Fixed GFX running on wall time instead of sim. time

I noticed beacons run when game is paused and also ignore simulation speed, always running at wall time. I remembered there are multiple other issues like this (props/water waves moving when paused) and I figured a way to tackle everything at once - I changed the time input for the entire scene update code (which is already consolidated into `GfxScene::UpdateScene()`) - instead of inputting wall time, I now input the adjusted simulation time, and I input zero if the game is paused or physics are globally paused.

The particles had a custom code to correctly calc. sim. time and skip the update entirely when paused. I reverted all that, expecting the adjusted time input to fix particles, but that didn't work. I already researched this at RigsOfRods#3138 and figured to use `Ogre::ParticleSystem::setSpeedFactor()` - that did the trick.

source/main/gfx/DustPool.cpp

@@ -24,6 +24,7 @@
 
 #include "Application.h"
 #include "GameContext.h"
+#include "GfxScene.h"
 #include "Terrain.h"
 #include "Water.h"
 
@@ -193,8 +194,15 @@ void DustPool::allocRipple(Vector3 pos, Vector3 vel)
 
 void DustPool::update()
 {
+    float speed_factor = 0.f;
+    if (App::sim_state->getEnum<SimState>() == SimState::RUNNING && !App::GetGameContext()->GetActorManager()->IsSimulationPaused())
+    {
+        speed_factor = App::GetGfxScene()->GetSimDataBuffer().simbuf_sim_speed;
+    }
+
     for (int i = 0; i < allocated; i++)
     {
+        pss[i]->setSpeedFactor(speed_factor);
         ParticleEmitter* emit = pss[i]->getEmitter(0);
         Vector3 ndir = velocities[i];
         Real vel = ndir.length();

source/main/gfx/DustPool.h

@@ -80,7 +80,7 @@ class DustPool
     Ogre::SceneNode* sns[MAX_DUSTS];
     Ogre::SceneNode* parent_snode;
     Ogre::Vector3 positions[MAX_DUSTS];
-    Ogre::Vector3 velocities[MAX_DUSTS];
+    Ogre::Vector3 velocities[MAX_DUSTS]; //!< Velocity in wall time, ignoring the time scale.
     float rates[MAX_DUSTS];
     int allocated;
     int size;

source/main/gfx/GfxScene.cpp

@@ -89,6 +89,9 @@ void GfxScene::Init()
 
 void GfxScene::UpdateScene(float dt)
 {
+    // NOTE: The `dt` parameter here is simulation time (0 when paused), not real time!
+    // ================================================================================
+
     // Actors - start threaded tasks
     for (GfxActor* gfx_actor: m_live_gfx_actors)
     {
@@ -114,13 +117,14 @@ void GfxScene::UpdateScene(float dt)
     // Particles
     if (App::gfx_particles_mode->getInt() == 1)
     {
+        // Generate particles as needed
         for (GfxActor* gfx_actor: m_all_gfx_actors)
         {
-            if (!m_simbuf.simbuf_sim_paused && !gfx_actor->GetSimDataBuffer().simbuf_physics_paused)
-            {
-                gfx_actor->UpdateParticles(m_simbuf.simbuf_sim_speed * dt);
-            }
+            float dt_actor = (!gfx_actor->GetSimDataBuffer().simbuf_physics_paused) ? dt : 0.f;
+            gfx_actor->UpdateParticles(dt_actor);
         }
+
+        // Update particle movement
         for (auto itor : m_dustpools)
         {
             itor.second->update();
@@ -197,7 +201,7 @@ void GfxScene::UpdateScene(float dt)
     // HUD - network labels (always update)
     for (GfxActor* gfx_actor: m_all_gfx_actors)
     {
-        gfx_actor->UpdateNetLabels(m_simbuf.simbuf_sim_speed * dt);
+        gfx_actor->UpdateNetLabels(dt);
     }
 
     // Player avatars
@@ -209,6 +213,7 @@ void GfxScene::UpdateScene(float dt)
     // Actors - update misc visuals
     for (GfxActor* gfx_actor: m_all_gfx_actors)
     {
+        float dt_actor = (!gfx_actor->GetSimDataBuffer().simbuf_physics_paused) ? dt : 0.f;
         if (gfx_actor->IsActorLive())
         {
             gfx_actor->UpdateRods();
@@ -217,17 +222,18 @@ void GfxScene::UpdateScene(float dt)
             gfx_actor->UpdateAirbrakes();
             gfx_actor->UpdateCParticles();
             gfx_actor->UpdateAeroEngines();
-            gfx_actor->UpdatePropAnimations(dt);
+            gfx_actor->UpdatePropAnimations(dt_actor);
             gfx_actor->UpdateRenderdashRTT();
         }
         // Beacon flares must always be updated
-        gfx_actor->UpdateProps(dt, (gfx_actor == player_gfx_actor));
+        gfx_actor->UpdateProps(dt_actor, (gfx_actor == player_gfx_actor));
         // Blinkers (turn signals) must always be updated
-        gfx_actor->UpdateFlares(dt, (gfx_actor == player_gfx_actor));
+        gfx_actor->UpdateFlares(dt_actor, (gfx_actor == player_gfx_actor));
     }
     if (player_gfx_actor != nullptr)
     {
-        player_gfx_actor->UpdateVideoCameras(dt);
+        float dt_actor = (!player_gfx_actor->GetSimDataBuffer().simbuf_physics_paused) ? dt : 0.f;
+        player_gfx_actor->UpdateVideoCameras(dt_actor);
 
         // The old-style render-to-texture dashboard (based on OGRE overlays)
         if (m_simbuf.simbuf_player_actor->ar_driveable == TRUCK && m_simbuf.simbuf_player_actor->ar_engine != nullptr)

source/main/main.cpp

@@ -1676,6 +1676,13 @@ int main(int argc, char *argv[])
                 App::GetGfxScene()->BufferSimulationData();
             }
 
+            // Calculate elapsed simulation time (taking simulation speed and pause into account)
+            float dt_sim = 0.f;
+            if (App::sim_state->getEnum<SimState>() == SimState::RUNNING && !App::GetGameContext()->GetActorManager()->IsSimulationPaused())
+            {
+                dt_sim = dt * App::GetGameContext()->GetActorManager()->GetSimulationSpeed();
+            }
+
             // Advance simulation
             if (App::sim_state->getEnum<SimState>() == SimState::RUNNING)
             {
@@ -1689,7 +1696,7 @@ int main(int argc, char *argv[])
             }
             else if (App::app_state->getEnum<AppState>() == AppState::SIMULATION)
             {
-                App::GetGfxScene()->UpdateScene(dt); // Draws GUI as well
+                App::GetGfxScene()->UpdateScene(dt_sim); // Draws GUI as well
             }
 
             // Render!