diff options
Diffstat (limited to 'source/blender/geometry/intern/uv_parametrizer.c')
| -rw-r--r-- | source/blender/geometry/intern/uv_parametrizer.c | 112 |
1 files changed, 96 insertions, 16 deletions
diff --git a/source/blender/geometry/intern/uv_parametrizer.c b/source/blender/geometry/intern/uv_parametrizer.c index c75a302f8dc..38924c718c3 100644 --- a/source/blender/geometry/intern/uv_parametrizer.c +++ b/source/blender/geometry/intern/uv_parametrizer.c @@ -148,7 +148,8 @@ typedef struct PChart { } lscm; struct PChartPack { float rescale, area; - float size[2] /* , trans[2] */; + float size[2]; + float origin[2]; } pack; } u; @@ -3306,8 +3307,10 @@ static float p_face_stretch(PFace *f) area = p_face_uv_area_signed(f); - if (area <= 0.0f) { /* flipped face -> infinite stretch */ - return 1e10f; + if (area <= 0.0f) { + /* When a face is flipped, provide a large penalty. + * Add on a slight gradient to unflip the face, see also: T99781. */ + return 1e8f * (1.0f + p_edge_uv_length(e1) + p_edge_uv_length(e2) + p_edge_uv_length(e3)); } w = 1.0f / (2.0f * area); @@ -4243,7 +4246,10 @@ void GEO_uv_parametrizer_pack(ParamHandle *handle, } } -void GEO_uv_parametrizer_average(ParamHandle *phandle, bool ignore_pinned) +void GEO_uv_parametrizer_average(ParamHandle *phandle, + bool ignore_pinned, + bool scale_uv, + bool shear) { PChart *chart; int i; @@ -4256,17 +4262,93 @@ void GEO_uv_parametrizer_average(ParamHandle *phandle, bool ignore_pinned) } for (i = 0; i < phandle->ncharts; i++) { - PFace *f; chart = phandle->charts[i]; if (ignore_pinned && (chart->flag & PCHART_HAS_PINS)) { continue; } + p_chart_uv_bbox(chart, minv, maxv); + mid_v2_v2v2(chart->u.pack.origin, minv, maxv); + + if (scale_uv || shear) { + /* It's possible that for some "bad" inputs, the following iteration will converge slowly or + * perhaps even diverge. Rather than infinite loop, we only iterate a maximum of `max_iter` + * times. (Also useful when making changes to the calculation.) */ + int max_iter = 10; + for (int j = 0; j < max_iter; j++) { + /* An island could contain millions of polygons. When summing many small values, we need to + * use double precision in the accumulator to maintain accuracy. Note that the individual + * calculations only need to be at single precision.*/ + double scale_cou = 0; + double scale_cov = 0; + double scale_cross = 0; + double weight_sum = 0; + for (PFace *f = chart->faces; f; f = f->nextlink) { + float m[2][2], s[2][2]; + PVert *va = f->edge->vert; + PVert *vb = f->edge->next->vert; + PVert *vc = f->edge->next->next->vert; + s[0][0] = va->uv[0] - vc->uv[0]; + s[0][1] = va->uv[1] - vc->uv[1]; + s[1][0] = vb->uv[0] - vc->uv[0]; + s[1][1] = vb->uv[1] - vc->uv[1]; + /* Find the "U" axis and "V" axis in triangle co-ordinates. Normally this would require + * SVD, but in 2D we can use a cheaper matrix inversion instead.*/ + if (!invert_m2_m2(m, s)) { + continue; + } + float cou[3], cov[3]; /* i.e. Texture "U" and texture "V" in 3D co-ordinates.*/ + for (int k = 0; k < 3; k++) { + cou[k] = m[0][0] * (va->co[k] - vc->co[k]) + m[0][1] * (vb->co[k] - vc->co[k]); + cov[k] = m[1][0] * (va->co[k] - vc->co[k]) + m[1][1] * (vb->co[k] - vc->co[k]); + } + const float weight = p_face_area(f); + scale_cou += len_v3(cou) * weight; + scale_cov += len_v3(cov) * weight; + if (shear) { + normalize_v3(cov); + normalize_v3(cou); + + /* Why is scale_cross called `cross` when we call `dot`? The next line calculates: + * `scale_cross += length(cross(cross(cou, face_normal), cov))` + * By construction, both `cou` and `cov` are orthogonal to the face normal. + * By definition, the normal vector has unit length. */ + scale_cross += dot_v3v3(cou, cov) * weight; + } + weight_sum += weight; + } + if (scale_cou * scale_cov < 1e-10f) { + break; + } + const float scale_factor_u = scale_uv ? sqrtf(scale_cou / scale_cov) : 1.0f; + + /* Compute correction transform. */ + float t[2][2]; + t[0][0] = scale_factor_u; + t[1][0] = clamp_f((float)(scale_cross / weight_sum), -0.5f, 0.5f); + t[0][1] = 0; + t[1][1] = 1.0f / scale_factor_u; + + /* Apply the correction. */ + p_chart_uv_transform(chart, t); + + /* How far from the identity transform are we? [[1,0],[0,1]] */ + const float err = fabsf(t[0][0] - 1.0f) + fabsf(t[1][0]) + fabsf(t[0][1]) + + fabsf(t[1][1] - 1.0f); + + const float tolerance = 1e-6f; /* Trade accuracy for performance. */ + if (err < tolerance) { + /* Too slow? Use Richardson Extrapolation to accelerate the convergence.*/ + break; + } + } + } + chart->u.pack.area = 0.0f; /* 3d area */ chart->u.pack.rescale = 0.0f; /* UV area, abusing rescale for tmp storage, oh well :/ */ - for (f = chart->faces; f; f = f->nextlink) { + for (PFace *f = chart->faces; f; f = f->nextlink) { chart->u.pack.area += p_face_area(f); chart->u.pack.rescale += fabsf(p_face_uv_area_signed(f)); } @@ -4292,18 +4374,16 @@ void GEO_uv_parametrizer_average(ParamHandle *phandle, bool ignore_pinned) if (chart->u.pack.area != 0.0f && chart->u.pack.rescale != 0.0f) { fac = chart->u.pack.area / chart->u.pack.rescale; - /* Get the island center */ - p_chart_uv_bbox(chart, minv, maxv); - trans[0] = (minv[0] + maxv[0]) / -2.0f; - trans[1] = (minv[1] + maxv[1]) / -2.0f; - - /* Move center to 0,0 */ - p_chart_uv_translate(chart, trans); + /* Average scale. */ p_chart_uv_scale(chart, sqrtf(fac / tot_fac)); - /* Move to original center */ - trans[0] = -trans[0]; - trans[1] = -trans[1]; + /* Get the current island center. */ + p_chart_uv_bbox(chart, minv, maxv); + + /* Move to original center. */ + mid_v2_v2v2(trans, minv, maxv); + negate_v2(trans); + add_v2_v2(trans, chart->u.pack.origin); p_chart_uv_translate(chart, trans); } } |