Cleanup: Move mesh legacy conversion to a separate file

It's helpful to make the separation of legacy data formats explicit,
because it declutters actively changed code and makes it clear which
areas do not follow Blender's current design. In this case I separated
the `MFace`/"tessface" conversion code into a separate blenkernel
.cc file and header. This also makes refactoring to remove these
functions simpler because they're easier to find.

In the future, conversions to the `MLoopUV` type and `MVert`
can be implemented here for the same reasons (see T95965).

Differential Revision: https://developer.blender.org/D15396

1 files changed, 2 insertions, 76 deletions

diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
index ffbd824712a..98fa551590c 100644
--- a/source/blender/blenkernel/intern/mesh.cc
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -47,6 +47,7 @@
 #include "BKE_main.h"
 #include "BKE_material.h"
 #include "BKE_mesh.h"
+#include "BKE_mesh_legacy_convert.h"
 #include "BKE_mesh_runtime.h"
 #include "BKE_mesh_wrapper.h"
 #include "BKE_modifier.h"
@@ -755,7 +756,7 @@ static void mesh_ensure_tessellation_customdata(Mesh *me)
     if (tottex_tessface != tottex_original || totcol_tessface != totcol_original) {
       BKE_mesh_tessface_clear(me);
 
-      CustomData_from_bmeshpoly(&me->fdata, &me->ldata, me->totface);
+      BKE_mesh_add_mface_layers(&me->fdata, &me->ldata, me->totface);
 
       /* TODO: add some `--debug-mesh` option. */
       if (G.debug & G_DEBUG) {
@@ -1352,74 +1353,6 @@ void BKE_mesh_orco_ensure(Object *ob, Mesh *mesh)
   CustomData_add_layer(&mesh->vdata, CD_ORCO, CD_ASSIGN, orcodata, mesh->totvert);
 }
 
-int BKE_mesh_mface_index_validate(MFace *mface, CustomData *fdata, int mfindex, int nr)
-{
-  /* first test if the face is legal */
-  if ((mface->v3 || nr == 4) && mface->v3 == mface->v4) {
-    mface->v4 = 0;
-    nr--;
-  }
-  if ((mface->v2 || mface->v4) && mface->v2 == mface->v3) {
-    mface->v3 = mface->v4;
-    mface->v4 = 0;
-    nr--;
-  }
-  if (mface->v1 == mface->v2) {
-    mface->v2 = mface->v3;
-    mface->v3 = mface->v4;
-    mface->v4 = 0;
-    nr--;
-  }
-
-  /* Check corrupt cases, bow-tie geometry,
-   * can't handle these because edge data won't exist so just return 0. */
-  if (nr == 3) {
-    if (
-        /* real edges */
-        mface->v1 == mface->v2 || mface->v2 == mface->v3 || mface->v3 == mface->v1) {
-      return 0;
-    }
-  }
-  else if (nr == 4) {
-    if (
-        /* real edges */
-        mface->v1 == mface->v2 || mface->v2 == mface->v3 || mface->v3 == mface->v4 ||
-        mface->v4 == mface->v1 ||
-        /* across the face */
-        mface->v1 == mface->v3 || mface->v2 == mface->v4) {
-      return 0;
-    }
-  }
-
-  /* prevent a zero at wrong index location */
-  if (nr == 3) {
-    if (mface->v3 == 0) {
-      static int corner_indices[4] = {1, 2, 0, 3};
-
-      SWAP(uint, mface->v1, mface->v2);
-      SWAP(uint, mface->v2, mface->v3);
-
-      if (fdata) {
-        CustomData_swap_corners(fdata, mfindex, corner_indices);
-      }
-    }
-  }
-  else if (nr == 4) {
-    if (mface->v3 == 0 || mface->v4 == 0) {
-      static int corner_indices[4] = {2, 3, 0, 1};
-
-      SWAP(uint, mface->v1, mface->v3);
-      SWAP(uint, mface->v2, mface->v4);
-
-      if (fdata) {
-        CustomData_swap_corners(fdata, mfindex, corner_indices);
-      }
-    }
-  }
-
-  return nr;
-}
-
 Mesh *BKE_mesh_from_object(Object *ob)
 {
   if (ob == nullptr) {
@@ -1709,13 +1642,6 @@ void BKE_mesh_translate(Mesh *me, const float offset[3], const bool do_keys)
   BKE_mesh_tag_coords_changed_uniformly(me);
 }
 
-void BKE_mesh_tessface_ensure(Mesh *mesh)
-{
-  if (mesh->totpoly && mesh->totface == 0) {
-    BKE_mesh_tessface_calc(mesh);
-  }
-}
-
 void BKE_mesh_tessface_clear(Mesh *mesh)
 {
   mesh_tessface_clear_intern(mesh, true);