blender
/
blender
136
404
Fork 586
Code Issues 6.2k Pull Requests 761 Projects 19 Wiki Activity

Fix T90782: add uv pack option to specify margin as a fraction 

A refactor of the margin calculation of UV packing, in anticipation
of multiple packing methods soon becoming available.

Three margin scaling methods are now available:

* "Add", Simple method, just add the margin. [0]
    (The default margin scale from Blender 2.8 and earlier.)
* "Scaled", Use scale of existing UVs to multiply margin.
    (The default from Blender 3.3+)
* "Fraction", a new (slow) method to precisely specify
    a fraction of the UV unit square for margin. [1]

The "fraction" code path implements a novel combined search / secant
root finding method which exploits domain knowledge to accelerate
convergence while remaining robust against bad input.

[0]: Resolves T85978
[1]: Resolves T90782

Differential Revision: https://developer.blender.org/D16121
This commit is contained in:
Chris Blackbourn 2022-10-12 10:57:17 +13:00
parent a376c4c3c3
commit c2256bf7f7
Notes: blender-bot 2023-02-14 10:37:50 +01:00 
Referenced by issue #90782, UV: unwrap. Margin size is not related to any useful measure
Referenced by issue #85978, Smart UV island margin value changed since C rewrite
Referenced by issue #63391, Smart UV Unwrap - bad island spaceing
3 changed files with 253 additions and 67 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
source/blender/editors/include/ED_uvedit.h
View File

@ -339,12 +339,20 @@ bool ED_uvedit_udim_params_from_image_space(const struct SpaceImage *sima,
bool use_active,
struct UVMapUDIM_Params *udim_params);
typedef enum {
ED_UVPACK_MARGIN_SCALED = 0, /* Use scale of existing UVs to multiply margin. */
ED_UVPACK_MARGIN_ADD, /* Just add the margin, ignoring any UV scale. */
ED_UVPACK_MARGIN_FRACTION, /* Specify a precise fraction of final UV output. */
} eUVPackIsland_MarginMethod;
struct UVPackIsland_Params {
uint rotate : 1;
uint only_selected_uvs : 1;
uint only_selected_faces : 1;
uint use_seams : 1;
uint correct_aspect : 1;
eUVPackIsland_MarginMethod margin_method; /* Which formula to use when scaling island margin. */
float margin; /* Additional space to add around each island. */
};
/**

