Geometry Nodes: better support for byte color attributes

Since {rBeae36be372a6b16ee3e76eff0485a47da4f3c230} the distinction
between float and byte colors is more explicit in the ui. So far, geometry
nodes couldn't really deal with byte colors in general. This patch fixes that.
There is still only one color socket, which contains float colors. Conversion
to and from byte colors is done when read from or writing to attributes.

* Support writing to byte color attributes in Store Named Attribute node.
* Support converting to/from byte color in attribute conversion operator.
* Support propagating byte color attributes.
* Add all the implicit conversions from byte colors to the other types.
* Display byte colors as integers in spreadsheet.

Differential Revision: https://developer.blender.org/D14705

3 files changed, 28 insertions, 4 deletions

diff --git a/source/blender/blenlib/BLI_math_base.hh b/source/blender/blenlib/BLI_math_base.hh
index 83f414f853a..81f5343056e 100644
--- a/source/blender/blenlib/BLI_math_base.hh
+++ b/source/blender/blenlib/BLI_math_base.hh
@@ -102,7 +102,10 @@ template<typename T, BLI_ENABLE_IF((is_math_float_type<T>))> inline T fract(cons
   return a - std::floor(a);
 }
 
-template<typename T, typename FactorT, BLI_ENABLE_IF((is_math_float_type<FactorT>))>
+template<typename T,
+         typename FactorT,
+         BLI_ENABLE_IF((std::is_arithmetic_v<T>)),
+         BLI_ENABLE_IF((is_math_float_type<FactorT>))>
 inline T interpolate(const T &a, const T &b, const FactorT &t)
 {
   return a * (1 - t) + b * t;
diff --git a/source/blender/blenlib/BLI_math_color.hh b/source/blender/blenlib/BLI_math_color.hh
index 5195cfb6238..b16053509cf 100644
--- a/source/blender/blenlib/BLI_math_color.hh
+++ b/source/blender/blenlib/BLI_math_color.hh
@@ -15,9 +15,22 @@
 
 namespace blender::math {
 
-inline ColorGeometry4f interpolate(const ColorGeometry4f &a,
-                                   const ColorGeometry4f &b,
-                                   const float t)
+template<eAlpha Alpha>
+inline ColorSceneLinear4f<Alpha> interpolate(const ColorSceneLinear4f<Alpha> &a,
+                                             const ColorSceneLinear4f<Alpha> &b,
+                                             const float t)
+{
+  return {math::interpolate(a.r, b.r, t),
+          math::interpolate(a.g, b.g, t),
+          math::interpolate(a.b, b.b, t),
+          math::interpolate(a.a, b.a, t)};
+}
+
+template<eAlpha Alpha>
+inline ColorSceneLinearByteEncoded4b<Alpha> interpolate(
+    const ColorSceneLinearByteEncoded4b<Alpha> &a,
+    const ColorSceneLinearByteEncoded4b<Alpha> &b,
+    const float t)
 {
   return {math::interpolate(a.r, b.r, t),
           math::interpolate(a.g, b.g, t),
diff --git a/source/blender/blenlib/BLI_math_vec_types.hh b/source/blender/blenlib/BLI_math_vec_types.hh
index 0850864d86f..e36bbedee32 100644
--- a/source/blender/blenlib/BLI_math_vec_types.hh
+++ b/source/blender/blenlib/BLI_math_vec_types.hh
@@ -201,6 +201,14 @@ template<typename T, int Size> struct vec_base : public vec_struct_base<T, Size>
     }
   }
 
+  template<typename U, BLI_ENABLE_IF((std::is_convertible_v<U, T>))>
+  explicit vec_base(const U *ptr)
+  {
+    for (int i = 0; i < Size; i++) {
+      (*this)[i] = ptr[i];
+    }
+  }
+
   vec_base(const T (*ptr)[Size]) : vec_base(static_cast<const T *>(ptr[0]))
   {
   }