type]) {
+        activeMat[type].repeat.set(uvTiling[0] * uvScale, uvTiling[1] * uvScale);
+        activeMat[type].offset.set(uvOffset[0], uvOffset[1]);
+        activeMat[type].rotation = uvRotation * (Math.PI / 180);
+        activeMat[type].needsUpdate = true;
+      }
     });
 
     mesh.visible = sceneObj.visible;