Mesh: Move bevel weight out of MVert and MEdge

As described in T95966, the goal is to move to a "struct of arrays"
approach rather than gathering an arbitrary set of data in hard-coded
structs. This has performance benefits, but also code complexity
benefits (this patch removes plenty of code, though the boilerplate
for the new operators outweighs that here).

To mirror the internal change, the options for storing mesh bevel
weights are converted into operators that add or remove the layer,
like for some other layers.

The most complex change is to the solidify modifier, where bevel
weights had special handling. Other than that, most changes are
removing clearing of the weights, boilerplate for the add/remove
operators, and removing the manual transfer of bevel weights
in bmesh - mesh conversion.

Eventually bevel weights can become a fully generic attribute,
but for now this patch aims to avoid most functional changes.

Bevel weights are still written and read from the mesh in the old way,
so neither forward nor backward compatibility are affected. As described
in T95965, writing in the old format will be done until 4.0.

Differential Revision: https://developer.blender.org/D14077

1 files changed, 61 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/mesh_legacy_convert.cc b/source/blender/blenkernel/intern/mesh_legacy_convert.cc
index 2f67e303095..10fc8ff3195 100644
--- a/source/blender/blenkernel/intern/mesh_legacy_convert.cc
+++ b/source/blender/blenkernel/intern/mesh_legacy_convert.cc
@@ -918,6 +918,67 @@ void BKE_mesh_add_mface_layers(CustomData *fdata, CustomData *ldata, int total)
 /** \} */
 
 /* -------------------------------------------------------------------- */
+/** \name Bevel Weight Conversion
+ * \{ */
+
+void BKE_mesh_legacy_bevel_weight_from_layers(Mesh *mesh)
+{
+  using namespace blender;
+  MutableSpan<MVert> verts = mesh->verts_for_write();
+  if (const float *weights = static_cast<const float *>(
+          CustomData_get_layer(&mesh->vdata, CD_BWEIGHT))) {
+    mesh->cd_flag |= ME_CDFLAG_VERT_BWEIGHT;
+    for (const int i : verts.index_range()) {
+      verts[i].bweight = std::clamp(weights[i], 0.0f, 1.0f) * 255.0f;
+    }
+  }
+  else {
+    mesh->cd_flag &= ~ME_CDFLAG_VERT_BWEIGHT;
+    for (const int i : verts.index_range()) {
+      verts[i].bweight = 0;
+    }
+  }
+  MutableSpan<MEdge> edges = mesh->edges_for_write();
+  if (const float *weights = static_cast<const float *>(
+          CustomData_get_layer(&mesh->edata, CD_BWEIGHT))) {
+    mesh->cd_flag |= ME_CDFLAG_EDGE_BWEIGHT;
+    for (const int i : edges.index_range()) {
+      edges[i].bweight = std::clamp(weights[i], 0.0f, 1.0f) * 255.0f;
+    }
+  }
+  else {
+    mesh->cd_flag &= ~ME_CDFLAG_EDGE_BWEIGHT;
+    for (const int i : edges.index_range()) {
+      edges[i].bweight = 0;
+    }
+  }
+}
+
+void BKE_mesh_legacy_bevel_weight_to_layers(Mesh *mesh)
+{
+  using namespace blender;
+  const Span<MVert> verts = mesh->verts();
+  if (mesh->cd_flag & ME_CDFLAG_VERT_BWEIGHT) {
+    float *weights = static_cast<float *>(
+        CustomData_add_layer(&mesh->vdata, CD_BWEIGHT, CD_CONSTRUCT, nullptr, verts.size()));
+    for (const int i : verts.index_range()) {
+      weights[i] = verts[i].bweight / 255.0f;
+    }
+  }
+
+  const Span<MEdge> edges = mesh->edges();
+  if (mesh->cd_flag & ME_CDFLAG_EDGE_BWEIGHT) {
+    float *weights = static_cast<float *>(
+        CustomData_add_layer(&mesh->edata, CD_BWEIGHT, CD_CONSTRUCT, nullptr, edges.size()));
+    for (const int i : edges.index_range()) {
+      weights[i] = edges[i].bweight / 255.0f;
+    }
+  }
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
 /** \name Hide Attribute and Legacy Flag Conversion
  * \{ */