Cycles: code refactor to bake using regular render session and tiles

There should be no user visible change from this, except that tile size
now affects performance. The goal here is to simplify bake denoising in
D3099, letting it reuse more denoising tiles and pass code.

A lot of code is now shared with regular rendering, with the two main
differences being that we read some render result passes from the bake API
when starting to render a tile, and call the bake kernel instead of the
path trace kernel.

With this kind of design where Cycles asks for tiles from the bake API,
it should eventually be easier to reduce memory usage, show tiles as
they are baked, or bake multiple passes at once, though there's still
quite some work needed for that.

Reviewers: #cycles

Subscribers: monio, wmatyjewicz, lukasstockner97, michaelknubben

Differential Revision: https://developer.blender.org/D3108

6 files changed, 79 insertions, 141 deletions

diff --git a/intern/cycles/blender/addon/__init__.py b/intern/cycles/blender/addon/__init__.py
index 3d2a52d0cf6..3ab352e52a2 100644
--- a/intern/cycles/blender/addon/__init__.py
+++ b/intern/cycles/blender/addon/__init__.py
@@ -82,8 +82,8 @@ class CyclesRender(bpy.types.RenderEngine):
     def render(self, depsgraph):
         engine.render(self, depsgraph)
 
-    def bake(self, depsgraph, obj, pass_type, pass_filter, object_id, pixel_array, num_pixels, depth, result):
-        engine.bake(self, depsgraph, obj, pass_type, pass_filter, object_id, pixel_array, num_pixels, depth, result)
+    def bake(self, depsgraph, obj, pass_type, pass_filter, width, height):
+        engine.bake(self, depsgraph, obj, pass_type, pass_filter, width, height)
 
     # viewport render
     def view_update(self, context, depsgraph):
diff --git a/intern/cycles/blender/addon/engine.py b/intern/cycles/blender/addon/engine.py
index a1b063430f5..e7ea5e7a1f6 100644
--- a/intern/cycles/blender/addon/engine.py
+++ b/intern/cycles/blender/addon/engine.py
@@ -168,11 +168,11 @@ def render(engine, depsgraph):
         _cycles.render(engine.session, depsgraph.as_pointer())
 
 
-def bake(engine, depsgraph, obj, pass_type, pass_filter, object_id, pixel_array, num_pixels, depth, result):
+def bake(engine, depsgraph, obj, pass_type, pass_filter, width, height):
     import _cycles
     session = getattr(engine, "session", None)
     if session is not None:
-        _cycles.bake(engine.session, depsgraph.as_pointer(), obj.as_pointer(), pass_type, pass_filter, object_id, pixel_array.as_pointer(), num_pixels, depth, result.as_pointer())
+        _cycles.bake(engine.session, depsgraph.as_pointer(), obj.as_pointer(), pass_type, pass_filter, width, height)
 
 
 def reset(engine, data, depsgraph):
diff --git a/intern/cycles/blender/blender_python.cpp b/intern/cycles/blender/blender_python.cpp
index 8c7c0bc1daa..79c16856462 100644
--- a/intern/cycles/blender/blender_python.cpp
+++ b/intern/cycles/blender/blender_python.cpp
@@ -298,22 +298,18 @@ static PyObject *render_func(PyObject * /*self*/, PyObject *args)
 static PyObject *bake_func(PyObject * /*self*/, PyObject *args)
 {
   PyObject *pysession, *pydepsgraph, *pyobject;
-  PyObject *pypixel_array, *pyresult;
   const char *pass_type;
-  int num_pixels, depth, object_id, pass_filter;
+  int pass_filter, width, height;
 
   if (!PyArg_ParseTuple(args,
-                        "OOOsiiOiiO",
+                        "OOOsiii",
                         &pysession,
                         &pydepsgraph,
                         &pyobject,
                         &pass_type,
                         &pass_filter,
-                        &object_id,
-                        &pypixel_array,
-                        &num_pixels,
-                        &depth,
-                        &pyresult))
+                        &width,
+                        &height))
     return NULL;
 
   BlenderSession *session = (BlenderSession *)PyLong_AsVoidPtr(pysession);
@@ -326,23 +322,9 @@ static PyObject *bake_func(PyObject * /*self*/, PyObject *args)
   RNA_id_pointer_create((ID *)PyLong_AsVoidPtr(pyobject), &objectptr);
   BL::Object b_object(objectptr);
 
