The size, in bytes, of a single vertex.
This is derived by adding together all of the vertex attributes.
For example, the Multi Pipeline has the following attributes:
inPosition - (size 2 x gl.FLOAT) = 8 inTexCoord - (size 2 x gl.FLOAT) = 8 inTexId - (size 1 x gl.FLOAT) = 4 inTintEffect - (size 1 x gl.FLOAT) = 4 inTint - (size 4 x gl.UNSIGNED_BYTE) = 4
The total, in this case, is 8 + 8 + 4 + 4 + 4 = 28.
This is calculated automatically during the createAttributes
method.