This,
wireframe :: Double -> Double -> Double -> IO ()
wireframe wx wy wz = do
-- yz plane
renderPrimitive LineLoop $ do
vertex $ Vertex3 0.0 0.0 0.0
vertex $ Vertex3 0.0 wy 0.0
vertex $ Vertex3 0.0 wy wz
vertex $ Vertex3 0.0 0.0 wz
produces this:
No instance for (VertexComponent Double)
arising from a use of `vertex'
Possible fix:
add an instance declaration for (VertexComponent Double)
In the expression: vertex
In a stmt of a 'do' block: vertex $ Vertex3 0.0 wy 0.0
In the second argument of `($)', namely
`do { vertex $ Vertex3 0.0 0.0 0.0;
vertex $ Vertex3 0.0 wy 0.0;
vertex $ Vertex3 0.0 wy wz;
vertex $ Vertex3 0.0 0.0 wz }'
and thusly this :-(
Changing the declaration to GLdouble -> GLdouble -> GLdouble -> IO() and using
(0.0::GLdouble) fixes it, and I'm not clear on why it's not automagic. There
are many times I see the compiler doing type conversion an numerican arguments
although sometimes the occasional fracSomethingIntegralorOther is required.
I was hoping for some enlightenment.
Thank you.
Brian
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