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tornavis/source/blender/blenkernel/intern/multires_unsubdivide.cc

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/* SPDX-FileCopyrightText: 2020 Blender Authors
*
* SPDX-License-Identifier: GPL-2.0-or-later */
/** \file
* \ingroup bke
*
* This implements the un-subdivide algorithm, which generates a lower resolution base mesh and
* its corresponding grids to match a given original mesh.
*/
#include "MEM_guardedalloc.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_modifier_types.h"
#include "DNA_scene_types.h"
#include "BLI_gsqueue.h"
#include "BLI_math_vector.h"
#include "BKE_customdata.hh"
#include "BKE_lib_id.h"
#include "BKE_mesh.hh"
#include "BKE_mesh_mapping.hh"
#include "BKE_mesh_runtime.hh"
#include "BKE_modifier.hh"
#include "BKE_multires.hh"
#include "BKE_subdiv.hh"
#include "BKE_subsurf.hh"
#include "bmesh.h"
#include "DEG_depsgraph_query.hh"
#include "multires_reshape.hh"
#include "multires_unsubdivide.hh"
/* This is done in the following steps:
*
* - If there are already grids in the original mesh,
* convert them from tangent displacement to object space coordinates.
* - Assign data-layers to the original mesh to map vertices to a new base mesh.
* These data-layers store the indices of the elements in the original mesh.
* This way the original indices are
* preserved when doing mesh modifications (removing and dissolving vertices)
* when building the new base mesh.
* - Try to find a lower resolution base mesh. This is done by flood fill operation that tags the
* center vertices of the lower level grid.
* If the algorithm can tag all vertices correctly,
* the lower level base mesh is generated by dissolving the tagged vertices.
* - Use the data-layers to map vertices from the base mesh to the original mesh and original to
* base mesh.
* - Find two adjacent vertices on the base mesh to a given vertex to map that loop from base mesh
* to original mesh
* - Extract the grid from the original mesh from that loop. If there are no grids in the original
* mesh, build the new grid directly from the vertex coordinates by iterating in a grid pattern
* over them. If there are grids in the original mesh, iterate in a grid pattern over the faces,
* reorder all the coordinates of the grid in that face and copy those coordinates to the new
* base mesh grid.
* - Copy the new grid data over to a new allocated MDISP layer with the appropriate size to store
* the new levels.
* - Convert the grid data from object space to tangent displacement.
*/
/**
* Used to check if a vertex is in a disconnected element ID.
*/
static bool is_vertex_in_id(BMVert *v, const int *elem_id, int elem)
{
const int v_index = BM_elem_index_get(v);
return elem_id[v_index] == elem;
}
static bool is_vertex_pole_three(BMVert *v)
{
return !BM_vert_is_boundary(v) && (BM_vert_edge_count(v) == 3);
}
static bool is_vertex_pole(BMVert *v)
{
return !BM_vert_is_boundary(v) && (BM_vert_edge_count(v) == 3 || BM_vert_edge_count(v) >= 5);
}
/**
* Returns the first pole that is found in an element ID.
*
* Tries to give priority to 3 vert poles as they generally generate better results in cases were
* the un-subdivide solution is ambiguous.
*/
static BMVert *unsubdivide_find_any_pole(BMesh *bm, int *elem_id, int elem)
{
BMIter iter;
BMVert *v;
BMVert *pole = nullptr;
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
if (is_vertex_in_id(v, elem_id, elem) && is_vertex_pole_three(v)) {
return v;
}
if (is_vertex_in_id(v, elem_id, elem) && is_vertex_pole(v)) {
pole = v;
}
}
return pole;
}
/**
* Checks if the mesh is all quads.
*
* TODO(pablodp606): This can perform additional checks if they are faster than trying to search
* for an un-subdivide solution. This way it is possible to cancel the operation faster.
*/
static bool unsubdivide_is_all_quads(BMesh *bm)
{
BMIter iter;
BMIter iter_a;
BMFace *f;
BMVert *v;
int count = 0;
if (bm->totface < 3) {
return false;
}
BM_ITER_MESH (f, &iter, bm, BM_FACES_OF_MESH) {
count = 0;
BM_ITER_ELEM (v, &iter_a, f, BM_VERTS_OF_FACE) {
count++;
}
if (count != 4) {
return false;
}
}
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
if (BM_vert_is_wire(v)) {
return false;
}
if (BM_vert_edge_count(v) == 0) {
return false;
}
}
return true;
}
/**
* Returns true if from_v and to_v, which should be part of the same quad face, are diagonals.
*/
static bool is_vertex_diagonal(BMVert *from_v, BMVert *to_v)
{
return !BM_edge_exists(from_v, to_v);
}
/**
* Generates a possible solution for un-subdivision by tagging the (0,0)
* vertices of the possible grids.
*
* This works using a flood fill operation using the quads diagonals to jump to the next vertex.
*
* If initial_vertex is part of the base mesh solution, the flood fill should tag only the (0.0)
* vertices of the grids that need to be dissolved, and nothing else.
