I'm working on a tool to convert COLLADA files to my engines own format, and I'm having some issues with fetching vertex attributes.

The FCDGeometrySource::GetValue(index) provide me with a pointer to the first element in an attribute. The problem is that for some of the vertex-attributes (like texture coordinates), the element count can vary - 2D textures can use 2 component coordinates, 3D textures or projected 2D textures can use 3 or 4 coordinates. And some COLLADA exporters vary the count of texture coordinates they output - the version of ColladaMax I have installed writes three component texture coordinates, whereas most other exporters writes two component texture coordinates.

The way I understand the COLLADA-spec, the amount of elements to utilize for a given vertex attribute is defined by the amount of param-subtags in the accessor-tag for the given source.

Is there some way of finding this count from the FCollada-API?

If not, I must make a guess, risking reading an invalid r-coordinate ("r" is OpenGL terminology - ColladaMax seems to call it "P") for a set of texture coordinates that doesn't have one, causing incorrect mapping of textures using those coordinates. Or worse, I could end up discarding important information for meshes that are using the vertex attributes for non-trivial purposes. I often use vertex-attributes to pre-calculate different kinds of usage-specific data, and I'd like to be able to do this before exporting from COLLADA.

I have seen some people using the stride to guess what the size should be. This is not a robust solution since vertex data can be interleaved inside a single float-array, causing mismatch between the size and stride. And in my case, they usually are.

Sorry for bumping this, but I'm really looking for a solution to this. I've been able to progress in my current project since the data is always exported from 3DS Max, but an upcoming project this isn't the case.