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 dimensions. 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 640x480. 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 com-
mand 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 coordinates are floating point values. (lx, ly, lz) is the location the eye is looking at -- a point
that the viewing transformation will map to the center of the screen. (ux, uy, uz) indicates the up direction. It is the coordi-
nate of a point that the viewing transformation 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 distances
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 positive, 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 absolute values no larger than 255. Their absolute values 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 transformation commands operate on
the top of the stack. All objects to be drawn are operated on by this transformation.
} pop the transformation stack
R angle axis
Rotate by the given angle (in degrees) about the specified 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 directions.
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 a components of the numbered color table entry. Color components must be integers between 0 (black)
and 255 (full on).
l x y z
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) rep-
resentation of the display on standard output. Exit exits.
SOURCE
/sys/src/fb/cpr.c
/sys/src/fb/cprview.c
CPR(9.1)