247
source/blender/editors/uvedit/uvedit_islands.cc
View File

@ -403,6 +403,203 @@ int bm_mesh_calc_uv_islands(const Scene *scene,
/** \} */
static float pack_islands_scale_margin(const blender::Vector<FaceIsland *> &island_vector,
BoxPack *box_array,
const float scale,
const float margin)
{
for (const int index : island_vector.index_range()) {
FaceIsland *island = island_vector[index];
BoxPack *box = &box_array[index];
box->index = index;
box->w = BLI_rctf_size_x(&island->bounds_rect) * scale + 2 * margin;
box->h = BLI_rctf_size_y(&island->bounds_rect) * scale + 2 * margin;
}
float max_u, max_v;
BLI_box_pack_2d(box_array, island_vector.size(), &max_u, &max_v);
return max_ff(max_u, max_v);
}
static float pack_islands_margin_fraction(const blender::Vector<FaceIsland *> &island_vector,
BoxPack *box_array,
const float margin_fraction)
{
/*
* Root finding using a combined search / modified-secant method.
* First, use a robust search procedure to bracket the root within a factor of 10.
* Then, use a modified-secant method to converge.
*
* This is a specialized solver using domain knowledge to accelerate convergence.
*/
float scale_low = 0.0f;
float value_low = 0.0f;
float scale_high = 0.0f;
float value_high = 0.0f;
float scale_last = 0.0f;
/* Scaling smaller than `min_scale_roundoff` is unlikely to fit and
* will destroy information in existing UVs. */
float min_scale_roundoff = 1e-5f;
/* Certain inputs might have poor convergence properties.
* Use `max_iteration` to prevent an infinite loop. */
int max_iteration = 25;
for (int iteration = 0; iteration < max_iteration; iteration++) {
float scale = 1.0f;
if (iteration == 0) {
BLI_assert(iteration == 0);
BLI_assert(scale == 1.0f);
BLI_assert(scale_low == 0.0f);
BLI_assert(scale_high == 0.0f);
}
else if (scale_low == 0.0f) {
BLI_assert(scale_high > 0.0f);
/* Search mode, shrink layout until we can find a scale that fits. */
scale = scale_high * 0.1f;
}
else if (scale_high == 0.0f) {
BLI_assert(scale_low > 0.0f);
/* Search mode, grow layout until we can find a scale that doesn't fit. */
scale = scale_low * 10.0f;
}
else {
/* Bracket mode, use modified secant method to find root. */
BLI_assert(scale_low > 0.0f);
BLI_assert(scale_high > 0.0f);
BLI_assert(value_low <= 0.0f);
BLI_assert(value_high >= 0.0f);
if (scale_high < scale_low * 1.0001f) {
/* Convergence. */
break;
}
/* Secant method for area. */
scale = (sqrtf(scale_low) * value_high - sqrtf(scale_high) * value_low) /
(value_high - value_low);
scale = scale * scale;
if (iteration & 1) {
/* Modified binary-search to improve robustness. */
scale = sqrtf(scale * sqrtf(scale_low * scale_high));
}
}
scale = max_ff(scale, min_scale_roundoff);
/* Evaluate our `f`. */
scale_last = scale;
float max_uv = pack_islands_scale_margin(
island_vector, box_array, scale_last, margin_fraction);
float value = sqrtf(max_uv) - 1.0f;
if (value <= 0.0f) {
scale_low = scale;
value_low = value;
}
else {
scale_high = scale;
value_high = value;
if (scale == min_scale_roundoff) {
/* Unable to pack without damaging UVs. */
scale_low = scale;
break;
}
}
}
const bool flush = true;
if (flush) {
/* Write back best pack as a side-effect. First get best pack. */
if (scale_last != scale_low) {
scale_last = scale_low;
float max_uv = pack_islands_scale_margin(
island_vector, box_array, scale_last, margin_fraction);
UNUSED_VARS(max_uv);
/* TODO (?): `if (max_uv < 1.0f) { scale_last /= max_uv; }` */
}
/* Then expand FaceIslands by the correct amount. */
for (const int index : island_vector.index_range()) {
BoxPack *box = &box_array[index];
box->x /= scale_last;
box->y /= scale_last;
FaceIsland *island = island_vector[index];
BLI_rctf_pad(
&island->bounds_rect, margin_fraction / scale_last, margin_fraction / scale_last);
}
}
return scale_last;
}
static float calc_margin_from_aabb_length_sum(const blender::Vector<FaceIsland *> &island_vector,
const struct UVPackIsland_Params &params)
{
/* Logic matches behavior from #GEO_uv_parametrizer_pack.
* Attempt to give predictable results
* not dependent on current UV scale by using
* `aabb_length_sum` (was "`area`") to multiply
* the margin by the length (was "area").
*/
double aabb_length_sum = 0.0f;
for (FaceIsland *island : island_vector) {
float w = BLI_rctf_size_x(&island->bounds_rect);
float h = BLI_rctf_size_y(&island->bounds_rect);
aabb_length_sum += sqrtf(w * h);
}
return params.margin * aabb_length_sum * 0.1f;
}
static BoxPack *pack_islands_params(const blender::Vector<FaceIsland *> &island_vector,
const struct UVPackIsland_Params &params,
float r_scale[2])
{
BoxPack *box_array = static_cast<BoxPack *>(
MEM_mallocN(sizeof(*box_array) * island_vector.size(), __func__));
