EEVEE: Rework deformation motion blur

This change how motion data are indexed inside the ghash.
We follow cycles closely now and use evaluated ID pointers.

By removing the hack, it fixes T78561 (No Motion Blur on linked objects)

3 files changed, 94 insertions, 60 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_data.c b/source/blender/draw/engines/eevee/eevee_data.c
index b7db6fef918..564e985b601 100644
--- a/source/blender/draw/engines/eevee/eevee_data.c
+++ b/source/blender/draw/engines/eevee/eevee_data.c
@@ -29,6 +29,7 @@
 
 #include "BKE_duplilist.h"
 #include "BKE_modifier.h"
+#include "BKE_object.h"
 
 #include "DEG_depsgraph_query.h"
 
@@ -42,15 +43,20 @@
 static void eevee_motion_blur_mesh_data_free(void *val)
 {
   EEVEE_GeometryMotionData *geom_mb = (EEVEE_GeometryMotionData *)val;
+  EEVEE_HairMotionData *hair_mb = (EEVEE_HairMotionData *)val;
   switch (geom_mb->type) {
-    case EEVEE_HAIR_GEOM_MOTION_DATA:
-      for (int i = 0; i < ARRAY_SIZE(geom_mb->vbo); i++) {
-        GPU_VERTBUF_DISCARD_SAFE(geom_mb->hair_pos[i]);
-        DRW_TEXTURE_FREE_SAFE(geom_mb->hair_pos_tx[i]);
+    case EEVEE_MOTION_DATA_HAIR:
+      for (int j = 0; j < hair_mb->psys_len; j++) {
+        for (int i = 0; i < ARRAY_SIZE(hair_mb->psys[0].hair_pos); i++) {
+          GPU_VERTBUF_DISCARD_SAFE(hair_mb->psys[j].hair_pos[i]);
+        }
+        for (int i = 0; i < ARRAY_SIZE(hair_mb->psys[0].hair_pos); i++) {
+          DRW_TEXTURE_FREE_SAFE(hair_mb->psys[j].hair_pos_tx[i]);
+        }
       }
       break;
 
-    case EEVEE_MESH_GEOM_MOTION_DATA:
+    case EEVEE_MOTION_DATA_MESH:
       for (int i = 0; i < ARRAY_SIZE(geom_mb->vbo); i++) {
         GPU_VERTBUF_DISCARD_SAFE(geom_mb->vbo[i]);
       }
@@ -148,9 +154,7 @@ EEVEE_ObjectMotionData *EEVEE_motion_blur_object_data_get(EEVEE_MotionBlurData *
   return ob_step;
 }
 
-static EEVEE_GeometryMotionData *motion_blur_geometry_data_get(EEVEE_MotionBlurData *mb,
-                                                               Object *ob,
-                                                               bool hair)
+static void *motion_blur_deform_data_get(EEVEE_MotionBlurData *mb, Object *ob, bool hair)
 {
   if (mb->geom == NULL) {
     return NULL;
@@ -161,13 +165,29 @@ static EEVEE_GeometryMotionData *motion_blur_geometry_data_get(EEVEE_MotionBlurD
     key = dup->ob;
   }
   else {
+    key = ob;
+  }
+  /* Only use data for object that have no modifiers. */
+  if (!BKE_object_is_modified(DRW_context_state_get()->scene, ob)) {
     key = ob->data;
   }
   key = (char *)key + (int)hair;
   EEVEE_GeometryMotionData *geom_step = BLI_ghash_lookup(mb->geom, key);
   if (geom_step == NULL) {
-    geom_step = MEM_callocN(sizeof(EEVEE_GeometryMotionData), __func__);
-    geom_step->type = hair ? EEVEE_HAIR_GEOM_MOTION_DATA : EEVEE_MESH_GEOM_MOTION_DATA;
+    if (hair) {
+      EEVEE_HairMotionData *hair_step;
+      /* Ugly, we allocate for each modifiers and just fill based on modifier index in the list. */
+      int psys_len = (ob->type != OB_HAIR) ? BLI_listbase_count(&ob->modifiers) : 1;
+      hair_step = MEM_callocN(sizeof(EEVEE_HairMotionData) + sizeof(hair_step->psys[0]) * psys_len,
+                              __func__);
+      hair_step->psys_len = psys_len;
+      geom_step = (EEVEE_GeometryMotionData *)hair_step;
+      geom_step->type = EEVEE_MOTION_DATA_HAIR;
+    }
+    else {
+      geom_step = MEM_callocN(sizeof(EEVEE_GeometryMotionData), __func__);
+      geom_step->type = EEVEE_MOTION_DATA_MESH;
+    }
     BLI_ghash_insert(mb->geom, key, geom_step);
   }
   return geom_step;
@@ -175,12 +195,12 @@ static EEVEE_GeometryMotionData *motion_blur_geometry_data_get(EEVEE_MotionBlurD
 
