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, 41 insertions, 0 deletions

diff --git a/source/blender/compositor/operations/COM_DifferenceMatteOperation.cc b/source/blender/compositor/operations/COM_DifferenceMatteOperation.cc
index 0acdfc1651f..31714b03b06 100644
--- a/source/blender/compositor/operations/COM_DifferenceMatteOperation.cc
+++ b/source/blender/compositor/operations/COM_DifferenceMatteOperation.cc
@@ -29,6 +29,7 @@ DifferenceMatteOperation::DifferenceMatteOperation()
 
   this->m_inputImage1Program = nullptr;
   this->m_inputImage2Program = nullptr;
+  flags.can_be_constant = true;
 }
 
 void DifferenceMatteOperation::initExecution()
@@ -86,4 +87,44 @@ void DifferenceMatteOperation::executePixelSampled(float output[4],
   }
 }
 
+void DifferenceMatteOperation::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 *color1 = it.in(0);
+    const float *color2 = it.in(1);
+
+    float difference = (fabsf(color2[0] - color1[0]) + fabsf(color2[1] - color1[1]) +
+                        fabsf(color2[2] - color1[2]));
+
+    /* Average together the distances. */
+    difference = difference / 3.0f;
+
+    const float tolerance = m_settings->t1;
+    const float falloff = m_settings->t2;
+
+    /* Make 100% transparent. */
+    if (difference <= tolerance) {
+      it.out[0] = 0.0f;
+    }
+    /* In the falloff region, make partially transparent. */
+    else if (difference <= falloff + tolerance) {
+      difference = difference - tolerance;
+      const float alpha = difference / falloff;
+      /* Only change if more transparent than before. */
+      if (alpha < color1[3]) {
+        it.out[0] = alpha;
+      }
+      else { /* Leave as before. */
+        it.out[0] = color1[3];
+      }
+    }
+    else {
+      /* Foreground object. */
+      it.out[0] = color1[3];
+    }
+  }
+}
+
 }  // namespace blender::compositor