Ported Mesh Deform modifier

This modifier still has issues that are not related to this port:

- While editing the deformation mesh, the deformed mesh doesn't update.
  This update only happens after exiting edit mode, making editing
  cumbersome.
- Binding doesn't work yet. It works fine when binding in master and
  loading pre-bound in 2.8. This was also an issue before this port, and
  will be investigated separately.

8 files changed, 189 insertions, 63 deletions

diff --git a/source/blender/blenkernel/BKE_mesh.h b/source/blender/blenkernel/BKE_mesh.h
index 2adc1dbb6e3..6e10bc71cb5 100644
--- a/source/blender/blenkernel/BKE_mesh.h
+++ b/source/blender/blenkernel/BKE_mesh.h
@@ -102,11 +102,15 @@ void BKE_mesh_update_customdata_pointers(struct Mesh *me, const bool do_ensure_t
 void BKE_mesh_ensure_skin_customdata(struct Mesh *me);
 
 struct Mesh *BKE_mesh_new_nomain(int numVerts, int numEdges, int numTessFaces,int numLoops, int numPolys);
-struct Mesh * BKE_mesh_from_template(
+struct Mesh *BKE_mesh_from_template(
         const struct Mesh *me_src,
         int numVerts, int numEdges, int numTessFaces,
         int numLoops, int numPolys);
 
+/* These functions construct a new Mesh, contrary to BKE_mesh_from_nurbs which modifies ob itself. */
+struct Mesh *BKE_new_mesh_nomain_from_curve(struct Object *ob);
+struct Mesh *BKE_new_mesh_nomain_from_curve_displist(struct Object *ob, struct ListBase *dispbase);
+
 bool BKE_mesh_ensure_edit_data(struct Mesh *me);
 bool BKE_mesh_clear_edit_data(struct Mesh *me);
 
@@ -182,6 +186,8 @@ int  BKE_mesh_mselect_find(struct Mesh *me, int index, int type);
 int  BKE_mesh_mselect_active_get(struct Mesh *me, int type);
 void BKE_mesh_mselect_active_set(struct Mesh *me, int index, int type);
 
+void BKE_mesh_apply_vert_coords(struct Mesh *mesh, float (*vertCoords)[3]);
+
 /* *** mesh_runtime.c *** */
 
 void BKE_mesh_runtime_recalc_looptri(struct Mesh *mesh);
diff --git a/source/blender/blenkernel/intern/mesh.c b/source/blender/blenkernel/intern/mesh.c
index cece1a7c4c6..25e8405f69d 100644
--- a/source/blender/blenkernel/intern/mesh.c
+++ b/source/blender/blenkernel/intern/mesh.c
@@ -1497,6 +1497,58 @@ int BKE_mesh_nurbs_displist_to_mdata(
 	return 0;
 }
 
+Mesh *BKE_new_mesh_nomain_from_curve_displist(Object *ob, ListBase *dispbase)
+{
+	Curve *cu = ob->data;
+	Mesh *mesh;
+	MVert *allvert;
+	MEdge *alledge;
+	MLoop *allloop;
+	MPoly *allpoly;
+	MLoopUV *alluv = NULL;
+	int totvert, totedge, totloop, totpoly;
+	bool use_orco_uv = (cu->flag & CU_UV_ORCO) != 0;
+
+	if (BKE_mesh_nurbs_displist_to_mdata(
+	        ob, dispbase, &allvert, &totvert, &alledge,
+	        &totedge, &allloop, &allpoly, (use_orco_uv) ? &alluv : NULL,
+	        &totloop, &totpoly) != 0)
+	{
+		/* Error initializing mdata. This often happens when curve is empty */
+		return BKE_mesh_new_nomain(0, 0, 0, 0, 0);
+	}
+
+	mesh = BKE_mesh_new_nomain(totvert, totedge, 0, totloop, totpoly);
+	mesh->runtime.cd_dirty_vert |= CD_MASK_NORMAL;
+
+	memcpy(mesh->mvert, allvert, totvert * sizeof(MVert));
+	memcpy(mesh->medge, alledge, totedge * sizeof(MEdge));
+	memcpy(mesh->mloop, allloop, totloop * sizeof(MLoop));
+	memcpy(mesh->mpoly, allpoly, totpoly * sizeof(MPoly));
+
+	if (alluv) {
+		const char *uvname = "Orco";
+		CustomData_add_layer_named(&mesh->ldata, CD_MLOOPUV, CD_ASSIGN, alluv, totloop, uvname);
+	}
+
+	MEM_freeN(allvert);
+	MEM_freeN(alledge);
+	MEM_freeN(allloop);
+	MEM_freeN(allpoly);
+
+	return mesh;
+}
+
+Mesh *BKE_new_mesh_nomain_from_curve(Object *ob)
+{
+	ListBase disp = {NULL, NULL};
+
+	if (ob->curve_cache) {
+		disp = ob->curve_cache->disp;
+	}
+
+	return BKE_new_mesh_nomain_from_curve_displist(ob, &disp);
+}
 
