/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2017 by Blender Foundation.
 * All rights reserved.
 *
 * Contributor(s): Blender Foundation, Mike Erwin, Dalai Felinto
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file draw_cache_impl_mesh.c
 *  \ingroup draw
 *
 * \brief Mesh API for render engines
 */

#include "MEM_guardedalloc.h"

#include "BLI_utildefines.h"
#include "BLI_math_vector.h"

#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"

#include "BKE_customdata.h"
#include "BKE_DerivedMesh.h"
#include "BKE_editmesh.h"
#include "BKE_mesh.h"

#include "bmesh.h"

#include "GPU_batch.h"

#include "draw_cache_impl.h"  /* own include */

static void mesh_batch_cache_clear(Mesh *me);

/* ---------------------------------------------------------------------- */
/* Mesh/BMesh Interface, direct access to basic data. */

static int mesh_render_verts_len_get(Mesh *me)
{
	return me->edit_btmesh ? me->edit_btmesh->bm->totvert : me->totvert;
}

static int mesh_render_edges_len_get(Mesh *me)
{
	return me->edit_btmesh ? me->edit_btmesh->bm->totedge : me->totedge;
}

static int mesh_render_looptri_len_get(Mesh *me)
{
	return me->edit_btmesh ? me->edit_btmesh->tottri : poly_to_tri_count(me->totpoly, me->totloop);
}

static int mesh_render_polys_len_get(Mesh *me)
{
	return me->edit_btmesh ? me->edit_btmesh->bm->totface : me->totpoly;
}

static int mesh_render_mat_ct_get(Mesh *me)
{
	return MAX2(1, me->totcol);
}

static int UNUSED_FUNCTION(mesh_render_loops_len_get)(Mesh *me)
{
	return me->edit_btmesh ? me->edit_btmesh->bm->totloop : me->totloop;
}

/* ---------------------------------------------------------------------- */
/* Mesh/BMesh Interface, indirect, partially cached access to complex data. */

typedef struct EdgeAdjacentPolys {
	int count;
	int face_index[2];
} EdgeAdjacentPolys;

typedef struct EdgeDrawAttr {
	unsigned char v_flag;
	unsigned char e_flag;
	unsigned char crease;
	unsigned char bweight;
} EdgeDrawAttr;

typedef struct MeshRenderData {
	int types;

	int vert_len;
	int edge_len;
	int tri_len;
	int loop_len;
	int poly_len;
	int mat_ct;
	int loose_vert_len;
	int loose_edge_len;

	BMEditMesh *edit_bmesh;
	MVert *mvert;
	MEdge *medge;
	MLoop *mloop;
	MPoly *mpoly;

	BMVert *eve_act;
	BMEdge *eed_act;
	BMFace *efa_act;

	int crease_ofs;
	int bweight_ofs;

	/* Data created on-demand (usually not for bmesh-based data). */
	EdgeAdjacentPolys *edges_adjacent_polys;
	MLoopTri *mlooptri;
	int *loose_edges;
	int *loose_verts;

	float (*poly_normals)[3];
	short (*poly_normals_short)[3];
	short (*vert_normals_short)[3];
} MeshRenderData;

enum {
	MR_DATATYPE_VERT       = 1 << 0,
	MR_DATATYPE_EDGE       = 1 << 1,
	MR_DATATYPE_LOOPTRI    = 1 << 2,
	MR_DATATYPE_LOOP       = 1 << 3,
	MR_DATATYPE_POLY       = 1 << 4,
	MR_DATATYPE_OVERLAY    = 1 << 5,
};

/**
 * These functions look like they would be slow but they will typically return true on the first iteration.
 * Only false when all attached elements are hidden.
 */
static bool bm_vert_has_visible_edge(const BMVert *v)
{
	const BMEdge *e_iter, *e_first;

	e_iter = e_first = v->e;
	do {
		if (!BM_elem_flag_test(e_iter, BM_ELEM_HIDDEN)) {
			return true;
		}
	} while ((e_iter = BM_DISK_EDGE_NEXT(e_iter, v)) != e_first);
	return false;
}

static bool bm_edge_has_visible_face(const BMEdge *e)
{
	const BMLoop *l_iter, *l_first;
	l_iter = l_first = e->l;
	do {
		if (!BM_elem_flag_test(l_iter->f, BM_ELEM_HIDDEN)) {
			return true;
		}
	} while ((l_iter = l_iter->radial_next) != l_first);
	return false;
}


static MeshRenderData *mesh_render_data_create(Mesh *me, const int types)
{
	MeshRenderData *rdata = MEM_callocN(sizeof(*rdata), __func__);
	rdata->types = types;
	rdata->mat_ct = mesh_render_mat_ct_get(me);

	if (me->edit_btmesh) {
		BMEditMesh *embm = me->edit_btmesh;
		BMesh *bm = embm->bm;

		rdata->edit_bmesh = embm;

		int bm_ensure_types = 0;
		if (types & (MR_DATATYPE_VERT)) {
			rdata->vert_len = bm->totvert;
			bm_ensure_types |= BM_VERT;
		}
		if (types & (MR_DATATYPE_EDGE)) {
			rdata->edge_len = bm->totedge;
			bm_ensure_types |= BM_EDGE;
		}
		if (types & MR_DATATYPE_LOOPTRI) {
			BKE_editmesh_tessface_calc(embm);
			rdata->tri_len = embm->tottri;
		}
		if (types & MR_DATATYPE_LOOP) {
			rdata->loop_len = bm->totloop;
			bm_ensure_types |= BM_LOOP;
		}
		if (types & MR_DATATYPE_POLY) {
			rdata->poly_len = bm->totface;
			bm_ensure_types |= BM_FACE;
		}
		if (types & MR_DATATYPE_OVERLAY) {
			rdata->efa_act = BM_mesh_active_face_get(bm, false, true);
			rdata->eed_act = BM_mesh_active_edge_get(bm);
			rdata->eve_act = BM_mesh_active_vert_get(bm);
			rdata->crease_ofs = CustomData_get_offset(&bm->edata, CD_CREASE);
			rdata->bweight_ofs = CustomData_get_offset(&bm->edata, CD_BWEIGHT);
		}
		BM_mesh_elem_index_ensure(bm, bm_ensure_types);
		BM_mesh_elem_table_ensure(bm, bm_ensure_types & ~BM_LOOP);
		if (types & MR_DATATYPE_OVERLAY) {
			rdata->loose_vert_len = rdata->loose_edge_len = 0;

			int *lverts = rdata->loose_verts = MEM_mallocN(rdata->vert_len * sizeof(int), "Loose Vert");
			int *ledges = rdata->loose_edges = MEM_mallocN(rdata->edge_len * sizeof(int), "Loose Edges");

			{
				BLI_assert((bm->elem_table_dirty & BM_VERT) == 0);
				BMVert **vtable = bm->vtable;
				for (int i = 0; i < bm->totvert; i++) {
					const BMVert *v = vtable[i];
					if (!BM_elem_flag_test(v, BM_ELEM_HIDDEN)) {
						/* Loose vert */
						if (v->e == NULL || !bm_vert_has_visible_edge(v)) {
							lverts[rdata->loose_vert_len++] = i;
						}
					}
				}
			}