*/
static void unsubdivide_face_center_vertex_tag(BMesh *bm, BMVert *initial_vertex)
{
bool *visited_verts = static_cast<bool *>(
MEM_calloc_arrayN(bm->totvert, sizeof(bool), "visited vertices"));
GSQueue *queue;
queue = BLI_gsqueue_new(sizeof(BMVert *));
/* Add and tag the vertices connected by a diagonal to initial_vertex to the flood fill queue. If
* initial_vertex is a pole and there is a valid solution, those vertices should be the (0,0) of
* the grids for the loops of initial_vertex. */
BMIter iter;
BMIter iter_a;
BMFace *f;
BMVert *neighbor_v;
BM_ITER_ELEM (f, &iter, initial_vertex, BM_FACES_OF_VERT) {
BM_ITER_ELEM (neighbor_v, &iter_a, f, BM_VERTS_OF_FACE) {
int neighbor_vertex_index = BM_elem_index_get(neighbor_v);
if (neighbor_v != initial_vertex && is_vertex_diagonal(neighbor_v, initial_vertex)) {
BLI_gsqueue_push(queue, &neighbor_v);
visited_verts[neighbor_vertex_index] = true;
BM_elem_flag_set(neighbor_v, BM_ELEM_TAG, true);
}
}
}
/* Repeat a similar operation for all vertices in the queue. */
/* In this case, add to the queue the vertices connected by 2 steps using the diagonals in any
* direction. If a solution exists and `initial_vertex` was a pole, this is guaranteed that will
* tag all the (0,0) vertices of the grids, and nothing else. */
/* If it was not a pole, it may or may not find a solution, even if the solution exists. */
while (!BLI_gsqueue_is_empty(queue)) {
BMVert *from_v;
BLI_gsqueue_pop(queue, &from_v);
/* Get the diagonals (first connected step) */
GSQueue *diagonals;
diagonals = BLI_gsqueue_new(sizeof(BMVert *));
BM_ITER_ELEM (f, &iter, from_v, BM_FACES_OF_VERT) {
BM_ITER_ELEM (neighbor_v, &iter_a, f, BM_VERTS_OF_FACE) {
if (neighbor_v != from_v && is_vertex_diagonal(neighbor_v, from_v)) {
BLI_gsqueue_push(diagonals, &neighbor_v);
}
}
}
/* Do the second connected step. This vertices are the ones that are added to the flood fill
* queue. */
while (!BLI_gsqueue_is_empty(diagonals)) {
BMVert *diagonal_v;
BLI_gsqueue_pop(diagonals, &diagonal_v);
BM_ITER_ELEM (f, &iter, diagonal_v, BM_FACES_OF_VERT) {
BM_ITER_ELEM (neighbor_v, &iter_a, f, BM_VERTS_OF_FACE) {
int neighbor_vertex_index = BM_elem_index_get(neighbor_v);
if (!visited_verts[neighbor_vertex_index] && neighbor_v != diagonal_v &&
is_vertex_diagonal(neighbor_v, diagonal_v))
{
BLI_gsqueue_push(queue, &neighbor_v);
visited_verts[neighbor_vertex_index] = true;
BM_elem_flag_set(neighbor_v, BM_ELEM_TAG, true);
}
}
}
}
BLI_gsqueue_free(diagonals);
}
BLI_gsqueue_free(queue);
MEM_freeN(visited_verts);
}
/**
* This function checks if the current status of the #BMVert tags
* corresponds to a valid un-subdivide solution.
*
* This means that all vertices corresponding to the (0,0) grid coordinate should be tagged.
*
* On a valid solution, the following things should happen:
* - No boundary vertices should be tagged
* - No vertices connected by an edge or a quad diagonal to a tagged vertex should be tagged
* - All boundary vertices should have one vertex connected by an edge or a diagonal tagged
*/
static bool unsubdivide_is_center_vertex_tag_valid(BMesh *bm, int *elem_id, int elem)
{
BMVert *v, *neighbor_v;
BMIter iter, iter_a, iter_b;
BMFace *f;
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
if (is_vertex_in_id(v, elem_id, elem)) {
if (BM_elem_flag_test(v, BM_ELEM_TAG)) {
/* Tagged vertex in boundary */
if (BM_vert_is_boundary(v)) {
return false;
}
/* Tagged vertex with connected tagged vertex. */
BM_ITER_ELEM (f, &iter_a, v, BM_FACES_OF_VERT) {
BM_ITER_ELEM (neighbor_v, &iter_b, f, BM_VERTS_OF_FACE) {
if (neighbor_v != v && BM_elem_flag_test(neighbor_v, BM_ELEM_TAG)) {
return false;
}
}
}
}
if (BM_vert_is_boundary(v)) {
/* Un-tagged vertex in boundary without connected tagged vertices. */
bool any_tagged = false;
BM_ITER_ELEM (f, &iter_a, v, BM_FACES_OF_VERT) {
BM_ITER_ELEM (neighbor_v, &iter_b, f, BM_VERTS_OF_FACE) {
if (neighbor_v != v && BM_elem_flag_test(neighbor_v, BM_ELEM_TAG)) {
any_tagged = true;
}
}
}
if (!any_tagged) {
return false;
}
}
}
}
return true;
}
/**
* Search and validates an un-subdivide solution for a given element ID.
*/
static bool unsubdivide_tag_disconnected_mesh_element(BMesh *bm, int *elem_id, int elem)
{
/* First, get vertex candidates to try to generate possible un-subdivide solution. */
/* Find a vertex pole. If there is a solution on an all quad base mesh, this vertex should be
* part of the base mesh. If it isn't, then there is no solution. */
GSQueue *initial_vertex = BLI_gsqueue_new(sizeof(BMVert *));
BMVert *initial_vertex_pole = unsubdivide_find_any_pole(bm, elem_id, elem);
if (initial_vertex_pole != nullptr) {
BLI_gsqueue_push(initial_vertex, &initial_vertex_pole);
}
/* Also try from the different 4 vertices of a quad in the current
* disconnected element ID. If a solution exists the search should return a valid solution from
* one of these vertices. */
BMFace *f, *init_face = nullptr;
BMVert *v;
BMIter iter_a, iter_b;
BM_ITER_MESH (f, &iter_a, bm, BM_FACES_OF_MESH) {
BM_ITER_ELEM (v, &iter_b, f, BM_VERTS_OF_FACE) {
if (is_vertex_in_id(v, elem_id, elem)) {
init_face = f;
break;
}
}
if (init_face != nullptr) {
break;
}
}
BM_ITER_ELEM (v, &iter_a, init_face, BM_VERTS_OF_FACE) {
BLI_gsqueue_push(initial_vertex, &v);
}
bool valid_tag_found = false;
/* Check all vertex candidates to a solution. */
while (!BLI_gsqueue_is_empty(initial_vertex)) {
BMVert *iv;
BLI_gsqueue_pop(initial_vertex, &iv);
/* Generate a possible solution. */
unsubdivide_face_center_vertex_tag(bm, iv);
/* Check if the solution is valid. If it is, stop searching. */
if (unsubdivide_is_center_vertex_tag_valid(bm, elem_id, elem)) {
valid_tag_found = true;
break;
}
/* If the solution is not valid, reset the state of all tags in this disconnected element ID
* and try again. */
BMVert *v_reset;
BMIter iter;
BM_ITER_MESH (v_reset, &iter, bm, BM_VERTS_OF_MESH) {
if (is_vertex_in_id(v_reset, elem_id, elem)) {
BM_elem_flag_set(v_reset, BM_ELEM_TAG, false);
}
}
}
BLI_gsqueue_free(initial_vertex);
return valid_tag_found;
}
/**
* Uses a flood fill operation to generate a different ID for each disconnected mesh element.
