Specifying attribute layout for AttributeBuffer

[axel22]

Currently the AttributeBuffer's render method takes an array of tuples to specify the layout of the attributes.

Maybe we should have a separate class for doing this, e.g. AttributeBuffer.Layout that takes a sequence of name and size tuples:

AttributeBuffer.Layout(
  "position" -> 3, // or even some datatype describing vec3, at some point
  "normal" -> 3,
  "textureCoord" -> 2
)

This layout should be the constructor parameter for the AttributeBuffer.

When the buffer is used with a particular shader, which attributes are used should be specified explictily:

// cached somewhere
val myShaderAttributes = List("position", "textureCoord")

// during rendering
buffer.render(mode, myShaderAttributes)

From the myShaderAttributes list and the Layout, the render call should set the appropriate attribute buffer pointers.

[axel22]

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[axel22]

@storm-enroute-bot