217 lines
7.1 KiB
C++
217 lines
7.1 KiB
C++
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/** \file
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* \ingroup eduv
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*/
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#include "GEO_uv_pack.hh"
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#include "BLI_boxpack_2d.h"
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#include "BLI_convexhull_2d.h"
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#include "BLI_listbase.h"
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#include "BLI_math.h"
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#include "BLI_rect.h"
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#include "DNA_meshdata_types.h"
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#include "DNA_scene_types.h"
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#include "DNA_space_types.h"
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#include "MEM_guardedalloc.h"
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namespace blender::geometry {
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static float pack_islands_scale_margin(const Span<PackIsland *> &island_vector,
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BoxPack *box_array,
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const float scale,
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const float margin)
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{
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for (const int64_t index : island_vector.index_range()) {
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PackIsland *island = island_vector[index];
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BoxPack *box = &box_array[index];
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box->index = (int)index;
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box->w = BLI_rctf_size_x(&island->bounds_rect) * scale + 2 * margin;
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box->h = BLI_rctf_size_y(&island->bounds_rect) * scale + 2 * margin;
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}
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float max_u, max_v;
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BLI_box_pack_2d(box_array, (int)island_vector.size(), &max_u, &max_v);
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return max_ff(max_u, max_v);
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}
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static float pack_islands_margin_fraction(const Span<PackIsland *> &island_vector,
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BoxPack *box_array,
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const float margin_fraction)
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{
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/*
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* Root finding using a combined search / modified-secant method.
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* First, use a robust search procedure to bracket the root within a factor of 10.
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* Then, use a modified-secant method to converge.
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*
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* This is a specialized solver using domain knowledge to accelerate convergence. */
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float scale_low = 0.0f;
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float value_low = 0.0f;
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float scale_high = 0.0f;
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float value_high = 0.0f;
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float scale_last = 0.0f;
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/* Scaling smaller than `min_scale_roundoff` is unlikely to fit and
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* will destroy information in existing UVs. */
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float min_scale_roundoff = 1e-5f;
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/* Certain inputs might have poor convergence properties.
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* Use `max_iteration` to prevent an infinite loop. */
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int max_iteration = 25;
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for (int iteration = 0; iteration < max_iteration; iteration++) {
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float scale = 1.0f;
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if (iteration == 0) {
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BLI_assert(iteration == 0);
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BLI_assert(scale == 1.0f);
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BLI_assert(scale_low == 0.0f);
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BLI_assert(scale_high == 0.0f);
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}
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else if (scale_low == 0.0f) {
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BLI_assert(scale_high > 0.0f);
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/* Search mode, shrink layout until we can find a scale that fits. */
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scale = scale_high * 0.1f;
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}
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else if (scale_high == 0.0f) {
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BLI_assert(scale_low > 0.0f);
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/* Search mode, grow layout until we can find a scale that doesn't fit. */
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scale = scale_low * 10.0f;
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}
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else {
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/* Bracket mode, use modified secant method to find root. */
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BLI_assert(scale_low > 0.0f);
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BLI_assert(scale_high > 0.0f);
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BLI_assert(value_low <= 0.0f);
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BLI_assert(value_high >= 0.0f);
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if (scale_high < scale_low * 1.0001f) {
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/* Convergence. */
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break;
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}
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/* Secant method for area. */
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scale = (sqrtf(scale_low) * value_high - sqrtf(scale_high) * value_low) /
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(value_high - value_low);
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scale = scale * scale;
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if (iteration & 1) {
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/* Modified binary-search to improve robustness. */
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scale = sqrtf(scale * sqrtf(scale_low * scale_high));
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}
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}
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scale = max_ff(scale, min_scale_roundoff);
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/* Evaluate our `f`. */
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scale_last = scale;
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float max_uv = pack_islands_scale_margin(
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island_vector, box_array, scale_last, margin_fraction);
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float value = sqrtf(max_uv) - 1.0f;
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if (value <= 0.0f) {