 /* this may fail replacing ob->data, be sure to check ob->type */
 void BKE_mesh_from_nurbs_displist(Object *ob, ListBase *dispbase, const bool use_orco_uv, const char *obdata_name)
@@ -2226,6 +2278,22 @@ void BKE_mesh_mselect_active_set(Mesh *me, int index, int type)
 	           (me->mselect[me->totselect - 1].type  == type));
 }
 
+
+void BKE_mesh_apply_vert_coords(Mesh *mesh, float (*vertCoords)[3])
+{
+	MVert *vert;
+	int i;
+
+	/* this will just return the pointer if it wasn't a referenced layer */
+	vert = CustomData_duplicate_referenced_layer(&mesh->vdata, CD_MVERT, mesh->totvert);
+	mesh->mvert = vert;
+
+	for (i = 0; i < mesh->totvert; ++i, ++vert)
+		copy_v3_v3(vert->co, vertCoords[i]);
+
+	mesh->runtime.cd_dirty_vert |= CD_MASK_NORMAL;
+}
+
 /**
  * Compute 'split' (aka loop, or per face corner's) normals.
  *
@@ -2781,7 +2849,6 @@ Mesh *BKE_mesh_new_from_object(
 	return tmpmesh;
 }
 
-
 /* **** Depsgraph evaluation **** */
 
 void BKE_mesh_eval_geometry(Depsgraph *depsgraph,
diff --git a/source/blender/editors/armature/meshlaplacian.c b/source/blender/editors/armature/meshlaplacian.c
index eaae7dacbba..5503a4880df 100644
--- a/source/blender/editors/armature/meshlaplacian.c
+++ b/source/blender/editors/armature/meshlaplacian.c
@@ -833,7 +833,7 @@ typedef struct MeshDeformBind {
 	int size, size3;
 
 	/* meshes */
-	DerivedMesh *cagedm;
+	Mesh *cagemesh;
 	float (*cagecos)[3];
 	float (*vertexcos)[3];
 	int totvert, totcagevert;
@@ -863,7 +863,7 @@ typedef struct MeshDeformBind {
 		const MLoop *mloop;
 		const MLoopTri *looptri;
 		const float (*poly_nors)[3];
-	} cagedm_cache;
+	} cagemesh_cache;
 } MeshDeformBind;
 