*/
static int unsubdivide_init_elem_ids(BMesh *bm, int *elem_id)
{
bool *visited_verts = static_cast<bool *>(
MEM_calloc_arrayN(bm->totvert, sizeof(bool), "visited vertices"));
int current_id = 0;
for (int i = 0; i < bm->totvert; i++) {
if (!visited_verts[i]) {
GSQueue *queue;
queue = BLI_gsqueue_new(sizeof(BMVert *));
visited_verts[i] = true;
elem_id[i] = current_id;
BMVert *iv = BM_vert_at_index(bm, i);
BLI_gsqueue_push(queue, &iv);
while (!BLI_gsqueue_is_empty(queue)) {
BMIter iter;
BMVert *current_v, *neighbor_v;
BMEdge *ed;
BLI_gsqueue_pop(queue, &current_v);
BM_ITER_ELEM (ed, &iter, current_v, BM_EDGES_OF_VERT) {
neighbor_v = BM_edge_other_vert(ed, current_v);
const int neighbor_index = BM_elem_index_get(neighbor_v);
if (!visited_verts[neighbor_index]) {
visited_verts[neighbor_index] = true;
elem_id[neighbor_index] = current_id;
BLI_gsqueue_push(queue, &neighbor_v);
}
}
}
current_id++;
BLI_gsqueue_free(queue);
}
}
MEM_freeN(visited_verts);
return current_id;
}
/**
* Builds a base mesh one subdivision level down from the current original mesh if the original
* mesh has a valid solution stored in the #BMVert tags.
*/
static void unsubdivide_build_base_mesh_from_tags(BMesh *bm)
{
BMVert *v;
BMIter iter;
/* Stores the vertices which correspond to (1, 0) and (0, 1) of the grids in the select flag. */
BM_mesh_elem_hflag_enable_all(bm, BM_VERT | BM_EDGE | BM_FACE, BM_ELEM_SELECT, false);
BMVert *v_neighbor;
BMIter iter_a;
BMEdge *ed;
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
BM_ITER_ELEM (ed, &iter_a, v, BM_EDGES_OF_VERT) {
v_neighbor = BM_edge_other_vert(ed, v);
if (BM_elem_flag_test(v_neighbor, BM_ELEM_TAG)) {
BM_elem_flag_set(v, BM_ELEM_SELECT, false);
}
}
}
/* Dissolves the (0,0) vertices of the grids. */
BMO_op_callf(bm,
(BMO_FLAG_DEFAULTS & ~BMO_FLAG_RESPECT_HIDE),
"dissolve_verts verts=%hv use_face_split=%b use_boundary_tear=%b",
BM_ELEM_TAG,
false,
true);
BM_mesh_elem_hflag_disable_all(bm, BM_VERT | BM_EDGE | BM_FACE, BM_ELEM_TAG, false);
/* Copy the select flag to the tag flag. */
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
if (!BM_elem_flag_test(v, BM_ELEM_SELECT)) {
BM_elem_flag_set(v, BM_ELEM_TAG, true);
}
}
/* Dissolves the (1,0) and (0,1) vertices of the grids. */
BMO_op_callf(bm,
(BMO_FLAG_DEFAULTS & ~BMO_FLAG_RESPECT_HIDE),
"dissolve_verts verts=%hv use_face_split=%b use_boundary_tear=%b",
BM_ELEM_TAG,
false,
true);
}
/**
* Main function to get a base mesh one level down from the current original mesh if it exists.
*
* This searches for different un-subdivide solutions and stores them as a combination of #BMVert
* flags for each disconnected mesh element.
*
* If the solution for all elements are valid, it builds a new base mesh based on those tags by
* dissolving and merging vertices.
*/
static bool multires_unsubdivide_single_level(BMesh *bm)
{
/* Do a first check to make sure that it makes sense to search for un-subdivision in this mesh.
*/
if (!unsubdivide_is_all_quads(bm)) {
return false;
};
/* Initialize the vertex table. */
BM_mesh_elem_table_init(bm, BM_VERT);
BM_mesh_elem_table_ensure(bm, BM_VERT);
/* Build disconnected elements IDs. Each disconnected mesh element is evaluated separately. */
int *elem_id = static_cast<int *>(MEM_calloc_arrayN(bm->totvert, sizeof(int), " ELEM ID"));
const int tot_ids = unsubdivide_init_elem_ids(bm, elem_id);
bool valid_tag_found = true;
/* Reset the #BMesh flags as they are used to store data during the un-subdivide process. */
BM_mesh_elem_hflag_disable_all(bm, BM_VERT | BM_EDGE | BM_FACE, BM_ELEM_TAG, false);
BM_mesh_elem_hflag_disable_all(bm, BM_VERT | BM_EDGE | BM_FACE, BM_ELEM_SELECT, false);
/* For each disconnected mesh element ID, search if an un-subdivide solution is possible. The
* whole un-subdivide process fails if a single disconnected mesh element fails. */
for (int id = 0; id < tot_ids; id++) {
/* Try to the #BMesh vertex flag tags corresponding to an un-subdivide solution. */
if (!unsubdivide_tag_disconnected_mesh_element(bm, elem_id, id)) {
valid_tag_found = false;
break;
}
}
/* If a solution was found for all elements IDs, build the new base mesh using the solution
* stored in the BMVert tags. */
if (valid_tag_found) {
unsubdivide_build_base_mesh_from_tags(bm);
}
MEM_freeN(elem_id);
return valid_tag_found;
}
/**
* Returns the next edge and vertex in the direction of a given edge.
