Fix deferred lighting one-frame stale InvViewProj shadow flicker

SceneBase::Update called m_lightManager->UpdateAndBind() before object
updates. LightManager::UpdateDeferredCB builds InvViewProj from the
static Camera matrices, but the Camera object's Update() (which
refreshes those matrices) ran afterward, so the deferred CB was one
frame stale. The lighting pass reconstructed world positions from this
stale InvViewProj while the depth buffer had been written with the
fresh matrices, producing a coherent world-space shear on any camera
rotation. That shear projected every visible fragment into the wrong
shadow-map texels simultaneously, causing full-terrain shadow flashes
on vertical mouselook, jumping, and fast movement.

Fix: update objects first so Camera::View/Projection reflect the
current frame, then call UpdateAndBind so the deferred CB, shadow UBO,
and geometry/lighting passes all see the same matrices.

Author: CanReader

Engine/src/SceneBase.cpp

@@ -136,15 +136,22 @@ void SceneBase::Begin() {
 void SceneBase::Update(float deltaTime) {
     if (!bActive) return;
 
-    if (m_lightManager)
-        m_lightManager->UpdateAndBind();
-
+    // Update objects FIRST so Camera::View/Projection reflect this frame's
+    // rotation/position before any render-side UBO computes InvViewProj.
+    // Why: LightManager::UpdateDeferredCB reads the static Camera matrices
+    //      to build InvViewProj for the deferred lighting pass. If it ran
+    //      before the camera object updated, InvViewProj was one frame stale
+    //      and the lighting pass reconstructed wrong world positions on any
+    //      camera rotation, causing whole-terrain shadow flicker.
     for (size_t i = 0; i < Objects.GetSize(); ++i) {
         if (Objects[i] && Objects[i]->IsActive() && !Objects[i]->HasParent()) {
             Objects[i]->Update(deltaTime);
         }
     }
 
+    if (m_lightManager)
+        m_lightManager->UpdateAndBind();
+
     if (m_skybox)
         m_skybox->Render();