 typedef struct MeshDeformIsect {
@@ -888,9 +888,9 @@ static void harmonic_ray_callback(void *userdata, int index, const BVHTreeRay *r
 {
 	struct MeshRayCallbackData *data = userdata;
 	MeshDeformBind *mdb = data->mdb;
-	const MLoop *mloop = mdb->cagedm_cache.mloop;
-	const MLoopTri *looptri = mdb->cagedm_cache.looptri, *lt;
-	const float (*poly_nors)[3] = mdb->cagedm_cache.poly_nors;
+	const MLoop *mloop = mdb->cagemesh_cache.mloop;
+	const MLoopTri *looptri = mdb->cagemesh_cache.looptri, *lt;
+	const float (*poly_nors)[3] = mdb->cagemesh_cache.poly_nors;
 	MeshDeformIsect *isec = data->isec;
 	float no[3], co[3], dist;
 	float *face[3];
@@ -954,9 +954,9 @@ static MDefBoundIsect *meshdeform_ray_tree_intersect(MeshDeformBind *mdb, const
 	if (BLI_bvhtree_ray_cast_ex(mdb->bvhtree, isect_mdef.start, vec_normal,
 	                            0.0, &hit, harmonic_ray_callback, &data, BVH_RAYCAST_WATERTIGHT) != -1)
 	{
-		const MLoop *mloop = mdb->cagedm_cache.mloop;
-		const MLoopTri *lt = &mdb->cagedm_cache.looptri[hit.index];
-		const MPoly *mp = &mdb->cagedm_cache.mpoly[lt->poly];
+		const MLoop *mloop = mdb->cagemesh_cache.mloop;
+		const MLoopTri *lt = &mdb->cagemesh_cache.looptri[hit.index];
+		const MPoly *mp = &mdb->cagemesh_cache.mpoly[lt->poly];
 		const float (*cagecos)[3] = mdb->cagecos;
 		const float len = isect_mdef.lambda;
 		MDefBoundIsect *isect;
@@ -1131,8 +1131,8 @@ static void meshdeform_bind_floodfill(MeshDeformBind *mdb)
 
 static float meshdeform_boundary_phi(const MeshDeformBind *mdb, const MDefBoundIsect *isect, int cagevert)
 {
-	const MLoop *mloop = mdb->cagedm_cache.mloop;
-	const MPoly *mp = &mdb->cagedm_cache.mpoly[isect->poly_index];
+	const MLoop *mloop = mdb->cagemesh_cache.mloop;
+	const MPoly *mp = &mdb->cagemesh_cache.mpoly[isect->poly_index];
 	int i;
 
 	for (i = 0; i < mp->totloop; i++) {
@@ -1447,7 +1447,7 @@ static void harmonic_coordinates_bind(Scene *UNUSED(scene), MeshDeformModifierDa
 	mdb->totalphi = MEM_callocN(sizeof(float) * mdb->size3, "MeshDeformBindTotalPhi");
 	mdb->boundisect = MEM_callocN(sizeof(*mdb->boundisect) * mdb->size3, "MDefBoundIsect");
 	mdb->semibound = MEM_callocN(sizeof(int) * mdb->size3, "MDefSemiBound");
-	mdb->bvhtree = bvhtree_from_mesh_get(&mdb->bvhdata, mdb->cagedm, BVHTREE_FROM_LOOPTRI, 4);
+	mdb->bvhtree = BKE_bvhtree_from_mesh_looptri(&mdb->bvhdata, mdb->cagemesh, FLT_EPSILON * 100, 4, 6);
 	mdb->inside = MEM_callocN(sizeof(int) * mdb->totvert, "MDefInside");
 
 	if (mmd->flag & MOD_MDEF_DYNAMIC_BIND)
@@ -1460,11 +1460,11 @@ static void harmonic_coordinates_bind(Scene *UNUSED(scene), MeshDeformModifierDa
 
 	/* initialize data from 'cagedm' for reuse */
 	{
-		DerivedMesh *dm = mdb->cagedm;
-		mdb->cagedm_cache.mpoly = dm->getPolyArray(dm);
-		mdb->cagedm_cache.mloop = dm->getLoopArray(dm);
-		mdb->cagedm_cache.looptri = dm->getLoopTriArray(dm);
-		mdb->cagedm_cache.poly_nors = dm->getPolyDataArray(dm, CD_NORMAL);  /* can be NULL */
+		Mesh *me = mdb->cagemesh;
+		mdb->cagemesh_cache.mpoly = me->mpoly;
+		mdb->cagemesh_cache.mloop = me->mloop;
+		mdb->cagemesh_cache.looptri = BKE_mesh_get_looptri_array(me);
+		mdb->cagemesh_cache.poly_nors = CustomData_get_layer(&me->pdata, CD_NORMAL);  /* can be NULL */
 	}
 