*/
static BMEdge *edge_step(BMVert *v, BMEdge *edge, BMVert **r_next_vertex)
{
BMIter iter;
BMEdge *test_edge;
if (edge == nullptr) {
(*r_next_vertex) = v;
return edge;
}
(*r_next_vertex) = BM_edge_other_vert(edge, v);
BM_ITER_ELEM (test_edge, &iter, (*r_next_vertex), BM_EDGES_OF_VERT) {
if (!BM_edge_share_quad_check(test_edge, edge)) {
return test_edge;
}
}
return nullptr;
}
static BMFace *face_step(BMEdge *edge, BMFace *f)
{
BMIter iter;
BMFace *face_iter;
BM_ITER_ELEM (face_iter, &iter, edge, BM_FACES_OF_EDGE) {
if (BM_face_share_edge_check(face_iter, f)) {
return face_iter;
}
}
return f;
}
/**
* Returns the other edge which belongs to the face f which is different from edge_x and shares
* initial_vertex.
*/
static BMEdge *get_initial_edge_y(BMFace *f, BMEdge *edge_x, BMVert *initial_vertex)
{
BMIter iter;
BMEdge *test_edge;
BM_ITER_ELEM (test_edge, &iter, f, BM_EDGES_OF_FACE) {
if (edge_x != test_edge) {
if (test_edge->v1 != initial_vertex && test_edge->v2 == initial_vertex) {
return test_edge;
}
if (test_edge->v2 != initial_vertex && test_edge->v1 == initial_vertex) {
return test_edge;
}
}
}
return nullptr;
}
/**
* Writes the current mdisp data into the corresponding area of quad face giving its corner's loop.
*/
static void write_loop_in_face_grid(
float (*face_grid)[3], MDisps *mdisp, int face_grid_size, int orig_grid_size, int loop)
{
int origin[2];
int step_x[2];
int step_y[2];
const int grid_offset = orig_grid_size - 1;
origin[0] = grid_offset;
origin[1] = grid_offset;
switch (loop) {
case 0:
step_x[0] = -1;
step_x[1] = 0;
step_y[0] = 0;
step_y[1] = -1;
break;
case 1:
step_x[0] = 0;
step_x[1] = 1;
step_y[0] = -1;
step_y[1] = -0;
break;
case 2:
step_x[0] = 1;
step_x[1] = 0;
step_y[0] = 0;
step_y[1] = 1;
break;
case 3:
step_x[0] = 0;
step_x[1] = -1;
step_y[0] = 1;
step_y[1] = 0;
break;
default:
BLI_assert_msg(0, "Should never happen");
break;
}
for (int y = 0; y < orig_grid_size; y++) {
for (int x = 0; x < orig_grid_size; x++) {
const int remap_x = origin[1] + (step_x[1] * x) + (step_y[1] * y);
const int remap_y = origin[0] + (step_x[0] * x) + (step_y[0] * y);
const int final_index = remap_x + remap_y * face_grid_size;
copy_v3_v3(face_grid[final_index], mdisp->disps[x + y * orig_grid_size]);
}
}
}
/**
* Writes a buffer containing the 4 grids in the correct orientation of the 4 loops of a face into
* the main #MultiresUnsubdivideGrid that is being extracted.
*/
static void write_face_grid_in_unsubdivide_grid(MultiresUnsubdivideGrid *grid,
float (*face_grid)[3],
int face_grid_size,
int gunsub_x,
int gunsub_y)
{
const int grid_it = face_grid_size - 1;
for (int y = 0; y < face_grid_size; y++) {
for (int x = 0; x < face_grid_size; x++) {
const int remap_x = (grid_it * gunsub_x) + x;
const int remap_y = (grid_it * gunsub_y) + y;
const int remap_index_y = grid->grid_size - remap_x - 1;
const int remap_index_x = grid->grid_size - remap_y - 1;
const int grid_index = remap_index_x + (remap_index_y * grid->grid_size);
copy_v3_v3(grid->grid_co[grid_index], face_grid[x + y * face_grid_size]);
}
}
}
/**
* Stores the data from the mdisps grids of the loops of the face f
* into the new grid for the new base mesh.
*
* Used when there are already grids in the original mesh.
*/
static void store_grid_data(MultiresUnsubdivideContext *context,
MultiresUnsubdivideGrid *grid,
BMVert *v,
BMFace *f,
int grid_x,
int grid_y)
{
Mesh *original_mesh = context->original_mesh;
const blender::OffsetIndices faces = original_mesh->faces();
const blender::Span<int> corner_verts = original_mesh->corner_verts();
const blender::IndexRange face = faces[BM_elem_index_get(f)];
const int corner_vertex_index = BM_elem_index_get(v);
/* Calculates an offset to write the grids correctly oriented in the main
* #MultiresUnsubdivideGrid. */
int loop_offset = 0;
for (int i = 0; i < face.size(); i++) {
const int loop_index = face[i];
if (corner_verts[loop_index] == corner_vertex_index) {
loop_offset = i;
break;
}
}
/* Write the 4 grids of the current quad with the right orientation into the face_grid buffer. */
const int grid_size = BKE_ccg_gridsize(context->num_original_levels);
const int face_grid_size = BKE_ccg_gridsize(context->num_original_levels + 1);
const int face_grid_area = face_grid_size * face_grid_size;
float(*face_grid)[3] = static_cast<float(*)[3]>(
MEM_calloc_arrayN(face_grid_area, sizeof(float[3]), "face_grid"));
for (int i = 0; i < face.size(); i++) {
const int loop_index = face[i];
MDisps *mdisp = &context->original_mdisp[loop_index];
int quad_loop = i - loop_offset;
if (quad_loop < 0) {
quad_loop += 4;
}
if (quad_loop >= 4) {
quad_loop -= 4;
}
write_loop_in_face_grid(face_grid, mdisp, face_grid_size, grid_size, quad_loop);
}
/* Write the face_grid buffer in the correct position in the #MultiresUnsubdivideGrids that is
* being extracted. */
write_face_grid_in_unsubdivide_grid(grid, face_grid, face_grid_size, grid_x, grid_y);
MEM_freeN(face_grid);
}
/**
* Stores the data into the new grid from a #BMVert.
