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blender-archive/source/blender/blenkernel/intern/cdderivedmesh.cc
Hans Goudey 16fbadde36 Mesh: Replace MLoop struct with generic attributes
Implements #102359.

Split the `MLoop` struct into two separate integer arrays called
`corner_verts` and `corner_edges`, referring to the vertex each corner
is attached to and the next edge around the face at each corner. These
arrays can be sliced to give access to the edges or vertices in a face.
Then they are often referred to as "poly_verts" or "poly_edges".

The main benefits are halving the necessary memory bandwidth when only
one array is used and simplifications from using regular integer indices
instead of a special-purpose struct.

The commit also starts a renaming from "loop" to "corner" in mesh code.

Like the other mesh struct of array refactors, forward compatibility is
kept by writing files with the older format. This will be done until 4.0
to ease the transition process.

Looking at a small portion of the patch should give a good impression
for the rest of the changes. I tried to make the changes as small as
possible so it's easy to tell the correctness from the diff. Though I
found Blender developers have been very inventive over the last decade
when finding different ways to loop over the corners in a face.

For performance, nearly every piece of code that deals with `Mesh` is
slightly impacted. Any algorithm that is memory bottle-necked should
see an improvement. For example, here is a comparison of interpolating
a vertex float attribute to face corners (Ryzen 3700x):

**Before** (Average: 3.7 ms, Min: 3.4 ms)
```
threading::parallel_for(loops.index_range(), 4096, [&](IndexRange range) {
  for (const int64_t i : range) {
    dst[i] = src[loops[i].v];
  }
});
```

**After** (Average: 2.9 ms, Min: 2.6 ms)
```
array_utils::gather(src, corner_verts, dst);
```

That's an improvement of 28% to the average timings, and it's also a
simplification, since an index-based routine can be used instead.
For more examples using the new arrays, see the design task.

