Skip to content

Instantly share code, notes, and snippets.

@mahulst

mahulst/RayTriangleIntersect.elm

Created September 16, 2017 10:02
Show Gist options
  • Save mahulst/64f4725cb76c3f459357fb7b20784a27 to your computer and use it in GitHub Desktop.
Save mahulst/64f4725cb76c3f459357fb7b20784a27 to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. mahulst created this gist Sep 16, 2017.
    55 changes: 55 additions & 0 deletions RayTriangleIntersect.elm
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,55 @@
    rayTriangleIntersect : Vec3 -> Vec3 -> ( Vec3, Vec3, Vec3 ) -> Maybe Vec3
    rayTriangleIntersect rayOrigin rayDirection ( triangle0, triangle1, triangle2 ) =
    let
    epsilon =
    0.000001

    edge1 =
    Vec3.sub triangle1 triangle0

    edge2 =
    Vec3.sub triangle2 triangle0

    pvec =
    Vec3.cross rayDirection edge2

    det =
    Vec3.dot edge1 pvec
    in
    if det < epsilon then
    Nothing
    else
    let
    tvec =
    Vec3.sub rayOrigin triangle0

    u =
    Vec3.dot tvec pvec
    in
    if u < 0 || u > det then
    Nothing
    else
    let
    qvec =
    Vec3.cross tvec edge1

    v =
    Vec3.dot rayDirection qvec
    in
    if v < 0 || u + v > det then
    Nothing
    else
    let
    t =
    (Vec3.dot edge2 qvec) / det

    v0 =
    (Vec3.getX rayOrigin) + t * (Vec3.getX rayDirection)

    v1 =
    (Vec3.getY rayOrigin) + t * (Vec3.getY rayDirection)

    v2 =
    (Vec3.getZ rayOrigin) + t * (Vec3.getZ rayDirection)
    in
    Just (vec3 v0 v1 v2)