-  void *b_result = PyLong_AsVoidPtr(pyresult);
-
-  PointerRNA bakepixelptr;
-  RNA_pointer_create(NULL, &RNA_BakePixel, PyLong_AsVoidPtr(pypixel_array), &bakepixelptr);
-  BL::BakePixel b_bake_pixel(bakepixelptr);
-
   python_thread_state_save(&session->python_thread_state);
 
-  session->bake(b_depsgraph,
-                b_object,
-                pass_type,
-                pass_filter,
-                object_id,
-                b_bake_pixel,
-                (size_t)num_pixels,
-                depth,
-                (float *)b_result);
+  session->bake(b_depsgraph, b_object, pass_type, pass_filter, width, height);
 
   python_thread_state_restore(&session->python_thread_state);
 
diff --git a/intern/cycles/blender/blender_session.cpp b/intern/cycles/blender/blender_session.cpp
index 5ea96d6bdfd..31b09695632 100644
--- a/intern/cycles/blender/blender_session.cpp
+++ b/intern/cycles/blender/blender_session.cpp
@@ -247,9 +247,7 @@ void BlenderSession::reset_session(BL::BlendData &b_data, BL::Depsgraph &b_depsg
 
 void BlenderSession::free_session()
 {
-  if (sync)
-    delete sync;
-
+  delete sync;
   delete session;
 }
 
@@ -317,6 +315,7 @@ static void end_render_result(BL::RenderEngine &b_engine,
 
 void BlenderSession::do_write_update_render_tile(RenderTile &rtile,
                                                  bool do_update_only,
+                                                 bool do_read_only,
                                                  bool highlight)
 {
   int x = rtile.x - session->tile_manager.params.full_x;
@@ -342,7 +341,23 @@ void BlenderSession::do_write_update_render_tile(RenderTile &rtile,
 
   BL::RenderLayer b_rlay = *b_single_rlay;
 
-  if (do_update_only) {
+  if (do_read_only) {
+    /* copy each pass */
+    BL::RenderLayer::passes_iterator b_iter;
+
+    for (b_rlay.passes.begin(b_iter); b_iter != b_rlay.passes.end(); ++b_iter) {
+      BL::RenderPass b_pass(*b_iter);
+
+      /* find matching pass type */
+      PassType pass_type = BlenderSync::get_pass_type(b_pass);
+      int components = b_pass.channels();
+
+      rtile.buffers->set_pass_rect(pass_type, components, (float *)b_pass.rect());
+    }
+
+    end_render_result(b_engine, b_rr, false, false, false);
+  }
+  else if (do_update_only) {
     /* Sample would be zero at initial tile update, which is only needed
      * to tag tile form blender side as IN PROGRESS for proper highlight
      * no buffers should be sent to blender yet. For denoise we also
@@ -362,9 +377,14 @@ void BlenderSession::do_write_update_render_tile(RenderTile &rtile,
   }
 }
 
+void BlenderSession::read_render_tile(RenderTile &rtile)
+{
+  do_write_update_render_tile(rtile, false, true, false);
+}
+
 void BlenderSession::write_render_tile(RenderTile &rtile)
 {
-  do_write_update_render_tile(rtile, false, false);
+  do_write_update_render_tile(rtile, false, false, false);
 }
 
 void BlenderSession::update_render_tile(RenderTile &rtile, bool highlight)
@@ -374,9 +394,9 @@ void BlenderSession::update_render_tile(RenderTile &rtile, bool highlight)
    * would need to be investigated a bit further, but for now shall be fine
    */
   if (!b_engine.is_preview())
-    do_write_update_render_tile(rtile, true, highlight);
+    do_write_update_render_tile(rtile, true, false, highlight);
   else
-    do_write_update_render_tile(rtile, false, false);
+    do_write_update_render_tile(rtile, false, false, false);
 }
 
 static void add_cryptomatte_layer(BL::RenderResult &b_rr, string name, string manifest)
@@ -593,25 +613,6 @@ void BlenderSession::render(BL::Depsgraph &b_depsgraph_)
 #endif
 }
 
