Compositor: Full-frame base system

This patch adds the base code needed to make the full-frame system work for both current tiled/per-pixel implementation of operations and full-frame.

Two execution models:
- Tiled: Current implementation. Renders execution groups in tiles from outputs to input. Not all operations are buffered. Runs the tiled/per-pixel implementation.
- FullFrame: All operations are buffered. Fully renders operations from inputs to outputs. Runs full-frame implementation of operations if available otherwise the current tiled/per-pixel. Creates output buffers on first read and free them as soon as all its readers have finished, reducing peak memory usage of complex/long trees. Operations are multi-threaded but do not run in parallel as Tiled (will be done in another patch).

This should allow us to convert operations to full-frame in small steps with the system already working and solve the problem of high memory usage.

FullFrame breaking changes respect Tiled system, mainly:
- Translate, Rotate, Scale, and Transform take effect immediately instead of next buffered operation.
- Any sampling is always done over inputs instead of last buffered operation.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D11113

1 files changed, 26 insertions, 0 deletions

diff --git a/source/blender/compositor/intern/COM_MultiThreadedOperation.cc b/source/blender/compositor/intern/COM_MultiThreadedOperation.cc
new file mode 100644
index 00000000000..c54c2edccb0
--- /dev/null
+++ b/source/blender/compositor/intern/COM_MultiThreadedOperation.cc
@@ -0,0 +1,26 @@
+#include "COM_MultiThreadedOperation.h"
+#include "COM_ExecutionSystem.h"
+
+namespace blender::compositor {
+
+MultiThreadedOperation::MultiThreadedOperation()
+{
+  m_num_passes = 1;
+  flags.is_fullframe_operation = true;
+}
+
+void MultiThreadedOperation::update_memory_buffer(MemoryBuffer *output,
+                                                  const rcti &output_area,
+                                                  blender::Span<MemoryBuffer *> inputs,
+                                                  ExecutionSystem &exec_system)
+{
+  for (int current_pass = 0; current_pass < m_num_passes; current_pass++) {
+    update_memory_buffer_started(output, output_area, inputs, exec_system, current_pass);
+    exec_system.execute_work(output_area, [=, &exec_system](const rcti &split_rect) {
+      update_memory_buffer_partial(output, split_rect, inputs, exec_system, current_pass);
+    });
+    update_memory_buffer_finished(output, output_area, inputs, exec_system, current_pass);
+  }
+}
+
+}  // namespace blender::compositor