1 files changed, 24 insertions, 8 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_engine.c b/source/blender/draw/engines/eevee/eevee_engine.c
index 5d5bd7ea9ba..7d1f40ba5d8 100644
--- a/source/blender/draw/engines/eevee/eevee_engine.c
+++ b/source/blender/draw/engines/eevee/eevee_engine.c
@@ -401,7 +401,7 @@ static void eevee_id_world_update(void *vedata, World *wo)
   EEVEE_StorageList *stl = ((EEVEE_Data *)vedata)->stl;
   LightCache *lcache = stl->g_data->light_cache;
 
-  if (lcache == NULL || lcache == stl->lookdev_lightcache) {
+  if (ELEM(lcache, NULL, stl->lookdev_lightcache)) {
     /* Avoid Lookdev viewport clearing the update flag (see T67741). */
     return;
   }
@@ -459,12 +459,28 @@ static void eevee_render_to_image(void *vedata,
   EEVEE_render_modules_init(vedata, engine, depsgraph);
 
   int initial_frame = CFRA;
-  int steps = max_ii(1, scene->eevee.motion_blur_steps);
-  int time_steps_tot = (do_motion_blur) ? steps : 1;
+  float initial_subframe = SUBFRA;
+  float shuttertime = (do_motion_blur) ? scene->eevee.motion_blur_shutter : 0.0f;
+  int time_steps_tot = (do_motion_blur) ? max_ii(1, scene->eevee.motion_blur_steps) : 1;
   g_data->render_tot_samples = divide_ceil_u(scene->eevee.taa_render_samples, time_steps_tot);
-  /* Centered on frame for now. */
-  float time = CFRA - scene->eevee.motion_blur_shutter / 2.0f;
-  float time_step = scene->eevee.motion_blur_shutter / time_steps_tot;
+  /* Compute start time. The motion blur will cover `[time ...time + shuttertime]`. */
+  float time = initial_frame + initial_subframe;
+  switch (scene->eevee.motion_blur_position) {
+    case SCE_EEVEE_MB_START:
+      /* No offset. */
+      break;
+    case SCE_EEVEE_MB_CENTER:
+      time -= shuttertime * 0.5f;
+      break;
+    case SCE_EEVEE_MB_END:
+      time -= shuttertime;
+      break;
+    default:
+      BLI_assert(!"Invalid motion blur position enum!");
+      break;
+  }
+
+  float time_step = shuttertime / time_steps_tot;
   for (int i = 0; i < time_steps_tot && !RE_engine_test_break(engine); i++) {
     float time_prev = time;
     float time_curr = time + time_step * 0.5f;
@@ -562,9 +578,9 @@ static void eevee_render_to_image(void *vedata,
   /* Restore original viewport size. */
   DRW_render_viewport_size_set((int[2]){g_data->size_orig[0], g_data->size_orig[1]});
 
-  if (CFRA != initial_frame) {
+  if (CFRA != initial_frame || SUBFRA != initial_subframe) {
     /* Restore original frame number. This is because the render pipeline expects it. */
-    RE_engine_frame_set(engine, initial_frame, 0.0f);
+    RE_engine_frame_set(engine, initial_frame, initial_subframe);
   }
 }