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

1 files changed, 26 insertions, 6 deletions

diff --git a/intern/cycles/render/session.cpp b/intern/cycles/render/session.cpp
index f7df81a0601..361a1465aac 100644
--- a/intern/cycles/render/session.cpp
+++ b/intern/cycles/render/session.cpp
@@ -410,7 +410,16 @@ bool Session::acquire_tile(RenderTile &rtile, Device *tile_device, uint tile_typ
   rtile.num_samples = tile_manager.state.num_samples;
   rtile.resolution = tile_manager.state.resolution_divider;
   rtile.tile_index = tile->index;
-  rtile.task = tile->state == Tile::DENOISE ? RenderTile::DENOISE : RenderTile::PATH_TRACE;
+
+  if (tile->state == Tile::DENOISE) {
+    rtile.task = RenderTile::DENOISE;
+  }
+  else if (read_bake_tile_cb) {
+    rtile.task = RenderTile::BAKE;
+  }
+  else {
+    rtile.task = RenderTile::PATH_TRACE;
+  }
 
   tile_lock.unlock();
 
@@ -451,11 +460,20 @@ bool Session::acquire_tile(RenderTile &rtile, Device *tile_device, uint tile_typ
   rtile.buffers = tile->buffers;
   rtile.sample = tile_manager.state.sample;
 
-  /* this will tag tile as IN PROGRESS in blender-side render pipeline,
-   * which is needed to highlight currently rendering tile before first
-   * sample was processed for it
-   */
-  update_tile_sample(rtile);
+  if (read_bake_tile_cb) {
+    /* This will read any passes needed as input for baking. */
+    {
+      thread_scoped_lock tile_lock(tile_mutex);
+      read_bake_tile_cb(rtile);
+    }
+    rtile.buffers->buffer.copy_to_device();
+  }
+  else {
+    /* This will tag tile as IN PROGRESS in blender-side render pipeline,
+     * which is needed to highlight currently rendering tile before first
+     * sample was processed for it. */
+    update_tile_sample(rtile);
+  }
 
   return true;
 }
@@ -484,6 +502,7 @@ void Session::release_tile(RenderTile &rtile, const bool need_denoise)
   bool delete_tile;
 
   if (tile_manager.finish_tile(rtile.tile_index, need_denoise, delete_tile)) {
+    /* Finished tile pixels write. */
     if (write_render_tile_cb && params.progressive_refine == false) {
       write_render_tile_cb(rtile);
     }
@@ -494,6 +513,7 @@ void Session::release_tile(RenderTile &rtile, const bool need_denoise)
     }
   }
   else {
+    /* In progress tile pixels update. */
     if (update_render_tile_cb && params.progressive_refine == false) {
       update_render_tile_cb(rtile, false);
     }