cli: add option to disable attribute coding

Sometimes it is useful to encode geometry without attributes.  However,
the common test condition configurations all enable attribute coding.
In order to avoid rewriting the configuration files, the
"disableAttributeCoding" option configures the encoder as if no
attributes are specified.

tmc3/TMC3.cpp

@@ -52,6 +52,9 @@ struct Parameters {
   // output mode for ply writing (binary or ascii)
   bool outputBinaryPly;
 
+  // when true, configure the encoder as if no attributes are specified
+  bool disableAttributeCoding;
+
   std::string uncompressedDataPath;
   std::string compressedStreamPath;
   std::string reconstructedDataPath;
@@ -282,6 +285,10 @@ ParseParameters(int argc, char* argv[], Parameters& params)
     params.encoder.gps.geom_unique_points_flag, true,
     "Enables removal of duplicated points")
 
+  ("disableAttributeCoding",
+    params.disableAttributeCoding, false,
+    "Ignore attribute coding configuration")
+
   (po::Section("Geometry"))
 
   // tools
@@ -404,6 +411,13 @@ ParseParameters(int argc, char* argv[], Parameters& params)
       1.0f / params.encoder.sps.donotuse_trisoup_int_to_orig_scale;
   }
 
+  // support disabling attribute coding (simplifies configuration)
+  if (params.disableAttributeCoding) {
+    params.encoder.attributeIdxMap.clear();
+    params.encoder.sps.attributeSets.clear();
+    params.encoder.aps.clear();
+  }
+
   // fixup any per-attribute settings
   for (const auto& it : params.encoder.attributeIdxMap) {
     auto& attr_sps = params.encoder.sps.attributeSets[it.second];