feat: [Remote rendering 3.2b] save state reads from server camera (#111)

Co-authored-by: pyansys-ci-bot <92810346+pyansys-ci-bot@users.noreply.github.com>

Author: LKasianAnsys

doc/changelog.d/111.added.md

@@ -0,0 +1 @@
+[Remote rendering 3.2b] save state reads from server camera

src/ansys/visor/viewer/models/persist/scene/persisted_scene_state.py

@@ -75,7 +75,6 @@ class PersistedSceneState(BaseModel):
     cross_section_enabled: bool | None = None
     edges_enabled: bool | None = None
     bounding_box_enabled: bool | None = None
-    camera: VisorCameraState | None = None
     dataset_states: Dict[str, "PersistedDatasetState"] = Field(default_factory=dict)
     variable_states: Dict[str, "VisorVariableState"] = Field(default_factory=dict)
     model_config = ConfigDict(arbitrary_types_allowed=True)

src/ansys/visor/viewer/vtk/scene/base.py

@@ -157,6 +157,16 @@ async def get_state(self, timeout: float) -> PersistedViewerStateV1:
         The registry hands out live ``RuntimeDatasetState`` objects that the per-part
         setters mutate from the trame daemon thread, so each one is deep-copied under
         ``_vtk_lock``.  The lock is taken after the ``await`` and never held across one.
+
+        The camera is the second thing the browser's reply does not get to supply.
+        It comes from the renderer's record, which is authoritative, rather than
+        from the reply or from the pipeline ``vtkCamera``: the pipeline is the
+        record's projection, and reading it back would re-import whatever drift
+        VTK introduced -- ``ResetCamera`` rewrites ``clipping_range``.  The
+        assignment is unconditional.  A ``None`` record means no camera was ever
+        written, and writing that ``None`` through is what says so; the guard for
+        "absent says nothing" belongs to the load path, in :meth:`apply_state`,
+        not here.
         """
         runtime_state = await self._get_runtime_state_async(timeout)
 
@@ -165,6 +175,7 @@ async def get_state(self, timeout: float) -> PersistedViewerStateV1:
                 dataset_id: dataset_state.model_copy(deep=True)
                 for dataset_id, dataset_state in self._dataset_registry.runtime_state_dict.items()
             }
+            runtime_state.scene.camera = self._renderer.get_camera_state()
         runtime_state.scene.dataset_states = registry_dataset_states
 
         persisted = self._state_mapper.runtime_to_persisted(runtime_state)

src/ansys/visor/visor-client/src/renderer/IRenderer.ts

@@ -25,6 +25,17 @@ export type VisorCameraState = Readonly<{
     parallelScale: number;
 }>;
 
+/** The seven camera fields that can be applied. No derived fields. */
+export type AppliedCameraState = Readonly<{
+    position: readonly number[];
+    focalPoint: readonly number[];
+    viewUp: readonly number[];
+    clippingRange: readonly number[];
+    parallelProjection: boolean;
+    viewAngle: number;
+    parallelScale: number;
+}>;
+
 /** Descriptor consumed by setColorVariableAsync. */
 export type ColorVariableDescriptor = Readonly<{
     spectrumId: string;
@@ -97,11 +108,11 @@ export interface IRenderer {
     setCameraViewAngleAsync(angle: number): Promise<void>;
     setCameraParallelScaleAsync(scale: number): Promise<void>;
     /**
-     * Apply an entire camera snapshot in one RPC. WasmRenderer implements it
+     * Apply the seven applied camera fields in one RPC. WasmRenderer implements it
      * by delegating to the seven per-field setters above. See §11 for the
      * Story 3.2 rationale (server-tracked camera + sync-back).
      */
-    setCameraStateAsync(state: VisorCameraState): Promise<void>;
+    setCameraStateAsync(state: AppliedCameraState): Promise<void>;
     /** Frame the scene on the given bounds; used by scene-graph rebuilds. */
     resetCameraAsync(bounds?: readonly number[]): Promise<void>;
 

src/ansys/visor/visor-client/src/renderer/NullRenderer.ts

@@ -1,4 +1,5 @@
 import {
+    AppliedCameraState,
     ColorVariableDescriptor,
     GeometryPickMode,
     IRenderer,
@@ -79,7 +80,7 @@ export class NullRenderer implements IRenderer {
         // no-op
     }
 
-    async setCameraStateAsync(_state: VisorCameraState): Promise<void> {
+    async setCameraStateAsync(_state: AppliedCameraState): Promise<void> {
         // no-op
     }
 

src/ansys/visor/visor-client/src/renderer/WasmRenderer.ts

@@ -1,4 +1,5 @@
 import {
+    AppliedCameraState,
     ColorVariableDescriptor,
     GeometryPickMode,
     IRenderer,
@@ -177,7 +178,7 @@ export class WasmRenderer implements IRenderer {
         await this.#vtkScene.camera.setParallelScale(scale);
     }
 