if (params.margin == 0.0f) {
/* Special case for zero margin. Margin_method is ignored as all formulas give same result. */
const float max_uv = pack_islands_scale_margin(island_vector, box_array, 1.0f, 0.0f);
r_scale[0] = 1.0f / max_uv;
r_scale[1] = r_scale[0];
return box_array;
}
if (params.margin_method == ED_UVPACK_MARGIN_FRACTION) {
/* Uses a line search on scale. ~10x slower than other method. */
const float scale = pack_islands_margin_fraction(island_vector, box_array, params.margin);
r_scale[0] = scale;
r_scale[1] = scale;
/* pack_islands_margin_fraction will pad FaceIslands, return early. */
return box_array;
}
float margin = params.margin;
switch (params.margin_method) {
case ED_UVPACK_MARGIN_ADD: /* Default for Blender 2.8 and earlier. */
break; /* Nothing to do. */
case ED_UVPACK_MARGIN_SCALED: /* Default for Blender 3.3 and later. */
margin = calc_margin_from_aabb_length_sum(island_vector, params);
break;
case ED_UVPACK_MARGIN_FRACTION: /* Added as an option in Blender 3.4. */
BLI_assert_unreachable(); /* Handled above. */
break;
default:
BLI_assert_unreachable();
}
const float max_uv = pack_islands_scale_margin(island_vector, box_array, 1.0f, margin);
r_scale[0] = 1.0f / max_uv;
r_scale[1] = r_scale[0];
for (int index = 0; index < island_vector.size(); index++) {
FaceIsland *island = island_vector[index];
BLI_rctf_pad(&island->bounds_rect, margin, margin);
}
return box_array;
}
/* -------------------------------------------------------------------- */
/** \name Public UV Island Packing
*
@ -455,19 +652,12 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
return;
}
float margin = scene->toolsettings->uvcalc_margin;
double area = 0.0f;
BoxPack *boxarray = static_cast<BoxPack *>(
MEM_mallocN(sizeof(*boxarray) * island_vector.size(), __func__));
/* Coordinates of bounding box containing all selected UVs. */
float selection_min_co[2], selection_max_co[2];
INIT_MINMAX2(selection_min_co, selection_max_co);
for (int index = 0; index < island_vector.size(); index++) {
FaceIsland *island = island_vector[index];
/* Skip calculation if using specified UDIM option. */
if (udim_params && (udim_params->use_target_udim == false)) {
float bounds_min[2], bounds_max[2];
@ -489,17 +679,6 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
bm_face_array_calc_bounds(
island->faces, island->faces_len, island->cd_loop_uv_offset, &island->bounds_rect);
BoxPack *box = &boxarray[index];
box->index = index;
box->x = 0.0f;
box->y = 0.0f;
box->w = BLI_rctf_size_x(&island->bounds_rect);
box->h = BLI_rctf_size_y(&island->bounds_rect);
if (margin > 0.0f) {
area += double(sqrtf(box->w * box->h));
}
}
/* Center of bounding box containing all selected UVs. */
@ -509,28 +688,8 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
selection_center[1] = (selection_min_co[1] + selection_max_co[1]) / 2.0f;
}
if (margin > 0.0f) {
/* Logic matches behavior from #GEO_uv_parametrizer_pack,
* use area so multiply the margin by the area to give
* predictable results not dependent on UV scale. */
margin = (margin * float(area)) * 0.1f;
for (int i = 0; i < island_vector.size(); i++) {
FaceIsland *island = island_vector[i];
BoxPack *box = &boxarray[i];
BLI_rctf_pad(&island->bounds_rect, margin, margin);
box->w = BLI_rctf_size_x(&island->bounds_rect);
box->h = BLI_rctf_size_y(&island->bounds_rect);
}
}
float boxarray_size[2];
BLI_box_pack_2d(boxarray, island_vector.size(), &boxarray_size[0], &boxarray_size[1]);
/* Don't change the aspect when scaling. */
boxarray_size[0] = boxarray_size[1] = max_ff(boxarray_size[0], boxarray_size[1]);
const float scale[2] = {1.0f / boxarray_size[0], 1.0f / boxarray_size[1]};
float scale[2] = {1.0f, 1.0f};
BoxPack *box_array = pack_islands_params(island_vector, *params, scale);
/* Tile offset. */
float base_offset[2] = {0.0f, 0.0f};
@ -580,14 +739,14 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
}
for (int i = 0; i < island_vector.size(); i++) {
FaceIsland *island = island_vector[boxarray[i].index];
FaceIsland *island = island_vector[box_array[i].index];
const float pivot[2] = {
island->bounds_rect.xmin,
island->bounds_rect.ymin,
};
const float offset[2] = {
((boxarray[i].x * scale[0]) - island->bounds_rect.xmin) + base_offset[0],
((boxarray[i].y * scale[1]) - island->bounds_rect.ymin) + base_offset[1],
((box_array[i].x * scale[0]) - island->bounds_rect.xmin) + base_offset[0],
((box_array[i].y * scale[1]) - island->bounds_rect.ymin) + base_offset[1],
};
for (int j = 0; j < island->faces_len; j++) {
BMFace *efa = island->faces[j];
@ -607,7 +766,7 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
MEM_freeN(island);
}
MEM_freeN(boxarray);
MEM_freeN(box_array);
}
/** \} */