			{
				BLI_assert((bm->elem_table_dirty & BM_EDGE) == 0);
				BMEdge **etable = bm->etable;
				for (int i = 0; i < bm->totedge; i++) {
					const BMEdge *e = etable[i];
					if (!BM_elem_flag_test(e, BM_ELEM_HIDDEN)) {
						/* Loose edge */
						if (e->l == NULL || !bm_edge_has_visible_face(e)) {
							ledges[rdata->loose_edge_len++] = i;
						}
					}
				}
			}

			rdata->loose_verts = MEM_reallocN(rdata->loose_verts, rdata->loose_vert_len * sizeof(int));
			rdata->loose_edges = MEM_reallocN(rdata->loose_edges, rdata->loose_edge_len * sizeof(int));
		}
	}
	else {
		if (types & (MR_DATATYPE_VERT)) {
			rdata->vert_len = me->totvert;
			rdata->mvert = CustomData_get_layer(&me->vdata, CD_MVERT);
		}
		if (types & (MR_DATATYPE_EDGE)) {
			rdata->edge_len = me->totedge;
			rdata->medge = CustomData_get_layer(&me->edata, CD_MEDGE);
		}
		if (types & MR_DATATYPE_LOOPTRI) {
			const int tri_len = rdata->tri_len = poly_to_tri_count(me->totpoly, me->totloop);
			rdata->mlooptri = MEM_mallocN(sizeof(*rdata->mlooptri) * tri_len, __func__);
			BKE_mesh_recalc_looptri(me->mloop, me->mpoly, me->mvert, me->totloop, me->totpoly, rdata->mlooptri);
		}
		if (types & MR_DATATYPE_LOOP) {
			rdata->loop_len = me->totloop;
			rdata->mloop = CustomData_get_layer(&me->ldata, CD_MLOOP);
		}
		if (types & MR_DATATYPE_POLY) {
			rdata->poly_len = me->totpoly;
			rdata->mpoly = CustomData_get_layer(&me->pdata, CD_MPOLY);
		}
	}

	return rdata;
}

static void mesh_render_data_free(MeshRenderData *rdata)
{
	if (rdata->loose_verts) {
		MEM_freeN(rdata->loose_verts);
	}
	if (rdata->loose_edges) {
		MEM_freeN(rdata->loose_edges);
	}
	if (rdata->edges_adjacent_polys) {
		MEM_freeN(rdata->edges_adjacent_polys);
	}
	if (rdata->mlooptri) {
		MEM_freeN(rdata->mlooptri);
	}
	if (rdata->poly_normals) {
		MEM_freeN(rdata->poly_normals);
	}
	if (rdata->poly_normals_short) {
		MEM_freeN(rdata->poly_normals_short);
	}
	if (rdata->vert_normals_short) {
		MEM_freeN(rdata->vert_normals_short);
	}
	MEM_freeN(rdata);
}

static int mesh_render_data_verts_len_get(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_VERT);
	return rdata->vert_len;
}

static int mesh_render_data_loose_verts_len_get(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_OVERLAY);
	return rdata->loose_vert_len;
}

static int mesh_render_data_edges_len_get(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_EDGE);
	return rdata->edge_len;
}

static int mesh_render_data_loose_edges_len_get(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_OVERLAY);
	return rdata->loose_edge_len;
}

static int mesh_render_data_looptri_len_get(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_LOOPTRI);
	return rdata->tri_len;
}

static int mesh_render_data_mat_ct_get(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_POLY);
	return rdata->mat_ct;
}

static int UNUSED_FUNCTION(mesh_render_data_loops_len_get)(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_LOOP);
	return rdata->loop_len;
}

static int mesh_render_data_polys_len_get(const MeshRenderData *rdata)
{
	BLI_assert(rdata->types & MR_DATATYPE_POLY);
	return rdata->poly_len;
}

static float *mesh_render_data_vert_co(const MeshRenderData *rdata, const int vert_idx)
{
	BLI_assert(rdata->types & MR_DATATYPE_VERT);

	if (rdata->edit_bmesh) {
		BMesh *bm = rdata->edit_bmesh->bm;
		BMVert *bv = BM_vert_at_index(bm, vert_idx);
		return bv->co;
	}
	else {
		return rdata->mvert[vert_idx].co;
	}
}

static short *mesh_render_data_vert_nor(const MeshRenderData *rdata, const int vert_idx)
{
	BLI_assert(rdata->types & MR_DATATYPE_VERT);

	if (rdata->edit_bmesh) {
		static short fno[3];
		BMesh *bm = rdata->edit_bmesh->bm;
		BMVert *bv = BM_vert_at_index(bm, vert_idx);
		normal_float_to_short_v3(fno, bv->no);
		return fno;
	}
	else {
		return rdata->mvert[vert_idx].no;
	}
}

static bool mesh_render_data_edge_verts_indices_get(
        const MeshRenderData *rdata, const int edge_idx,
        int r_vert_idx[2])
{
	BLI_assert(rdata->types & MR_DATATYPE_EDGE);

	if (rdata->edit_bmesh) {
		const BMEdge *bm_edge = BM_edge_at_index(rdata->edit_bmesh->bm, edge_idx);
		if (BM_elem_flag_test(bm_edge, BM_ELEM_HIDDEN)) {
			return false;
		}
		r_vert_idx[0] = BM_elem_index_get(bm_edge->v1);
		r_vert_idx[1] = BM_elem_index_get(bm_edge->v2);
	}
	else {
		const MEdge *me = &rdata->medge[edge_idx];
		r_vert_idx[0] = me->v1;
		r_vert_idx[1] = me->v2;
	}
	return true;
}

static bool mesh_render_data_pnors_pcenter_select_get(
        MeshRenderData *rdata, const int poly,
        float r_pnors[3], float r_center[3], bool *r_selected)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_LOOP | MR_DATATYPE_POLY));

	if (rdata->edit_bmesh) {
		const BMFace *bf = BM_face_at_index(rdata->edit_bmesh->bm, poly);
		if (BM_elem_flag_test(bf, BM_ELEM_HIDDEN)) {
			return false;
		}
		BM_face_calc_center_mean(bf, r_center);
		BM_face_calc_normal(bf, r_pnors);
		*r_selected = (BM_elem_flag_test(bf, BM_ELEM_SELECT) != 0) ? true : false;
	}
	else {
		MVert *mvert = rdata->mvert;
		const MPoly *mpoly = rdata->mpoly + poly;
		const MLoop *mloop = rdata->mloop + mpoly->loopstart;

		BKE_mesh_calc_poly_center(mpoly, mloop, mvert, r_center);
		BKE_mesh_calc_poly_normal(mpoly, mloop, mvert, r_pnors);

		*r_selected = false; /* No selection if not in edit mode */
	}

	return true;
}

static bool mesh_render_data_edge_vcos_manifold_pnors(
        MeshRenderData *rdata, const int edge_index,
        float **r_vco1, float **r_vco2, float **r_pnor1, float **r_pnor2, bool *r_is_manifold)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_EDGE | MR_DATATYPE_LOOP | MR_DATATYPE_POLY));

	if (rdata->edit_bmesh) {
		BMesh *bm = rdata->edit_bmesh->bm;
		BMEdge *bm_edge = BM_edge_at_index(bm, edge_index);
		if (BM_elem_flag_test(bm_edge, BM_ELEM_HIDDEN)) {
			return false;
		}
		*r_vco1 = bm_edge->v1->co;
		*r_vco2 = bm_edge->v2->co;
		if (BM_edge_is_manifold(bm_edge)) {
			*r_pnor1 = bm_edge->l->f->no;
			*r_pnor2 = bm_edge->l->radial_next->f->no;
			*r_is_manifold = true;
		}
		else {
			*r_is_manifold = false;
		}
	}
	else {
		MVert *mvert = rdata->mvert;
		MEdge *medge = rdata->medge;
		EdgeAdjacentPolys *eap = rdata->edges_adjacent_polys;
		float (*pnors)[3] = rdata->poly_normals;

		if (!eap) {
			const MLoop *mloop = rdata->mloop;
			const MPoly *mpoly = rdata->mpoly;
			const int poly_len = rdata->poly_len;
			const bool do_pnors = (pnors == NULL);

			eap = rdata->edges_adjacent_polys = MEM_callocN(sizeof(*eap) * rdata->edge_len, __func__);
			if (do_pnors) {
				pnors = rdata->poly_normals = MEM_mallocN(sizeof(*pnors) * poly_len, __func__);
			}

			for (int i = 0; i < poly_len; i++, mpoly++) {
				if (do_pnors) {
					BKE_mesh_calc_poly_normal(mpoly, mloop + mpoly->loopstart, mvert, pnors[i]);
				}

				const int loopend = mpoly->loopstart + mpoly->totloop;
				for (int j = mpoly->loopstart; j < loopend; j++) {
					const int edge_idx = mloop[j].e;
					if (eap[edge_idx].count < 2) {
						eap[edge_idx].face_index[eap[edge_idx].count] = i;
					}
					eap[edge_idx].count++;
				}
			}
		}
		BLI_assert(eap && pnors);

