linev · Oct 19, 2026 · Oct 18, 2026 · Oct 18, 2026 · Oct 18, 2026 · Oct 18, 2026
@@ -88,7 +88,6 @@ private:
    Bool_t  fHasAxesBBox{kFALSE};  ///< see SetAxesBBox()
    Float_t fAxesBBox[6]{};        ///< xmin, ymin, zmin, xmax, ymax, zmax
 
-   Float_t fMotionMaxHz{60.f};    ///< see SetMotionMaxHz(); 0 freezes
    Float_t fRenderMaxHz{0.f};     ///< see SetRenderMaxHz(); 0 is uncapped
    bool      fBlackBackground{false};
 
@@ -161,14 +160,8 @@ public:
    void ClearAxesBBox();
    Bool_t HasAxesBBox() const { return fHasAxesBBox; }
 
-   /// Cap on how often this viewer applies streamed motion, in updates per
-   /// second, clamped to [0, 240]. Zero freezes motion; SetExtrapolateMotion()
-   /// only controls drawing between updates.
-   Float_t GetMotionMaxHz() const { return fMotionMaxHz; }
-   void    SetMotionMaxHz(Float_t);
-
    /// Cap on how often the animation loop redraws this viewer, in frames per
-   /// second, clamped to [0, 240]. Zero means uncapped, unlike SetMotionMaxHz().
+   /// second, clamped to [0, 240]. Zero means uncapped.
    Float_t GetRenderMaxHz() const { return fRenderMaxHz; }
    void    SetRenderMaxHz(Float_t);
    // clang-format on

@@ -1483,8 +1483,7 @@ void REveElement::AddStamp(UChar_t bits)
 
 void REveElement::BuildRenderData()
 {
-   if (fMainTrans.get())
-   {
+   if (fMainTrans && fRenderData) {
       fRenderData->SetMatrix(fMainTrans->Array());
    }
 }

@@ -354,10 +354,8 @@ void REveLineProjected::SetDepthLocal(Float_t d)
 {
    SetDepthCommon(d, this, fBBox);
 
-   Int_t    n = fSize;
-   Float_t *p = & fPoints[0].fZ;
-   for (Int_t i = 0; i < n; ++i, p+=3)
-      *p = fDepth;
+   for (Int_t i = 0; i < fSize; ++i)
+      fPoints[i].fZ = fDepth;
 }
 
 ////////////////////////////////////////////////////////////////////////////////

@@ -1151,13 +1151,22 @@ void REveManager::StreamSceneChangesToJson()
 
 ////////////////////////////////////////////////////////////////////////////////
 /// Send transformation-only changes on the motion channel: the same websocket,
-/// outside the BeginChanges/EndChanges cycle, with no acknowledgement. A
-/// connection for which RWebWindow::CanSend(id, true) is false skips the
-/// message. Each message is absolute state, but a client that skips the last
-/// one keeps the old state until the element changes again.
+/// outside the BeginChanges/EndChanges cycle, with no acknowledgement. The
+/// message is sent directly, so it goes only when every connection can take a
+/// direct send. Otherwise the elements stay stamped and go out with the
+/// regular changes, which carry the same matrix and motion. The motion's t0 is
+/// stamped by REveTrans::SetMotion(), so the delay does not shift the
+/// trajectory.
 
 void REveManager::SendMotionChanges()
 {
+   if (fConnList.empty())
+      return;
+
+   for (auto &conn : fConnList)
+      if (!fWebWindow->CanSend(conn.fId, true))
+         return;
+
    nlohmann::json arr = nlohmann::json::array();
 
    fWorld->StreamMotionChanges(arr);
@@ -1167,21 +1176,19 @@ void REveManager::SendMotionChanges()
          s->StreamMotionChanges(arr);
    }
 
