Cleanup: simplify uv packing api

source/blender/editors/uvedit/uvedit_unwrap_ops.cc

@@ -1388,7 +1388,6 @@ static void uvedit_pack_islands_multi(const Scene *scene,
   for (int i = 0; i < island_vector.size(); i++) {
     FaceIsland *face_island = island_vector[i];
     blender::geometry::PackIsland *pack_island = new blender::geometry::PackIsland();
-    pack_island->bounds_rect = face_island->bounds_rect;
     pack_island->caller_index = i;
     pack_island->aspect_y = face_island->aspect_y;
     pack_island->angle = 0.0f;

source/blender/geometry/GEO_uv_pack.hh

@@ -72,7 +72,7 @@ class UVPackIsland_Params {
 
 class PackIsland {
  public:
-  /** Bounding rectangle of input. Will be calculated automatically in a future update. */
+  /** Calculated automatically. */
   rctf bounds_rect;
   /** Aspect ratio, required for rotation. */
   float aspect_y;

source/blender/geometry/intern/uv_pack.cc

@@ -7,6 +7,7 @@
 #include "GEO_uv_pack.hh"
 
 #include "BLI_array.hh"
+#include "BLI_bounds.hh"
 #include "BLI_boxpack_2d.h"
 #include "BLI_convexhull_2d.h"
 #include "BLI_listbase.h"
@@ -125,6 +126,7 @@ void PackIsland::add_polygon(const blender::Span<float2> uvs, MemArena *arena, H
 void PackIsland::finalize_geometry(const UVPackIsland_Params &params, MemArena *arena, Heap *heap)
 {
   BLI_assert(triangle_vertices_.size() >= 3);
+
   const eUVPackIsland_ShapeMethod shape_method = params.shape_method;
   if (shape_method == ED_UVPACK_SHAPE_CONVEX) {
     /* Compute convex hull of existing triangles. */
@@ -154,6 +156,17 @@ void PackIsland::finalize_geometry(const UVPackIsland_Params &params, MemArena *
 
     BLI_heap_clear(heap, nullptr);
   }
+
+  Bounds<float2> triangle_bounds = *bounds::min_max(triangle_vertices_.as_span());
+  float2 aabb_min = triangle_bounds.min;
+  float2 aabb_max = triangle_bounds.max;
+  float2 pivot = (aabb_min + aabb_max) * 0.5f;
+  float2 half_diagonal = (aabb_max - aabb_min) * 0.5f;
+
+  bounds_rect.xmin = pivot.x - half_diagonal.x;
+  bounds_rect.ymin = pivot.y - half_diagonal.y;
+  bounds_rect.xmax = pivot.x + half_diagonal.x;
+  bounds_rect.ymax = pivot.y + half_diagonal.y;
 }
 
 UVPackIsland_Params::UVPackIsland_Params()
@@ -944,7 +957,7 @@ static float pack_islands_margin_fraction(const Span<PackIsland *> &island_vecto
       /* TODO (?): `if (max_uv < 1.0f) { scale_last /= max_uv; }` */
     }
 
-    /* Then expand FaceIslands by the correct amount. */
+    /* Then expand PackIslands by the correct amount. */
     for (const int64_t index : island_vector.index_range()) {
       BoxPack *box = &box_array[index];
       box->x /= scale_last;
@@ -998,7 +1011,7 @@ static BoxPack *pack_islands_box_array(const Span<PackIsland *> &islands,
     const float scale = pack_islands_margin_fraction(islands, box_array, params.margin, params);
     r_scale[0] = scale;
     r_scale[1] = scale;
-    /* pack_islands_margin_fraction will pad FaceIslands, return early. */
+    /* pack_islands_margin_fraction will pad PackIslands, return early. */
     return box_array;
   }
 

source/blender/geometry/intern/uv_parametrizer.cc

@@ -4144,7 +4144,17 @@ void uv_parametrizer_pack(ParamHandle *handle, float margin, bool do_rotate, boo
   }
 
   uv_parametrizer_scale_x(handle, 1.0f / handle->aspect_y);
+
   Vector<PackIsland *> pack_island_vector;
+
+  UVPackIsland_Params params;
+  params.rotate = do_rotate;
+  params.margin = margin;
+  params.margin_method = ED_UVPACK_MARGIN_SCALED;
+
+  MemArena *arena = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, __func__);
+  Heap *heap = BLI_heap_new();
+
   int unpacked = 0;
   for (int i = 0; i < handle->ncharts; i++) {
     PChart *chart = handle->charts[i];
@@ -4159,21 +4169,19 @@ void uv_parametrizer_pack(ParamHandle *handle, float margin, bool do_rotate, boo
     pack_island->caller_index = i;
     pack_island->aspect_y = handle->aspect_y;
     pack_island->angle = 0.0f;
+
+    for (PFace *f = chart->faces; f; f = f->nextlink) {
+      PVert *v0 = f->edge->vert;
+      PVert *v1 = f->edge->next->vert;
+      PVert *v2 = f->edge->next->next->vert;
+      pack_island->add_triangle(v0->uv, v1->uv, v2->uv);
+    }
+    pack_island->finalize_geometry(params, arena, heap);
+
     pack_island_vector.append(pack_island);
-
-    float minv[2];
-    float maxv[2];
-    p_chart_uv_bbox(chart, minv, maxv);
-    pack_island->bounds_rect.xmin = minv[0];
-    pack_island->bounds_rect.ymin = minv[1];
-    pack_island->bounds_rect.xmax = maxv[0];
-    pack_island->bounds_rect.ymax = maxv[1];
   }
-
-  UVPackIsland_Params params;
-  params.rotate = do_rotate;
-  params.margin = margin;
-  params.margin_method = ED_UVPACK_MARGIN_SCALED;
+  BLI_heap_free(heap, nullptr);
+  BLI_memarena_free(arena);
 
   float scale[2] = {1.0f, 1.0f};
   pack_islands(pack_island_vector, params, scale);