		*r_vco1 = mvert[medge[edge_index].v1].co;
		*r_vco2 = mvert[medge[edge_index].v2].co;
		if (eap[edge_index].count == 2) {
			*r_pnor1 = pnors[eap[edge_index].face_index[0]];
			*r_pnor2 = pnors[eap[edge_index].face_index[1]];
			*r_is_manifold = true;
		}
		else {
			*r_is_manifold = false;
		}
	}

	return true;
}

static bool mesh_render_data_looptri_vert_indices_get(
        const MeshRenderData *rdata, const int tri_idx,
        int r_vert_idx[3])
{
	BLI_assert(rdata->types & (MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP));

	if (rdata->edit_bmesh) {
		const BMLoop **bm_looptri = (const BMLoop **)rdata->edit_bmesh->looptris[tri_idx];
		if (BM_elem_flag_test(bm_looptri[0]->f, BM_ELEM_HIDDEN)) {
			return false;
		}
		r_vert_idx[0] = BM_elem_index_get(bm_looptri[0]->v);
		r_vert_idx[1] = BM_elem_index_get(bm_looptri[1]->v);
		r_vert_idx[2] = BM_elem_index_get(bm_looptri[2]->v);
	}
	else {
		const unsigned int *l_idx = rdata->mlooptri[tri_idx].tri;
		const MLoop *l_tri[3] = {&rdata->mloop[l_idx[0]], &rdata->mloop[l_idx[1]], &rdata->mloop[l_idx[2]]};
		r_vert_idx[0] = l_tri[0]->v;
		r_vert_idx[1] = l_tri[1]->v;
		r_vert_idx[2] = l_tri[2]->v;
	}

	return true;
}

static bool mesh_render_data_looptri_mat_index_get(
        const MeshRenderData *rdata, const int tri_idx,
        short *r_face_mat)
{
	BLI_assert(rdata->types & (MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP | MR_DATATYPE_POLY));

	if (rdata->edit_bmesh) {
		const BMLoop **bm_looptri = (const BMLoop **)rdata->edit_bmesh->looptris[tri_idx];
		if (BM_elem_flag_test(bm_looptri[0]->f, BM_ELEM_HIDDEN)) {
			return false;
		}
		*r_face_mat = ((BMFace *)bm_looptri[0]->f)->mat_nr;
	}
	else {
		const int poly_idx = rdata->mlooptri[tri_idx].poly; ;
		const MPoly *poly = &rdata->mpoly[poly_idx]; ;
		*r_face_mat = poly->mat_nr;
	}

	return true;
}

/**
 * Version of #mesh_render_data_looptri_verts_indices_get that assigns
 * edge indices too \a r_edges_idx (-1 for non-existant edges).
 */
static bool mesh_render_data_looptri_vert_edge_indices_get(
        const MeshRenderData *rdata, const int tri_idx,
        int r_vert_idx[3], int r_edges_idx[3])
{
	BLI_assert(rdata->types & (MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP));

	unsigned int e_pair_edge[2];
	unsigned int e_pair_loop[2];

	if (rdata->edit_bmesh) {
		const BMLoop **bm_looptri = (const BMLoop **)rdata->edit_bmesh->looptris[tri_idx];

		if (BM_elem_flag_test(bm_looptri[0]->f, BM_ELEM_HIDDEN)) {
			return false;
		}

		/* assign 'r_edges_idx' & 'r_vert_idx' */
		int j, j_next;
		for (j = 2, j_next = 0; j_next < 3; j = j_next++) {
			const BMLoop *l = bm_looptri[j], *l_next = bm_looptri[j_next];
			const BMEdge *e = l->e;
			ARRAY_SET_ITEMS(e_pair_edge, BM_elem_index_get(e->v1), BM_elem_index_get(e->v2));
			ARRAY_SET_ITEMS(e_pair_loop, BM_elem_index_get(l->v), BM_elem_index_get(l_next->v));
			if ((e_pair_edge[0] == e_pair_loop[0] && e_pair_edge[1] == e_pair_loop[1]) ||
			    (e_pair_edge[0] == e_pair_loop[1] && e_pair_edge[1] == e_pair_loop[0]))
			{
				r_edges_idx[j] = BM_elem_index_get(l->e);
			}
			else {
				r_edges_idx[j] = -1;
			}
			r_vert_idx[j] = e_pair_loop[0];  /* BM_elem_index_get(l->v) */
		}
	}
	else {
		const unsigned int *l_idx = rdata->mlooptri[tri_idx].tri;
		const MLoop *l_tri[3] = {&rdata->mloop[l_idx[0]], &rdata->mloop[l_idx[1]], &rdata->mloop[l_idx[2]]};

		/* assign 'r_edges_idx' & 'r_vert_idx' */
		int j, j_next;
		for (j = 2, j_next = 0; j_next < 3; j = j_next++) {
			const MLoop *l = l_tri[j], *l_next = l_tri[j_next];
			const MEdge *e = &rdata->medge[l->e]; \
			ARRAY_SET_ITEMS(e_pair_edge, e->v1, e->v2);
			ARRAY_SET_ITEMS(e_pair_loop, l->v, l_next->v);
			if ((e_pair_edge[0] == e_pair_loop[0] && e_pair_edge[1] == e_pair_loop[1]) ||
			    (e_pair_edge[0] == e_pair_loop[1] && e_pair_edge[1] == e_pair_loop[0]))
			{
				r_edges_idx[j] = l->e;
			}
			else {
				r_edges_idx[j] = -1;
			}
			r_vert_idx[j] = e_pair_loop[0];  /* l->v */
		}
	}

	return true;
}

static bool mesh_render_data_looptri_cos_nors_smooth_get(
        MeshRenderData *rdata, const int tri_idx,
        float *(*r_vert_cos)[3], short **r_tri_nor, short *(*r_vert_nors)[3], bool *r_is_smooth)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP | MR_DATATYPE_POLY));

	if (rdata->edit_bmesh) {
		const BMLoop **bm_looptri = (const BMLoop **)rdata->edit_bmesh->looptris[tri_idx];

		if (BM_elem_flag_test(bm_looptri[0]->f, BM_ELEM_HIDDEN)) {
			return false;
		}

		short (*pnors_short)[3] = rdata->poly_normals_short;
		short (*vnors_short)[3] = rdata->vert_normals_short;

		if (!pnors_short) {
			BMesh *bm = rdata->edit_bmesh->bm;
			BMIter fiter;
			BMFace *face;
			int i;

			pnors_short = rdata->poly_normals_short = MEM_mallocN(sizeof(*pnors_short) * rdata->poly_len, __func__);
			BM_ITER_MESH_INDEX(face, &fiter, bm, BM_FACES_OF_MESH, i) {
				normal_float_to_short_v3(pnors_short[i], face->no);
			}
		}
		if (!vnors_short) {
			BMesh *bm = rdata->edit_bmesh->bm;
			BMIter viter;
			BMVert *vert;
			int i;

			vnors_short = rdata->vert_normals_short = MEM_mallocN(sizeof(*vnors_short) * rdata->vert_len, __func__);
			BM_ITER_MESH_INDEX(vert, &viter, bm, BM_VERT, i) {
				normal_float_to_short_v3(vnors_short[i], vert->no);
			}
		}

