Cycles: progressive refine option

Just makes progressive refine :)

This means the whole image would be refined gradually using as much
threads as it's set in performance settings. Having enough tiles is
required to have this option working as it's expected.

Technically it's implemented by repeatedly computing next sample for
all the tiles before switching to next sample.

This works around 7-12% slower than regular tile-based rendering, so
use this option only if you really need it.

This commit also fixes progressive update of image when Save Buffers
option is enabled.

And one more thing this commit fixes is handling display buffer with
Save Buffers option enabled. If this option is enabled image buffer
wouldn't have neither byte nor float buffer until image is fully
rendered which could backfire in missing image while rendering in
cases color management cache became full.

This issue solved by allocating byte buffer for image buffer from
tile update callback.

Patch was reviewed by Brecht. He also made some minor edits to
original version to patch. Thanks, man!

intern/cycles/render/session.cpp

@@ -96,6 +96,9 @@ Session::~Session()
 		display->write(device, params.output_path);
 	}
 
+	foreach(RenderBuffers *buffers, tile_buffers)
+		delete buffers;
+
 	delete buffers;
 	delete display;
 	delete scene;
@@ -173,6 +176,8 @@ bool Session::draw_gpu(BufferParams& buffer_params)
 
 void Session::run_gpu()
 {
+	bool tiles_written = false;
+
 	start_time = time_dt();
 	reset_time = time_dt();
 	paused_time = 0.0;
@@ -267,10 +272,15 @@ void Session::run_gpu()
 			if(device->error_message() != "")
 				progress.set_cancel(device->error_message());
 
+			tiles_written = update_progressive_refine(progress.get_cancel());
+
 			if(progress.get_cancel())
 				break;
 		}
 	}
+
+	if(!tiles_written)
+		update_progressive_refine(true);
 }
 
 /* CPU Session */
@@ -313,8 +323,12 @@ bool Session::draw_cpu(BufferParams& buffer_params)
 
 bool Session::acquire_tile(Device *tile_device, RenderTile& rtile)
 {
-	if(progress.get_cancel())
-		return false;
+	if(progress.get_cancel()) {
+		if(params.progressive_refine == false) {
+			/* for progressive refine current sample should be finished for all tiles */
+			return false;
+		}
+	}
 
 	thread_scoped_lock tile_lock(tile_mutex);
 
@@ -338,7 +352,7 @@ bool Session::acquire_tile(Device *tile_device, RenderTile& rtile)
 
 	/* in case of a permant buffer, return it, otherwise we will allocate
 	 * a new temporary buffer */
-	if(!write_render_tile_cb) {
+	if(!params.background) {
 		tile_manager.state.buffer.get_offset_stride(rtile.offset, rtile.stride);
 
 		rtile.buffer = buffers->buffer.device_pointer;
@@ -360,9 +374,35 @@ bool Session::acquire_tile(Device *tile_device, RenderTile& rtile)
 
 	buffer_params.get_offset_stride(rtile.offset, rtile.stride);
 
-	/* allocate buffers */
 	RenderBuffers *tilebuffers = new RenderBuffers(tile_device);
-	tilebuffers->reset(tile_device, buffer_params);
+
+	/* allocate buffers */
+	if(params.progressive_refine) {
+		int tile_x = rtile.x / params.tile_size.x;
+		int tile_y = rtile.y / params.tile_size.y;
+
+		int tile_index = tile_y * tile_manager.state.tile_w + tile_x;
+
+		tile_lock.lock();
+
+		if(tile_buffers.size() == 0)
+			tile_buffers.resize(tile_manager.state.num_tiles, NULL);
+
+		tilebuffers = tile_buffers[tile_index];
+		if(tilebuffers == NULL) {
+			tilebuffers = new RenderBuffers(tile_device);
+			tile_buffers[tile_index] = tilebuffers;
+
+			tilebuffers->reset(tile_device, buffer_params);
+		}
+
+		tile_lock.unlock();
+	}
+	else {
+		tilebuffers = new RenderBuffers(tile_device);
+
+		tilebuffers->reset(tile_device, buffer_params);
+	}
 
 	rtile.buffer = tilebuffers->buffer.device_pointer;
 	rtile.rng_state = tilebuffers->rng_state.device_pointer;
@@ -377,9 +417,11 @@ void Session::update_tile_sample(RenderTile& rtile)
 	thread_scoped_lock tile_lock(tile_mutex);
 
 	if(update_render_tile_cb) {
-		/* todo: optimize this by making it thread safe and removing lock */
+		if(params.progressive_refine == false) {
+			/* todo: optimize this by making it thread safe and removing lock */
 
-		update_render_tile_cb(rtile);
+			update_render_tile_cb(rtile);
+		}
 	}
 
 	update_status_time();
@@ -390,10 +432,12 @@ void Session::release_tile(RenderTile& rtile)
 	thread_scoped_lock tile_lock(tile_mutex);
 
 	if(write_render_tile_cb) {
-		/* todo: optimize this by making it thread safe and removing lock */
-		write_render_tile_cb(rtile);
+		if(params.progressive_refine == false) {
+			/* todo: optimize this by making it thread safe and removing lock */
+			write_render_tile_cb(rtile);
 
-		delete rtile.buffers;
+			delete rtile.buffers;
+		}
 	}
 
 	update_status_time();
@@ -401,6 +445,8 @@ void Session::release_tile(RenderTile& rtile)
 
 void Session::run_cpu()
 {
+	bool tiles_written = false;
+
 	{
 		/* reset once to start */
 		thread_scoped_lock reset_lock(delayed_reset.mutex);
@@ -502,10 +548,15 @@ void Session::run_cpu()
 
 			if(device->error_message() != "")
 				progress.set_cancel(device->error_message());
+
+			tiles_written = update_progressive_refine(progress.get_cancel());
 		}
 
 		progress.set_update();
 	}
+
+	if(!tiles_written)
+		update_progressive_refine(true);
 }
 
 void Session::run()
@@ -722,6 +773,7 @@ void Session::path_trace()
 	task.get_cancel = function_bind(&Progress::get_cancel, &this->progress);
 	task.update_tile_sample = function_bind(&Session::update_tile_sample, this, _1);
 	task.update_progress_sample = function_bind(&Session::update_progress_sample, this);
+	task.need_finish_queue = params.progressive_refine;
 
 	device->task_add(task);
 }
@@ -752,5 +804,24 @@ void Session::tonemap()
 	display_outdated = false;
 }
 
-CCL_NAMESPACE_END
+bool Session::update_progressive_refine(bool cancel)
+{
+	int sample = tile_manager.state.sample + 1;
 
+	if(params.progressive_refine) {
+		foreach(RenderBuffers *buffers, tile_buffers) {
+			RenderTile rtile;
+			rtile.buffers = buffers;
+			rtile.sample = sample;
+
+			if(rtile.sample == params.samples || cancel)
+				write_render_tile_cb(rtile);
+			else
+				update_render_tile_cb(rtile);
+		}
+	}
+
+	return sample == params.samples;
+}
+
+CCL_NAMESPACE_END