-   if (arr.empty() || fConnList.empty())
+   if (arr.empty())
       return;
 
    nlohmann::json msg = {};
    // clang-format off
    msg["content"] = "Motion";
-   msg["t"]       = REveUtil::ServerTimeMs();
    msg["els"]     = arr;
    // clang-format on
 
    std::string data = msg.dump();
 
    for (auto &conn : fConnList)
-      if (fWebWindow->CanSend(conn.fId, true))
-         fWebWindow->Send(conn.fId, data);
+      fWebWindow->Send(conn.fId, data);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1414,7 +1421,8 @@ void REveManager::BeginChange()
 /// Stop accepting changes and stream them. If the clients have not yet
 /// acknowledged the previous changes, keep the stamps and let the last
 /// acknowledgement in WindowData() flush them. Stamps coalesce per element.
-/// Motion changes are sent in either case. Changes made by a MIR are not held
+/// Motion changes are sent in either case when the connections can take a
+/// direct send, see SendMotionChanges(). Changes made by a MIR are not held
 /// back.
 
 void REveManager::EndChange()
@@ -1426,7 +1434,7 @@ void REveManager::EndChange()
    std::unique_lock<std::mutex> lock(fServerState.fMutex);
 
    // Motion is outside the change cycle, so it is sent even when changes
-   // are held.
+   // are held. What cannot be sent now stays stamped and goes with them.
    SendMotionChanges();
 
    if (!fConnList.empty() && !ClientConnectionsFree()) {

@@ -93,16 +93,19 @@ void REveProjection::ProjectPointfv(const REveTrans* t, const Float_t* p, Float_
 
 ////////////////////////////////////////////////////////////////////////////////
 /// Project double array, converting it to global coordinate system first if
-/// transformation matrix is set.
+/// transformation matrix is set. `p` and `v` may be the same array.
 /// This is a bit piggish as we convert the doubles to floats and back.
 
 void REveProjection::ProjectPointdv(const REveTrans* t, const Double_t* p, Double_t* v, Float_t d)
 {
    Float_t x, y, z;
    if (t)
    {
-      t->Multiply(p, v);
-      x = v[0]; y = v[1]; z = v[2];
+      Double_t buf[3];
+      t->Multiply(p, buf);
+      x = buf[0];
+      y = buf[1];
+      z = buf[2];
    }
    else
    {

@@ -151,15 +151,6 @@ void REveViewer::SetRenderMaxHz(Float_t hz)
    StampObjProps();
 }
 
-////////////////////////////////////////////////////////////////////////////////
-/// Cap the rate at which this viewer applies streamed motion; 0 freezes it.
-
-void REveViewer::SetMotionMaxHz(Float_t hz)
-{
-   fMotionMaxHz = hz < 0.f ? 0.f : (hz > 240.f ? 240.f : hz);
-   StampObjProps();
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 /// Set the point the camera looks at and orbits around, either the world
 /// origin or the center of the scene bounding box. Clients reset their camera
@@ -290,7 +281,6 @@ int REveViewer::WriteCoreJson(nlohmann::json &j, Int_t rnr_offset)
    j["CameraCenter"] = fCameraCenter;
    j["ExtrapolateMotion"] = fExtrapolateMotion;
    j["AxesUpAxis"] = fAxesUpAxis;
-   j["MotionMaxHz"] = fMotionMaxHz;
    j["RenderMaxHz"] = fRenderMaxHz;
    // clang-format off
    if (fHasAxesBBox)

@@ -16,6 +16,7 @@
 #include <ROOT/REveProjections.hxx>
 #include <ROOT/REveProjectionBases.hxx>
 #include <ROOT/REveProjectionManager.hxx>
+#include <ROOT/REveTrans.hxx>
 
 namespace REX = ROOT::Experimental;
 