-static void populate_bake_data(BakeData *data,
-                               const int object_id,
-                               BL::BakePixel &pixel_array,
-                               const int num_pixels)
-{
-  BL::BakePixel bp = pixel_array;
-
-  int i;
-  for (i = 0; i < num_pixels; i++) {
-    if (bp.object_id() == object_id) {
-      data->set(i, bp.primitive_id(), bp.uv(), bp.du_dx(), bp.du_dy(), bp.dv_dx(), bp.dv_dy());
-    }
-    else {
-      data->set_null(i);
-    }
-    bp = bp.next();
-  }
-}
-
 static int bake_pass_filter_get(const int pass_filter)
 {
   int flag = BAKE_FILTER_NONE;
@@ -642,43 +643,26 @@ void BlenderSession::bake(BL::Depsgraph &b_depsgraph_,
                           BL::Object &b_object,
                           const string &pass_type,
                           const int pass_filter,
-                          const int object_id,
-                          BL::BakePixel &pixel_array,
-                          const size_t num_pixels,
-                          const int /*depth*/,
-                          float result[])
+                          const int bake_width,
+                          const int bake_height)
 {
   b_depsgraph = b_depsgraph_;
 
   ShaderEvalType shader_type = get_shader_type(pass_type);
-
-  /* Set baking flag in advance, so kernel loading can check if we need
-   * any baking capabilities.
-   */
-  scene->bake_manager->set_baking(true);
-
-  /* ensure kernels are loaded before we do any scene updates */
-  session->load_kernels();
-
-  if (shader_type == SHADER_EVAL_UV) {
-    /* force UV to be available */
-    Pass::add(PASS_UV, scene->film->passes);
-  }
-
   int bake_pass_filter = bake_pass_filter_get(pass_filter);
-  bake_pass_filter = BakeManager::shader_type_to_pass_filter(shader_type, bake_pass_filter);
 
-  /* force use_light_pass to be true if we bake more than just colors */
-  if (bake_pass_filter & ~BAKE_FILTER_COLOR) {
-    Pass::add(PASS_LIGHT, scene->film->passes);
-  }
+  /* Initialize bake manager, before we load the baking kernels. */
+  scene->bake_manager->set(scene, b_object.name(), shader_type, bake_pass_filter);
 
-  /* create device and update scene */
-  scene->film->tag_update(scene);
-  scene->integrator->tag_update(scene);
+  /* Passes are identified by name, so in order to return the combined pass we need to set the
+   * name. */
+  Pass::add(PASS_COMBINED, scene->film->passes, "Combined");
+
+  session->read_bake_tile_cb = function_bind(&BlenderSession::read_render_tile, this, _1);
+  session->write_render_tile_cb = function_bind(&BlenderSession::write_render_tile, this, _1);
 
   if (!session->progress.get_cancel()) {
-    /* update scene */
+    /* Sync scene. */
     BL::Object b_camera_override(b_engine.camera_override());
     sync->sync_camera(b_render, b_camera_override, width, height, "");
     sync->sync_data(
@@ -686,75 +670,43 @@ void BlenderSession::bake(BL::Depsgraph &b_depsgraph_,
     builtin_images_load();
   }
 
-  BakeData *bake_data = NULL;
+  /* Object might have been disabled for rendering or excluded in some
+   * other way, in that case Blender will report a warning afterwards. */
+  bool object_found = false;
+  foreach (Object *ob, scene->objects) {
+    if (ob->name == b_object.name()) {
+      object_found = true;
+      break;
+    }
+  }
 
-  if (!session->progress.get_cancel()) {
-    /* get buffer parameters */
+  if (object_found && !session->progress.get_cancel()) {
+    /* Get session and buffer parameters. */
     SessionParams session_params = BlenderSync::get_session_params(
         b_engine, b_userpref, b_scene, background);
-    BufferParams buffer_params = BlenderSync::get_buffer_params(
-        b_scene, b_render, b_v3d, b_rv3d, scene->camera, width, height);
+    session_params.progressive_refine = false;
 
-    scene->bake_manager->set_shader_limit((size_t)b_engine.tile_x(), (size_t)b_engine.tile_y());
+    BufferParams buffer_params;
+    buffer_params.width = bake_width;
+    buffer_params.height = bake_height;
+    buffer_params.passes = scene->film->passes;
 
