calling CustomDataTypeClass::Calculate() [SOLVED]

On 27/07/2016 at 03:40, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   R17 
Language(s) :     C++  ;

Hi! I'm trying to interpolate between two GeData values. But when I call CustomDataTypeClass::Calculate(),
it always gives me GV_CALC_ERR_UNDEFINED . Does someone know what I'm doing wrong?

Thanks a lot in advance,


GeData InterpolateValues(GeData const& left, GeData const& right, BaseList2D* node, Float w) {
  Int32 const type = left.GetType();
  if (type != right.GetType()) return left;
  // Load the CustomDataTypeClass plugin for this datatype.
  CUSTOMDATATYPEPLUGIN* plug = FindCustomDataTypePlugin(left.GetType());
  if (!plug) return left;
  auto data = static_cast<CustomDataTypeClass*>(plug->adr);
  if (!data) return left;
  GeData res = left;
  GvError err = (data->*plug->Calculate)(
  if (err != GV_IO_ERR_NONE) {
    // Always gets here with err == GV_CALC_ERR_UNDEFINED
    GePrint("Oh Noes! " + String::IntToString(err));
  return res;
        // Calling example
	GeData l(10);
	GeData r(50);
	GeData res = InterpolateValues(l, r, nullptr, 0.5);
	Int32 val = res.GetInt32();

On 28/07/2016 at 08:22, xxxxxxxx wrote:

Hi Niklas,

I'm terribly sorry, I haven't found as much time to investigate it, as I had planned and wished.
Just wanted to let you know, I'm on it.
What I found so far: Your Calculate() call ends up in the "base implementation" of that function, which does nothing more than returning GV_CALC_ERR_UNDEFINED. So actually under the given circumstances, the result is actually correct 😉
I'll continue with this tomorrow.

On 29/07/2016 at 08:58, xxxxxxxx wrote:

Hi Niklas,

the reason is quite simple: Only very few custom data types implement Calculate(). From the public ones, SplineData is actually the only one (and even this implements only GV_CALC_CLR, GV_CALC_ADD and GV_CALC_MIX).
So actually your example is correct, but it works only on data types that implemented Calculate()... SplineData that is. 😊

On 29/07/2016 at 10:51, xxxxxxxx wrote:

Thank you for your time and effort, Andreas. 🙂 Originally I didn't expect FindCustomDataTypePlugin()
to actually return not-null for any of the standard datatypes (LONG, REAL, etc.), but since it did, I
expected it to be implemented for these types as well.

Anyway, now that I know I just do some special handling for the datatypes that I want to support
proper interpolation for, and eventually use the CustomDataTypePlugin for any ID that I don't know
or don't handle.

Thanks again!