staggered boundary generation: direction index should point to fluid cell when...

staggered boundary generation: direction index should point to fluid cell when inner_or_boundary=False

In that case, the index vector contains the boundary cells, so the direction should point to the fluid cell.
When inner_or_boundary=True, the index vector contains the fluid cells and the direction points to the boundary cell.

python/lbmpy_walberla/boundary.py

@@ -41,6 +41,10 @@ def generate_boundary(generation_context, class_name, boundary_object, lb_method
         stencil = lb_method.stencil
 
     stencil_info = [(i, d, ", ".join([str(e) for e in d])) for i, d in enumerate(stencil)]
+    inv_dirs = []
+    for direction in stencil:
+        inverse_dir = tuple([-i for i in direction])
+        inv_dirs.append(stencil.index(inverse_dir))
 
     context = {
         'class_name': boundary_object.name,
@@ -48,6 +52,7 @@ def generate_boundary(generation_context, class_name, boundary_object, lb_method
         'StructDeclaration': struct_from_numpy_dtype(struct_name, index_struct_dtype),
         'kernel': KernelInfo(kernel),
         'stencil_info': stencil_info,
+        'inverse_directions' : inv_dirs,
         'dim': lb_method.dim,
         'target': target,
         'namespace': 'lbm',

python/pystencils_walberla/boundary.py

@@ -41,6 +41,10 @@ def generate_staggered_boundary(generation_context, class_name, boundary_object,
         stencil = neighbor_stencil
 
     stencil_info = [(i, d, ", ".join([str(e) for e in d])) for i, d in enumerate(stencil)]
+    inv_dirs = []
+    for direction in stencil:
+        inverse_dir = tuple([-i for i in direction])
+        inv_dirs.append(stencil.index(inverse_dir))
 
     context = {
         'class_name': boundary_object.name,
@@ -48,6 +52,7 @@ def generate_staggered_boundary(generation_context, class_name, boundary_object,
         'StructDeclaration': struct_from_numpy_dtype(struct_name, index_struct_dtype),
         'kernel': KernelInfo(kernel),
         'stencil_info': stencil_info,
+        'inverse_directions' : inv_dirs,
         'dim': dim,
         'target': target,
         'namespace': 'pystencils',
@@ -95,6 +100,10 @@ def generate_staggered_flux_boundary(generation_context, class_name, boundary_ob
         stencil = neighbor_stencil
 
     stencil_info = [(i, d, ", ".join([str(e) for e in d])) for i, d in enumerate(stencil)]
+    inv_dirs = []
+    for direction in stencil:
+        inverse_dir = tuple([-i for i in direction])
+        inv_dirs.append(stencil.index(inverse_dir))
 
     context = {
         'class_name': boundary_object.name,
@@ -102,6 +111,7 @@ def generate_staggered_flux_boundary(generation_context, class_name, boundary_ob
         'StructDeclaration': struct_from_numpy_dtype(struct_name, index_struct_dtype),
         'kernel': KernelInfo(kernel),
         'stencil_info': stencil_info,
+        'inverse_directions' : inv_dirs,
         'dim': dim,
         'target': target,
         'namespace': 'pystencils',

python/pystencils_walberla/templates/Boundary.tmpl.h

@@ -164,7 +164,7 @@ public:
                 {% if inner_or_boundary -%}
                 auto element = {{StructName}}(it.x(), it.y(), {%if dim == 3%} it.z(), {%endif %} {{dirIdx}} );
                 {% else -%}
-                auto element = {{StructName}}(it.x() + cell_idx_c({{dirVec[0]}}), it.y() + cell_idx_c({{dirVec[1]}}), {%if dim == 3%} it.z() + cell_idx_c({{dirVec[2]}}), {%endif %} {{dirIdx}} );
+                auto element = {{StructName}}(it.x() + cell_idx_c({{dirVec[0]}}), it.y() + cell_idx_c({{dirVec[1]}}), {%if dim == 3%} it.z() + cell_idx_c({{dirVec[2]}}), {%endif %} {{inverse_directions[dirIdx]}} );
                 {% endif -%}
                 indexVectorAll.push_back( element );
                 if( inner.contains( it.x(), it.y(), it.z() ) )