19dbe049db
The result of detecting if a quad should flip the default 0-2 split
when tessellated only used a pre-calculated normal when available,
since the method of detecting the flip was different, the check for a
concave face could change depending on the existence of polygon-normals.
In practice this meant cycles render preview could use a different
tessellation than the GPU display.
While [0] exposed the bug, it's an inherent problem with having 2
methods of detecting concave quads.
Remove is_quad_flip_v3_first_third_fast_with_normal(..) and always
use is_quad_flip_v3_first_third_fast(..), because having to calculate
the normal inline has significant overhead.
Note that "bow-tie" quads may now render with a subdivision in a
different direction although they must be very distorted with both
triangles along the 0-2 split pointing away from each other.
Thanks to @HooglyBoogly for investigating the issue.
[0]: 16fbadde36.
328 lines
12 KiB
C++
328 lines
12 KiB
C++
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright 2001-2002 NaN Holding BV. All rights reserved. */
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/** \file
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* \ingroup bke
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*
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* This file contains code for polygon tessellation
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* (creating triangles from polygons).
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*
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* \see bmesh_mesh_tessellate.c for the #BMesh equivalent of this file.
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*/
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#include "BLI_enumerable_thread_specific.hh"
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#include "BLI_math.h"
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#include "BLI_memarena.h"
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#include "BLI_polyfill_2d.h"
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#include "BLI_task.h"
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#include "BKE_mesh.hh"
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#include "BLI_strict_flags.h"
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namespace blender::bke::mesh {
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/** Compared against total loops. */
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#define MESH_FACE_TESSELLATE_THREADED_LIMIT 4096
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/* -------------------------------------------------------------------- */
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/** \name Loop Tessellation
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*
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* Fill in #MLoopTri data-structure.
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* \{ */
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/**
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* \param face_normal: This will be optimized out as a constant.
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*/
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BLI_INLINE void mesh_calc_tessellation_for_face_impl(const Span<int> corner_verts,
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const blender::OffsetIndices<int> polys,
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const Span<float3> positions,
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uint poly_index,
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MLoopTri *mlt,
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MemArena **pf_arena_p,
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const bool face_normal,
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const float normal_precalc[3])
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{
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const uint mp_loopstart = uint(polys[poly_index].start());
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const uint mp_totloop = uint(polys[poly_index].size());
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auto create_tri = [&](uint i1, uint i2, uint i3) {
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mlt->tri[0] = mp_loopstart + i1;
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mlt->tri[1] = mp_loopstart + i2;
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mlt->tri[2] = mp_loopstart + i3;
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mlt->poly = poly_index;
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};
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switch (mp_totloop) {
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case 3: {
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create_tri(0, 1, 2);
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break;
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}
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case 4: {
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create_tri(0, 1, 2);
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MLoopTri *mlt_a = mlt++;
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create_tri(0, 2, 3);
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MLoopTri *mlt_b = mlt;
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if (UNLIKELY(is_quad_flip_v3_first_third_fast(positions[corner_verts[mlt_a->tri[0]]],
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positions[corner_verts[mlt_a->tri[1]]],
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positions[corner_verts[mlt_a->tri[2]]],
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positions[corner_verts[mlt_b->tri[2]]]))) {
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/* Flip out of degenerate 0-2 state. */
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mlt_a->tri[2] = mlt_b->tri[2];
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mlt_b->tri[0] = mlt_a->tri[1];
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}
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break;
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}
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default: {
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float axis_mat[3][3];
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/* Calculate `axis_mat` to project verts to 2D. */
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if (face_normal == false) {
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float normal[3];
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const float *co_curr, *co_prev;
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zero_v3(normal);
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/* Calc normal, flipped: to get a positive 2D cross product. */
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co_prev = positions[corner_verts[mp_loopstart + mp_totloop - 1]];
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for (uint j = 0; j < mp_totloop; j++) {
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co_curr = positions[corner_verts[mp_loopstart + j]];
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add_newell_cross_v3_v3v3(normal, co_prev, co_curr);
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co_prev = co_curr;
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}
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if (UNLIKELY(normalize_v3(normal) == 0.0f)) {
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normal[2] = 1.0f;
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}
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axis_dominant_v3_to_m3_negate(axis_mat, normal);
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}
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else {
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axis_dominant_v3_to_m3_negate(axis_mat, normal_precalc);
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}
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const uint totfilltri = mp_totloop - 2;
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MemArena *pf_arena = *pf_arena_p;
