UV: restore internal solver state variable

Removed in [0] however I think it helps track the state,
so restore the state and assertions.

[0]: 8ace65e3c6

source/blender/editors/uvedit/uvedit_unwrap_ops.cc

@@ -883,6 +883,7 @@ static void minimize_stretch_exit(bContext *C, wmOperator *op, bool cancel)
     blender::geometry::uv_parametrizer_flush(ms->handle);
   }
 
+  blender::geometry::uv_parametrizer_stretch_end(ms->handle);
   delete (ms->handle);
 
   for (uint ob_index = 0; ob_index < ms->objects_len; ob_index++) {

source/blender/geometry/GEO_uv_parametrizer.hh

@@ -23,11 +23,19 @@ struct PHash;
 using ParamKey = uintptr_t; /* Key (hash) for identifying verts and faces. */
 #define PARAM_KEY_MAX UINTPTR_MAX
 
+enum PHandleState {
+  PHANDLE_STATE_ALLOCATED,
+  PHANDLE_STATE_CONSTRUCTED,
+  PHANDLE_STATE_LSCM,
+  PHANDLE_STATE_STRETCH,
+};
+
 class ParamHandle {
  public:
   ParamHandle();
   ~ParamHandle();
 
+  PHandleState state;
   MemArena *arena;
   MemArena *polyfill_arena;
   Heap *polyfill_heap;
@@ -114,6 +122,7 @@ void uv_parametrizer_lscm_end(ParamHandle *handle);
 void uv_parametrizer_stretch_begin(ParamHandle *handle);
 void uv_parametrizer_stretch_blend(ParamHandle *handle, float blend);
 void uv_parametrizer_stretch_iter(ParamHandle *handle);
+void uv_parametrizer_stretch_end(ParamHandle *handle);
 
 /** \} */
 

source/blender/geometry/intern/uv_parametrizer.cc

@@ -3618,6 +3618,7 @@ static void p_chart_rotate_fit_aabb(PChart *chart)
 
 ParamHandle::ParamHandle()
 {
+  state = PHANDLE_STATE_ALLOCATED;
   arena = BLI_memarena_new(MEM_SIZE_OPTIMAL(1 << 16), "param construct arena");
   polyfill_arena = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, "param polyfill arena");
   polyfill_heap = BLI_heap_new_ex(BLI_POLYFILL_ALLOC_NGON_RESERVE);
@@ -3818,6 +3819,7 @@ void uv_parametrizer_face_add(ParamHandle *phandle,
                               const bool *select)
 {
   BLI_assert(nverts >= 3);
+  BLI_assert(phandle->state == PHANDLE_STATE_ALLOCATED);
 
   if (nverts > 3) {
     /* Protect against (manifold) geometry which has a non-manifold triangulation.
@@ -3897,6 +3899,8 @@ void uv_parametrizer_face_add(ParamHandle *phandle,
 
 void uv_parametrizer_edge_set_seam(ParamHandle *phandle, ParamKey *vkeys)
 {
+  BLI_assert(phandle->state == PHANDLE_STATE_ALLOCATED);
+
   PEdge *e = p_edge_lookup(phandle, vkeys);
   if (e) {
     e->flag |= PEDGE_SEAM;
@@ -3910,6 +3914,8 @@ void uv_parametrizer_construct_end(ParamHandle *phandle,
 {
   int i, j;
 
+  BLI_assert(phandle->state == PHANDLE_STATE_ALLOCATED);
+
   phandle->ncharts = p_connect_pairs(phandle, topology_from_uvs);
   phandle->charts = p_split_charts(phandle, phandle->construction_chart, phandle->ncharts);
 
@@ -3946,10 +3952,15 @@ void uv_parametrizer_construct_end(ParamHandle *phandle,
   }
 
   phandle->ncharts = j;
+
+  phandle->state = PHANDLE_STATE_CONSTRUCTED;
 }
 
 void uv_parametrizer_lscm_begin(ParamHandle *phandle, bool live, bool abf)
 {
+  BLI_assert(phandle->state == PHANDLE_STATE_CONSTRUCTED);
+  phandle->state = PHANDLE_STATE_LSCM;
+
   for (int i = 0; i < phandle->ncharts; i++) {
     for (PFace *f = phandle->charts[i]->faces; f; f = f->nextlink) {
       p_face_backup_uvs(f);
@@ -3960,6 +3971,8 @@ void uv_parametrizer_lscm_begin(ParamHandle *phandle, bool live, bool abf)
 
 void uv_parametrizer_lscm_solve(ParamHandle *phandle, int *count_changed, int *count_failed)
 {
+  BLI_assert(phandle->state == PHANDLE_STATE_LSCM);
+
   for (int i = 0; i < phandle->ncharts; i++) {
     PChart *chart = phandle->charts[i];
 
@@ -3996,16 +4009,23 @@ void uv_parametrizer_lscm_solve(ParamHandle *phandle, int *count_changed, int *c
 
 void uv_parametrizer_lscm_end(ParamHandle *phandle)
 {
+  BLI_assert(phandle->state == PHANDLE_STATE_LSCM);
+
   for (int i = 0; i < phandle->ncharts; i++) {
     p_chart_lscm_end(phandle->charts[i]);
 #if 0
     p_chart_complexify(phandle->charts[i]);
 #endif
   }
+
+  phandle->state = PHANDLE_STATE_CONSTRUCTED;
 }
 
 void uv_parametrizer_stretch_begin(ParamHandle *phandle)
 {
+  BLI_assert(phandle->state == PHANDLE_STATE_CONSTRUCTED);
+  phandle->state = PHANDLE_STATE_STRETCH;
+
   phandle->rng = BLI_rng_new(31415926);
   phandle->blend = 0.0f;
 
@@ -4027,16 +4047,24 @@ void uv_parametrizer_stretch_begin(ParamHandle *phandle)
 
 void uv_parametrizer_stretch_blend(ParamHandle *phandle, float blend)
 {
+  BLI_assert(phandle->state == PHANDLE_STATE_STRETCH);
   phandle->blend = blend;
 }
 
 void uv_parametrizer_stretch_iter(ParamHandle *phandle)
 {
+  BLI_assert(phandle->state == PHANDLE_STATE_STRETCH);
   for (int i = 0; i < phandle->ncharts; i++) {
     p_chart_stretch_minimize(phandle->charts[i], phandle->rng);
   }
 }
 
+void uv_parametrizer_stretch_end(ParamHandle *phandle)
+{
+  BLI_assert(phandle->state == PHANDLE_STATE_STRETCH);
+  phandle->state = PHANDLE_STATE_CONSTRUCTED;
+}
+
 void uv_parametrizer_pack(ParamHandle *handle, float margin, bool do_rotate, bool ignore_pinned)
 {
   if (handle->ncharts == 0) {