		(*r_vert_cos)[0] = bm_looptri[0]->v->co;
		(*r_vert_cos)[1] = bm_looptri[1]->v->co;
		(*r_vert_cos)[2] = bm_looptri[2]->v->co;
		*r_tri_nor = pnors_short[BM_elem_index_get(bm_looptri[0]->f)];
		(*r_vert_nors)[0] = vnors_short[BM_elem_index_get(bm_looptri[0]->v)];
		(*r_vert_nors)[1] = vnors_short[BM_elem_index_get(bm_looptri[1]->v)];
		(*r_vert_nors)[2] = vnors_short[BM_elem_index_get(bm_looptri[2]->v)];

		*r_is_smooth = BM_elem_flag_test_bool(bm_looptri[0]->f, BM_ELEM_SMOOTH);
	}
	else {
		const MLoopTri *mlt = &rdata->mlooptri[tri_idx];
		short (*pnors_short)[3] = rdata->poly_normals_short;

		if (!pnors_short) {
			float (*pnors)[3] = rdata->poly_normals;

			if (!pnors) {
				pnors = rdata->poly_normals = MEM_mallocN(sizeof(*pnors) * rdata->poly_len, __func__);
				BKE_mesh_calc_normals_poly(
				            rdata->mvert, NULL, rdata->vert_len,
				            rdata->mloop, rdata->mpoly, rdata->loop_len, rdata->poly_len, pnors, true);
			}

			pnors_short = rdata->poly_normals_short = MEM_mallocN(sizeof(*pnors_short) * rdata->poly_len, __func__);
			for (int i = 0; i < rdata->poly_len; i++) {
				normal_float_to_short_v3(pnors_short[i], pnors[i]);
			}
		}

		(*r_vert_cos)[0] = rdata->mvert[rdata->mloop[mlt->tri[0]].v].co;
		(*r_vert_cos)[1] = rdata->mvert[rdata->mloop[mlt->tri[1]].v].co;
		(*r_vert_cos)[2] = rdata->mvert[rdata->mloop[mlt->tri[2]].v].co;
		*r_tri_nor = pnors_short[mlt->poly];
		(*r_vert_nors)[0] = rdata->mvert[rdata->mloop[mlt->tri[0]].v].no;
		(*r_vert_nors)[1] = rdata->mvert[rdata->mloop[mlt->tri[1]].v].no;
		(*r_vert_nors)[2] = rdata->mvert[rdata->mloop[mlt->tri[2]].v].no;

		*r_is_smooth = (rdata->mpoly[mlt->poly].flag & ME_SMOOTH) != 0;
	}
	return true;
}

/* First 2 bytes are bit flags
 * 3rd is for sharp edges
 * 4rd is for creased edges */
enum {
	VFLAG_VERTEX_ACTIVE   = 1 << 0,
	VFLAG_VERTEX_SELECTED = 1 << 1,
	VFLAG_FACE_ACTIVE     = 1 << 2,
	VFLAG_FACE_SELECTED   = 1 << 3,
};

enum {
	VFLAG_EDGE_EXISTS   = 1 << 0,
	VFLAG_EDGE_ACTIVE   = 1 << 1,
	VFLAG_EDGE_SELECTED = 1 << 2,
	VFLAG_EDGE_SEAM     = 1 << 3,
	VFLAG_EDGE_SHARP    = 1 << 4,
	/* Beware to not go over 1 << 7
	 * (see gpu_shader_edit_mesh_overlay_geom.glsl) */
};

static unsigned char mesh_render_data_looptri_flag(MeshRenderData *rdata, const int f)
{
	unsigned char fflag = 0;

	if (rdata->edit_bmesh) {
		BMFace *bf = rdata->edit_bmesh->looptris[f][0]->f;

		if (bf == rdata->efa_act)
			fflag |= VFLAG_FACE_ACTIVE;

		if (BM_elem_flag_test(bf, BM_ELEM_SELECT))
			fflag |= VFLAG_FACE_SELECTED;
	}

	return fflag;
}

static EdgeDrawAttr *mesh_render_data_edge_flag(MeshRenderData *rdata, const int e)
{
	static EdgeDrawAttr eattr;
	memset(&eattr, 0, sizeof(eattr));

	if (e == -1) {
		return &eattr;
	}

	/* if edge exists */
	if (rdata->edit_bmesh) {
		BMesh *bm = rdata->edit_bmesh->bm;
		BMEdge *be = NULL;

		be = BM_edge_at_index(bm, e);

		eattr.e_flag |= VFLAG_EDGE_EXISTS;

		if (be == rdata->eed_act)
			eattr.e_flag |= VFLAG_EDGE_ACTIVE;

		if (BM_elem_flag_test(be, BM_ELEM_SELECT))
			eattr.e_flag |= VFLAG_EDGE_SELECTED;

		if (BM_elem_flag_test(be, BM_ELEM_SEAM))
			eattr.e_flag |= VFLAG_EDGE_SEAM;

		if (!BM_elem_flag_test(be, BM_ELEM_SMOOTH))
			eattr.e_flag |= VFLAG_EDGE_SHARP;

		/* Use a byte for value range */
		if (rdata->crease_ofs != -1) {
			float crease = BM_ELEM_CD_GET_FLOAT(be, rdata->crease_ofs);
			if (crease > 0) {
				eattr.crease = (char)(crease * 255.0f);
			}
		}

		/* Use a byte for value range */
		if (rdata->bweight_ofs != -1) {
			float bweight = BM_ELEM_CD_GET_FLOAT(be, rdata->bweight_ofs);
			if (bweight > 0) {
				eattr.bweight = (char)(bweight * 255.0f);
			}
		}
	}
	else {
		eattr.e_flag |= VFLAG_EDGE_EXISTS;
	}

	return &eattr;
}

static unsigned char mesh_render_data_vertex_flag(MeshRenderData *rdata, const int v)
{

	unsigned char vflag = 0;

	if (rdata->edit_bmesh) {
		BMesh *bm = rdata->edit_bmesh->bm;
		BMVert *bv = BM_vert_at_index(bm, v);

		/* Current vertex */
		if (bv == rdata->eve_act)
			vflag |= VFLAG_VERTEX_ACTIVE;

		if (BM_elem_flag_test(bv, BM_ELEM_SELECT))
			vflag |= VFLAG_VERTEX_SELECTED;
	}

	return vflag;
}

static void add_overlay_tri(
        MeshRenderData *rdata, VertexBuffer *vbo, const unsigned int pos_id, const unsigned int edgeMod_id,
        const int tri_vert_idx[3], const int tri_edge_idx[3], const int f, const int base_vert_idx)
{
	const float *pos;
	EdgeDrawAttr *eattr;
	unsigned char  fflag;
	unsigned char  vflag;

	pos = mesh_render_data_vert_co(rdata, tri_vert_idx[0]);
	eattr = mesh_render_data_edge_flag(rdata, tri_edge_idx[1]);
	fflag = mesh_render_data_looptri_flag(rdata, f);
	vflag = mesh_render_data_vertex_flag(rdata, tri_vert_idx[0]);
	eattr->v_flag = fflag | vflag;
	VertexBuffer_set_attrib(vbo, pos_id, base_vert_idx + 0, pos);
	VertexBuffer_set_attrib(vbo, edgeMod_id, base_vert_idx + 0, eattr);

	pos = mesh_render_data_vert_co(rdata, tri_vert_idx[1]);
	eattr = mesh_render_data_edge_flag(rdata, tri_edge_idx[2]);
	vflag = mesh_render_data_vertex_flag(rdata, tri_vert_idx[1]);
	eattr->v_flag = fflag | vflag;
	VertexBuffer_set_attrib(vbo, pos_id, base_vert_idx + 1, pos);
	VertexBuffer_set_attrib(vbo, edgeMod_id, base_vert_idx + 1, eattr);