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if (UNLIKELY(pf_arena == nullptr)) {
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pf_arena = *pf_arena_p = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, __func__);
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}
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uint(*tris)[3] = static_cast<uint(*)[3]>(
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BLI_memarena_alloc(pf_arena, sizeof(*tris) * size_t(totfilltri)));
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float(*projverts)[2] = static_cast<float(*)[2]>(
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BLI_memarena_alloc(pf_arena, sizeof(*projverts) * size_t(mp_totloop)));
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for (uint j = 0; j < mp_totloop; j++) {
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mul_v2_m3v3(projverts[j], axis_mat, positions[corner_verts[mp_loopstart + j]]);
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}
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BLI_polyfill_calc_arena(projverts, mp_totloop, 1, tris, pf_arena);
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/* Apply fill. */
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for (uint j = 0; j < totfilltri; j++, mlt++) {
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const uint *tri = tris[j];
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create_tri(tri[0], tri[1], tri[2]);
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}
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BLI_memarena_clear(pf_arena);
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break;
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}
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}
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#undef ML_TO_MLT
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}
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static void mesh_calc_tessellation_for_face(const Span<int> corner_verts,
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const blender::OffsetIndices<int> polys,
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const Span<float3> positions,
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uint poly_index,
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MLoopTri *mlt,
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MemArena **pf_arena_p)
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{
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mesh_calc_tessellation_for_face_impl(
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corner_verts, polys, positions, poly_index, mlt, pf_arena_p, false, nullptr);
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}
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static void mesh_calc_tessellation_for_face_with_normal(const Span<int> corner_verts,
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const blender::OffsetIndices<int> polys,
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const Span<float3> positions,
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uint poly_index,
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MLoopTri *mlt,
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MemArena **pf_arena_p,
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const float normal_precalc[3])
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{
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mesh_calc_tessellation_for_face_impl(
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corner_verts, polys, positions, poly_index, mlt, pf_arena_p, true, normal_precalc);
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}
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static void mesh_recalc_looptri__single_threaded(const Span<int> corner_verts,
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const blender::OffsetIndices<int> polys,
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const Span<float3> positions,
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MLoopTri *mlooptri,
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const float (*poly_normals)[3])
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{
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MemArena *pf_arena = nullptr;
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uint tri_index = 0;
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if (poly_normals != nullptr) {
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for (const int64_t i : polys.index_range()) {
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mesh_calc_tessellation_for_face_with_normal(corner_verts,
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polys,
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positions,
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uint(i),
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&mlooptri[tri_index],
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&pf_arena,
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poly_normals[i]);
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tri_index += uint(polys[i].size() - 2);
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}
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}
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else {
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for (const int64_t i : polys.index_range()) {
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mesh_calc_tessellation_for_face(
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corner_verts, polys, positions, uint(i), &mlooptri[tri_index], &pf_arena);
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tri_index += uint(polys[i].size() - 2);
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}
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}
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if (pf_arena) {
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BLI_memarena_free(pf_arena);
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pf_arena = nullptr;
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}
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BLI_assert(tri_index == uint(poly_to_tri_count(int(polys.size()), int(corner_verts.size()))));
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}
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struct TessellationUserData {
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Span<int> corner_verts;
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blender::OffsetIndices<int> polys;
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Span<float3> positions;
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/** Output array. */
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MutableSpan<MLoopTri> mlooptri;
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/** Optional pre-calculated polygon normals array. */
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const float (*poly_normals)[3];
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};
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struct TessellationUserTLS {
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MemArena *pf_arena;
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};
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static void mesh_calc_tessellation_for_face_fn(void *__restrict userdata,
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const int index,
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const TaskParallelTLS *__restrict tls)
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{
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const TessellationUserData *data = static_cast<const TessellationUserData *>(userdata);
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TessellationUserTLS *tls_data = static_cast<TessellationUserTLS *>(tls->userdata_chunk);
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const int tri_index = poly_to_tri_count(index, int(data->polys[index].start()));
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mesh_calc_tessellation_for_face_impl(data->corner_verts,
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data->polys,
