CPR(9.1) CPR(9.1)
NAME
cpr, cprview - cheesy polygon renderer and viewer
SYNOPSIS
fb/cpr [ -a aspect ] [ -c rgbaz ] [ -w nx ny ] file ...
fb/cprview [ file ... ]
DESCRIPTION
Cpr creates an image from a list of polygons in three dimen-
sions. Its output is a picture file, written to standard
output. The -w flag sets the width and height of the output
file. The default size is 640×480. The -a flag indicates
the aspect ratio of the image. The default aspect ratio is
the ratio of the output file's width and height, in pixels.
It may be set independently to handle displays with non-
square pixels. The -c flag indicates which channels the
output image should have. Possible values are -crgb (the
default), -crgba, and -crgbaz.
Cpr's input is a simple textual command language, read from
the input files named on the command line (default standard
input). Each command is a single character followed by
arguments, separated by spaces. The commands are:
v fov near far ex ey ez lx ly lz ux uy uz
Set viewing parameters. Fov is the horizontal field-
of-view angle. (ex, ey, ez) is the eye location from
which the scene is viewed. These and all other coordi-
nates are floating point values. (lx, ly, lz) is the
location the eye is looking at - a point that the view-
ing transformation will map to the center of the
screen. (ux, uy, uz) indicates the up direction. It
is the coordinate of a point that the viewing transfor-
mation will map somewhere on the ray ascending from
(lx, ly, lz) through the top of the screen. Exactly
where on that ray the image of (ux, uy, uz) is depends
on the field of view angle. Near and far are the dis-
tances from the eyepoint to the near and far clipping
planes. Objects closer than near or farther than far
will not be displayed. Both near and far must be posi-
tive, with far>near.
t x0 y0 z0 x1 y1 z1 x2 y2 z2 c0 c1
draw a triangle. (x0, y0, z0), (x1, y1, z1), and (x2,
y2, z2) are the corners of the triangle. C0 and c1 are
the colors of the two sides of the triangle, with c0
being the color of the side from which the vertices are
viewed clockwise. Color values are integers with abso-
lute values no larger than 255. Their absolute values
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CPR(9.1) CPR(9.1)
index a table of colors whose entries are set using the
c command (vide infra). A positive color indicates
that the object should be drawn in exactly that color;
a negative value means that the polygon should be a
shade of that color computed according to the light
source position.
p c0 c1 [ x y z ]* ;
draw a polygon. C0 and c1 are the colors of its two
sides. The (x, y, z) values are its vertices.
h c0 c1 nx ny x0 y0 x1 y1 file
draw a height field from a file of z values. C0 and c1
are its colors. X0, y0, x1, and y1 give the range of x
and y values. The file contains an array of nx by ny
floating point numbers, in row major order, in the
native floating-point representation of the machine
running cpr. This is not portable.
s c0 c1 x y z r
draw a sphere of the given color, with center at (x, y,
z) and radius r.
{ push the transformation stack. Cpr maintains a stack
of transformation matrices. The following transforma-
tion commands operate on the top of the stack. All
objects to be drawn are operated on by this transforma-
tion.
} pop the transformation stack
R angle axis
Rotate by the given angle (in degrees) about the speci-
fied axis, which must be 0 for x, 1 for y, or 2 for z.
T dx dy dz
Translate by the given offset
S sx sy sz
Scale by the given factors in the x, y, and z direc-
tions.
M m00 m01 m02 m03 m10 m11 ... m33
Multiply the top of the transformation stack by the
given matrix.
c num r g b a
Set the red, green, blue and α components of the num-
bered color table entry. Color components must be
integers between 0 (black) and 255 (full on).
l x y z
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CPR(9.1) CPR(9.1)
Set the direction that the light source shines from.
b r g b a
Clear the background to the given color.
Cprview displays a wire frame version of a cpr image in a
window. Dragging with button 1 rotates the image. Button 2
pops up a reread menu item that causes the input files to be
reread. Button 3 pops up a menu containing output and exit
items. Output writes a pic(1) representation of the display
on standard output. Exit exits.
SOURCE
/sys/src/fb/cpr.c
/sys/src/fb/cprview.c
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