 EEVEE_GeometryMotionData *EEVEE_motion_blur_geometry_data_get(EEVEE_MotionBlurData *mb, Object *ob)
 {
-  return motion_blur_geometry_data_get(mb, ob, false);
+  return motion_blur_deform_data_get(mb, ob, false);
 }
 
-EEVEE_GeometryMotionData *EEVEE_motion_blur_hair_data_get(EEVEE_MotionBlurData *mb, Object *ob)
+EEVEE_HairMotionData *EEVEE_motion_blur_hair_data_get(EEVEE_MotionBlurData *mb, Object *ob)
 {
-  return motion_blur_geometry_data_get(mb, ob, true);
+  return motion_blur_deform_data_get(mb, ob, true);
 }
 
 /* View Layer data. */
diff --git a/source/blender/draw/engines/eevee/eevee_motion_blur.c b/source/blender/draw/engines/eevee/eevee_motion_blur.c
index e3dd4252018..a02007fede9 100644
--- a/source/blender/draw/engines/eevee/eevee_motion_blur.c
+++ b/source/blender/draw/engines/eevee/eevee_motion_blur.c
@@ -289,7 +289,14 @@ void EEVEE_motion_blur_hair_cache_populate(EEVEE_ViewLayerData *UNUSED(sldata),
     /* Store transform  */
     DRW_hair_duplimat_get(ob, psys, md, mb_data->obmat[mb_step]);
 
-    EEVEE_GeometryMotionData *mb_geom = EEVEE_motion_blur_hair_data_get(&effects->motion_blur, ob);
+    EEVEE_HairMotionData *mb_hair = EEVEE_motion_blur_hair_data_get(&effects->motion_blur, ob);
+    int psys_id = (md != NULL) ? BLI_findindex(&ob->modifiers, md) : 0;
+
+    if (psys_id >= mb_hair->psys_len) {
+      /* This should never happen. It means the modifier list was changed by frame evaluation. */
+      BLI_assert(0);
+      return;
+    }
 
     if (mb_step == MB_CURR) {
       /* Fill missing matrices if the object was hidden in previous or next frame. */
@@ -300,18 +307,21 @@ void EEVEE_motion_blur_hair_cache_populate(EEVEE_ViewLayerData *UNUSED(sldata),
         copy_m4_m4(mb_data->obmat[MB_NEXT], mb_data->obmat[MB_CURR]);
       }
 
+      GPUTexture *tex_prev = mb_hair->psys[psys_id].hair_pos_tx[MB_PREV];
+      GPUTexture *tex_next = mb_hair->psys[psys_id].hair_pos_tx[MB_NEXT];
+
       grp = DRW_shgroup_hair_create_sub(ob, psys, md, effects->motion_blur.hair_grp);
       DRW_shgroup_uniform_mat4(grp, "prevModelMatrix", mb_data->obmat[MB_PREV]);
       DRW_shgroup_uniform_mat4(grp, "currModelMatrix", mb_data->obmat[MB_CURR]);
       DRW_shgroup_uniform_mat4(grp, "nextModelMatrix", mb_data->obmat[MB_NEXT]);
-      DRW_shgroup_uniform_texture(grp, "prvBuffer", mb_geom->hair_pos_tx[MB_PREV]);
-      DRW_shgroup_uniform_texture(grp, "nxtBuffer", mb_geom->hair_pos_tx[MB_NEXT]);
-      DRW_shgroup_uniform_bool(grp, "useDeform", &mb_geom->use_deform, 1);
+      DRW_shgroup_uniform_texture(grp, "prvBuffer", tex_prev);
+      DRW_shgroup_uniform_texture(grp, "nxtBuffer", tex_next);
+      DRW_shgroup_uniform_bool(grp, "useDeform", &mb_hair->use_deform, 1);
     }
     else {
       /* Store vertex position buffer. */
-      mb_geom->hair_pos[mb_step] = DRW_hair_pos_buffer_get(ob, psys, md);
-      mb_geom->use_deform = true;
+      mb_hair->psys[psys_id].hair_pos[mb_step] = DRW_hair_pos_buffer_get(ob, psys, md);
+      mb_hair->use_deform = true;
     }
   }
 }
@@ -375,17 +385,6 @@ void EEVEE_motion_blur_cache_populate(EEVEE_ViewLayerData *UNUSED(sldata),
       }
 
