UV: Box and lasso selection for partially intersecting edges

In UV edge mode, box and lasso selections allow edge selections only
when the entire edge is contained within the selection area. This
doesn't consider any edges that partially overlap with the selection
area.

This is  now fixed by adding a second pass, similar to how these
operators work for edit-mesh selections. Now if both operators are
unable to find any edges contained within the selection area, then
they will perform a second pass which checks for edges that partially
intersect with the selection area.

Now edge selection in the UV editor matches edit-mesh edge-selection
when drawing wire-frame.

Resolves T99443.

Ref D15362

1 files changed, 35 insertions, 0 deletions

diff --git a/source/blender/editors/interface/view2d.cc b/source/blender/editors/interface/view2d.cc
index ee4bfd351ae..1bf7e25b154 100644
--- a/source/blender/editors/interface/view2d.cc
+++ b/source/blender/editors/interface/view2d.cc
@@ -1695,6 +1695,41 @@ void UI_view2d_view_to_region_fl(
   *r_region_y = v2d->mask.ymin + (y * BLI_rcti_size_y(&v2d->mask));
 }
 
+bool UI_view2d_view_to_region_segment_clip(const View2D *v2d,
+                                           const float xy_a[2],
+                                           const float xy_b[2],
+                                           int r_region_a[2],
+                                           int r_region_b[2])
+{
+  rctf rect_unit;
+  rect_unit.xmin = rect_unit.ymin = 0.0f;
+  rect_unit.xmax = rect_unit.ymax = 1.0f;
+
+  /* Express given coordinates as proportional values. */
+  const float s_a[2] = {
+      (xy_a[0] - v2d->cur.xmin) / BLI_rctf_size_x(&v2d->cur),
+      (xy_a[1] - v2d->cur.ymin) / BLI_rctf_size_y(&v2d->cur),
+  };
+  const float s_b[2] = {
+      (xy_b[0] - v2d->cur.xmin) / BLI_rctf_size_x(&v2d->cur),
+      (xy_b[1] - v2d->cur.ymin) / BLI_rctf_size_y(&v2d->cur),
+  };
+
+  /* Set initial value in case coordinates lie outside bounds. */
+  r_region_a[0] = r_region_b[0] = r_region_a[1] = r_region_b[1] = V2D_IS_CLIPPED;
+
+  if (BLI_rctf_isect_segment(&rect_unit, s_a, s_b)) {
+    r_region_a[0] = (int)(v2d->mask.xmin + (s_a[0] * BLI_rcti_size_x(&v2d->mask)));
+    r_region_a[1] = (int)(v2d->mask.ymin + (s_a[1] * BLI_rcti_size_y(&v2d->mask)));
+    r_region_b[0] = (int)(v2d->mask.xmin + (s_b[0] * BLI_rcti_size_x(&v2d->mask)));
+    r_region_b[1] = (int)(v2d->mask.ymin + (s_b[1] * BLI_rcti_size_y(&v2d->mask)));
+
+    return true;
+  }
+
+  return false;
+}
+
 void UI_view2d_view_to_region_rcti(const View2D *v2d, const rctf *rect_src, rcti *rect_dst)
 {
   const float cur_size[2] = {BLI_rctf_size_x(&v2d->cur), BLI_rctf_size_y(&v2d->cur)};