### Section View

This section defines the 3D view of a raytracer scene with the sistem VRC (3D viewing-reference coordinate).

To define exactly all the attributes you can see in [1].

section_view = { . vcr . { [ def_vrp | def_prp | def_vup | def_vpn | def_umax | def_umin | def_vmax |

def_vmin | def_type | def_f | def_b | def_fon | def_bon ] } . }

def_vrp = vrp . point . ;

def_prp = prp . point . ;

def_vup = vup . point . ;

def_vpn = vpn . point . ;

def_umax = umax . number_real . ;

def_umin = umin . number_real . ;

def_vmax = vmax . number_real . ;

def_vmin = vmin . number_real . ;

def_type = type . number_integer . ;

def_f = f . number_real . ;

def_b = b . number_real . ;

def_fon = fon . number_integer . ;

def_bon = bon . number_integer . ;

section_view

complete definition of the view 3D.

def_vrp

definition of the view reference point ( VRP ) , the origin of VCR system.

With the VPN defines the plane of the image.

def_prp

definition of the projection reference point ( PRP ).

def_vup

definition of the view up vector ( VUP ), which limit the v axis on the image plane.

def_vpn

definition of the view-plane normal ( VPN ), is the n axis of the VRC system.

With the VPN defines the plane of the image.

def_umax

def_umin

def_vmax

def_vmin

definition of limitis of the image window on the view plane.

def_type

Type of projection.

1 means perspective projection , while 0 means parallel projection.

def_f

the front distance ( F ). This parameter will be ignored.

def_b

the la back distance ( B ). This parameter will be ignored.

def_fon

This parameter will be ignored.

def_bon

This parameter will be ignored.