	pos = mesh_render_data_vert_co(rdata, tri_vert_idx[2]);
	eattr = mesh_render_data_edge_flag(rdata, tri_edge_idx[0]);
	vflag = mesh_render_data_vertex_flag(rdata, tri_vert_idx[2]);
	eattr->v_flag = fflag | vflag;
	VertexBuffer_set_attrib(vbo, pos_id, base_vert_idx + 2, pos);
	VertexBuffer_set_attrib(vbo, edgeMod_id, base_vert_idx + 2, eattr);
}

static void add_overlay_loose_edge(
        MeshRenderData *rdata, VertexBuffer *vbo, const unsigned int pos_id, const unsigned int edgeMod_id,
        const int v1, const int v2, const int e, const int base_vert_idx)
{
	EdgeDrawAttr *eattr = mesh_render_data_edge_flag(rdata, e);
	const float *pos = mesh_render_data_vert_co(rdata, v1);
	eattr->v_flag = mesh_render_data_vertex_flag(rdata, v1);
	VertexBuffer_set_attrib(vbo, pos_id, base_vert_idx + 0, pos);
	VertexBuffer_set_attrib(vbo, edgeMod_id, base_vert_idx + 0, eattr);

	pos = mesh_render_data_vert_co(rdata, v2);
	eattr->v_flag = mesh_render_data_vertex_flag(rdata, v2);
	VertexBuffer_set_attrib(vbo, pos_id, base_vert_idx + 1, pos);
	VertexBuffer_set_attrib(vbo, edgeMod_id, base_vert_idx + 1, eattr);
}

static void add_overlay_loose_vert(
        MeshRenderData *rdata, VertexBuffer *vbo, const unsigned int pos_id, const unsigned int edgeMod_id,
        const int v, const int base_vert_idx)
{
	unsigned char vflag[4] = {0, 0, 0, 0};
	const float *pos = mesh_render_data_vert_co(rdata, v);
	vflag[0] = mesh_render_data_vertex_flag(rdata, v);
	VertexBuffer_set_attrib(vbo, pos_id, base_vert_idx + 0, pos);
	VertexBuffer_set_attrib(vbo, edgeMod_id, base_vert_idx + 0, vflag);
}

/* ---------------------------------------------------------------------- */
/* Mesh Batch Cache */

typedef struct MeshBatchCache {
	VertexBuffer *pos_in_order;
	VertexBuffer *nor_in_order;
	ElementList *edges_in_order;
	ElementList *triangles_in_order;

	Batch *all_verts;
	Batch *all_edges;
	Batch *all_triangles;

	VertexBuffer *pos_with_normals;
	Batch *triangles_with_normals;
	Batch *points_with_normals;
	Batch *fancy_edges; /* owns its vertex buffer (not shared) */

	/* Maybe have shaded_triangles_data split into pos_nor and uv_tangent
	 * to minimise data transfer for skinned mesh. */
	VertexBuffer *shaded_triangles_data;
	ElementList **shaded_triangles_in_order;
	Batch **shaded_triangles;

	/* TODO : split in 2 buffers to avoid unnecessary
	 * data transfer when selecting/deselecting
	 * and combine into one batch and use offsets to render
	 * Tri / edges / verts separately */
	Batch *overlay_triangles;
	Batch *overlay_loose_verts;
	Batch *overlay_loose_edges;
	Batch *overlay_facedots;

	/* settings to determine if cache is invalid */
	bool is_dirty;
	int edge_len;
	int tri_len;
	int poly_len;
	int vert_len;
	int mat_ct;
	bool is_editmode;
} MeshBatchCache;

/* Batch cache management. */

static bool mesh_batch_cache_valid(Mesh *me)
{
	MeshBatchCache *cache = me->batch_cache;

	if (cache == NULL) {
		return false;
	}

	/* XXX find another place for this */
	if (cache->mat_ct != mesh_render_mat_ct_get(me)) {
		cache->is_dirty = true;
	}

	if (cache->is_editmode != (me->edit_btmesh != NULL)) {
		return false;
	}

	if (cache->is_dirty == false) {
		return true;
	}
	else {
		if (cache->is_editmode) {
			return false;
		}
		else if ((cache->vert_len != mesh_render_verts_len_get(me)) ||
		         (cache->edge_len != mesh_render_edges_len_get(me)) ||
		         (cache->tri_len  != mesh_render_looptri_len_get(me)) ||
		         (cache->poly_len != mesh_render_polys_len_get(me)) ||
		         (cache->mat_ct   != mesh_render_mat_ct_get(me)))
		{
			return false;
		}
	}

	return true;
}

static void mesh_batch_cache_init(Mesh *me)
{
	MeshBatchCache *cache = me->batch_cache;

	if (!cache) {
		cache = me->batch_cache = MEM_callocN(sizeof(*cache), __func__);
	}
	else {
		memset(cache, 0, sizeof(*cache));
	}

	cache->is_editmode = me->edit_btmesh != NULL;

	if (cache->is_editmode == false) {
		cache->edge_len = mesh_render_edges_len_get(me);
		cache->tri_len = mesh_render_looptri_len_get(me);
		cache->poly_len = mesh_render_polys_len_get(me);
		cache->vert_len = mesh_render_verts_len_get(me);
	}

	cache->mat_ct = mesh_render_mat_ct_get(me);

	cache->is_dirty = false;
}

static MeshBatchCache *mesh_batch_cache_get(Mesh *me)
{
	if (!mesh_batch_cache_valid(me)) {
		mesh_batch_cache_clear(me);
		mesh_batch_cache_init(me);
	}
	return me->batch_cache;
}

void DRW_mesh_batch_cache_dirty(Mesh *me, int mode)
{
	MeshBatchCache *cache = me->batch_cache;
	if (cache == NULL) {
		return;
	}
	switch (mode) {
		case BKE_MESH_BATCH_DIRTY_ALL:
			cache->is_dirty = true;
			break;
		case BKE_MESH_BATCH_DIRTY_SELECT:
			/* TODO Separate Flag vbo */
			BATCH_DISCARD_ALL_SAFE(cache->overlay_triangles);
			BATCH_DISCARD_ALL_SAFE(cache->overlay_loose_verts);
			BATCH_DISCARD_ALL_SAFE(cache->overlay_loose_edges);
			BATCH_DISCARD_ALL_SAFE(cache->overlay_facedots);
			break;
		default:
			BLI_assert(0);
	}
}

static void mesh_batch_cache_clear(Mesh *me)
{
	MeshBatchCache *cache = me->batch_cache;
	if (!cache) {
		return;
	}

	BATCH_DISCARD_SAFE(cache->all_verts);
	BATCH_DISCARD_SAFE(cache->all_edges);
	BATCH_DISCARD_SAFE(cache->all_triangles);

	VERTEXBUFFER_DISCARD_SAFE(cache->pos_in_order);
	ELEMENTLIST_DISCARD_SAFE(cache->edges_in_order);
	ELEMENTLIST_DISCARD_SAFE(cache->triangles_in_order);

	BATCH_DISCARD_ALL_SAFE(cache->overlay_triangles);
	BATCH_DISCARD_ALL_SAFE(cache->overlay_loose_verts);
	BATCH_DISCARD_ALL_SAFE(cache->overlay_loose_edges);
	BATCH_DISCARD_ALL_SAFE(cache->overlay_facedots);

	BATCH_DISCARD_SAFE(cache->triangles_with_normals);
	BATCH_DISCARD_SAFE(cache->points_with_normals);
	VERTEXBUFFER_DISCARD_SAFE(cache->pos_with_normals);

	BATCH_DISCARD_ALL_SAFE(cache->fancy_edges);

