math_transform.hpp

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#ifndef MATH_TRANSFORM_HPP
#define MATH_TRANSFORM_HPP

#include "math.hpp"
#include "opengl.hpp"

template<typename FloatT>
gmtl::Matrix<FloatT,4,4> makeTransformPerspective(FloatT fovy, FloatT aspect, FloatT znear, FloatT zfar)
{
  FloatT f = 1/Math::tan( Math::deg2Rad(fovy)/2 ),
         dp = znear - zfar;
  gmtl::Matrix<FloatT,4,4> r;
  r.set(
      f/aspect, 0,0,0
    , 0, f, 0, 0
    , 0, 0, (zfar+znear)/dp, (2*zfar*znear)/dp
    , 0, 0, -1, 0
  );
  return r;
}

template<typename FloatT>
gmtl::Matrix<FloatT,4,4> makeInversePerspective(FloatT fovy, FloatT aspect, FloatT znear, FloatT zfar)
{
  FloatT f = 1/Math::tan( Math::deg2Rad(fovy)/2 ),
         dp = znear - zfar;
  gmtl::Matrix<FloatT,4,4> r;
  r.set(
      aspect/f, 0,0,0
    , 0, 1/f, 0, 0
    , 0, 0, (zfar+znear)/dp, (2*zfar*znear)/dp
    , 0, 0, -1, 0
    );
  return r;
}

template<typename FloatT>
gmtl::Matrix<FloatT,4,4> makeTransformOrtho(FloatT l, FloatT r, FloatT b, FloatT t, FloatT n, FloatT f)
{

  gmtl::Matrix<FloatT,4,4> result;
  result.set(
    FloatT(2.0)/(r-l), 0, 0, -(r+l)/(r-l),
    0, FloatT(2.0)/(t-b), 0, -(t+b)/(t-b),
    0, 0, FloatT(-2.0)/(f-n), -(f+n)/(f-n),
    0, 0, 0, FloatT(1)
  );
  return result;
}

template<typename FloatT>
gmtl::Matrix<FloatT,4,4> makeInverseOrtho(FloatT l, FloatT r, FloatT b, FloatT t, FloatT n, FloatT f)
{
  gmtl::Matrix<FloatT,4,4> result;
  result.set(
    (r-l)/2, 0, 0, (r+l)/2,
    0, (t-b)/2, 0, (t+b)/2,
    0, 0, (f-n)/-2, (n+f)/2,
    0, 0, 0, 1
  );
  return result;
}

#endif // MATH_TRANSFORM_HPP