Compositor: Full frame matte nodes

Adds full frame implementation to Channel Key, Chroma Key, Color Key,
Color Spill, Cryptomatte, Difference Key, Distance Key, Keying,
Keying Screen and Luminance Key nodes. The other nodes
in "Matte" sub-menu are submitted separately.

No functional changes.

Part of T88150.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D12220

1 files changed, 45 insertions, 0 deletions

diff --git a/source/blender/compositor/operations/COM_KeyingOperation.cc b/source/blender/compositor/operations/COM_KeyingOperation.cc
index e786e4b8219..3edb5a5d34e 100644
--- a/source/blender/compositor/operations/COM_KeyingOperation.cc
+++ b/source/blender/compositor/operations/COM_KeyingOperation.cc
@@ -110,4 +110,49 @@ void KeyingOperation::executePixelSampled(float output[4], float x, float y, Pix
   }
 }
 
+void KeyingOperation::update_memory_buffer_partial(MemoryBuffer *output,
+                                                   const rcti &area,
+                                                   Span<MemoryBuffer *> inputs)
+{
+  for (BuffersIterator<float> it = output->iterate_with(inputs, area); !it.is_end(); ++it) {
+    const float *pixel_color = it.in(0);
+    const float *screen_color = it.in(1);
+
+    const int primary_channel = max_axis_v3(screen_color);
+    const float min_pixel_color = min_fff(pixel_color[0], pixel_color[1], pixel_color[2]);
+
+    if (min_pixel_color > 1.0f) {
+      /* Overexposure doesn't happen on screen itself and usually happens
+       * on light sources in the shot, this need to be checked separately
+       * because saturation and falloff calculation is based on the fact
+       * that pixels are not overexposed.
+       */
+      it.out[0] = 1.0f;
+    }
+    else {
+      const float saturation = get_pixel_saturation(pixel_color, m_screenBalance, primary_channel);
+      const float screen_saturation = get_pixel_saturation(
+          screen_color, m_screenBalance, primary_channel);
+
+      if (saturation < 0) {
+        /* Means main channel of pixel is different from screen,
+         * assume this is completely a foreground.
+         */
+        it.out[0] = 1.0f;
+      }
+      else if (saturation >= screen_saturation) {
+        /* Matched main channels and higher saturation on pixel
+         * is treated as completely background.
+         */
+        it.out[0] = 0.0f;
+      }
+      else {
+        /* Nice alpha falloff on edges. */
+        const float distance = 1.0f - saturation / screen_saturation;
+        it.out[0] = distance;
+      }
+    }
+  }
+}
+
 }  // namespace blender::compositor