	VERTEXBUFFER_DISCARD_SAFE(cache->shaded_triangles_data);
	if (cache->shaded_triangles_in_order) {
		for (int i = 0; i < cache->mat_ct; ++i) {
			ELEMENTLIST_DISCARD_SAFE(cache->shaded_triangles_in_order[i]);
		}
	}
	if (cache->shaded_triangles) {
		for (int i = 0; i < cache->mat_ct; ++i) {
			BATCH_DISCARD_SAFE(cache->shaded_triangles[i]);
		}
	}

	MEM_SAFE_FREE(cache->shaded_triangles_in_order);
	MEM_SAFE_FREE(cache->shaded_triangles);
}

void DRW_mesh_batch_cache_free(Mesh *me)
{
	mesh_batch_cache_clear(me);
	MEM_SAFE_FREE(me->batch_cache);
}

/* Batch cache usage. */

static VertexBuffer *mesh_batch_cache_get_shading_data(MeshRenderData *rdata, MeshBatchCache *cache)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP | MR_DATATYPE_POLY));

	if (cache->shaded_triangles_data == NULL) {
		unsigned int vidx = 0, nidx = 0;

		static VertexFormat format = { 0 };
		static unsigned int pos_id, nor_id;
		if (format.attrib_ct == 0) {
			/* initialize vertex format */
			/* TODO add tangent, UVs */
			pos_id = VertexFormat_add_attrib(&format, "pos", COMP_F32, 3, KEEP_FLOAT);
			nor_id = VertexFormat_add_attrib(&format, "nor", COMP_I16, 3, NORMALIZE_INT_TO_FLOAT);
		}

		const int tri_len = mesh_render_data_looptri_len_get(rdata);

		VertexBuffer *vbo = cache->shaded_triangles_data = VertexBuffer_create_with_format(&format);

		const int vbo_len_capacity = tri_len * 3;
		int vbo_len_used = 0;
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);

		/* TODO deduplicate all verts and make use of ElementList in mesh_batch_cache_get_shaded_triangles_in_order. */
		for (int i = 0; i < tri_len; i++) {
			float *tri_vert_cos[3];
			short *tri_nor, *tri_vert_nors[3];
			bool is_smooth;

			if (mesh_render_data_looptri_cos_nors_smooth_get(
			        rdata, i, &tri_vert_cos, &tri_nor, &tri_vert_nors, &is_smooth))
			{
				if (is_smooth) {
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_vert_nors[0]);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_vert_nors[1]);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_vert_nors[2]);
				}
				else {
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_nor);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_nor);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_nor);
				}

				VertexBuffer_set_attrib(vbo, pos_id, vidx++, tri_vert_cos[0]);
				VertexBuffer_set_attrib(vbo, pos_id, vidx++, tri_vert_cos[1]);
				VertexBuffer_set_attrib(vbo, pos_id, vidx++, tri_vert_cos[2]);
			}
		}
		vbo_len_used = vidx;

		if (vbo_len_capacity != vbo_len_used) {
			VertexBuffer_resize_data(vbo, vbo_len_used);
		}
	}
	return cache->shaded_triangles_data;
}

static VertexBuffer *mesh_batch_cache_get_pos_and_normals(MeshRenderData *rdata, MeshBatchCache *cache)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP | MR_DATATYPE_POLY));

	if (cache->pos_with_normals == NULL) {
		unsigned int vidx = 0, nidx = 0;

		static VertexFormat format = { 0 };
		static unsigned int pos_id, nor_id;
		if (format.attrib_ct == 0) {
			/* initialize vertex format */
			pos_id = VertexFormat_add_attrib(&format, "pos", COMP_F32, 3, KEEP_FLOAT);
			nor_id = VertexFormat_add_attrib(&format, "nor", COMP_I16, 3, NORMALIZE_INT_TO_FLOAT);
		}

		const int tri_len = mesh_render_data_looptri_len_get(rdata);

		VertexBuffer *vbo = cache->pos_with_normals = VertexBuffer_create_with_format(&format);

		const int vbo_len_capacity = tri_len * 3;
		int vbo_len_used = 0;
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);

		for (int i = 0; i < tri_len; i++) {
			float *tri_vert_cos[3];
			short *tri_nor, *tri_vert_nors[3];
			bool is_smooth;

			if (mesh_render_data_looptri_cos_nors_smooth_get(
			        rdata, i, &tri_vert_cos, &tri_nor, &tri_vert_nors, &is_smooth))
			{
				if (is_smooth) {
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_vert_nors[0]);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_vert_nors[1]);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_vert_nors[2]);
				}
				else {
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_nor);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_nor);
					VertexBuffer_set_attrib(vbo, nor_id, nidx++, tri_nor);
				}

				VertexBuffer_set_attrib(vbo, pos_id, vidx++, tri_vert_cos[0]);
				VertexBuffer_set_attrib(vbo, pos_id, vidx++, tri_vert_cos[1]);
				VertexBuffer_set_attrib(vbo, pos_id, vidx++, tri_vert_cos[2]);
			}
		}
		vbo_len_used = vidx;

		if (vbo_len_capacity != vbo_len_used) {
			VertexBuffer_resize_data(vbo, vbo_len_used);
		}
	}
	return cache->pos_with_normals;
}

static VertexBuffer *mesh_batch_cache_get_pos_and_nor_in_order(MeshRenderData *rdata, MeshBatchCache *cache)
{
	BLI_assert(rdata->types & MR_DATATYPE_VERT);

	if (cache->pos_in_order == NULL) {
		static VertexFormat format = { 0 };
		static unsigned pos_id, nor_id;
		if (format.attrib_ct == 0) {
			/* initialize vertex format */
			pos_id = VertexFormat_add_attrib(&format, "pos", COMP_F32, 3, KEEP_FLOAT);
			nor_id = VertexFormat_add_attrib(&format, "nor", COMP_I16, 3, NORMALIZE_INT_TO_FLOAT);
		}

		VertexBuffer *vbo = cache->pos_in_order = VertexBuffer_create_with_format(&format);
		const int vbo_len_capacity = mesh_render_data_verts_len_get(rdata);
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);
		for (int i = 0; i < vbo_len_capacity; ++i) {
			VertexBuffer_set_attrib(vbo, pos_id, i, mesh_render_data_vert_co(rdata, i));
			VertexBuffer_set_attrib(vbo, nor_id, i, mesh_render_data_vert_nor(rdata, i));
		}
	}

	return cache->pos_in_order;
}

static ElementList *mesh_batch_cache_get_edges_in_order(MeshRenderData *rdata, MeshBatchCache *cache)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_EDGE));

	if (cache->edges_in_order == NULL) {
		printf("Caching edges in order...\n");
		const int vert_len = mesh_render_data_verts_len_get(rdata);
		const int edge_len = mesh_render_data_edges_len_get(rdata);

		ElementListBuilder elb;
		ElementListBuilder_init(&elb, PRIM_LINES, edge_len, vert_len);
		for (int i = 0; i < edge_len; ++i) {
			int vert_idx[2];
			if (mesh_render_data_edge_verts_indices_get(rdata, i, vert_idx)) {
				add_line_vertices(&elb, vert_idx[0], vert_idx[1]);
			}
		}
		cache->edges_in_order = ElementList_build(&elb);
	}

	return cache->edges_in_order;
}

static ElementList *mesh_batch_cache_get_triangles_in_order(MeshRenderData *rdata, MeshBatchCache *cache)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI));

	if (cache->triangles_in_order == NULL) {
		const int vert_len = mesh_render_data_verts_len_get(rdata);
		const int tri_len = mesh_render_data_looptri_len_get(rdata);

