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Mesh: concave quad support

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Previously quads always split along first-third vertices.
This is still the default, to avoid flickering with animated deformation
however concave quads that would create two opposing triangles now use
second-fourth split.

Reported as T53999 although this issue has been known limitation
for a long time.
This commit is contained in:
Campbell Barton
2018-02-08 23:38:17 +11:00
parent 5f2b4002f4
commit f088c6b9f6
4 changed files with 37 additions and 0 deletions
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13
source/blender/blenkernel/intern/mesh_evaluate.c
View File

@@ -2945,9 +2945,22 @@ void BKE_mesh_recalc_looptri(
}
else if (mp_totloop == 4) {
ML_TO_MLT(0, 1, 2);
MLoopTri *mlt_a = mlt;
mlooptri_index++;
ML_TO_MLT(0, 2, 3);
MLoopTri *mlt_b = mlt;
mlooptri_index++;
if (UNLIKELY(is_quad_flip_v3_first_third_fast(
mvert[mloop[mlt_a->tri[0]].v].co,
mvert[mloop[mlt_a->tri[1]].v].co,
mvert[mloop[mlt_a->tri[2]].v].co,
mvert[mloop[mlt_b->tri[2]].v].co)))
{
/* flip out of degenerate 0-2 state. */
mlt_a->tri[2] = mlt_b->tri[2];
mlt_b->tri[0] = mlt_a->tri[1];
}
}
#endif /* USE_TESSFACE_SPEEDUP */
else {

1
source/blender/blenlib/BLI_math_geom.h
View File

@@ -85,6 +85,7 @@ bool is_quad_convex_v3(const float v1[3], const float v2[3], const float v3[3],
bool is_quad_convex_v2(const float v1[2], const float v2[2], const float v3[2], const float v4[2]);
bool is_poly_convex_v2(const float verts[][2], unsigned int nr);
int is_quad_flip_v3(const float v1[3], const float v2[3], const float v3[3], const float v4[3]);
bool is_quad_flip_v3_first_third_fast(const float v0[3], const float v1[3], const float v2[3], const float v3[3]);
/********************************* Distance **********************************/

12
source/blender/blenlib/intern/math_geom.c
View File

@@ -4903,6 +4903,18 @@ int is_quad_flip_v3(const float v1[3], const float v2[3], const float v3[3], con
return ret;
}
bool is_quad_flip_v3_first_third_fast(const float v1[3], const float v2[3], const float v3[3], const float v4[3])
{
float d_12[3], d_13[3], d_14[3];
float cross_a[3], cross_b[3];
sub_v3_v3v3(d_12, v2, v1);
sub_v3_v3v3(d_13, v3, v1);
sub_v3_v3v3(d_14, v4, v1);
cross_v3_v3v3(cross_a, d_12, d_13);
cross_v3_v3v3(cross_b, d_14, d_13);
return dot_v3v3(cross_a, cross_b) > 0.0f;
}
/**
* Return the value which the distance between points will need to be scaled by,
* to define a handle, given both points are on a perfect circle.

11
source/blender/bmesh/intern/bmesh_polygon.c
View File

@@ -1426,6 +1426,17 @@ void BM_mesh_calc_tessellation(BMesh *bm, BMLoop *(*looptris)[3], int *r_looptri
(l_ptr_a[2] = l_ptr_b[1] = l = l->next);
( l_ptr_b[2] = l->next);
#endif
if (UNLIKELY(is_quad_flip_v3_first_third_fast(
l_ptr_a[0]->v->co,
l_ptr_a[1]->v->co,
l_ptr_a[2]->v->co,
l_ptr_b[2]->v->co)))
{
/* flip out of degenerate 0-2 state. */
l_ptr_a[2] = l_ptr_b[2];
l_ptr_b[0] = l_ptr_a[1];
}
}
#endif /* USE_TESSFACE_SPEEDUP */