[Bf-blender-cvs] [0b0e45252b1] blender-v2.92-release: Geometry Nodes: Use a default value in the point scale node

[Hans Goudey]

Commit: 0b0e45252b11bbc1c0d96a3e04a4087d02f765e3
Author: Hans Goudey
Date:   Fri Jan 15 11:04:32 2021 -0600
Branches: blender-v2.92-release
https://developer.blender.org/rB0b0e45252b11bbc1c0d96a3e04a4087d02f765e3

Geometry Nodes: Use a default value in the point scale node

This commit adds the ability to provide a default value to
`attribute_try_get_for_output` and uses it for the `Point Scale` node,
which is important because the node uses multiplication.

The idea is to keep "name-specific" functionality in nodes rather than in
the attribute API, otherwise the complexity will be hard to keep track of.
So this fix doesn't apply to the Attribute Vector Math node, but hopfully
that is okay since that's now a lower level node for this purpose anyway.

Differential Revision: https://developer.blender.org/D10115

===================================================================

M	source/blender/blenkernel/BKE_geometry_set.hh
M	source/blender/blenkernel/intern/attribute_access.cc
M	source/blender/nodes/geometry/nodes/node_geo_point_scale.cc

===================================================================

diff --git a/source/blender/blenkernel/BKE_geometry_set.hh b/source/blender/blenkernel/BKE_geometry_set.hh
index 57fad6bcdf6..391bd243edf 100644
--- a/source/blender/blenkernel/BKE_geometry_set.hh
+++ b/source/blender/blenkernel/BKE_geometry_set.hh
@@ -242,7 +242,8 @@ class GeometryComponent {
 
   /**
    * If an attribute with the given params exist, it is returned.
-   * If no attribute with the given name exists, it is created and returned.
+   * If no attribute with the given name exists, create it and
+   * fill it with the default value if it is provided.
    * If an attribute with the given name but different domain or type exists, a temporary attribute
    * is created that has to be saved after the output has been computed. This avoids deleting
    * another attribute, before a computation is finished.
@@ -251,7 +252,8 @@ class GeometryComponent {
    */
   OutputAttributePtr attribute_try_get_for_output(const blender::StringRef attribute_name,
                                                   const AttributeDomain domain,
-                                                  const CustomDataType data_type);
+                                                  const CustomDataType data_type,
+                                                  const void *default_value = nullptr);
 };
 
 template<typename T>
diff --git a/source/blender/blenkernel/intern/attribute_access.cc b/source/blender/blenkernel/intern/attribute_access.cc
index 6739294a2c4..a7939beae90 100644
--- a/source/blender/blenkernel/intern/attribute_access.cc
+++ b/source/blender/blenkernel/intern/attribute_access.cc
@@ -814,7 +814,8 @@ blender::bke::ReadAttributePtr GeometryComponent::attribute_get_constant_for_rea
 
 OutputAttributePtr GeometryComponent::attribute_try_get_for_output(const StringRef attribute_name,
                                                                    const AttributeDomain domain,
-                                                                   const CustomDataType data_type)
+                                                                   const CustomDataType data_type,
+                                                                   const void *default_value)
 {
   BLI_assert(this->attribute_domain_with_type_supported(domain, data_type));
 
@@ -827,6 +828,11 @@ OutputAttributePtr GeometryComponent::attribute_try_get_for_output(const StringR
   if (!attribute) {
     this->attribute_try_create(attribute_name, domain, data_type);
     attribute = this->attribute_try_get_for_write(attribute_name);
+    if (default_value != nullptr) {
+      void *data = attribute->get_span_for_write_only().data();
+      cpp_type->fill_initialized(default_value, data, attribute->size());
+      attribute->apply_span();
+    }
     return OutputAttributePtr(std::move(attribute));
   }
 
diff --git a/source/blender/nodes/geometry/nodes/node_geo_point_scale.cc b/source/blender/nodes/geometry/nodes/node_geo_point_scale.cc
index e5cbe27768d..47fca93d2ab 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_point_scale.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_point_scale.cc
@@ -34,8 +34,9 @@ namespace blender::nodes {
 
 static void execute_on_component(GeoNodeExecParams params, GeometryComponent &component)
 {
+  static const float3 scale_default = float3(1.0f);
   OutputAttributePtr scale_attribute = component.attribute_try_get_for_output(
-      "scale", ATTR_DOMAIN_POINT, CD_PROP_FLOAT3);
+      "scale", ATTR_DOMAIN_POINT, CD_PROP_FLOAT3, &scale_default);
   ReadAttributePtr attribute = params.get_input_attribute(
       "Factor", component, ATTR_DOMAIN_POINT, CD_PROP_FLOAT3, nullptr);
   if (!attribute) {