* Used when there are no grids in the original mesh.
*/
static void store_vertex_data(MultiresUnsubdivideGrid *grid, BMVert *v, int grid_x, int grid_y)
{
const int remap_index_y = grid->grid_size - 1 - grid_x;
const int remap_index_x = grid->grid_size - 1 - grid_y;
const int grid_index = remap_index_x + (remap_index_y * grid->grid_size);
copy_v3_v3(grid->grid_co[grid_index], v->co);
}
/**
* Main function to extract data from the original bmesh and MDISPS as grids for the new base mesh.
*/
static void multires_unsubdivide_extract_single_grid_from_face_edge(
MultiresUnsubdivideContext *context,
BMFace *f1,
BMEdge *e1,
bool flip_grid,
MultiresUnsubdivideGrid *grid)
{
BMVert *initial_vertex;
BMEdge *initial_edge_x;
BMEdge *initial_edge_y;
const int grid_size = BKE_ccg_gridsize(context->num_new_levels);
const int unsubdiv_grid_size = grid->grid_size = BKE_ccg_gridsize(context->num_total_levels);
grid->grid_size = unsubdiv_grid_size;
grid->grid_co = static_cast<float(*)[3]>(MEM_calloc_arrayN(
unsubdiv_grid_size * unsubdiv_grid_size, sizeof(float[3]), "grids coordinates"));
/* Get the vertex on the corner of the grid. This vertex was tagged previously as it also exist
* on the base mesh. */
initial_edge_x = e1;
if (BM_elem_flag_test(initial_edge_x->v1, BM_ELEM_TAG)) {
initial_vertex = initial_edge_x->v1;
}
else {
initial_vertex = initial_edge_x->v2;
}
/* From that vertex, get the edge that defines the grid Y axis for extraction. */
initial_edge_y = get_initial_edge_y(f1, initial_edge_x, initial_vertex);
if (flip_grid) {
BMEdge *edge_temp;
edge_temp = initial_edge_x;
initial_edge_x = initial_edge_y;
initial_edge_y = edge_temp;
}
int grid_x = 0;
int grid_y = 0;
BMVert *current_vertex_x = initial_vertex;
BMEdge *edge_x = initial_edge_x;
BMVert *current_vertex_y = initial_vertex;
BMEdge *edge_y = initial_edge_y;
BMEdge *prev_edge_y = initial_edge_y;
BMFace *current_face = f1;
BMFace *grid_face = f1;
/* If the data is going to be extracted from the already existing grids, there is no need to go
* to the last vertex of the iteration as that coordinate is also included in the grids
* corresponding to the loop of the face of the previous iteration. */
int grid_iteration_max_steps = grid_size;
if (context->num_original_levels > 0) {
grid_iteration_max_steps = grid_size - 1;
}
/* Iterate over the mesh vertices in a grid pattern using the axis defined by the two initial
* edges. */
while (grid_y < grid_iteration_max_steps) {
grid_face = current_face;
while (grid_x < grid_iteration_max_steps) {
if (context->num_original_levels == 0) {
/* If there were no grids on the original mesh, extract the data directly from the
* vertices. */
store_vertex_data(grid, current_vertex_x, grid_x, grid_y);
edge_x = edge_step(current_vertex_x, edge_x, &current_vertex_x);
}
else {
/* If there were grids in the original mesh, extract the data from the grids and iterate
* over the faces. */
store_grid_data(context, grid, current_vertex_x, grid_face, grid_x, grid_y);
edge_x = edge_step(current_vertex_x, edge_x, &current_vertex_x);
grid_face = face_step(edge_x, grid_face);
}
grid_x++;
}
grid_x = 0;
edge_y = edge_step(current_vertex_y, edge_y, &current_vertex_y);
current_vertex_x = current_vertex_y;
/* Get the next edge_x to extract the next row of the grid. This needs to be done because there
* may be two edges connected to current_vertex_x that belong to two different grids. */
BMIter iter;
BMEdge *ed;
BMFace *f;
BM_ITER_ELEM (ed, &iter, current_vertex_x, BM_EDGES_OF_VERT) {
if (ed != prev_edge_y && BM_edge_in_face(ed, current_face)) {
edge_x = ed;
break;
}
}
BM_ITER_ELEM (f, &iter, edge_x, BM_FACES_OF_EDGE) {
if (f != current_face) {
current_face = f;
break;
}
}
prev_edge_y = edge_y;
grid_y++;
}
}
/**
* Returns the l+1 and l-1 vertices of the base mesh face were the grid from the face f1 and edge
* e1 is going to be extracted.
*
* These vertices should always have an corresponding existing vertex on the base mesh.