65
source/blender/editors/uvedit/uvedit_unwrap_ops.c
View File

@ -1125,7 +1125,6 @@ static int pack_islands_exec(bContext *C, wmOperator *op)
}
/* RNA props */
const bool rotate = RNA_boolean_get(op->ptr, "rotate");
const int udim_source = RNA_enum_get(op->ptr, "udim_source");
if (RNA_struct_property_is_set(op->ptr, "margin")) {
scene->toolsettings->uvcalc_margin = RNA_float_get(op->ptr, "margin");
@ -1139,21 +1138,36 @@ static int pack_islands_exec(bContext *C, wmOperator *op)
const bool use_udim_params = ED_uvedit_udim_params_from_image_space(
sima, use_active, &udim_params);
ED_uvedit_pack_islands_multi(scene,
objects,
objects_len,
use_udim_params ? &udim_params : NULL,
&(struct UVPackIsland_Params){
.rotate = rotate,
.only_selected_uvs = true,
.only_selected_faces = true,
.correct_aspect = true,
});
struct UVPackIsland_Params params = {
.rotate = RNA_boolean_get(op->ptr, "rotate"),
.only_selected_uvs = true,
.only_selected_faces = true,
.correct_aspect = true,
.margin_method = RNA_enum_get(op->ptr, "margin_method"),
.margin = RNA_float_get(op->ptr, "margin"),
};
ED_uvedit_pack_islands_multi(
scene, objects, objects_len, use_udim_params ? &udim_params : NULL, &params);
MEM_freeN(objects);
return OPERATOR_FINISHED;
}
const EnumPropertyItem pack_margin_method[] = {
{ED_UVPACK_MARGIN_SCALED,
"SCALED",
0,
"Scaled",
"Use scale of existing UVs to multiply margin"},
{ED_UVPACK_MARGIN_ADD, "ADD", 0, "Add", "Just add the margin, ignoring any UV scale"},
{ED_UVPACK_MARGIN_FRACTION,
"FRACTION",
0,
"Fraction",
"Specify a precise fraction of final UV output"},
{0, NULL, 0, NULL, NULL},
};
void UV_OT_pack_islands(wmOperatorType *ot)
{
static const EnumPropertyItem pack_target[] = {
@ -1180,6 +1194,8 @@ void UV_OT_pack_islands(wmOperatorType *ot)
/* properties */
RNA_def_enum(ot->srna, "udim_source", pack_target, PACK_UDIM_SRC_CLOSEST, "Pack to", "");
RNA_def_boolean(ot->srna, "rotate", true, "Rotate", "Rotate islands for best fit");
RNA_def_enum(
ot->srna, "margin_method", pack_margin_method, ED_UVPACK_MARGIN_SCALED, "Margin Method", "");
RNA_def_float_factor(
ot->srna, "margin", 0.001f, 0.0f, 1.0f, "Margin", "Space between islands", 0.0f, 1.0f);
}
@ -2098,6 +2114,8 @@ void UV_OT_unwrap(wmOperatorType *ot)
0,
"Use Subdivision Surface",
"Map UVs taking vertex position after Subdivision Surface modifier has been applied");
RNA_def_enum(
ot->srna, "margin_method", pack_margin_method, ED_UVPACK_MARGIN_SCALED, "Margin Method", "");
RNA_def_float_factor(
ot->srna, "margin", 0.001f, 0.0f, 1.0f, "Margin", "Space between islands", 0.0f, 1.0f);
}
@ -2118,7 +2136,6 @@ typedef struct ThickFace {
static int smart_uv_project_thickface_area_cmp_fn(const void *tf_a_p, const void *tf_b_p)
{
const ThickFace *tf_a = (ThickFace *)tf_a_p;
const ThickFace *tf_b = (ThickFace *)tf_b_p;
@ -2412,17 +2429,17 @@ static int smart_project_exec(bContext *C, wmOperator *op)
/* Depsgraph refresh functions are called here. */
const bool correct_aspect = RNA_boolean_get(op->ptr, "correct_aspect");
ED_uvedit_pack_islands_multi(scene,
objects_changed,
object_changed_len,
NULL,
&(struct UVPackIsland_Params){
.rotate = true,
.only_selected_uvs = only_selected_uvs,
.only_selected_faces = true,
.correct_aspect = correct_aspect,
.use_seams = true,
});
const struct UVPackIsland_Params params = {
.rotate = true,
.only_selected_uvs = only_selected_uvs,
.only_selected_faces = true,
.correct_aspect = correct_aspect,
.use_seams = true,
.margin_method = RNA_enum_get(op->ptr, "margin_method"),
.margin = RNA_float_get(op->ptr, "island_margin"),
};
ED_uvedit_pack_islands_multi(scene, objects_changed, object_changed_len, NULL, &params);
/* #ED_uvedit_pack_islands_multi only supports `per_face_aspect = false`. */
const bool per_face_aspect = false;
@ -2464,6 +2481,8 @@ void UV_OT_smart_project(wmOperatorType *ot)
DEG2RADF(89.0f));
RNA_def_property_float_default(prop, DEG2RADF(66.0f));
RNA_def_enum(
ot->srna, "margin_method", pack_margin_method, ED_UVPACK_MARGIN_SCALED, "Margin Method", "");
RNA_def_float(ot->srna,
"island_margin",
0.0f,