fix trail creation for partial time steps

3 files changed, 6 insertions, 3 deletions

diff --git a/source/blender/simulations/bparticles/core.hpp b/source/blender/simulations/bparticles/core.hpp
index d1cf9939262..808dce63a5e 100644
--- a/source/blender/simulations/bparticles/core.hpp
+++ b/source/blender/simulations/bparticles/core.hpp
@@ -937,7 +937,7 @@ inline ArrayRef<float> OffsetHandlerInterface::durations()
 
 inline TimeSpan OffsetHandlerInterface::time_span(uint pindex)
 {
-  float duration = m_step_data.remaining_durations[pindex];
+  float duration = m_step_data.remaining_durations[pindex] * m_time_factors[pindex];
   return TimeSpan(m_step_data.step_end_time - duration, duration);
 }
 
diff --git a/source/blender/simulations/bparticles/forces.cpp b/source/blender/simulations/bparticles/forces.cpp
index e9e83744be4..1d859a3adc4 100644
--- a/source/blender/simulations/bparticles/forces.cpp
+++ b/source/blender/simulations/bparticles/forces.cpp
@@ -59,11 +59,14 @@ void CreateTrailHandler::execute(OffsetHandlerInterface &interface)
   SmallVector<float3> new_positions;
   SmallVector<float> new_birth_times;
   for (uint pindex : particles.pindices()) {
+    float time_factor = interface.time_factors()[pindex];
     TimeSpan time_span = interface.time_span(pindex);
     float current_time = frequency * (std::floor(time_span.start() / frequency) + 1.0f);
+
+    float3 total_offset = position_offsets[pindex] * time_factor;
     while (current_time < time_span.end()) {
       float factor = time_span.get_factor_safe(current_time);
-      new_positions.append(positions[pindex] + position_offsets[pindex] * factor);
+      new_positions.append(positions[pindex] + total_offset * factor);
       new_birth_times.append(current_time);
       current_time += frequency;
     }
diff --git a/source/blender/simulations/bparticles/simulate.cpp b/source/blender/simulations/bparticles/simulate.cpp
index 90f7116cd4e..5845e7c9518 100644
--- a/source/blender/simulations/bparticles/simulate.cpp
+++ b/source/blender/simulations/bparticles/simulate.cpp
@@ -539,7 +539,7 @@ BLI_NOINLINE static void ensure_required_containers_exist(ParticlesState &state,
 
   for (std::string type_name : description.particle_types().keys()) {
     if (!containers.contains(type_name)) {
-      ParticlesContainer *container = new ParticlesContainer({}, 100);
+      ParticlesContainer *container = new ParticlesContainer({}, 1000);
       containers.add_new(type_name, container);
     }
   }