		ElementListBuilder elb;
		ElementListBuilder_init(&elb, PRIM_TRIANGLES, tri_len, vert_len);
		for (int i = 0; i < tri_len; ++i) {
			int tri_vert_idx[3];
			if (mesh_render_data_looptri_vert_indices_get(rdata, i, tri_vert_idx)) {
				add_triangle_vertices(&elb, tri_vert_idx[0], tri_vert_idx[1], tri_vert_idx[2]);
			}
		}
		cache->triangles_in_order = ElementList_build(&elb);
	}

	return cache->triangles_in_order;
}

static ElementList **mesh_batch_cache_get_shaded_triangles_in_order(MeshRenderData *rdata, MeshBatchCache *cache)
{
	BLI_assert(rdata->types & (MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI | MR_DATATYPE_POLY));

	if (cache->shaded_triangles_in_order == NULL) {
		const int tri_len = mesh_render_data_looptri_len_get(rdata);
		const int mat_ct = mesh_render_data_mat_ct_get(rdata);

		int *mat_tri_len = MEM_callocN(sizeof(*mat_tri_len) * mat_ct, "mat_tri_len");
		cache->shaded_triangles_in_order = MEM_callocN(sizeof(*cache->shaded_triangles) * mat_ct, "shaded_triangles_in_order");
		ElementListBuilder *elb = MEM_callocN(sizeof(*elb) * mat_ct, "shaded ElementListBuilder");

		for (int i = 0; i < tri_len; ++i) {
			short ma_id;
			if (mesh_render_data_looptri_mat_index_get(rdata, i, &ma_id)) {
				mat_tri_len[ma_id] += 1;
			}
		}

		/* Init ELBs. */
		for (int i = 0; i < mat_ct; ++i) {
			ElementListBuilder_init(&elb[i], PRIM_TRIANGLES, mat_tri_len[i], tri_len * 3);
		}

		/* Populate ELBs. */
		unsigned int nidx = 0;
		for (int i = 0; i < tri_len; ++i) {
			short ma_id;

			/* TODO deduplicate verts see mesh_batch_cache_get_shading_data */
			if (mesh_render_data_looptri_mat_index_get(rdata, i, &ma_id)) {
				add_triangle_vertices(&elb[ma_id], nidx + 0, nidx + 1, nidx + 2);
				nidx += 3;
			}
		}

		/* Build ELBs. */
		for (int i = 0; i < mat_ct; ++i) {
			cache->shaded_triangles_in_order[i] = ElementList_build(&elb[i]);
		}

		MEM_freeN(mat_tri_len);
		MEM_freeN(elb);
	}

	return cache->shaded_triangles_in_order;
}

Batch *DRW_mesh_batch_cache_get_all_edges(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->all_edges == NULL) {
		/* create batch from Mesh */
		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT | MR_DATATYPE_EDGE);

		cache->all_edges = Batch_create(PRIM_LINES, mesh_batch_cache_get_pos_and_nor_in_order(rdata, cache),
		                                mesh_batch_cache_get_edges_in_order(rdata, cache));

		mesh_render_data_free(rdata);
	}

	return cache->all_edges;
}

Batch *DRW_mesh_batch_cache_get_all_triangles(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->all_triangles == NULL) {
		/* create batch from DM */
		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI);

		cache->all_triangles = Batch_create(PRIM_TRIANGLES, mesh_batch_cache_get_pos_and_nor_in_order(rdata, cache),
		                                    mesh_batch_cache_get_triangles_in_order(rdata, cache));

		mesh_render_data_free(rdata);
	}

	return cache->all_triangles;
}

Batch *DRW_mesh_batch_cache_get_triangles_with_normals(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->triangles_with_normals == NULL) {
		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP | MR_DATATYPE_POLY);

		cache->triangles_with_normals = Batch_create(PRIM_TRIANGLES, mesh_batch_cache_get_pos_and_normals(rdata, cache), NULL);

		mesh_render_data_free(rdata);
	}

	return cache->triangles_with_normals;
}

Batch *DRW_mesh_batch_cache_get_points_with_normals(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->points_with_normals == NULL) {
		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT | MR_DATATYPE_LOOPTRI | MR_DATATYPE_LOOP | MR_DATATYPE_POLY);

		cache->points_with_normals = Batch_create(PRIM_POINTS, mesh_batch_cache_get_pos_and_normals(rdata, cache), NULL);

		mesh_render_data_free(rdata);
	}

	return cache->points_with_normals;
}

Batch *DRW_mesh_batch_cache_get_all_verts(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->all_verts == NULL) {
		/* create batch from DM */
		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT);

		cache->all_verts = Batch_create(PRIM_POINTS, mesh_batch_cache_get_pos_and_nor_in_order(rdata, cache), NULL);

		mesh_render_data_free(rdata);
	}

	return cache->all_verts;
}

Batch *DRW_mesh_batch_cache_get_fancy_edges(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->fancy_edges == NULL) {
		/* create batch from DM */
		static VertexFormat format = { 0 };
		static unsigned int pos_id, n1_id, n2_id;
		if (format.attrib_ct == 0) {
			/* initialize vertex format */
			pos_id = VertexFormat_add_attrib(&format, "pos", COMP_F32, 3, KEEP_FLOAT);

#if USE_10_10_10 /* takes 1/3 the space */
			n1_id = VertexFormat_add_attrib(&format, "N1", COMP_I10, 3, NORMALIZE_INT_TO_FLOAT);
			n2_id = VertexFormat_add_attrib(&format, "N2", COMP_I10, 3, NORMALIZE_INT_TO_FLOAT);
#else
			n1_id = VertexFormat_add_attrib(&format, "N1", COMP_F32, 3, KEEP_FLOAT);
			n2_id = VertexFormat_add_attrib(&format, "N2", COMP_F32, 3, KEEP_FLOAT);
#endif
		}
		VertexBuffer *vbo = VertexBuffer_create_with_format(&format);

		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT | MR_DATATYPE_EDGE | MR_DATATYPE_LOOP | MR_DATATYPE_POLY);

		const int edge_len = mesh_render_data_edges_len_get(rdata);

		const int vbo_len_capacity = edge_len * 2; /* these are PRIM_LINE verts, not mesh verts */
		int vbo_len_used = 0;
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);
		for (int i = 0; i < edge_len; ++i) {
			float *vcos1, *vcos2;
			float *pnor1 = NULL, *pnor2 = NULL;
			bool is_manifold;

			if (mesh_render_data_edge_vcos_manifold_pnors(rdata, i, &vcos1, &vcos2, &pnor1, &pnor2, &is_manifold)) {

#if USE_10_10_10
				PackedNormal n1value = { .x = 0, .y = 0, .z = +511 };
				PackedNormal n2value = { .x = 0, .y = 0, .z = -511 };

				if (is_manifold) {
					n1value = convert_i10_v3(pnor1);
					n2value = convert_i10_v3(pnor2);
				}

				const PackedNormal *n1 = &n1value;
				const PackedNormal *n2 = &n2value;
#else
				const float dummy1[3] = { 0.0f, 0.0f, +1.0f };
				const float dummy2[3] = { 0.0f, 0.0f, -1.0f };

				const float *n1 = (is_manifold) ? pnor1 : dummy1;
				const float *n2 = (is_manifold) ? pnor2 : dummy2;
#endif

				VertexBuffer_set_attrib(vbo, pos_id, 2 * i, vcos1);
				VertexBuffer_set_attrib(vbo, n1_id, 2 * i, n1);
				VertexBuffer_set_attrib(vbo, n2_id, 2 * i, n2);

