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Polyfill Beautify: option to rotate out of degenerate state 

Needed for 3D iterative edge-rotation to avoid flipping when projected
from different angles,
but could keep zero area faces in 2D polygons.
This commit is contained in:
Campbell Barton 2017-09-15 18:14:17 +10:00
parent fdb8e17936
commit c594087488
Notes: blender-bot 2023-02-14 06:34:43 +01:00 
Referenced by issue #53683, 2.79a release
Referenced by issue #52761, BMesh Boolean - Freaks out sometimes
3 changed files with 20 additions and 10 deletions
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8
source/blender/blenlib/BLI_polyfill2d_beautify.h
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@ -33,8 +33,12 @@ void BLI_polyfill_beautify(
/* structs for reuse */
struct MemArena *arena, struct Heap *eheap, struct EdgeHash *eh);
float BLI_polyfill_beautify_quad_rotate_calc(
const float v1[2], const float v2[2], const float v3[2], const float v4[2]);
float BLI_polyfill_beautify_quad_rotate_calc_ex(
const float v1[2], const float v2[2], const float v3[2], const float v4[2],
const bool lock_degenerate);
#define BLI_polyfill_beautify_quad_rotate_calc(v1, v2, v3, v4) \
BLI_polyfill_beautify_quad_rotate_calc_ex(v1, v2, v3, v4, false)
/* avoid realloc's when creating new structures for polyfill ngons */
#define BLI_POLYFILL_ALLOC_NGON_RESERVE 64

15
source/blender/blenlib/intern/polyfill2d_beautify.c
View File

@ -123,8 +123,9 @@ BLI_INLINE bool is_boundary_edge(unsigned int i_a, unsigned int i_b, const unsig
*
* \return (negative number means the edge can be rotated, lager == better).
*/
float BLI_polyfill_beautify_quad_rotate_calc(
const float v1[2], const float v2[2], const float v3[2], const float v4[2])
float BLI_polyfill_beautify_quad_rotate_calc_ex(
const float v1[2], const float v2[2], const float v3[2], const float v4[2],
const bool lock_degenerate)
{
/* not a loop (only to be able to break out) */
do {
@ -136,12 +137,12 @@ float BLI_polyfill_beautify_quad_rotate_calc(
const float area_2x_123 = cross_tri_v2(v1, v2, v3);
const float area_2x_134 = cross_tri_v2(v1, v3, v4);
{
BLI_assert((ELEM(v1, v2, v3, v4) == false) &&
(ELEM(v2, v1, v3, v4) == false) &&
(ELEM(v3, v1, v2, v4) == false) &&
(ELEM(v4, v1, v2, v3) == false));
BLI_assert((ELEM(v1, v2, v3, v4) == false) &&
(ELEM(v2, v1, v3, v4) == false) &&
(ELEM(v3, v1, v2, v4) == false) &&
(ELEM(v4, v1, v2, v3) == false));
if (lock_degenerate) {
is_zero_a = (fabsf(area_2x_234) <= FLT_EPSILON);
is_zero_b = (fabsf(area_2x_241) <= FLT_EPSILON);

7
source/blender/bmesh/tools/bmesh_beautify.c
View File

@ -182,7 +182,12 @@ static float bm_edge_calc_rotate_beauty__area(
}
}
return BLI_polyfill_beautify_quad_rotate_calc(v1_xy, v2_xy, v3_xy, v4_xy);
/**
* Important to lock degenerate here,
* since the triangle pars will be projected into different 2D spaces.
* Allowing to rotate out of a degenerate state can flip the faces (when performed iteratively).
*/
return BLI_polyfill_beautify_quad_rotate_calc_ex(v1_xy, v2_xy, v3_xy, v4_xy, true);
} while (false);
return FLT_MAX;