 	/* make bounding box equal size in all directions, add padding, and compute
@@ -1576,7 +1576,7 @@ static void harmonic_coordinates_bind(Scene *UNUSED(scene), MeshDeformModifierDa
 }
 
 void ED_mesh_deform_bind_callback(
-        Scene *scene, MeshDeformModifierData *mmd, DerivedMesh *cagedm,
+        Scene *scene, MeshDeformModifierData *mmd, Mesh *cagemesh,
         float *vertexcos, int totvert, float cagemat[4][4])
 {
 	MeshDeformBind mdb;
@@ -1592,12 +1592,12 @@ void ED_mesh_deform_bind_callback(
 	mdb.vertexcos = MEM_callocN(sizeof(float) * 3 * totvert, "MeshDeformCos");
 	mdb.totvert = totvert;
 	
-	mdb.cagedm = cagedm;
-	mdb.totcagevert = mdb.cagedm->getNumVerts(mdb.cagedm);
+	mdb.cagemesh = cagemesh;
+	mdb.totcagevert = mdb.cagemesh->totvert;
 	mdb.cagecos = MEM_callocN(sizeof(*mdb.cagecos) * mdb.totcagevert, "MeshDeformBindCos");
 	copy_m4_m4(mdb.cagemat, cagemat);
 
-	mvert = mdb.cagedm->getVertArray(mdb.cagedm);
+	mvert = mdb.cagemesh->mvert;
 	for (a = 0; a < mdb.totcagevert; a++)
 		copy_v3_v3(mdb.cagecos[a], mvert[a].co);
 	for (a = 0; a < mdb.totvert; a++)
diff --git a/source/blender/editors/include/ED_armature.h b/source/blender/editors/include/ED_armature.h
index 8b5886d65f1..2934745484a 100644
--- a/source/blender/editors/include/ED_armature.h
+++ b/source/blender/editors/include/ED_armature.h
@@ -43,7 +43,7 @@ struct Depsgraph;
 struct IDProperty;
 struct ListBase;
 struct MeshDeformModifierData;
-struct DerivedMesh;
+struct Mesh;
 struct Object;
 struct ReportList;
 struct Scene;
@@ -230,7 +230,7 @@ struct Object *ED_pose_object_from_context(struct bContext *C);
 void ED_mesh_deform_bind_callback(
         struct Scene *scene,
         struct MeshDeformModifierData *mmd,
-        struct DerivedMesh *cagedm,
+        struct Mesh *cagemesh,
         float *vertexcos, int totvert, float cagemat[4][4]);
 
 #ifdef __cplusplus
diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index cfa101b0b6e..148ffed7c7f 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -32,6 +32,8 @@
  * (ONLY ADD NEW ITEMS AT THE END)
  */
 
+struct Mesh;
+
 typedef enum ModifierType {
 	eModifierType_None              = 0,
 	eModifierType_Subsurf           = 1,
@@ -718,7 +720,7 @@ typedef struct MeshDeformModifierData {
 	float *bindcos;                 /* deprecated storage of cage coords */
 
 	/* runtime */
-	void (*bindfunc)(struct Scene *scene, struct MeshDeformModifierData *mmd, struct DerivedMesh *cagedm,
+	void (*bindfunc)(struct Scene *scene, struct MeshDeformModifierData *mmd, struct Mesh *cagemesh,
 	                 float *vertexcos, int totvert, float cagemat[4][4]);
 } MeshDeformModifierData;
 
diff --git a/source/blender/modifiers/intern/MOD_meshdeform.c b/source/blender/modifiers/intern/MOD_meshdeform.c
index 8b25d192f7f..de3c3d94ad0 100644
--- a/source/blender/modifiers/intern/MOD_meshdeform.c
+++ b/source/blender/modifiers/intern/MOD_meshdeform.c
@@ -32,6 +32,7 @@
  *  \ingroup modifiers
  */
 
+#include "DNA_mesh_types.h"
 #include "DNA_meshdata_types.h"
 #include "DNA_object_types.h"
 #include "DNA_scene_types.h"
@@ -40,9 +41,10 @@
 #include "BLI_task.h"
 #include "BLI_utildefines.h"
 