*/
static void multires_unsubdivide_get_grid_corners_on_base_mesh(BMFace *f1,
BMEdge *e1,
BMVert **r_corner_x,
BMVert **r_corner_y)
{
BMVert *initial_vertex;
BMEdge *initial_edge_x;
BMEdge *initial_edge_y;
initial_edge_x = e1;
if (BM_elem_flag_test(initial_edge_x->v1, BM_ELEM_TAG)) {
initial_vertex = initial_edge_x->v1;
}
else {
initial_vertex = initial_edge_x->v2;
}
/* From that vertex, get the edge that defines the grid Y axis for extraction. */
initial_edge_y = get_initial_edge_y(f1, initial_edge_x, initial_vertex);
BMVert *current_vertex_x = initial_vertex;
BMEdge *edge_x = initial_edge_x;
BMVert *current_vertex_y = initial_vertex;
BMEdge *edge_y = initial_edge_y;
/* Do an edge step until it finds a tagged vertex, which is part of the base mesh. */
/* x axis */
edge_x = edge_step(current_vertex_x, edge_x, &current_vertex_x);
while (!BM_elem_flag_test(current_vertex_x, BM_ELEM_TAG)) {
edge_x = edge_step(current_vertex_x, edge_x, &current_vertex_x);
}
(*r_corner_x) = current_vertex_x;
/* Same for y axis */
edge_y = edge_step(current_vertex_y, edge_y, &current_vertex_y);
while (!BM_elem_flag_test(current_vertex_y, BM_ELEM_TAG)) {
edge_y = edge_step(current_vertex_y, edge_y, &current_vertex_y);
}
(*r_corner_y) = current_vertex_y;
}
static BMesh *get_bmesh_from_mesh(Mesh *mesh)
{
const BMAllocTemplate allocsize = BMALLOC_TEMPLATE_FROM_ME(mesh);
BMeshCreateParams bm_create_params{};
bm_create_params.use_toolflags = true;
BMesh *bm = BM_mesh_create(&allocsize, &bm_create_params);
BMeshFromMeshParams bm_from_me_params{};
bm_from_me_params.calc_face_normal = true;
bm_from_me_params.calc_vert_normal = true;
BM_mesh_bm_from_me(bm, mesh, &bm_from_me_params);
return bm;
}
/* Data-layer names to store the original indices of the elements before modifying the mesh. */
static const char lname[] = "l_remap_index";
static const char vname[] = "v_remap_index";
static void multires_unsubdivide_free_original_datalayers(Mesh *mesh)
{
const int l_layer_index = CustomData_get_named_layer_index(
&mesh->loop_data, CD_PROP_INT32, lname);
if (l_layer_index != -1) {
CustomData_free_layer(&mesh->loop_data, CD_PROP_INT32, mesh->totloop, l_layer_index);
}
const int v_layer_index = CustomData_get_named_layer_index(
&mesh->vert_data, CD_PROP_INT32, vname);
if (v_layer_index != -1) {
CustomData_free_layer(&mesh->vert_data, CD_PROP_INT32, mesh->totvert, v_layer_index);
}
}
/**
* Generates two data-layers to map loops and vertices from base mesh to original mesh after
* dissolving the vertices.
*/
static void multires_unsubdivide_add_original_index_datalayers(Mesh *mesh)
{
multires_unsubdivide_free_original_datalayers(mesh);
int *l_index = static_cast<int *>(CustomData_add_layer_named(
&mesh->loop_data, CD_PROP_INT32, CD_SET_DEFAULT, mesh->totloop, lname));
int *v_index = static_cast<int *>(CustomData_add_layer_named(
&mesh->vert_data, CD_PROP_INT32, CD_SET_DEFAULT, mesh->totvert, vname));
/* Initialize these data-layer with the indices in the current mesh. */
for (int i = 0; i < mesh->totloop; i++) {
l_index[i] = i;
}
for (int i = 0; i < mesh->totvert; i++) {
v_index[i] = i;
}
}
static void multires_unsubdivide_prepare_original_bmesh_for_extract(
MultiresUnsubdivideContext *context)
{
Mesh *original_mesh = context->original_mesh;
Mesh *base_mesh = context->base_mesh;
BMesh *bm_original_mesh = context->bm_original_mesh = get_bmesh_from_mesh(original_mesh);
/* Initialize the elem tables. */
BM_mesh_elem_table_ensure(bm_original_mesh, BM_EDGE);
BM_mesh_elem_table_ensure(bm_original_mesh, BM_FACE);
BM_mesh_elem_table_ensure(bm_original_mesh, BM_VERT);
/* Disable all flags. */
BM_mesh_elem_hflag_disable_all(
bm_original_mesh, BM_VERT | BM_EDGE | BM_FACE, BM_ELEM_TAG, false);
BM_mesh_elem_hflag_disable_all(
bm_original_mesh, BM_VERT | BM_EDGE | BM_FACE, BM_ELEM_SELECT, false);
/* Get the mapping data-layer. */
context->base_to_orig_vmap = static_cast<const int *>(
CustomData_get_layer_named(&base_mesh->vert_data, CD_PROP_INT32, vname));
/* Tag the base mesh vertices in the original mesh. */
for (int i = 0; i < base_mesh->totvert; i++) {
int vert_basemesh_index = context->base_to_orig_vmap[i];
BMVert *v = BM_vert_at_index(bm_original_mesh, vert_basemesh_index);
BM_elem_flag_set(v, BM_ELEM_TAG, true);
}
context->loop_to_face_map = original_mesh->corner_to_face_map();
}
/**
* Checks the orientation of the loops to flip the x and y axis when extracting the grid if
* necessary.