       if (mb_geom->use_deform) {
-        EEVEE_ObjectEngineData *oedata = EEVEE_object_data_ensure(ob);
-        if (!oedata->geom_update) {
-          /* FIXME(fclem) There can be false positive where the actual mesh is not updated.
-           * This avoids a crash but removes the motion blur from some object.
-           * Maybe an issue with depsgraph tagging. */
-          mb_geom->use_deform = false;
-          oedata->geom_update = false;
-
-          GPU_VERTBUF_DISCARD_SAFE(mb_geom->vbo[MB_PREV]);
-          GPU_VERTBUF_DISCARD_SAFE(mb_geom->vbo[MB_NEXT]);
-        }
         /* Keep to modify later (after init). */
         mb_geom->batch = batch;
       }
@@ -445,29 +444,36 @@ void EEVEE_motion_blur_cache_finish(EEVEE_Data *vedata)
        BLI_ghashIterator_done(&ghi) == false;
        BLI_ghashIterator_step(&ghi)) {
     EEVEE_GeometryMotionData *mb_geom = BLI_ghashIterator_getValue(&ghi);
+    EEVEE_HairMotionData *mb_hair = (EEVEE_HairMotionData *)mb_geom;
 
     if (!mb_geom->use_deform) {
       continue;
     }
 
     switch (mb_geom->type) {
-      case EEVEE_HAIR_GEOM_MOTION_DATA:
+      case EEVEE_MOTION_DATA_HAIR:
         if (mb_step == MB_CURR) {
           /* TODO(fclem) Check if vertex count mismatch. */
-          mb_geom->use_deform = true;
+          mb_hair->use_deform = true;
         }
         else {
-          mb_geom->hair_pos[mb_step] = GPU_vertbuf_duplicate(mb_geom->hair_pos[mb_step]);
+          for (int i = 0; i < mb_hair->psys_len; i++) {
+            if (mb_hair->psys[i].hair_pos[mb_step] == NULL) {
+              continue;
+            }
+            mb_hair->psys[i].hair_pos[mb_step] = GPU_vertbuf_duplicate(
+                mb_hair->psys[i].hair_pos[mb_step]);
 
-          /* Create vbo immediately to bind to texture buffer. */
-          GPU_vertbuf_use(mb_geom->hair_pos[mb_step]);
+            /* Create vbo immediately to bind to texture buffer. */
+            GPU_vertbuf_use(mb_hair->psys[i].hair_pos[mb_step]);
 
-          mb_geom->hair_pos_tx[mb_step] = GPU_texture_create_from_vertbuf(
-              mb_geom->hair_pos[mb_step]);
+            mb_hair->psys[i].hair_pos_tx[mb_step] = GPU_texture_create_from_vertbuf(
+                mb_hair->psys[i].hair_pos[mb_step]);
+          }
         }
         break;
 
-      case EEVEE_MESH_GEOM_MOTION_DATA:
+      case EEVEE_MOTION_DATA_MESH:
         if (mb_step == MB_CURR) {
           /* Modify batch to have data from adjacent frames. */
           GPUBatch *batch = mb_geom->batch;
@@ -549,16 +555,19 @@ void EEVEE_motion_blur_swap_data(EEVEE_Data *vedata)
        BLI_ghashIterator_done(&ghi) == false;
        BLI_ghashIterator_step(&ghi)) {
     EEVEE_GeometryMotionData *mb_geom = BLI_ghashIterator_getValue(&ghi);
+    EEVEE_HairMotionData *mb_hair = (EEVEE_HairMotionData *)mb_geom;
 
