nff

[Game.Programming].Academic - Graphics Gems (6 books source code)

Neutral File Format

Presently the following entities are supported by the modified NFF:

A simple perspective frustum

A background color description

A positional (vs. directional) light source description

A surface properties description

Triangle descriptions

NFF files contain lines of text. For each entity, the first field
defines its type. The rest of the line and possibly other lines
contain further information about the entity.

Entities include:

"v" - viewing vectors and angles

"b" - background color

"l" - positional diffuse light location

"s" - positional specular light location

"f" - object material properties

"pp" - triangular patch primitive

These are explained below.

Viewpoint location 

Template:

"v"

"from" Fx Fy Fz

"at" Ax Ay Az

"up" Ux Uy Uz

"angle" angle

"hither" hither

"yon" yon

"resolution" xres yres

Type Specification:

v

from float float float

at float float float

up float float float

angle float

hither float

yon float

resolution integer integer

Description:

From: the eye location in XYZ.

At: a position to be at the center of the image, in XYZ world
coordinates. A.k.a. "lookat".

Up: a vector defining which direction is up, as an XYZ vector.

Angle: in degrees, defined as from the center of top pixel row to
bottom pixel row and left column to right column.

Hither: distance of the hither plane from the eye.

Yon: distance of the yon plane from the eye.

Resolution: in pixels, in x and in y (currently ignored).

Note that no assumptions are made about normalizing the data (e.g. the
from-at distance does not have to be 1). Also, vectors are not
required to be perpendicular to each other.

For all databases, the aspect ratio is 1.0.

A view entity must be defined before any objects are defined.

Background color

Template:

"b" R G B

Type Specification:

b float float float

Description:

Background color is given R,G and B values between 0 and 1.	

Positional Diffuse light

Template:

"l" X Y Z IpR IpG IpB

Type Specification:

l float float float float float float

Description:

A diffuse light is defined by its XYZ position. All light entities
must be defined before any objects are defined. Light source position
and its Red, Green and Blue components, in the range 0.0 to 1.0 are
specified. Up to NUM_LIGHT_SOURCES light sources can be specified.

Positional Specular light

Template:

"s" X Y Z IpR IpG IpB ks n

Type Specification:

l float float float float float float float integer

Description:

A specular light is defined by its XYZ position. All light entities
must be defined before any objects are defined. Light source position
and its Red, Green and Blue components, in the range 0.0 to 1.0 are
specified. At most one specular light source can be specified. The
specular reflection coefficient (ks) in the range 0.0 to 1.0 and the
specular exponent (n) are also specified.

Fill color and shading parameters

Template:

"f" OdR OdG OdB Kd Ka c1 c2 

Format:

f float float float float float float float float

Description:

OdR, OdG and OdB specify the object's diffuse color (RGB triple) in
the range 0.0 to 1.0. Kd is the diffuse reflection coefficient, Ka the
ambient reflection coefficient, c1 and c2 are the parameters for the
attenuation function fatt(d) = 1/(1 + c1*d + c2 * d * d) used for the
light source where "d" is the distance of a point from the light
source (See the textbook by Foley, van Dam, Feiner, Hughes and
Phillips, Chapter 14). Usually, 0 <= Kd <= 1 and 0 <= Ka <= 1, and Kd
and Ka are independent.

Triangular patch 

Template:

"pp" total_vertices

vert1.x vert1.y vert1.z norm1.x norm1.y norm1.z

[etc. for total_vertices vertices]

Format:

pp integer

[float float float float float float] <-- for total_vertices vertices

Description:

All objects are considered one-sided. A patch is defined by a set of
vertices and their normals. With these databases, a patch is defined
to have all points coplanar. A patch has only one side, with the order
of the vertices being counterclockwise as you face the patch
(right-handed coordinate system). The first two edges must form a
non-zero convex angle, so that the normal and side visibility can be
determined. Note that, since only triangular patches are supported
total_vertices shown must always be 3.