Pull Request: blender/blender#104424
2023-03-20 15:55:13 +01:00

260 lines
7.4 KiB
C++

/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright 2006 Blender Foundation. All rights reserved. */
/** \file
* \ingroup bke
* Implementation of #CDDerivedMesh.
* BKE_cdderivedmesh.h contains the function prototypes for this file.
*/
#include <climits>
#include <cmath>
#include <cstring>
#include "atomic_ops.h"
#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BKE_DerivedMesh.h"
#include "BKE_cdderivedmesh.h"
#include "BKE_curve.h"
#include "BKE_editmesh.h"
#include "BKE_mesh.hh"
#include "BKE_mesh_mapping.h"
#include "BKE_object.h"
#include "BKE_paint.h"
#include "BKE_pbvh.h"
#include "DNA_curve_types.h" /* for Curve */
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_object_types.h"
#include "MEM_guardedalloc.h"
struct CDDerivedMesh {
DerivedMesh dm;
/* these point to data in the DerivedMesh custom data layers,
* they are only here for efficiency and convenience */
float (*vert_positions)[3];
const blender::float3 *vert_normals;
MEdge *medge;
MFace *mface;
int *corner_verts;
int *corner_edges;
MPoly *mpoly;
/* Cached */
struct PBVH *pbvh;
bool pbvh_draw;
/* Mesh connectivity */
MeshElemMap *pmap;
int *pmap_mem;
};
/**************** DerivedMesh interface functions ****************/
static int cdDM_getNumVerts(DerivedMesh *dm)
{
return dm->numVertData;
}
static int cdDM_getNumEdges(DerivedMesh *dm)
{
return dm->numEdgeData;
}
static int cdDM_getNumLoops(DerivedMesh *dm)
{
return dm->numLoopData;
}
static int cdDM_getNumPolys(DerivedMesh *dm)
{
return dm->numPolyData;
}
static void cdDM_copyVertArray(DerivedMesh *dm, float (*r_positions)[3])
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
memcpy(r_positions, cddm->vert_positions, sizeof(float[3]) * dm->numVertData);
}
static void cdDM_copyEdgeArray(DerivedMesh *dm, MEdge *r_edge)
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
memcpy(r_edge, cddm->medge, sizeof(*r_edge) * dm->numEdgeData);
}
static void cdDM_copyCornerVertArray(DerivedMesh *dm, int *r_corner_verts)
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
memcpy(r_corner_verts, cddm->corner_verts, sizeof(*r_corner_verts) * dm->numLoopData);
}
static void cdDM_copyCornerEdgeArray(DerivedMesh *dm, int *r_corner_edges)
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
memcpy(r_corner_edges, cddm->corner_edges, sizeof(*r_corner_edges) * dm->numLoopData);
}
static void cdDM_copyPolyArray(DerivedMesh *dm, MPoly *r_poly)
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
memcpy(r_poly, cddm->mpoly, sizeof(*r_poly) * dm->numPolyData);
}
static void cdDM_getVertCo(DerivedMesh *dm, int index, float r_co[3])
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
copy_v3_v3(r_co, cddm->vert_positions[index]);
}
static void cdDM_getVertNo(DerivedMesh *dm, int index, float r_no[3])
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
copy_v3_v3(r_no, cddm->vert_normals[index]);
}
static void cdDM_recalc_looptri(DerivedMesh *dm)
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
const uint totpoly = dm->numPolyData;
const uint totloop = dm->numLoopData;
DM_ensure_looptri_data(dm);
BLI_assert(totpoly == 0 || cddm->dm.looptris.array_wip != NULL);
blender::bke::mesh::looptris_calc(
{reinterpret_cast<const blender::float3 *>(cddm->vert_positions), dm->numVertData},
{cddm->mpoly, totpoly},
{cddm->corner_verts, totloop},
{dm->looptris.array_wip, dm->looptris.num});
BLI_assert(cddm->dm.looptris.array == NULL);
atomic_cas_ptr(
(void **)&cddm->dm.looptris.array, cddm->dm.looptris.array, cddm->dm.looptris.array_wip);
cddm->dm.looptris.array_wip = nullptr;
}
static void cdDM_free_internal(CDDerivedMesh *cddm)
{
if (cddm->pmap) {
MEM_freeN(cddm->pmap);
}
if (cddm->pmap_mem) {
MEM_freeN(cddm->pmap_mem);
}
}
static void cdDM_release(DerivedMesh *dm)
{
CDDerivedMesh *cddm = (CDDerivedMesh *)dm;
if (DM_release(dm)) {
cdDM_free_internal(cddm);
MEM_freeN(cddm);
}
}
/**************** CDDM interface functions ****************/
static CDDerivedMesh *cdDM_create(const char *desc)
{
CDDerivedMesh *cddm = MEM_cnew<CDDerivedMesh>(desc);
DerivedMesh *dm = &cddm->dm;
dm->getNumVerts = cdDM_getNumVerts;
dm->getNumEdges = cdDM_getNumEdges;
dm->getNumLoops = cdDM_getNumLoops;
dm->getNumPolys = cdDM_getNumPolys;
dm->copyVertArray = cdDM_copyVertArray;
dm->copyEdgeArray = cdDM_copyEdgeArray;
dm->copyCornerVertArray = cdDM_copyCornerVertArray;
dm->copyCornerEdgeArray = cdDM_copyCornerEdgeArray;
dm->copyPolyArray = cdDM_copyPolyArray;
dm->getVertDataArray = DM_get_vert_data_layer;
dm->getEdgeDataArray = DM_get_edge_data_layer;
dm->recalcLoopTri = cdDM_recalc_looptri;
dm->getVertCo = cdDM_getVertCo;
dm->getVertNo = cdDM_getVertNo;
dm->release = cdDM_release;
return cddm;
}
static DerivedMesh *cdDM_from_mesh_ex(Mesh *mesh,
eCDAllocType alloctype,
const CustomData_MeshMasks *mask)
{
CDDerivedMesh *cddm = cdDM_create(__func__);
DerivedMesh *dm = &cddm->dm;
CustomData_MeshMasks cddata_masks = *mask;
cddata_masks.lmask &= ~CD_MASK_MDISPS;
/* this does a referenced copy, with an exception for fluidsim */
DM_init(dm,
DM_TYPE_CDDM,
mesh->totvert,
mesh->totedge,
0 /* `mesh->totface` */,
mesh->totloop,
mesh->totpoly);
/* This should actually be dm->deformedOnly = mesh->runtime.deformed_only,
* but only if the original mesh had its deformed_only flag correctly set
* (which isn't generally the case). */
dm->deformedOnly = 1;
CustomData_merge(&mesh->vdata, &dm->vertData, cddata_masks.vmask, alloctype, mesh->totvert);
CustomData_merge(&mesh->edata, &dm->edgeData, cddata_masks.emask, alloctype, mesh->totedge);
CustomData_merge(&mesh->fdata,
&dm->faceData,
cddata_masks.fmask | CD_MASK_ORIGINDEX,
alloctype,
0 /* `mesh->totface` */);
CustomData_merge(&mesh->ldata, &dm->loopData, cddata_masks.lmask, alloctype, mesh->totloop);
CustomData_merge(&mesh->pdata, &dm->polyData, cddata_masks.pmask, alloctype, mesh->totpoly);
cddm->vert_positions = static_cast<float(*)[3]>(CustomData_get_layer_named_for_write(
&dm->vertData, CD_PROP_FLOAT3, "position", mesh->totvert));
/* Though this may be an unnecessary calculation, simply retrieving the layer may return nothing
* or dirty normals. */
cddm->vert_normals = mesh->vert_normals().data();
cddm->medge = static_cast<MEdge *>(
CustomData_get_layer_for_write(&dm->edgeData, CD_MEDGE, mesh->totedge));
cddm->corner_verts = static_cast<int *>(CustomData_get_layer_named_for_write(
&dm->loopData, CD_PROP_INT32, ".corner_vert", mesh->totloop));
cddm->corner_edges = static_cast<int *>(CustomData_get_layer_named_for_write(
&dm->loopData, CD_PROP_INT32, ".corner_edge", mesh->totloop));
cddm->mpoly = static_cast<MPoly *>(
CustomData_get_layer_for_write(&dm->polyData, CD_MPOLY, mesh->totpoly));
#if 0
cddm->mface = CustomData_get_layer(&dm->faceData, CD_MFACE);
#else
cddm->mface = nullptr;
#endif
/* commented since even when CD_ORIGINDEX was first added this line fails
* on the default cube, (after editmode toggle too) - campbell */
#if 0
BLI_assert(CustomData_has_layer(&cddm->dm.faceData, CD_ORIGINDEX));
#endif
return dm;
}
DerivedMesh *CDDM_from_mesh(Mesh *mesh)
{
return cdDM_from_mesh_ex(mesh, CD_REFERENCE, &CD_MASK_MESH);
}