@@ -81,6 +82,22 @@ TEST(REveProjection, ScreenValRoundTrip)
    }
 }
 
+// ProjectPointdv() may project in place, as REveTrackProjected does for path
+// marks; a rotation must not read coordinates it has already overwritten.
+TEST(REveProjection, ProjectPointdvInPlace)
+{
+   REX::REveRPhiProjection p;
+   REX::REveTrans t;
+   t.RotateLF(1, 2, 0.5);
+   t.SetPos(10, 20, 0);
+
+   Double_t in[3] = {3, 4, 0}, out[3];
+   p.ProjectPointdv(&t, in, out, 0.f);
+   p.ProjectPointdv(&t, in, in, 0.f);
+   for (int i = 0; i < 3; ++i)
+      EXPECT_DOUBLE_EQ(in[i], out[i]) << "coordinate " << i;
+}
+
 TEST(REveProjection, ImportAndUpdate)
 {
    auto eve = REX::REveManager::Create();

@@ -109,10 +109,10 @@ static void makeProjectedView(REveManager *eveMng, REveElement *content, REvePro
    mng = new REveProjectionManager(type);
    mng->ImportElements(content, scene);
 
-   // Add the manager to the element tree. This gives it an element id, which the
-   // overlay buttons need as their MIR target, and streams its name, which shows
-   // the distortion, e.g. "RhoPhi (5.0)".
-   eveMng->GetWorld()->AddElement(mng);
+   // Add the manager to the scene it fills. This gives it an element id, which
+   // the overlay buttons need as their MIR target, and streams its name, which
+   // shows the distortion, e.g. "RhoPhi (5.0)".
+   scene->AddElement(mng);
 
    auto ovl = eveMng->SpawnNewScene(Form("%s Axis", name), name);
    ovl->SetIsOverlay(true);

@@ -400,7 +400,6 @@ sap.ui.define([
          // Motion settings, in a collapsed panel since they matter only while
          // something moves:
          //
-         //   MotionMaxHz        how often the update stream is applied
          //   RenderMaxHz        how often the result is drawn
          //   ExtrapolateMotion  whether anything is drawn between updates
          let motion = new sap.m.Panel({
@@ -411,10 +410,6 @@ sap.ui.define([
          });
          this.getView().byId("GED").addContent(motion);
 
-         this.makeSliderSetter(el.MotionMaxHz, "MotionMaxHz", null,
-            {min: 0, max: 60, step: 1,
-             tip: "Updates per second this viewer applies. 0 freezes the scene."},
-            motion);
          this.makeSliderSetter(el.RenderMaxHz, "RenderMaxHz", null,
             {min: 0, max: 120, step: 1,
              tip: "Animation redraws per second. 0 is uncapped -- every display frame."},

@@ -450,17 +450,19 @@ sap.ui.define([], function() {
                jQuery.extend(obj, em);
                this.ParseUpdateTriggersAndProcessPostStream(obj);
             }
-            else if (em.changeBit & this.EChangeBits.kCBColorSelection) {
-               delete em.render_data;
-               Object.assign(obj, em);
-            }
-            else if (em.changeBit & this.EChangeBits.kCBTransBBox) {
-               // Transformation-only update: no render data is streamed.
-               // render_data.matrix is updated here because a later rebuild,
-               // e.g. on a colour change, reads it.
-               Object.assign(obj, em);
-               if (em.matrix && obj.render_data)
-                  obj.render_data.matrix = em.matrix;
+            else {
+               if (em.changeBit & this.EChangeBits.kCBColorSelection) {
+                  delete em.render_data;
+                  Object.assign(obj, em);
+               }
+               if (em.changeBit & this.EChangeBits.kCBTransBBox) {
+                  // Transformation update: no render data is streamed.
+                  // render_data.matrix is updated here because a later rebuild,
+                  // e.g. on a colour change in the same message, reads it.
+                  Object.assign(obj, em);
+                  if (em.matrix && obj.render_data)
+                     obj.render_data.matrix = em.matrix;
+               }
             }
 
             this.callSceneElementChange(scene, em);
@@ -811,10 +813,6 @@ sap.ui.define([], function() {
             let obj = this.map[em.fElementId];
             if (!obj) continue;   // removed, or not yet created
 