				VertexBuffer_set_attrib(vbo, pos_id, 2 * i + 1, vcos2);
				VertexBuffer_set_attrib(vbo, n1_id, 2 * i + 1, n1);
				VertexBuffer_set_attrib(vbo, n2_id, 2 * i + 1, n2);

				vbo_len_used += 2;
			}
		}
		if (vbo_len_used != vbo_len_capacity) {
			VertexBuffer_resize_data(vbo, vbo_len_used);
		}

		cache->fancy_edges = Batch_create(PRIM_LINES, vbo, NULL);

		mesh_render_data_free(rdata);
	}

	return cache->fancy_edges;
}

static void mesh_batch_cache_create_overlay_batches(Mesh *me)
{
	/* Since MR_DATATYPE_OVERLAY is slow to generate, generate them all at once */
	int options = MR_DATATYPE_VERT | MR_DATATYPE_EDGE | MR_DATATYPE_LOOPTRI | MR_DATATYPE_OVERLAY;

	MeshBatchCache *cache = mesh_batch_cache_get(me);
	MeshRenderData *rdata = mesh_render_data_create(me, options);

	static VertexFormat format = { 0 };
	static unsigned pos_id, data_id;
	if (format.attrib_ct == 0) {
		/* initialize vertex format */
		pos_id = VertexFormat_add_attrib(&format, "pos", COMP_F32, 3, KEEP_FLOAT);
		data_id = VertexFormat_add_attrib(&format, "data", COMP_U8, 4, KEEP_INT);
	}

	const int tri_len = mesh_render_data_looptri_len_get(rdata);
	const int ledge_len = mesh_render_data_loose_edges_len_get(rdata);
	const int lvert_len = mesh_render_data_loose_verts_len_get(rdata);

	if (cache->overlay_triangles == NULL) {
		VertexBuffer *vbo = VertexBuffer_create_with_format(&format);
		const int vbo_len_capacity = tri_len * 3;
		int vbo_len_used = 0;
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);

		for (int i = 0; i < tri_len; ++i) {
			int tri_vert_idx[3], tri_edge_idx[3];
			if (mesh_render_data_looptri_vert_edge_indices_get(rdata, i, tri_vert_idx, tri_edge_idx)) {
				add_overlay_tri(
				        rdata, vbo, pos_id, data_id,
				        tri_vert_idx, tri_edge_idx, i, vbo_len_used);
				vbo_len_used += 3;
			}
		}
		if (vbo_len_used != vbo_len_capacity) {
			VertexBuffer_resize_data(vbo, vbo_len_used);
		}
		cache->overlay_triangles = Batch_create(PRIM_TRIANGLES, vbo, NULL);
	}

	if (cache->overlay_loose_edges == NULL) {
		VertexBuffer *vbo = VertexBuffer_create_with_format(&format);
		const int vbo_len_capacity = ledge_len * 2;
		int vbo_len_used = 0;
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);

		for (int i = 0; i < ledge_len; ++i) {
			int vert_idx[2];
			bool ok = mesh_render_data_edge_verts_indices_get(rdata, rdata->loose_edges[i], vert_idx);
			assert(ok);  /* we don't add */
			add_overlay_loose_edge(
			        rdata, vbo, pos_id, data_id,
			        vert_idx[0], vert_idx[1], rdata->loose_edges[i], vbo_len_used);
			vbo_len_used += 2;
		}
		BLI_assert(vbo_len_used == vbo_len_capacity);
		cache->overlay_loose_edges = Batch_create(PRIM_LINES, vbo, NULL);
	}

	if (cache->overlay_loose_verts == NULL) {
		VertexBuffer *vbo = VertexBuffer_create_with_format(&format);
		const int vbo_len_capacity = lvert_len;
		int vbo_len_used = 0;
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);

		for (int i = 0; i < lvert_len; ++i) {
			add_overlay_loose_vert(rdata, vbo, pos_id, data_id,
			                       rdata->loose_verts[i], vbo_len_used);
			vbo_len_used += 1;
		}
		BLI_assert(vbo_len_used == vbo_len_capacity);
		cache->overlay_loose_verts = Batch_create(PRIM_POINTS, vbo, NULL);
	}

	mesh_render_data_free(rdata);
}

Batch *DRW_mesh_batch_cache_get_overlay_triangles(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->overlay_triangles == NULL) {
		mesh_batch_cache_create_overlay_batches(me);
	}

	return cache->overlay_triangles;
}

Batch *DRW_mesh_batch_cache_get_overlay_loose_edges(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->overlay_loose_edges == NULL) {
		mesh_batch_cache_create_overlay_batches(me);
	}

	return cache->overlay_loose_edges;
}

Batch *DRW_mesh_batch_cache_get_overlay_loose_verts(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->overlay_loose_verts == NULL) {
		mesh_batch_cache_create_overlay_batches(me);
	}

	return cache->overlay_loose_verts;
}

Batch *DRW_mesh_batch_cache_get_overlay_facedots(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->overlay_facedots == NULL) {
		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT | MR_DATATYPE_LOOP | MR_DATATYPE_POLY);

		static VertexFormat format = { 0 };
		static unsigned pos_id, data_id;
		if (format.attrib_ct == 0) {
			/* initialize vertex format */
			pos_id = VertexFormat_add_attrib(&format, "pos", COMP_F32, 3, KEEP_FLOAT);
#if USE_10_10_10
			data_id = VertexFormat_add_attrib(&format, "norAndFlag", COMP_I10, 4, NORMALIZE_INT_TO_FLOAT);
#else
			data_id = VertexFormat_add_attrib(&format, "norAndFlag", COMP_F32, 4, KEEP_FLOAT);
#endif
		}

		const int vbo_len_capacity = mesh_render_data_polys_len_get(rdata);
		int vbo_len_used = 0;

		VertexBuffer *vbo = VertexBuffer_create_with_format(&format);
		VertexBuffer_allocate_data(vbo, vbo_len_capacity);

		for (int i = 0; i < vbo_len_capacity; ++i) {
			float pcenter[3], pnor[3];
			bool selected = false;

			if (mesh_render_data_pnors_pcenter_select_get(rdata, i, pnor, pcenter, &selected)) {

#if USE_10_10_10
				PackedNormal nor = { .x = 0, .y = 0, .z = -511 };
				nor = convert_i10_v3(pnor);
				nor.w = selected ? 1 : 0;
				VertexBuffer_set_attrib(vbo, data_id, i, &nor);
#else
				float nor[4] = {pnor[0], pnor[1], pnor[2], selected ? 1 : 0};
				VertexBuffer_set_attrib(vbo, data_id, i, nor);
#endif

				VertexBuffer_set_attrib(vbo, pos_id, i, pcenter);

				vbo_len_used += 1;
			}
		}
		if (vbo_len_used != vbo_len_capacity) {
			VertexBuffer_resize_data(vbo, vbo_len_used);
		}

		cache->overlay_facedots = Batch_create(PRIM_POINTS, vbo, NULL);

		mesh_render_data_free(rdata);
	}

	return cache->overlay_facedots;
}

Batch **DRW_mesh_batch_cache_get_surface_shaded(Mesh *me)
{
	MeshBatchCache *cache = mesh_batch_cache_get(me);

	if (cache->shaded_triangles == NULL) {
		/* create batch from DM */
		MeshRenderData *rdata = mesh_render_data_create(me, MR_DATATYPE_VERT | MR_DATATYPE_LOOP | MR_DATATYPE_LOOPTRI | MR_DATATYPE_POLY);

		const int mat_ct = mesh_render_data_mat_ct_get(rdata);

		cache->shaded_triangles = MEM_callocN(sizeof(*cache->shaded_triangles) * mat_ct, "shaded triangles batches");

		ElementList **el = mesh_batch_cache_get_shaded_triangles_in_order(rdata, cache);

		for (int i = 0; i < mat_ct; ++i) {
			cache->shaded_triangles[i] = Batch_create(PRIM_TRIANGLES, mesh_batch_cache_get_shading_data(rdata, cache), el[i]);
		}

		mesh_render_data_free(rdata);
	}

	return cache->shaded_triangles;
}

#undef MESH_RENDER_FUNCTION