In the format descriptions, %g denotes a floating point number and %d denotes an integer. Coordinates are given in world space.
| b |
Background color. A color is simply RGB with values between 0 and 1:
"b" R G B
Format:
b %g %g %g
If no background color is set, assume RGB = {0,0,0}.
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| v |
Viewpoint location. Description:
"v"
"from" Fx Fy Fz
"at" Ax Ay Az
"up" Ux Uy Uz
"angle" angle
"hither" hither
"resolution" xres yres
Format:
v
from %g %g %g
at %g %g %g
up %g %g %g
angle %g
hither %g
resolution %d %d
The parameters are:
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 [near] plane (if any) from the eye. Mostly
needed for hidden surface algorithms.
Resolution: in pixels, in x and in y.
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 some viewing parameters are always the same:
Yon is "at infinity."
Aspect ratio is 1.0.
A view entity must be defined before any objects are defined (this
requirement is so that NFF files can be displayed on the fly by hidden
surface machines).
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| f |
Fill color and shading parameters. Description:
"f" red green blue Kd Ks Shine T index_of_refraction
Format:
f %g %g %g %g %g %g %g %g
RGB is in terms of 0.0 to 1.0.
Kd is the diffuse component, Ks the specular, Shine is the Phong cosine
power for highlights, T is transmittance (fraction of contribution of the
transmitting ray). Usually, 0 <= Kd <= 1 and 0 <= Ks <= 1, though it is
not required that Kd + Ks == 1. Note that transmitting objects ( T > 0 )
are considered to have two sides for algorithms that need these (normally
objects have one side).
The fill color is used to color the objects following it until a new color
is assigned.
Note - for this project, you are only concerned with the first three arguments:
red, green, and blue. We will revisit the other arguments in project 5.
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| p |
Polygon. A polygon is defined as shown below:
"p" total_vertices
vert1.x vert1.y vert1.z
[etc. for total_vertices vertices]
Format:
p %d
[ %g %g %g ] <- for total_vertices vertices
A polygon is defined by a set of vertices. With these databases, a polygon
is defined to have all points coplanar. A polygon has only one side; the
order of the vertices is counterclockwise as you face the polygon
(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 by
using just the first three vertices.
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| s |
Sphere. A sphere is defined by a radius and center position:
"s" center.x center.y center.z radius
Format:
s %g %g %g %g
If the radius is negative, then only the sphere's inside is visible
(objects are normally considered one sided, with the outside visible).
Currently none of the SPD scenes make use of negative radii.
NOTE: Spheres are optional in this assignment.
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