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, 10 insertions, 0 deletions

diff --git a/source/blender/compositor/COM_defines.h b/source/blender/compositor/COM_defines.h
index ef889807030..5a52d216117 100644
--- a/source/blender/compositor/COM_defines.h
+++ b/source/blender/compositor/COM_defines.h
@@ -20,6 +20,16 @@
 
 namespace blender::compositor {
 
+enum class eExecutionModel {
+  /**
+   * Operations are executed from outputs to inputs grouped in execution groups and rendered
+   * in tiles.
+   */
+  Tiled,
+  /** Operations are fully rendered in order from inputs to outputs. */
+  FullFrame
+};
+
 /**
  * \brief possible data types for sockets
  * \ingroup Model