EEVEE: Motion Blur: Add accumulation motion blur for better precision

This revisit the render pipeline to support time slicing for better motion
blur.

We support accumulation with or without the Post-process motion blur.

If using the post-process, we reuse last step next motion data to avoid
another scene reevaluation.

This also adds support for hair motion blur which is handled in a similar
way as mesh motion blur.

The total number of samples is distributed evenly accross all timesteps to
avoid sampling weighting issues. For this reason, the sample count is
(internally) rounded up to the next multiple of the step count.

Only FX Motion BLur: {F8632258}

FX Motion Blur + 4 time steps: {F8632260}

FX Motion Blur + 32 time steps: {F8632261}

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D8079

1 files changed, 42 insertions, 44 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_render.c b/source/blender/draw/engines/eevee/eevee_render.c
index 00b42130e43..f903fa905e8 100644
--- a/source/blender/draw/engines/eevee/eevee_render.c
+++ b/source/blender/draw/engines/eevee/eevee_render.c
@@ -46,12 +46,6 @@
 
 #include "eevee_private.h"
 
-bool EEVEE_render_do_motion_blur(const struct Depsgraph *depsgraph)
-{
-  Scene *scene = DEG_get_evaluated_scene(depsgraph);
-  return (scene->eevee.flag & SCE_EEVEE_MOTION_BLUR_ENABLED) != 0;
-}
-
 /* Return true if init properly. */
 bool EEVEE_render_init(EEVEE_Data *ved, RenderEngine *engine, struct Depsgraph *depsgraph)
 {
@@ -137,6 +131,29 @@ bool EEVEE_render_init(EEVEE_Data *ved, RenderEngine *engine, struct Depsgraph *
                                                   &sldata->common_data);
   }
 
+  EEVEE_render_view_sync(vedata, engine, depsgraph);
+
+  /* TODO(sergey): Shall render hold pointer to an evaluated camera instead? */
+  struct Object *ob_camera_eval = DEG_get_evaluated_object(depsgraph, RE_GetCamera(engine->re));
+
+  DRWView *view = (DRWView *)DRW_view_default_get();
+  DRW_view_camtexco_set(view, camtexcofac);
+
+  /* `EEVEE_renderpasses_init` will set the active render passes used by `EEVEE_effects_init`.
+   * `EEVEE_effects_init` needs to go second for TAA. */
+  EEVEE_renderpasses_init(vedata);
+  EEVEE_effects_init(sldata, vedata, ob_camera_eval, false);
+  EEVEE_materials_init(sldata, vedata, stl, fbl);
+  EEVEE_shadows_init(sldata);
+  EEVEE_lightprobes_init(sldata, vedata);
+
+  return true;
+}
+
+void EEVEE_render_view_sync(EEVEE_Data *vedata, RenderEngine *engine, struct Depsgraph *depsgraph)
+{
+  EEVEE_PrivateData *g_data = vedata->stl->g_data;
+
   /* Set the pers & view matrix. */
   float winmat[4][4], viewmat[4][4], viewinv[4][4];
   /* TODO(sergey): Shall render hold pointer to an evaluated camera instead? */
@@ -149,20 +166,13 @@ bool EEVEE_render_init(EEVEE_Data *ved, RenderEngine *engine, struct Depsgraph *
   invert_m4_m4(viewmat, viewinv);
 
   DRWView *view = DRW_view_create(viewmat, winmat, NULL, NULL, NULL);
-  DRW_view_camtexco_set(view, camtexcofac);
   DRW_view_reset();
   DRW_view_default_set(view);
   DRW_view_set_active(view);
+}
 
-  /* `EEVEE_renderpasses_init` will set the active render passes used by `EEVEE_effects_init`.
-   * `EEVEE_effects_init` needs to go second for TAA. */
-  EEVEE_renderpasses_init(vedata);
-  EEVEE_effects_init(sldata, vedata, ob_camera_eval, false);
-  EEVEE_materials_init(sldata, vedata, stl, fbl);
-  EEVEE_shadows_init(sldata);
-  EEVEE_lightprobes_init(sldata, vedata);
-
-  /* INIT CACHE */
+void EEVEE_render_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
+{
   EEVEE_bloom_cache_init(sldata, vedata);
   EEVEE_depth_of_field_cache_init(sldata, vedata);
   EEVEE_effects_cache_init(sldata, vedata);
@@ -175,8 +185,6 @@ bool EEVEE_render_init(EEVEE_Data *ved, RenderEngine *engine, struct Depsgraph *
   EEVEE_subsurface_cache_init(sldata, vedata);
   EEVEE_temporal_sampling_cache_init(sldata, vedata);
   EEVEE_volumes_cache_init(sldata, vedata);
-
-  return true;
 }
 