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data->positions,
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uint(index),
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&data->mlooptri[tri_index],
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&tls_data->pf_arena,
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false,
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nullptr);
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}
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static void mesh_calc_tessellation_for_face_with_normal_fn(void *__restrict userdata,
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const int index,
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const TaskParallelTLS *__restrict tls)
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{
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const TessellationUserData *data = static_cast<const TessellationUserData *>(userdata);
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TessellationUserTLS *tls_data = static_cast<TessellationUserTLS *>(tls->userdata_chunk);
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const int tri_index = poly_to_tri_count(index, int(data->polys[index].start()));
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mesh_calc_tessellation_for_face_impl(data->corner_verts,
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data->polys,
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data->positions,
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uint(index),
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&data->mlooptri[tri_index],
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&tls_data->pf_arena,
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true,
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data->poly_normals[index]);
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}
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static void mesh_calc_tessellation_for_face_free_fn(const void *__restrict /*userdata*/,
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void *__restrict tls_v)
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{
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TessellationUserTLS *tls_data = static_cast<TessellationUserTLS *>(tls_v);
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if (tls_data->pf_arena) {
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BLI_memarena_free(tls_data->pf_arena);
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}
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}
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static void looptris_calc_all(const Span<float3> positions,
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const blender::OffsetIndices<int> polys,
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const Span<int> corner_verts,
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const Span<float3> poly_normals,
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MutableSpan<MLoopTri> looptris)
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{
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if (corner_verts.size() < MESH_FACE_TESSELLATE_THREADED_LIMIT) {
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mesh_recalc_looptri__single_threaded(corner_verts,
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polys,
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positions,
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looptris.data(),
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reinterpret_cast<const float(*)[3]>(poly_normals.data()));
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return;
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}
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struct TessellationUserTLS tls_data_dummy = {nullptr};
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struct TessellationUserData data {
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};
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data.corner_verts = corner_verts;
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data.polys = polys;
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data.positions = positions;
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data.mlooptri = looptris;
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data.poly_normals = reinterpret_cast<const float(*)[3]>(poly_normals.data());
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TaskParallelSettings settings;
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BLI_parallel_range_settings_defaults(&settings);
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settings.userdata_chunk = &tls_data_dummy;
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settings.userdata_chunk_size = sizeof(tls_data_dummy);
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settings.func_free = mesh_calc_tessellation_for_face_free_fn;
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BLI_task_parallel_range(0,
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int(polys.size()),
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&data,
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data.poly_normals ? mesh_calc_tessellation_for_face_with_normal_fn :
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mesh_calc_tessellation_for_face_fn,
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&settings);
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}
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void looptris_calc(const Span<float3> vert_positions,
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const OffsetIndices<int> polys,
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const Span<int> corner_verts,
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MutableSpan<MLoopTri> looptris)
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{
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looptris_calc_all(vert_positions, polys, corner_verts, {}, looptris);
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}
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void looptris_calc_with_normals(const Span<float3> vert_positions,
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const OffsetIndices<int> polys,
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const Span<int> corner_verts,
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const Span<float3> poly_normals,
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MutableSpan<MLoopTri> looptris)
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{
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BLI_assert(!poly_normals.is_empty() || polys.size() == 0);
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looptris_calc_all(vert_positions, polys, corner_verts, poly_normals, looptris);
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}
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/** \} */
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} // namespace blender::bke::mesh
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void BKE_mesh_recalc_looptri(const int *corner_verts,
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const int *poly_offsets,
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const float (*vert_positions)[3],
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int totvert,
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int totloop,
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int totpoly,
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MLoopTri *mlooptri)
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{
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blender::bke::mesh::looptris_calc(
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{reinterpret_cast<const blender::float3 *>(vert_positions), totvert},
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blender::Span(poly_offsets, totpoly + 1),
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{corner_verts, totloop},
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{mlooptri, poly_to_tri_count(totpoly, totloop)});
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}
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