CODEWITHSUNDEEP
haskellopengl
Stéphane Laurent
Stéphane Laurent

Reputation: 84699

Apply a transformation with Haskell OpenGL

With Haskell OpenGL, it is possible to apply a transformation to an object like this:

  preservingMatrix $ do
    translate myvector
    renderObject Solid $ Sphere' 0.2 50 50

The transformations translate, rotate, and scale are available. I would like to apply the transformation corresponding to an orthonormal 3x3 matrix M which is not a rotation. Is it possible and how ?

Of course, as a desperate solution I could decompose M into translations and rotations (this is possible if I correctly remember my maths courses).

Upvotes: 2

Views: 171

Answers (2)

Stéphane Laurent
Stéphane Laurent

Reputation: 84699

Yes, this is multMatrix. I've followed this example. If your matrix is 

a b c 
d e f 
g h i

then do something like

  ......
  preservingMatrix $ do
    myTransformation
    materialDiffuse Front $= green
    renderObject Solid $ Teapot 5
  swapBuffers
  where
    myTransformation = do
      m <- (newMatrix RowMajor [ a, b, c, 0
                               , d, e, f, 0
                               , g, h, i, 0
                               , 0, 0, 0, 1]) :: IO (GLmatrix GLfloat)
      multMatrix m

If you want to add a translation, do

  m <- (newMatrix RowMajor [ a, b, c, x
                           , d, e, f, y
                           , g, h, i, z
                           , 0, 0, 0, 1]) :: IO (GLmatrix GLfloat)

where (x,y,z)is the translation vector.

teapot

Upvotes: 1

Thomas
Thomas

Reputation: 182038

My Haskell is rusty and I've never used it with OpenGL before, but maybe you are looking for multMatrix?

Upvotes: 0

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