*/
static bool multires_unsubdivide_flip_grid_x_axis(const blender::OffsetIndices<int> faces,
const blender::Span<int> corner_verts,
int face_index,
int loop,
int v_x)
{
const blender::IndexRange face = faces[face_index];
const int v_first = corner_verts[face.start()];
if ((loop == (face.start() + (face.size() - 1))) && v_first == v_x) {
return true;
}
int next_l_index = loop + 1;
if (next_l_index < face.start() + face.size()) {
const int v_next = corner_verts[next_l_index];
if (v_next == v_x) {
return true;
}
}
return false;
}
static void multires_unsubdivide_extract_grids(MultiresUnsubdivideContext *context)
{
Mesh *original_mesh = context->original_mesh;
Mesh *base_mesh = context->base_mesh;
BMesh *bm_original_mesh = context->bm_original_mesh;
context->num_grids = base_mesh->totloop;
context->base_mesh_grids = static_cast<MultiresUnsubdivideGrid *>(
MEM_calloc_arrayN(base_mesh->totloop, sizeof(MultiresUnsubdivideGrid), "grids"));
/* Based on the existing indices in the data-layers, generate two vertex indices maps. */
/* From vertex index in original to vertex index in base and from vertex index in base to vertex
* index in original. */
int *orig_to_base_vmap = static_cast<int *>(
MEM_calloc_arrayN(bm_original_mesh->totvert, sizeof(int), "orig vmap"));
int *base_to_orig_vmap = static_cast<int *>(
MEM_calloc_arrayN(base_mesh->totvert, sizeof(int), "base vmap"));
context->base_to_orig_vmap = static_cast<const int *>(
CustomData_get_layer_named(&base_mesh->vert_data, CD_PROP_INT32, vname));
for (int i = 0; i < base_mesh->totvert; i++) {
base_to_orig_vmap[i] = context->base_to_orig_vmap[i];
}
/* If an index in original does not exist in base (it was dissolved when creating the new base
* mesh, return -1. */
for (int i = 0; i < original_mesh->totvert; i++) {
orig_to_base_vmap[i] = -1;
}
for (int i = 0; i < base_mesh->totvert; i++) {
const int orig_vertex_index = context->base_to_orig_vmap[i];
orig_to_base_vmap[orig_vertex_index] = i;
}
/* Add the original data-layers to the base mesh to have the loop indices stored in a data-layer,
* so they can be used from #BMesh. */
multires_unsubdivide_add_original_index_datalayers(base_mesh);
BMesh *bm_base_mesh = get_bmesh_from_mesh(base_mesh);
BMIter iter, iter_a, iter_b;
BMVert *v;
BMLoop *l, *lb;
BM_mesh_elem_table_ensure(bm_base_mesh, BM_VERT);
BM_mesh_elem_table_ensure(bm_base_mesh, BM_FACE);
/* Get the data-layer that contains the loops indices. */
const int base_l_offset = CustomData_get_offset_named(
&bm_base_mesh->ldata, CD_PROP_INT32, lname);
const blender::OffsetIndices faces = base_mesh->faces();
const blender::Span<int> corner_verts = base_mesh->corner_verts();
/* Main loop for extracting the grids. Iterates over the base mesh vertices. */
BM_ITER_MESH (v, &iter, bm_base_mesh, BM_VERTS_OF_MESH) {
/* For each base mesh vertex, get the corresponding #BMVert of the original mesh using the
* vertex map. */
const int orig_vertex_index = base_to_orig_vmap[BM_elem_index_get(v)];
BMVert *vert_original = BM_vert_at_index(bm_original_mesh, orig_vertex_index);
/* Iterate over the loops of that vertex in the original mesh. */
BM_ITER_ELEM (l, &iter_a, vert_original, BM_LOOPS_OF_VERT) {
/* For each loop, get the two vertices that should map to the l+1 and l-1 vertices in the
* base mesh of the face of grid that is going to be extracted. */
BMVert *corner_x, *corner_y;
multires_unsubdivide_get_grid_corners_on_base_mesh(l->f, l->e, &corner_x, &corner_y);
/* Map the two obtained vertices to the base mesh. */
const int corner_x_index = orig_to_base_vmap[BM_elem_index_get(corner_x)];
const int corner_y_index = orig_to_base_vmap[BM_elem_index_get(corner_y)];
/* Iterate over the loops of the same vertex in the base mesh. With the previously obtained
* vertices and the current vertex it is possible to get the index of the loop in the base
* mesh the grid that is going to be extracted belongs to. */
BM_ITER_ELEM (lb, &iter_b, v, BM_LOOPS_OF_VERT) {
BMFace *base_face = lb->f;
BMVert *base_corner_x = BM_vert_at_index(bm_base_mesh, corner_x_index);
BMVert *base_corner_y = BM_vert_at_index(bm_base_mesh, corner_y_index);
/* If this is the correct loop in the base mesh, the original vertex and the two corners
* should be in the loop's face. */
if (BM_vert_in_face(base_corner_x, base_face) && BM_vert_in_face(base_corner_y, base_face))
{
/* Get the index of the loop. */
const int base_mesh_loop_index = BM_ELEM_CD_GET_INT(lb, base_l_offset);
const int base_mesh_face_index = BM_elem_index_get(base_face);
/* Check the orientation of the loops in case that is needed to flip the x and y axis
* when extracting the grid. */
const bool flip_grid = multires_unsubdivide_flip_grid_x_axis(
faces, corner_verts, base_mesh_face_index, base_mesh_loop_index, corner_x_index);
/* Extract the grid for that loop. */
context->base_mesh_grids[base_mesh_loop_index].grid_index = base_mesh_loop_index;
multires_unsubdivide_extract_single_grid_from_face_edge(
context, l->f, l->e, !flip_grid, &context->base_mesh_grids[base_mesh_loop_index]);
break;
}
}
}
}
MEM_freeN(orig_to_base_vmap);
MEM_freeN(base_to_orig_vmap);
BM_mesh_free(bm_base_mesh);
multires_unsubdivide_free_original_datalayers(base_mesh);
}
static void multires_unsubdivide_private_extract_data_free(MultiresUnsubdivideContext *context)
{
if (context->bm_original_mesh != nullptr) {
BM_mesh_free(context->bm_original_mesh);
}
}
void multires_unsubdivide_context_init(MultiresUnsubdivideContext *context,
Mesh *original_mesh,
MultiresModifierData *mmd)
{
context->original_mesh = original_mesh;
context->num_new_levels = 0;
context->num_total_levels = 0;
context->num_original_levels = mmd->totlvl;
}
bool multires_unsubdivide_to_basemesh(MultiresUnsubdivideContext *context)
{
Mesh *original_mesh = context->original_mesh;
/* Prepare the data-layers to map base to original. */
multires_unsubdivide_add_original_index_datalayers(original_mesh);
BMesh *bm_base_mesh = get_bmesh_from_mesh(original_mesh);
/* Un-subdivide as many iterations as possible. */
context->num_new_levels = 0;
int num_levels_left = context->max_new_levels;
while (num_levels_left > 0 && multires_unsubdivide_single_level(bm_base_mesh)) {
context->num_new_levels++;
num_levels_left--;
}
/* If no un-subdivide steps were possible, free the bmesh, the map data-layers and stop. */
if (context->num_new_levels == 0) {
multires_unsubdivide_free_original_datalayers(original_mesh);
BM_mesh_free(bm_base_mesh);
return false;
}
/* Calculate the final levels for the new grids over base mesh. */
context->num_total_levels = context->num_new_levels + context->num_original_levels;
/* Store the new base-mesh as a mesh in context, free bmesh. */
context->base_mesh = BKE_mesh_new_nomain(0, 0, 0, 0);
BMeshToMeshParams bm_to_me_params{};
bm_to_me_params.calc_object_remap = true;
BM_mesh_bm_to_me(nullptr, bm_base_mesh, context->base_mesh, &bm_to_me_params);
BM_mesh_free(bm_base_mesh);
/* Initialize bmesh and maps for the original mesh and extract the grids. */
multires_unsubdivide_prepare_original_bmesh_for_extract(context);
multires_unsubdivide_extract_grids(context);
return true;
}
void multires_unsubdivide_context_free(MultiresUnsubdivideContext *context)
{
multires_unsubdivide_private_extract_data_free(context);
for (int i = 0; i < context->num_grids; i++) {
if (context->base_mesh_grids[i].grid_size > 0) {
MEM_SAFE_FREE(context->base_mesh_grids[i].grid_co);
}
}
MEM_SAFE_FREE(context->base_mesh_grids);
}
/**
* This function allocates new mdisps with the right size to fit the new extracted grids from the
* base mesh and copies the data to them.