     switch (mb_geom->type) {
-      case EEVEE_HAIR_GEOM_MOTION_DATA:
-        GPU_VERTBUF_DISCARD_SAFE(mb_geom->hair_pos[MB_PREV]);
-        DRW_TEXTURE_FREE_SAFE(mb_geom->hair_pos_tx[MB_PREV]);
-        mb_geom->hair_pos[MB_PREV] = mb_geom->hair_pos[MB_NEXT];
-        mb_geom->hair_pos_tx[MB_PREV] = mb_geom->hair_pos_tx[MB_NEXT];
+      case EEVEE_MOTION_DATA_HAIR:
+        for (int i = 0; i < mb_hair->psys_len; i++) {
+          GPU_VERTBUF_DISCARD_SAFE(mb_hair->psys[i].hair_pos[MB_PREV]);
+          DRW_TEXTURE_FREE_SAFE(mb_hair->psys[i].hair_pos_tx[MB_PREV]);
+          mb_hair->psys[i].hair_pos[MB_PREV] = mb_hair->psys[i].hair_pos[MB_NEXT];
+          mb_hair->psys[i].hair_pos_tx[MB_PREV] = mb_hair->psys[i].hair_pos_tx[MB_NEXT];
+        }
         break;
 
-      case EEVEE_MESH_GEOM_MOTION_DATA:
+      case EEVEE_MOTION_DATA_MESH:
         GPU_VERTBUF_DISCARD_SAFE(mb_geom->vbo[MB_PREV]);
         mb_geom->vbo[MB_PREV] = mb_geom->vbo[MB_NEXT];
 
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index dcc8ffb4c6f..a88eccc89a9 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -595,25 +595,30 @@ typedef struct EEVEE_ObjectMotionData {
 } EEVEE_ObjectMotionData;
 
 typedef enum eEEVEEMotionData {
-  EEVEE_MESH_GEOM_MOTION_DATA = 0,
-  EEVEE_HAIR_GEOM_MOTION_DATA,
+  EEVEE_MOTION_DATA_MESH = 0,
+  EEVEE_MOTION_DATA_HAIR,
 } eEEVEEMotionData;
 
+typedef struct EEVEE_HairMotionData {
+  /** Needs to be first to ensure casting. */
+  eEEVEEMotionData type;
+  int use_deform;
+  /** Allocator will alloc enough slot for all particle systems. Or 1 if it's a hair object. */
+  int psys_len;
+  struct {
+    struct GPUVertBuf *hair_pos[2];    /* Position buffer for time = t +/- step. */
+    struct GPUTexture *hair_pos_tx[2]; /* Buffer Texture of the corresponding VBO. */
+  } psys[0];
+} EEVEE_HairMotionData;
+
 typedef struct EEVEE_GeometryMotionData {
+  /** Needs to be first to ensure casting. */
   eEEVEEMotionData type;
-  int use_deform; /* To disable deform mb if vertcount mismatch. */
-  union {
-    struct {
-      /* Mesh */
-      struct GPUBatch *batch;    /* Batch for time = t. */
-      struct GPUVertBuf *vbo[2]; /* Vbo for time = t +/- step. */
-    };
-    struct {
-      /* Hair */
-      struct GPUVertBuf *hair_pos[2];    /* Position buffer for time = t +/- step. */
-      struct GPUTexture *hair_pos_tx[2]; /* Buffer Texture of the corresponding VBO. */
-    };
-  };
+  /** To disable deform mb if vertcount mismatch. */
+  int use_deform;
+
+  struct GPUBatch *batch;    /* Batch for time = t. */
+  struct GPUVertBuf *vbo[2]; /* Vbo for time = t +/- step. */
 } EEVEE_GeometryMotionData;
 
 /* ************ EFFECTS DATA ************* */
@@ -972,7 +977,7 @@ EEVEE_ObjectMotionData *EEVEE_motion_blur_object_data_get(EEVEE_MotionBlurData *
                                                           bool hair);
 EEVEE_GeometryMotionData *EEVEE_motion_blur_geometry_data_get(EEVEE_MotionBlurData *mb,
                                                               Object *ob);
-EEVEE_GeometryMotionData *EEVEE_motion_blur_hair_data_get(EEVEE_MotionBlurData *mb, Object *ob);
+EEVEE_HairMotionData *EEVEE_motion_blur_hair_data_get(EEVEE_MotionBlurData *mb, Object *ob);
 EEVEE_LightProbeEngineData *EEVEE_lightprobe_data_get(Object *ob);
 EEVEE_LightProbeEngineData *EEVEE_lightprobe_data_ensure(Object *ob);
 EEVEE_LightEngineData *EEVEE_light_data_get(Object *ob);