 /* Used by light cache. in this case engine is NULL. */
@@ -189,6 +197,8 @@ void EEVEE_render_cache(void *vedata,
   EEVEE_LightProbesInfo *pinfo = sldata->probes;
   bool cast_shadow = false;
 
+  eevee_id_update(vedata, &ob->id);
+
   if (pinfo->vis_data.collection) {
     /* Used for rendering probe with visibility groups. */
     bool ob_vis = BKE_collection_has_object_recursive(pinfo->vis_data.collection, ob);
@@ -485,27 +495,12 @@ static void eevee_render_draw_background(EEVEE_Data *vedata)
 
 void EEVEE_render_draw(EEVEE_Data *vedata, RenderEngine *engine, RenderLayer *rl, const rcti *rect)
 {
-  const DRWContextState *draw_ctx = DRW_context_state_get();
-  const Scene *scene_eval = DEG_get_evaluated_scene(draw_ctx->depsgraph);
   const char *viewname = RE_GetActiveRenderView(engine->re);
   EEVEE_PassList *psl = vedata->psl;
   EEVEE_StorageList *stl = vedata->stl;
   EEVEE_FramebufferList *fbl = vedata->fbl;
   DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
   EEVEE_ViewLayerData *sldata = EEVEE_view_layer_data_ensure();
-  EEVEE_PrivateData *g_data = stl->g_data;
-
-  /* FINISH CACHE */
-  EEVEE_volumes_cache_finish(sldata, vedata);
-  EEVEE_materials_cache_finish(sldata, vedata);
-  EEVEE_lights_cache_finish(sldata, vedata);
-  EEVEE_lightprobes_cache_finish(sldata, vedata);
-
-  EEVEE_effects_draw_init(sldata, vedata);
-  EEVEE_volumes_draw_init(sldata, vedata);
-
-  /* Sort transparents before the loop. */
-  DRW_pass_sort_shgroup_z(psl->transparent_pass);
 
   /* Push instances attributes to the GPU. */
   DRW_render_instance_buffer_finish();
@@ -515,20 +510,17 @@ void EEVEE_render_draw(EEVEE_Data *vedata, RenderEngine *engine, RenderLayer *rl
   GPU_framebuffer_bind(fbl->main_fb);
   DRW_hair_update();
 
-  uint tot_sample = scene_eval->eevee.taa_render_samples;
+  /* Sort transparents before the loop. */
+  DRW_pass_sort_shgroup_z(psl->transparent_pass);
+
+  uint tot_sample = stl->g_data->render_tot_samples;
   uint render_samples = 0;
 
   /* SSR needs one iteration to start properly. */
-  if (stl->effects->enabled_effects & EFFECT_SSR) {
+  if ((stl->effects->enabled_effects & EFFECT_SSR) && !stl->effects->ssr_was_valid_double_buffer) {
     tot_sample += 1;
   }
 
-  EEVEE_renderpasses_output_init(sldata, vedata, tot_sample);
-
-  if (RE_engine_test_break(engine)) {
-    return;
-  }
-
   while (render_samples < tot_sample && !RE_engine_test_break(engine)) {
     float clear_col[4] = {0.0f, 0.0f, 0.0f, 0.0f};
     float clear_depth = 1.0f;
@@ -624,6 +616,15 @@ void EEVEE_render_draw(EEVEE_Data *vedata, RenderEngine *engine, RenderLayer *rl
 
     RE_engine_update_progress(engine, (float)(render_samples++) / (float)tot_sample);
   }
+}
+
+void EEVEE_render_read_result(EEVEE_Data *vedata,
+                              RenderEngine *engine,
+                              RenderLayer *rl,
+                              const rcti *rect)
+{
+  const char *viewname = RE_GetActiveRenderView(engine->re);
+  EEVEE_ViewLayerData *sldata = EEVEE_view_layer_data_ensure();
 
   eevee_render_result_combined(rl, viewname, rect, vedata, sldata);
   eevee_render_result_mist(rl, viewname, rect, vedata, sldata);
@@ -638,9 +639,6 @@ void EEVEE_render_draw(EEVEE_Data *vedata, RenderEngine *engine, RenderLayer *rl
   eevee_render_result_bloom(rl, viewname, rect, vedata, sldata);
   eevee_render_result_volume_scatter(rl, viewname, rect, vedata, sldata);
   eevee_render_result_volume_transmittance(rl, viewname, rect, vedata, sldata);
-
-  /* Restore original viewport size. */
-  DRW_render_viewport_size_set((int[2]){g_data->size_orig[0], g_data->size_orig[1]});
 }
 
 void EEVEE_render_update_passes(RenderEngine *engine, Scene *scene, ViewLayer *view_layer)