calcNormal Function

public function calcNormal(p, obj)

Calculate the surface normal of a SDF at the point p numerically.

Arguments

Type IntentOptional Attributes Name
type(vector), intent(in) :: p

Position to evaluate at
class(sdf_base) :: obj

SDF to calcuate surface normal of.

Return Value type(vector)


Source Code

    type(vector) function calcNormal(p, obj)
        !! Calculate the surface normal of a SDF at the point p numerically.
        
        !> Position to evaluate at
        type(vector), intent(IN) :: p
        !> SDF to calcuate surface normal of.
        class(sdf_base) :: obj

        real(kind=wp) :: h
        type(vector) :: xyy, yyx, yxy, xxx

        h = 1e-6_wp
        xyy = vector(1._wp, -1._wp, -1._wp)
        yyx = vector(-1._wp, -1._wp, 1._wp)
        yxy = vector(-1._wp, 1._wp, -1._wp)
        xxx = vector(1._wp, 1._wp, 1._wp)

        calcNormal = xyy*obj%evaluate(p + xyy*h) +  &
                    yyx*obj%evaluate(p + yyx*h) +  &
                    yxy*obj%evaluate(p + yxy*h) +  &
                    xxx*obj%evaluate(p + xxx*h)

        calcNormal = calcNormal%magnitude()

    end function calcNormal