-#include "BKE_cdderivedmesh.h"
 #include "BKE_global.h"
+#include "BKE_library.h"
 #include "BKE_library_query.h"
+#include "BKE_mesh.h"
 #include "BKE_modifier.h"
 #include "BKE_deform.h"
 #include "BKE_editmesh.h"
@@ -273,17 +275,18 @@ static void meshdeform_vert_task(
 }
 
 static void meshdeformModifier_do(
-        ModifierData *md, struct Depsgraph *depsgraph, Object *ob, DerivedMesh *dm,
+        ModifierData *md, Object *ob, Mesh *mesh,
         float (*vertexCos)[3], int numVerts)
 {
 	MeshDeformModifierData *mmd = (MeshDeformModifierData *) md;
-	DerivedMesh *tmpdm, *cagedm;
+	Mesh *cagemesh;
 	MDeformVert *dvert = NULL;
 	float imat[4][4], cagemat[4][4], iobmat[4][4], icagemat[3][3], cmat[4][4];
 	float co[3], (*dco)[3], (*bindcagecos)[3];
 	int a, totvert, totcagevert, defgrp_index;
 	float (*cagecos)[3];
 	MeshdeformUserdata data;
+	bool free_cagemesh = false;
 
 	if (!mmd->object || (!mmd->bindcagecos && !mmd->bindfunc))
 		return;
@@ -299,23 +302,24 @@ static void meshdeformModifier_do(
 	 * We'll support this case once granular dependency graph is landed.
 	 */
 	if (mmd->object->mode & OB_MODE_EDIT) {
-		BMEditMesh *em = BKE_editmesh_from_object(mmd->object);
-		tmpdm = editbmesh_get_derived_cage_and_final(depsgraph, md->scene, mmd->object, em, 0, &cagedm);
-		if (tmpdm)
-			tmpdm->release(tmpdm);
+		/* TODO(Sybren): do we need to check the modifier mode in this case? */
+		/* TODO(Sybren): should we get from BMEditMesh *em = BKE_editmesh_from_object(mmd->object) instead? */
+		cagemesh = get_mesh_eval_for_modifier(ob, md->mode & eModifierMode_Render ? MOD_APPLY_RENDER : 0);
+	}
+	else {
+		cagemesh = get_mesh_eval_for_modifier(ob, md->mode & eModifierMode_Render ? MOD_APPLY_RENDER : 0);
 	}
-	else
-		cagedm = mmd->object->derivedFinal;
 
 	/* if we don't have one computed, use derivedmesh from data
 	 * without any modifiers */
-	if (!cagedm) {
-		cagedm = get_dm(mmd->object, NULL, NULL, NULL, false, false);
-		if (cagedm)
-			cagedm->needsFree = 1;
+	if (!cagemesh) {
+		cagemesh = get_mesh(mmd->object, NULL, NULL, NULL, false, false);
+		if (cagemesh) {
+			free_cagemesh = true;
+		}
 	}
 	
-	if (!cagedm) {
+	if (!cagemesh) {
 		modifier_setError(md, "Cannot get mesh from cage object");
 		return;
 	}
@@ -334,35 +338,33 @@ static void meshdeformModifier_do(
 		/* progress bar redraw can make this recursive .. */
 		if (!recursive) {
 			recursive = 1;
-			mmd->bindfunc(md->scene, mmd, cagedm, (float *)vertexCos, numVerts, cagemat);
+			mmd->bindfunc(md->scene, mmd, cagemesh, (float *)vertexCos, numVerts, cagemat);
 			recursive = 0;
 		}
 	}
 
 	/* verify we have compatible weights */
 	totvert = numVerts;
-	totcagevert = cagedm->getNumVerts(cagedm);
+	totcagevert = cagemesh->totvert;
 
 	if (mmd->totvert != totvert) {
 		modifier_setError(md, "Verts changed from %d to %d", mmd->totvert, totvert);
-		cagedm->release(cagedm);
+		if (free_cagemesh) BKE_id_free(NULL, cagemesh);
 		return;
 	}
 	else if (mmd->totcagevert != totcagevert) {
 		modifier_setError(md, "Cage verts changed from %d to %d", mmd->totcagevert, totcagevert);
-		cagedm->release(cagedm);
+		if (free_cagemesh) BKE_id_free(NULL, cagemesh);
 		return;
 	}
 	else if (mmd->bindcagecos == NULL) {
 		modifier_setError(md, "Bind data missing");
-		cagedm->release(cagedm);
+		if (free_cagemesh) BKE_id_free(NULL, cagemesh);
 		return;
 	}
 
