Output correct glTF type based on extension

[JoshuaStorm]

See #116

Also added a DeveloperError to be thrown if output path given has neither .glb or .gltf file extensions.

[coveralls]

Coverage increased (+0.004%) to 93.712% when pulling 24f1e79 on output-flag-extension into 0edf83e on master.

[lasalvavida]

@JoshuaStorm Can you add a test making sure the exception gets thrown?

[JoshuaStorm]

@lasalvavida I am actually unsure how we would go about testing gltf-pipeline since it is just the command line interface. We don't actually have a spec associated with gltf-pipeline yet.

[lasalvavida]

@JoshuaStorm You should move this check into lib/gltfPipeline.js processFileToDisk and processJsonToDisk. Add the test to specs/lib/gltfPipelineSpec.js.

[pjcozzi]

I don't know how all of this is wired together, but can't we just make sure that binary is set to true before this is called; otherwise, this is forcing some of the command-line logic deeper in the engine.

[pjcozzi]

We don't actually have a spec associated with gltf-pipeline yet.

I think this is fine for now.

[lasalvavida]

@pjcozzi I think this check and exception should be thrown in lib/gltfPipeline.js so that this also happens when gltf-pipeline is used as a node module, not just from command line.

[JoshuaStorm]

@lasalvavida That makes sense, I imagine we should do the same for the other two exceptions in gltf-pipeline as well?

[lasalvavida]

@JoshuaStorm That sounds good to me. Maybe add a validateOptions function and wrap all of that logic up in there.

[JoshuaStorm]

@lasalvavida On second thought, wouldn't it make most sense to check for these exceptions within the readGltf and writeGltf functions? We already do check most of them in these functions anyway.

[lasalvavida]

@lasalvavida On second thought, wouldn't it make most sense to check for these exceptions within the readGltf and writeGltf functions? We already do check most of them in these functions anyway.

That could work too; I'm fine with either.

[coveralls]

Coverage increased (+0.1%) to 93.805% when pulling eacb0de on output-flag-extension into 0edf83e on master.

[pjcozzi]

@lasalvavida please merge when you guys are happy.

[lasalvavida]

Tested; this resolves #116 correctly. Good job @JoshuaStorm!