-            // The message's own timestamp, so a viewer's rate cap can decide
-            // once for the whole message rather than once per element.
-            em.msg_t = resp.t;
-
             // Keep the model in step: a later rebuild reads render_data.matrix,
             // and a stale one would put the object back where it used to be.
             if (em.matrix && obj.render_data)

@@ -263,18 +263,14 @@ sap.ui.define(['rootui5/eve7/lib/EveManager'], function(EveManager) {
          let el = this.mgr.GetElement(msg.fElementId);
          if (!el) return;
 
-         // The viewer's rate cap. Dropping an update is safe because each
-         // carries absolute state.
-         let mo = this.glctrl ? this.glctrl.viewer.motion : null;
-         if (mo && !mo.acceptUpdate(msg.msg_t)) return;
-
          this.updateElementTrans(el, msg);
 
          // No endChanges() follows, so request the render here. Going through
          // Motion applies the viewer's render cap.
+         let mo = this.glctrl.viewer.motion;
          if (mo)
             mo.requestRender();
-         else if (this.glctrl && this.glctrl.viewer)
+         else
             this.glctrl.viewer.request_render();
       }
 

@@ -583,6 +583,8 @@ sap.ui.define([
          setTimeout(this.syncCamTransTimer.bind(this), 5000);
       }
 
+      /** Set scene_bbox from the scene. An empty scene gets a fallback box of
+       * +-100. Returns true when the scene was empty. */
       recalcSceneBBox()
       {
          // Exclude the axis: it is built from this box, and its ticks reach past
@@ -592,7 +594,8 @@ sap.ui.define([
          if (ax) this.scene.remove(ax);
          this.scene_bbox.setFromObject( this.scene );
          if (ax) this.scene.add(ax);
-         if (this.scene_bbox.isEmpty())
+         const empty = this.scene_bbox.isEmpty();
+         if (empty)
          {
             console.error("GlViewerRenderCore.positionCameraAndLights scene bbox empty", this.scene_bbox);
             const ext = 100;
@@ -602,6 +605,7 @@ sap.ui.define([
          if (this.axis3d) this.axis3d.setBBox(this.axes_bbox || this.scene_bbox);
 
          this.updateRenderBBox();
+         return empty;
       }
 
       /** The box the camera's near and far planes are fitted to: axes_bbox or
@@ -619,7 +623,9 @@ sap.ui.define([
 
       positionCameraAndLights()
       {
-         this.recalcSceneBBox();
+         // An empty scene leaves the camera framing the fallback box; render()
+         // fits it again when content arrives.
+         this.camera_needs_fit = this.recalcSceneBBox();
 
          let eveView = this.controller.mgr.GetElement(this.controller.eveViewerId);
 
@@ -760,8 +766,6 @@ sap.ui.define([
          this.axis3d.setBBox(this.axes_bbox || this.scene_bbox);
          this.updateRenderBBox();
 
-         if (eveView.MotionMaxHz !== undefined && this.motion)
-            this.motion.setMaxHz(eveView.MotionMaxHz);
          if (eveView.RenderMaxHz !== undefined && this.motion)
             this.motion.setRenderMaxHz(eveView.RenderMaxHz);
          if (eveView.ExtrapolateMotion !== undefined && this.motion)
@@ -844,8 +848,10 @@ sap.ui.define([
          if (this.annotations) this.annotations.layout();
          if (this.axis3d) this.axis3d.updateForCamera(this.camera);
          if (this.render_requested_recalc_sbbox) {
-            this.recalcSceneBBox();
+            const empty = this.recalcSceneBBox();
             this.render_requested_recalc_sbbox = false;
+            if (this.camera_needs_fit && !empty)
+               this.positionCameraAndLights();
          }
          if (this.camera.isPerspectiveCamera) {
             this.camera.optimizeNearFar(this.render_bbox || this.scene_bbox);