-	cagecos = MEM_malloc_arrayN(totcagevert, sizeof(*cagecos), "meshdeformModifier vertCos");
-
 	/* setup deformation data */
-	cagedm->getVertCos(cagedm, cagecos);
+	cagecos = BKE_mesh_vertexCos_get(cagemesh, NULL);
 	bindcagecos = (float(*)[3])mmd->bindcagecos;
 
 	/* We allocate 1 element extra to make it possible to
@@ -383,7 +385,7 @@ static void meshdeformModifier_do(
 			copy_v3_v3(dco[a], co);
 	}
 
-	modifier_get_vgroup(ob, dm, mmd->defgrp_name, &dvert, &defgrp_index);
+	modifier_get_vgroup_mesh(ob, mesh, mmd->defgrp_name, &dvert, &defgrp_index);
 
 	/* Initialize data to be pass to the for body function. */
 	data.mmd = mmd;
@@ -406,36 +408,38 @@ static void meshdeformModifier_do(
 	/* release cage derivedmesh */
 	MEM_freeN(dco);
 	MEM_freeN(cagecos);
-	cagedm->release(cagedm);
+	if (free_cagemesh) BKE_id_free(NULL, cagemesh);
 }
 
 static void deformVerts(ModifierData *md, const ModifierEvalContext *ctx,
-                        DerivedMesh *derivedData,
+                        Mesh *mesh,
                         float (*vertexCos)[3],
                         int numVerts)
 {
-	DerivedMesh *dm = get_dm(ctx->object, NULL, derivedData, NULL, false, false);
+	Mesh *mesh_src = get_mesh(ctx->object, NULL, mesh, NULL, false, false);
 
 	modifier_vgroup_cache(md, vertexCos); /* if next modifier needs original vertices */
 
-	meshdeformModifier_do(md, ctx->depsgraph, ctx->object, dm, vertexCos, numVerts);
+	meshdeformModifier_do(md, ctx->object, mesh, vertexCos, numVerts);
 
-	if (dm && dm != derivedData)
-		dm->release(dm);
+	if (mesh_src && mesh_src != mesh) {
+		BKE_id_free(NULL, mesh_src);
+	}
 }
 
 static void deformVertsEM(ModifierData *md, const ModifierEvalContext *ctx,
                           struct BMEditMesh *UNUSED(editData),
-                          DerivedMesh *derivedData,
+                          Mesh *mesh,
                           float (*vertexCos)[3],
                           int numVerts)
 {
-	DerivedMesh *dm = get_dm(ctx->object, NULL, derivedData, NULL, false, false);
+	Mesh *mesh_src = get_mesh(ctx->object, NULL, mesh, NULL, false, false);
 
-	meshdeformModifier_do(md, ctx->depsgraph, ctx->object, dm, vertexCos, numVerts);
+	meshdeformModifier_do(md, ctx->object, mesh, vertexCos, numVerts);
 
-	if (dm && dm != derivedData)
-		dm->release(dm);
+	if (mesh_src && mesh_src != mesh) {
+		BKE_id_free(NULL, mesh_src);
+	}
 }
 
 #define MESHDEFORM_MIN_INFLUENCE 0.00001f
@@ -512,16 +516,16 @@ ModifierTypeInfo modifierType_MeshDeform = {
 
 	/* copyData */          copyData,
 
-	/* deformVerts_DM */    deformVerts,
+	/* deformVerts_DM */    NULL,
 	/* deformMatrices_DM */ NULL,
-	/* deformVertsEM_DM */  deformVertsEM,
+	/* deformVertsEM_DM */  NULL,
 	/* deformMatricesEM_DM*/NULL,
 	/* applyModifier_DM */  NULL,
 	/* applyModifierEM_DM */NULL,
 