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scale_low = scale;
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value_low = value;
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}
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else {
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scale_high = scale;
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value_high = value;
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if (scale == min_scale_roundoff) {
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/* Unable to pack without damaging UVs. */
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scale_low = scale;
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break;
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}
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}
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}
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const bool flush = true;
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if (flush) {
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/* Write back best pack as a side-effect. First get best pack. */
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if (scale_last != scale_low) {
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scale_last = scale_low;
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float max_uv = pack_islands_scale_margin(
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island_vector, box_array, scale_last, margin_fraction);
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UNUSED_VARS(max_uv);
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/* TODO (?): `if (max_uv < 1.0f) { scale_last /= max_uv; }` */
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}
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/* Then expand FaceIslands by the correct amount. */
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for (const int64_t index : island_vector.index_range()) {
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BoxPack *box = &box_array[index];
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box->x /= scale_last;
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box->y /= scale_last;
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PackIsland *island = island_vector[index];
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BLI_rctf_pad(
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&island->bounds_rect, margin_fraction / scale_last, margin_fraction / scale_last);
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}
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}
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return scale_last;
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}
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static float calc_margin_from_aabb_length_sum(const Span<PackIsland *> &island_vector,
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const UVPackIsland_Params ¶ms)
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{
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/* Logic matches behavior from #GEO_uv_parametrizer_pack.
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* Attempt to give predictable results not dependent on current UV scale by using
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* `aabb_length_sum` (was "`area`") to multiply the margin by the length (was "area"). */
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double aabb_length_sum = 0.0f;
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for (PackIsland *island : island_vector) {
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float w = BLI_rctf_size_x(&island->bounds_rect);
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float h = BLI_rctf_size_y(&island->bounds_rect);
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aabb_length_sum += sqrtf(w * h);
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}
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return params.margin * aabb_length_sum * 0.1f;
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}
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BoxPack *pack_islands(const Span<PackIsland *> &island_vector,
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const UVPackIsland_Params ¶ms,
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float r_scale[2])
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{
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BoxPack *box_array = static_cast<BoxPack *>(
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MEM_mallocN(sizeof(*box_array) * island_vector.size(), __func__));
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if (params.margin == 0.0f) {
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/* Special case for zero margin. Margin_method is ignored as all formulas give same result. */
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const float max_uv = pack_islands_scale_margin(island_vector, box_array, 1.0f, 0.0f);
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r_scale[0] = 1.0f / max_uv;
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r_scale[1] = r_scale[0];
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return box_array;
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}
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if (params.margin_method == ED_UVPACK_MARGIN_FRACTION) {
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/* Uses a line search on scale. ~10x slower than other method. */
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const float scale = pack_islands_margin_fraction(island_vector, box_array, params.margin);
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r_scale[0] = scale;
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r_scale[1] = scale;
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/* pack_islands_margin_fraction will pad FaceIslands, return early. */
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return box_array;
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}
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float margin = params.margin;
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switch (params.margin_method) {
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case ED_UVPACK_MARGIN_ADD: /* Default for Blender 2.8 and earlier. */
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break; /* Nothing to do. */
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case ED_UVPACK_MARGIN_SCALED: /* Default for Blender 3.3 and later. */
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margin = calc_margin_from_aabb_length_sum(island_vector, params);
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break;
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case ED_UVPACK_MARGIN_FRACTION: /* Added as an option in Blender 3.4. */
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BLI_assert_unreachable(); /* Handled above. */
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break;
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default:
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BLI_assert_unreachable();
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}
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const float max_uv = pack_islands_scale_margin(island_vector, box_array, 1.0f, margin);
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r_scale[0] = 1.0f / max_uv;
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r_scale[1] = r_scale[0];
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for (int index = 0; index < island_vector.size(); index++) {
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PackIsland *island = island_vector[index];
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BLI_rctf_pad(&island->bounds_rect, margin, margin);
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}
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return box_array;
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}
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} // namespace blender::geometry
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