geomancy-0.4.0.0: src/Geomancy/Vulkan/DProjection.hs

module Geomancy.Vulkan.DProjection
  ( reverseDepthRH
  , reverseDepthOrthoRH
  , orthoRH
  ) where

import Geomancy.DMat4 (colMajor)
import Geomancy.DTransform (DTransform(..))

reverseDepthRH
  :: Double
  -> Double
  -> Double -> Double
  -> DTransform
reverseDepthRH fovRads zn width height =
  colMajor
    sx  0 0  0
    0  sy 0  0
    0   0 0 zn
    0   0 1  0
  where
    sx = sy * recipAspect
      where
        recipAspect = height / width
    sy = 1 / tan (fovRads / 2)

orthoRH :: Double -> Double -> Double -> Double -> DTransform
orthoRH near far width height =
  colMajor
    sx 0 0 0
    0 sy 0 0
    0  0 z w
    0  0 0 1
  where
    sx = 2 / width
    sy = 2 / height
    z = 1 / (far - near)
    w = near / (near - far)

reverseDepthOrthoRH :: Double -> Double -> Double -> Double -> DTransform
reverseDepthOrthoRH near far width height =
  colMajor
    sx 0 0 0
    0 sy 0 0
    0  0 z w
    0  0 0 1
  where
    sx = 2 / width
    sy = 2 / height
    z = 1 / (near - far)
    w = far / (far - near)