Add position, rotation, scale attributes to instances

This commit does not currently compile, I'm pushing it so I can
continue work on another computer.

source/blender/blenkernel/BKE_geometry_set.hh

@@ -452,7 +452,12 @@ class InstancesComponent : public GeometryComponent {
 
   bool is_empty() const final;
 
+  int attribute_domain_size(const AttributeDomain domain) const final;
+
   static constexpr inline GeometryComponentType static_type = GEO_COMPONENT_TYPE_INSTANCES;
+
+ private:
+  const blender::bke::ComponentAttributeProviders *get_attribute_providers() const final;
 };
 
 /** A geometry component that stores volume grids. */

source/blender/blenkernel/intern/geometry_component_instances.cc

@@ -14,6 +14,7 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
+#include "BLI_float3.hh"
 #include "BLI_float4x4.hh"
 #include "BLI_map.hh"
 #include "BLI_rand.hh"
@@ -23,13 +24,18 @@
 
 #include "DNA_collection_types.h"
 
+#include "BKE_attribute_access.hh"
 #include "BKE_geometry_set.hh"
 
+#include "attribute_access_intern.hh"
+
+using blender::float3;
 using blender::float4x4;
 using blender::Map;
 using blender::MutableSpan;
 using blender::Set;
 using blender::Span;
+using blender::bke::ReadAttributePtr;
 
 /* -------------------------------------------------------------------- */
 /** \name Geometry Component Implementation
@@ -171,3 +177,132 @@ blender::Span<int> InstancesComponent::almost_unique_ids() const
 }
 
 /** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Attribute Access
+ * \{ */
+
+int InstancesComponent::attribute_domain_size(const AttributeDomain domain) const
+{
+  BLI_assert(this->attribute_domain_supported(domain));
+  switch (domain) {
+    case ATTR_DOMAIN_POINT:
+      return this->instances_amount();
+    default:
+      BLI_assert(false);
+      break;
+  }
+  return 0;
+}
+
+namespace blender::bke {
+
+static float3 get_matrix_position(const float4x4 &matrix)
+{
+  return matrix.translation();
+}
+
+static void set_matrix_position(float4x4 &matrix, const float3 &translation)
+{
+  copy_v3_v3(matrix.ptr()[3], translation);
+}
+
+static float3 get_matrix_rotation(const float4x4 &matrix)
+{
+  return matrix.to_euler();
+}
+
+static void set_matrix_rotation(float4x4 &matrix, const float3 &rotation)
+{
+  float4x4 rotation_matrix;
+  loc_eul_size_to_mat4(rotation_matrix.values, float3(0), rotation, float3(1));
+  matrix = matrix * rotation_matrix;
+}
+
+static float3 get_matrix_scale(const float4x4 &matrix)
+{
+  return matrix.scale();
+}
+
+static void set_matrix_scale(float4x4 &matrix, const float3 &scale)
+{
+  float4x4 scale_matrix;
+  size_to_mat4(scale_matrix.values, scale);
+  matrix = matrix * scale_matrix;
+}
+
+template<float3 (*GetFunc)(const float4x4 &), void (*SetFunc)(float4x4 &, const float3 &)>
+class Float4x4AttributeProvider final : public BuiltinAttributeProvider {
+ public:
+  Float4x4AttributeProvider(std::string attribute_name)
+      : BuiltinAttributeProvider(std::move(attribute_name),
+                                 ATTR_DOMAIN_POINT,
+                                 CD_PROP_FLOAT3,
+                                 NonCreatable,
+                                 Writable,
+                                 NonDeletable)
+  {
+  }
+
+  ReadAttributePtr try_get_for_read(const GeometryComponent &component) const final
+  {
+    const InstancesComponent &instances_component = static_cast<const InstancesComponent &>(
+        component);
+    if (instances_component.instances_amount() == 0) {
+      return {};
+    }
+
+    return std::make_unique<DerivedArrayReadAttribute<float4x4, float3, GetFunc>>(
+        ATTR_DOMAIN_POINT, instances_component.transforms());
+  }
+
+  WriteAttributePtr try_get_for_write(GeometryComponent &component) const final
+  {
+    InstancesComponent &instances_component = static_cast<InstancesComponent &>(component);
+    if (instances_component.instances_amount() == 0) {
+      return {};
+    }
+
+    return std::make_unique<DerivedArrayWriteAttribute<float4x4, float3, GetFunc, SetFunc>>(
+        ATTR_DOMAIN_POINT, instances_component.transforms());
+  }
+
+  bool try_delete(GeometryComponent &UNUSED(component)) const final
+  {
+    return false;
+  }
+
+  bool try_create(GeometryComponent &UNUSED(component)) const final
+  {
+    return false;
+  }
+
+  bool exists(const GeometryComponent &component) const final
+  {
+    return component.attribute_domain_size(ATTR_DOMAIN_POINT) != 0;
+  }
+};
+
+/**
+ * In this function all the attribute providers for the instances component are created. Most data
+ * in this function is statically allocated, because it does not change over time.
+ */
+static ComponentAttributeProviders create_attribute_providers_for_instances()
+{
+  static Float4x4AttributeProvider<get_matrix_position, set_matrix_position> position("position");
+  static Float4x4AttributeProvider<get_matrix_rotation, set_matrix_rotation> rotation("rotation");
+  static Float4x4AttributeProvider<get_matrix_scale, set_matrix_scale> scale("scale");
+  return ComponentAttributeProviders({&position, &rotation, &scale}, {});
+}
+
+}  // namespace blender::bke
+
+const blender::bke::ComponentAttributeProviders *InstancesComponent::get_attribute_providers()
+    const
+{
+  static blender::bke::ComponentAttributeProviders providers =
+      blender::bke::create_attribute_providers_for_instances();
+  return &providers;
+}
+
+/** \} */

source/blender/blenlib/BLI_float4x4.hh

@@ -79,6 +79,25 @@ struct float4x4 {
     return m * float3(v);
   }
 
+  float3 translation() const
+  {
+    return float3(values[3]);
+  }
+
+  float3 to_euler() const
+  {
+    float3 euler;
+    mat4_to_eul(euler, values);
+    return euler;
+  }
+
+  float3 scale() const
+  {
+    float3 scale;
+    mat4_to_size(scale, values);
+    return scale;
+  }
+
   float4x4 inverted() const
   {
     float4x4 result;

source/blender/makesrna/intern/rna_space.c

@@ -3044,7 +3044,9 @@ static void rna_SpaceSpreadsheet_geometry_component_type_update(Main *UNUSED(bma
                                                                 PointerRNA *ptr)
 {
   SpaceSpreadsheet *sspreadsheet = (SpaceSpreadsheet *)ptr->data;
-  if (sspreadsheet->geometry_component_type == GEO_COMPONENT_TYPE_POINT_CLOUD) {
+  if (ELEM(sspreadsheet->geometry_component_type,
+           GEO_COMPONENT_TYPE_POINT_CLOUD,
+           GEO_COMPONENT_TYPE_INSTANCES)) {
     sspreadsheet->attribute_domain = ATTR_DOMAIN_POINT;
   }
 }
@@ -7320,6 +7322,11 @@ static void rna_def_space_spreadsheet(BlenderRNA *brna)
        ICON_POINTCLOUD_DATA,
        "Point Cloud",
        "Point cloud component containing only point data"},
+      {GEO_COMPONENT_TYPE_INSTANCES,
+       "INSTANCES",
+       ICON_EMPTY_AXIS,
+       "Instances",
+       "Instances of objects or collections"},
       {0, NULL, 0, NULL, NULL},
   };