*/
static void multires_create_grids_in_unsubdivided_base_mesh(MultiresUnsubdivideContext *context,
Mesh *base_mesh)
{
/* Free the current MDISPS and create a new ones. */
if (CustomData_has_layer(&base_mesh->loop_data, CD_MDISPS)) {
CustomData_free_layers(&base_mesh->loop_data, CD_MDISPS, base_mesh->totloop);
}
MDisps *mdisps = static_cast<MDisps *>(
CustomData_add_layer(&base_mesh->loop_data, CD_MDISPS, CD_SET_DEFAULT, base_mesh->totloop));
const int totdisp = pow_i(BKE_ccg_gridsize(context->num_total_levels), 2);
const int totloop = base_mesh->totloop;
BLI_assert(base_mesh->totloop == context->num_grids);
/* Allocate the MDISPS grids and copy the extracted data from context. */
for (int i = 0; i < totloop; i++) {
float(*disps)[3] = static_cast<float(*)[3]>(
MEM_calloc_arrayN(totdisp, sizeof(float[3]), __func__));
if (mdisps[i].disps) {
MEM_freeN(mdisps[i].disps);
}
for (int j = 0; j < totdisp; j++) {
if (context->base_mesh_grids[i].grid_co) {
copy_v3_v3(disps[j], context->base_mesh_grids[i].grid_co[j]);
}
}
mdisps[i].disps = disps;
mdisps[i].totdisp = totdisp;
mdisps[i].level = context->num_total_levels;
}
}
int multiresModifier_rebuild_subdiv(Depsgraph *depsgraph,
Object *object,
MultiresModifierData *mmd,
int rebuild_limit,
bool switch_view_to_lower_level)
{
Mesh *mesh = static_cast<Mesh *>(object->data);
multires_force_sculpt_rebuild(object);
MultiresUnsubdivideContext unsubdiv_context{};
MultiresReshapeContext reshape_context{};
multires_unsubdivide_context_init(&unsubdiv_context, mesh, mmd);
/* Convert and store the existing grids in object space if available. */
if (mmd->totlvl != 0) {
if (!multires_reshape_context_create_from_object(&reshape_context, depsgraph, object, mmd)) {
return 0;
}
multires_reshape_store_original_grids(&reshape_context);
multires_reshape_assign_final_coords_from_mdisps(&reshape_context);
unsubdiv_context.original_mdisp = reshape_context.mdisps;
}
/* Set the limit for the levels that should be rebuild. */
unsubdiv_context.max_new_levels = rebuild_limit;
/* Un-subdivide and create the data for the new grids. */
if (multires_unsubdivide_to_basemesh(&unsubdiv_context) == 0) {
/* If there was no possible to rebuild any level, free the data and return. */
if (mmd->totlvl != 0) {
multires_reshape_object_grids_to_tangent_displacement(&reshape_context);
multires_unsubdivide_context_free(&unsubdiv_context);
}
multires_reshape_context_free(&reshape_context);
return 0;
}
/* Free the reshape context used to convert the data from the original grids to object space. */
if (mmd->totlvl != 0) {
multires_reshape_context_free(&reshape_context);
}
/* Copy the new base mesh to the original mesh. */
Mesh *base_mesh = static_cast<Mesh *>(object->data);
BKE_mesh_nomain_to_mesh(unsubdiv_context.base_mesh, base_mesh, object);
multires_create_grids_in_unsubdivided_base_mesh(&unsubdiv_context, base_mesh);
/* Update the levels in the modifier. Force always to display at level 0 as it contains the new
* created level. */
mmd->totlvl = char(unsubdiv_context.num_total_levels);
if (switch_view_to_lower_level) {
mmd->sculptlvl = 0;
mmd->lvl = 0;
}
else {
mmd->sculptlvl = char(mmd->sculptlvl + unsubdiv_context.num_new_levels);
mmd->lvl = char(mmd->lvl + unsubdiv_context.num_new_levels);
}
mmd->renderlvl = char(mmd->renderlvl + unsubdiv_context.num_new_levels);
/* Create a reshape context to convert the MDISPS data to tangent displacement. It can be the
* same as the previous one as a new Subdivision needs to be created for the new base mesh. */
if (!multires_reshape_context_create_from_base_mesh(&reshape_context, depsgraph, object, mmd)) {
return 0;
}
multires_reshape_object_grids_to_tangent_displacement(&reshape_context);
multires_reshape_context_free(&reshape_context);
/* Free the un-subdivide context and return the total number of levels that were rebuild. */
const int rebuild_subdvis = unsubdiv_context.num_new_levels;
multires_unsubdivide_context_free(&unsubdiv_context);
return rebuild_subdvis;
}
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