Decode "offset" in STEP export tool

- Read "at" as inches
- Read "offset" as mm

pcbnew/kicad_plugin.cpp

@@ -1142,7 +1142,9 @@ void PCB_IO::format( MODULE* aModule, int aNestLevel ) const
 
             /* Write 3D model offset in mm
              * 4.0.x wrote "at" which was actually in inches
+             * 5.0.x onwards, 3D model offset is written using "offset"
              */
+
             m_out->Print( aNestLevel+2, "(offset (xyz %s %s %s))\n",
                           Double2Str( bs3D->m_Offset.x ).c_str(),
                           Double2Str( bs3D->m_Offset.y ).c_str(),

utils/kicad2step/pcb/kicadmodel.cpp

@@ -80,12 +80,37 @@ bool KICADMODEL::Read( SEXPR::SEXPR* aEntry )
         std::string name = child->GetChild( 0 )->GetSymbol();
         bool ret = true;
 
+        /*
+         * Version 4.x and prior used 'at' parameter,
+         * which was specified in inches.
+         */
         if( name == "at" )
+        {
             ret = Get3DCoordinate( child->GetChild( 1 ), m_offset );
+
+            if( ret )
+            {
+                m_offset.x *= 25.4f;
+                m_offset.y *= 25.4f;
+                m_offset.z *= 25.4f;
+            }
+        }
+        /*
+         * From 5.x onwards, 3D model is provided in 'offset',
+         * which is in millimetres
+         */
+        else if( name == "offset" )
+        {
+            ret = Get3DCoordinate( child->GetChild( 1 ), m_offset );
+        }
         else if( name == "scale" )
+        {
             ret = Get3DCoordinate( child->GetChild( 1 ), m_scale );
+        }
         else if( name == "rotate" )
+        {
             ret = GetXYZRotation( child->GetChild( 1 ), m_rotation );
+        }
 
         if( !ret )
             return false;