What are the shader attribute names corresponding to the various VertexFormat semantics
pc.SEMANTIC_POSITION
pc.SEMANTIC_NORMAL
pc.SEMANTIC_TANGENT
pc.SEMANTIC_BLENDWEIGHT
pc.SEMANTIC_BLENDINDICES
pc.SEMANTIC_COLOR
pc.SEMANTIC_TEXCOORD0
pc.SEMANTIC_TEXCOORD1
pc.SEMANTIC_TEXCOORD2
pc.SEMANTIC_TEXCOORD3
pc.SEMANTIC_TEXCOORD4
pc.SEMANTIC_TEXCOORD5
pc.SEMANTIC_TEXCOORD6
pc.SEMANTIC_TEXCOORD7
are they hardcoded or do I need / can I define them somehow?
Is there any way to add custom attributes to the vertex format?