-    /* set number of samples */
+    /* Update session. */
     session->tile_manager.set_samples(session_params.samples);
     session->reset(buffer_params, session_params.samples);
-    session->update_scene();
-
-    /* find object index. todo: is arbitrary - copied from mesh_displace.cpp */
-    size_t object_index = OBJECT_NONE;
-    int tri_offset = 0;
-
-    for (size_t i = 0; i < scene->objects.size(); i++) {
-      const Object *object = scene->objects[i];
-      const Geometry *geom = object->geometry;
-      if (object->name == b_object.name() && geom->type == Geometry::MESH) {
-        const Mesh *mesh = static_cast<const Mesh *>(geom);
-        object_index = i;
-        tri_offset = mesh->prim_offset;
-        break;
-      }
-    }
-
-    /* Object might have been disabled for rendering or excluded in some
-     * other way, in that case Blender will report a warning afterwards. */
-    if (object_index != OBJECT_NONE) {
-      int object = object_index;
-
-      bake_data = scene->bake_manager->init(object, tri_offset, num_pixels);
-      populate_bake_data(bake_data, object_id, pixel_array, num_pixels);
-    }
-
-    /* set number of samples */
-    session->tile_manager.set_samples(session_params.samples);
-    session->reset(buffer_params, session_params.samples);
-    session->update_scene();
 
     session->progress.set_update_callback(
         function_bind(&BlenderSession::update_bake_progress, this));
   }
 
   /* Perform bake. Check cancel to avoid crash with incomplete scene data. */
-  if (!session->progress.get_cancel() && bake_data) {
-    scene->bake_manager->bake(scene->device,
-                              &scene->dscene,
-                              scene,
-                              session->progress,
-                              shader_type,
-                              bake_pass_filter,
-                              bake_data,
-                              result);
+  if (object_found && !session->progress.get_cancel()) {
+    session->start();
+    session->wait();
   }
 
-  /* free all memory used (host and device), so we wouldn't leave render
-   * engine with extra memory allocated
-   */
-
-  session->device_free();
-
-  delete sync;
-  sync = NULL;
+  session->read_bake_tile_cb = function_null;
+  session->write_render_tile_cb = function_null;
 }
 
 void BlenderSession::do_write_update_render_result(BL::RenderLayer &b_rlay,
diff --git a/intern/cycles/blender/blender_session.h b/intern/cycles/blender/blender_session.h
index 3e6498bb655..34e952e312b 100644
--- a/intern/cycles/blender/blender_session.h
+++ b/intern/cycles/blender/blender_session.h
@@ -66,14 +66,12 @@ class BlenderSession {
             BL::Object &b_object,
             const string &pass_type,
             const int custom_flag,
-            const int object_id,
-            BL::BakePixel &pixel_array,
-            const size_t num_pixels,
-            const int depth,
-            float pixels[]);
+            const int bake_width,
+            const int bake_height);
 
   void write_render_result(BL::RenderLayer &b_rlay, RenderTile &rtile);
   void write_render_tile(RenderTile &rtile);
+  void read_render_tile(RenderTile &rtile);
 
   /* update functions are used to update display buffer only after sample was rendered
    * only needed for better visual feedback */
@@ -155,7 +153,10 @@ class BlenderSession {
   void do_write_update_render_result(BL::RenderLayer &b_rlay,
                                      RenderTile &rtile,
                                      bool do_update_only);
-  void do_write_update_render_tile(RenderTile &rtile, bool do_update_only, bool highlight);
+  void do_write_update_render_tile(RenderTile &rtile,
+                                   bool do_update_only,
+                                   bool do_read_only,
+                                   bool highlight);
 
   void builtin_images_load();
 
diff --git a/intern/cycles/blender/blender_sync.cpp b/intern/cycles/blender/blender_sync.cpp
index e8031be7dd1..f16305e737d 100644
--- a/intern/cycles/blender/blender_sync.cpp
+++ b/intern/cycles/blender/blender_sync.cpp
@@ -481,6 +481,9 @@ PassType BlenderSync::get_pass_type(BL::RenderPass &b_pass)
   MAP_PASS("AO", PASS_AO);
   MAP_PASS("Shadow", PASS_SHADOW);
 
+  MAP_PASS("BakePrimitive", PASS_BAKE_PRIMITIVE);
+  MAP_PASS("BakeDifferential", PASS_BAKE_DIFFERENTIAL);
+
 #ifdef __KERNEL_DEBUG__
   MAP_PASS("Debug BVH Traversed Nodes", PASS_BVH_TRAVERSED_NODES);
   MAP_PASS("Debug BVH Traversed Instances", PASS_BVH_TRAVERSED_INSTANCES);