Realtime Compositor: Anti-alias morphological threshold

This patch anti-aliases the output of the morphological threshold
operation in the Dilate/Erode node. This is done to match the CPU
implementation.

source/blender/nodes/composite/nodes/node_composite_dilate.cc

@@ -21,6 +21,7 @@
 
 #include "COM_algorithm_morphological_distance.hh"
 #include "COM_algorithm_morphological_distance_feather.hh"
+#include "COM_algorithm_smaa.hh"
 #include "COM_node_operation.hh"
 #include "COM_utilities.hh"
 
@@ -195,7 +196,7 @@ class DilateErodeOperation : public NodeOperation {
     input_mask.bind_as_texture(shader, "input_tx");
 
     const Domain domain = compute_domain();
-    Result &output_mask = get_result("Mask");
+    Result output_mask = context().create_temporary_result(ResultType::Float);
     output_mask.allocate_texture(domain);
     output_mask.bind_as_image(shader, "output_img");
 
@@ -204,6 +205,17 @@ class DilateErodeOperation : public NodeOperation {
     GPU_shader_unbind();
     output_mask.unbind_as_image();
     input_mask.unbind_as_texture();
+
+    /* For configurations where there is little user-specified inset, anti-alias the result for
+     * smoother edges. */
+    Result &output = get_result("Mask");
+    if (get_inset() < 2.0f) {
+      smaa(context(), output_mask, output);
+      output_mask.release();
+    }
+    else {
+      output.steal_data(output_mask);
+    }
   }
 
   /* See the discussion in the implementation for more information. */