fix bug in patching for degenerate patches

Author: Ahdhn

apps/NeoHookean/neo_hookean.cu

@@ -350,7 +350,7 @@ void neo_hookean(RXMeshStatic& rx, T dx)
             }
         }
 
-        RXMESH_INFO("\n===================\n");
+        RXMESH_INFO("===================");
 
         //  update velocity
         rx.for_each_vertex(

include/rxmesh/patcher/patcher.cu

@@ -557,6 +557,8 @@ void Patcher::get_multi_components(
             current_component.reserve(
                 static_cast<uint32_t>(static_cast<double>(m_num_faces) / 10.0));
 
+            current_component.push_back(f);
+
             std::queue<uint32_t> face_queue;
             face_queue.push(f);
             while (!face_queue.empty()) {
@@ -1007,7 +1009,7 @@ void Patcher::run_lloyd(uint32_t* d_face_patch,
                                                             d_ff_values,
                                                             d_queue);
 
-        if (max_patch_size < m_patch_size) {
+        if (max_patch_size <= m_patch_size) {
             shift<<<blocks_f, threads_f>>>(
                 m_num_faces, d_face_patch, d_patches_val);
 

include/rxmesh/patcher/patcher_kernel.cuh

@@ -267,21 +267,32 @@ __global__ static void add_more_seeds(const uint32_t  num_patches,
         const uint32_t p_end  = d_patches_offset[patch_id];
         const uint32_t p_size = p_end - p_start;
 
-        if (p_size > threshold) {
+
+        if (p_size >= threshold) {
 
             if (threadIdx.x == 0) {
                 // look for a boundary face
                 // printf("\n patch_id = %u, p_size = %u", patch_id, p_size);
 
+                bool added = false;
+
                 for (uint32_t f = p_start; f < p_end; ++f) {
                     uint32_t face = d_patches_val[f];
                     if (face & 1) {
+                        added = true;
                         uint32_t new_patch_id =
                             ::atomicAdd(d_new_num_patches, 1u);
                         d_seeds[new_patch_id] = face >> 1;
                         break;
                     }
                 }
+
+                if (!added) {
+                    // if we can not find a boundary edge (it is a single patch
+                    // or isolated), then add the first face
+                    uint32_t new_patch_id = ::atomicAdd(d_new_num_patches, 1u);
+                    d_seeds[new_patch_id] = d_patches_val[p_start] >> 1;
+                }
             }
         }
     }