-    async setCameraStateAsync(state: VisorCameraState): Promise<void> {
+    async setCameraStateAsync(state: AppliedCameraState): Promise<void> {
         // Sequential, not Promise.all, to preserve the observable ordering of
         // camera events any FPS/camera-changed listener sees (§11).
         await this.setCameraPositionAsync(state.position);

tests/integration/test_save_load_state.py

@@ -44,6 +44,7 @@
 from ansys.visor.viewer.app.visor_vtk import VisorVTK
 from ansys.visor.viewer.core.metadata import ExtendedMetadata
 from ansys.visor.viewer.models.common.part_properties import PartProperties
+from ansys.visor.viewer.models.common.visor_camera_state import VisorCameraState
 from ansys.visor.viewer.models.common.visor_ui_state import VisorUIState
 from ansys.visor.viewer.models.persist.dataset.persisted_dataset_state import PersistedDatasetState
 from ansys.visor.viewer.models.persist.persisted_viewer_state import PersistedViewerStateV1
@@ -100,6 +101,46 @@ def iface():
         pass
 
 
+# ------------------------------------------------------------------ #
+# Camera literals
+#
+# Hand-written, and different in every field between the two, so the saved
+# file names its source by value rather than by a recorded call.  No value
+# here originates from VTK.
+# ------------------------------------------------------------------ #
+
+RECORD_CAMERA_POSITION = [11.0, 12.0, 13.0]
+RECORD_CAMERA_CLIPPING_RANGE = [17.0, 18.0]
+REPLY_CAMERA_POSITION = [21.0, 22.0, 23.0]
+REPLY_CAMERA_CLIPPING_RANGE = [27.0, 28.0]
+
+
+def _record_camera() -> VisorCameraState:
+    """The camera the server's record holds at save time."""
+    return VisorCameraState(
+        position=RECORD_CAMERA_POSITION,
+        focal_point=[14.0, 15.0, 16.0],
+        view_up=[0.0, 1.0, 0.0],
+        clipping_range=RECORD_CAMERA_CLIPPING_RANGE,
+        parallel_projection=True,
+        view_angle=31.0,
+        parallel_scale=19.0,
+    )
+
+
+def _reply_camera() -> VisorCameraState:
+    """The camera the browser answers getState with."""
+    return VisorCameraState(
+        position=REPLY_CAMERA_POSITION,
+        focal_point=[24.0, 25.0, 26.0],
+        view_up=[1.0, 0.0, 0.0],
+        clipping_range=REPLY_CAMERA_CLIPPING_RANGE,
+        parallel_projection=False,
+        view_angle=32.0,
+        parallel_scale=29.0,
+    )
+
+
 # ================================================================== #
 # write_dataset / read_dataset round-trips
 # ================================================================== #
@@ -488,4 +529,47 @@ def test_reloading_the_saved_state_restores_the_registry(self, file_io, iface, t
         assert record.spectrum_id == "POINT::pressure::1"
         assert record.spectrum_component == 0
 
+    def test_saved_visor_json_carries_the_camera_record_not_the_browsers(self, iface, tmp_path):
+        """save_state writes the server's camera record, not the browser's reply.
+
+        The record is seeded through ``sync_camera``, which also projects onto
+        the pipeline camera, so record and pipeline hold the same values here.
+        This case therefore discriminates the **record from the browser's
+        reply** and nothing more; separating the record from its own pipeline
+        projection is done in tests/unit/vtk/scene/test_base.py, against a
+        renderer double whose pipeline read answers with different numbers.
+
+        No dataset is added, so ``finalize_scene``'s reset never runs and
+        cannot overwrite the seeded record with a VTK-derived one.
+        """
+        iface._scene._renderer.sync_camera(_record_camera())
+
+        # The browser answers getState with a different camera in every field.
+        # A pass therefore proves the file came from the record.
+        frontend_state = RuntimeAppState.from_components(
+            dark_mode=False,
+            unit="m",
+            dataset_states={},
+            camera=_reply_camera(),
+        )
+
+        async def _frontend_round_trip(timeout: float = 5.0):
+            return frontend_state
+
+        iface._scene._get_runtime_state_async = _frontend_round_trip
+        iface._server_manager = MagicMock()
+        iface._server_manager.running = True
+
+        asyncio.run(iface.save_state(str(tmp_path)))
+
+        with open(os.path.join(str(tmp_path), "visor.json"), "r") as fh:
+            written = json.load(fh)
+
+        # write_state dumps by_alias, so the camera's own fields are aliased.
+        camera = written["scene"]["camera"]
+        assert camera["position"] == RECORD_CAMERA_POSITION
+        assert camera["clippingRange"] == RECORD_CAMERA_CLIPPING_RANGE
+        assert camera["position"] != REPLY_CAMERA_POSITION
+        assert camera["clippingRange"] != REPLY_CAMERA_CLIPPING_RANGE
+