-	/* deformVerts */       NULL,
+	/* deformVerts */       deformVerts,
 	/* deformMatrices */    NULL,
-	/* deformVertsEM */     NULL,
+	/* deformVertsEM */     deformVertsEM,
 	/* deformMatricesEM */  NULL,
 	/* applyModifier */     NULL,
 	/* applyModifierEM */   NULL,
diff --git a/source/blender/modifiers/intern/MOD_util.c b/source/blender/modifiers/intern/MOD_util.c
index a5e4a33b791..fd3f9e91b9e 100644
--- a/source/blender/modifiers/intern/MOD_util.c
+++ b/source/blender/modifiers/intern/MOD_util.c
@@ -46,8 +46,10 @@
 
 #include "BKE_cdderivedmesh.h"
 #include "BKE_deform.h"
+#include "BKE_editmesh.h"
 #include "BKE_image.h"
 #include "BKE_lattice.h"
+#include "BKE_library.h"
 #include "BKE_mesh.h"
 
 #include "BKE_modifier.h"
@@ -57,6 +59,8 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "bmesh.h"
+
 void modifier_init_texture(const Scene *scene, Tex *tex)
 {
 	if (!tex)
@@ -281,6 +285,47 @@ DerivedMesh *get_dm(Object *ob, struct BMEditMesh *em, DerivedMesh *dm,
 	return dm;
 }
 
+/* returns a mesh if mesh == NULL, for deforming modifiers that need it */
+Mesh *get_mesh(Object *ob, struct BMEditMesh *em, Mesh *mesh,
+               float (*vertexCos)[3], bool use_normals, bool use_orco)
+{
+	if (mesh) {
+		/* pass */
+	}
+	else if (ob->type == OB_MESH) {
+		struct BMeshToMeshParams bmtmp = {0};
+		if (em) mesh = BKE_bmesh_to_mesh_nomain(em->bm, &bmtmp);
+		else {
+			BKE_id_copy_ex(NULL, ob->data, (ID **)&mesh,
+			               LIB_ID_CREATE_NO_MAIN |
+			               LIB_ID_CREATE_NO_USER_REFCOUNT |
+                           LIB_ID_CREATE_NO_DEG_TAG,
+			               false);
+		}
+
+		if (vertexCos) {
+			BKE_mesh_apply_vert_coords(mesh, vertexCos);
+			mesh->runtime.cd_dirty_vert |= CD_MASK_NORMAL;
+		}
+
+		if (use_orco) {
+			CustomData_add_layer(&mesh->vdata, CD_ORCO, CD_ASSIGN, BKE_mesh_orco_verts_get(ob), mesh->totvert);
+		}
+	}
+	else if (ELEM(ob->type, OB_FONT, OB_CURVE, OB_SURF)) {
+		/* TODO(sybren): get evaluated mesh from depsgraph once that's properly generated for curves. */
+		mesh = BKE_new_mesh_nomain_from_curve(ob);
+	}
+
+	if (use_normals) {
+		if (LIKELY(mesh)) {
+			BKE_mesh_ensure_normals(mesh);
+		}
+	}
+
+	return mesh;
+}
+
 /* Get derived mesh for other object, which is used as an operand for the modifier,
  * i.e. second operand for boolean modifier.
  */
diff --git a/source/blender/modifiers/intern/MOD_util.h b/source/blender/modifiers/intern/MOD_util.h
index 4ac864a17ef..c3858084354 100644
--- a/source/blender/modifiers/intern/MOD_util.h
+++ b/source/blender/modifiers/intern/MOD_util.h
@@ -54,6 +54,8 @@ struct DerivedMesh *get_cddm(struct Object *ob, struct BMEditMesh *em, struct De
                              float (*vertexCos)[3], bool use_normals);
 struct DerivedMesh *get_dm(struct Object *ob, struct BMEditMesh *em, struct DerivedMesh *dm,
                            float (*vertexCos)[3], bool use_normals, bool use_orco);
+struct Mesh *get_mesh(struct Object *ob, struct BMEditMesh *em, struct Mesh *mesh,
+                      float (*vertexCos)[3], bool use_normals, bool use_orco);
 struct DerivedMesh *get_dm_for_modifier(struct Object *ob, ModifierApplyFlag flag);
 struct Mesh *get_mesh_eval_for_modifier(struct Object *ob, ModifierApplyFlag flag);