[Problem G | 1993 Regional problem set | My ACM problem archive | my home page]

PostScript Emulation

In this problem you are required to recognize a small part of the PostScript language. Specifically, the commands listed below must be recognized. All commands will be given in lower-case letters. When the word number appears in the command description, a floating point value, with an optional sign and decimal point will be present in the input data. When two numbers appear in a command, the first refers to the x coordinate, and the second to the y coordinate. For simplicity, each command will appear on a line by itself, and a single blank will separate each component of the command. The end of line character will immediately follow each command, and a line with a single asterisk in column one will terminate the input.

**number rotate**represents the measure of an angle. This command rotates the coordinate system that may degrees counter clockwise about the current origin. his does not affect any lines that have already been drawn on the page. Example:`number`

will rotate the axes 90 degrees counterclockwise, so the positive y axis now points to the left, and the positive x axis points up.**90 rotate****number number translate**- Moves the origin of the coordinate system to the position
specified. The values are interpreted relative to the current
origin. Example:

would move the origin of the coordinate system to the upper right corner of the page. Now only points with negative x and y components will correspond to points on the physical page (assuming an 8.5" by 11" page in the portrait orientation).**612 792 translate** **number number scale**- This command applies the scaling factors given to the x and y
coordinates. In effect, the actual x and y sizes of objects are
multiplied by the respective scale factors. Example:

would cause a line drawn from (0,0) to (72,72) to appear as if it was drawn from the lower left corner of the page to a point three inches to the right of the left edge of the paper and two inches up from the bottom edge of the paper, assuming the original coordinate system was in effect just before the command.**3 2 scale** **number number moveto**- The current point is moved to the coordinates specified.
Example:

would move the current point to one inch from the left edge of the paper, and two inches up from the bottom edge, assuming the original coordinate system was in effect.**72 144 moveto** **number number rmoveto**- This command is like

, except the numbers specified give the coordinates of the new current point relative to the current position. Example:**moveto**

would move the current point set by the previous example two inches further to the right and one-half inch lower on the page. Thus the coordinates of the current point become (216,108). Notice that numbers can be negative!**144 -36 rmoveto** **number number lineto**- Draws a line from the current position to the position specified by the numbers. The current position becomes the position specified in the command. Example: (216,144), would draw a line from the current position to the point (216,144), and leave the current point there. If we assume the current position from the previous example, this would be a line from (216,108) to (216,144), or a half-inch vertical line.
**number number rlineto**- This is similar to

, but the coordinates given in the command are relative o the current position. Again, the end of the line that is drawn becomes the new current position. Example:**lineto**

will draw a two inch horizontal line from the current position two inches to the right. Using the current position left in the previous example, this draws a line from (216,144) to (216,288), and leaves the current point at (216,288).**0 144 rlineto**

**rotate**

, **translate**

, or **scale**

commands. That is, each
**moveto**

, **rmoveto,**

**lineto**

, and **rlineto**

command in the
original (input) program should appear in your output (most likely
with modified numbers), but the **rotate**

, **translate**

, and
**scale**

commands in the input must not appear in the output.
Assume the original coordinate system is in effect at the beginning
of execution. The numbers used with the commands in the
program you produce must be accurate to at least two fractional
digits.

Sample solution #2, with matrices

Sample Input

300 300 moveto 0 72 rlineto 2 1 scale 36 0 rlineto 1 -4 scale 0 18 rlineto 1 -0.25 scale 0.5 1 scale 300 300 translate 90 rotate 0 0 moveto 0 72 rlineto 2 1 scale 36 0 rlineto 1 -4 scale 0 18 rlineto *

300 300 moveto 0 72 rlineto 72 0 rlineto 0 -72 rlineto 300 300 moveto -72 0 rlineto 0 72 rlineto 72 0 rlineto

400 500 moveto 300 400 lineto 0.5 0.4 scale 200 200 lineto 95 rotate 250 -200 lineto -100 -100 translate 0.5 0.1 scale 250 70 lineto 250 70 rmoveto 150 250 rlineto *

400 500 moveto 300 400 lineto 100 80 lineto 88.725 106.592 lineto 45.2336 13.2041 lineto -8.93393 49.5657 rmoveto -15.7208 29.0143 rlineto

This page maintained by Ed Karrels.

Last updated September 20, 1999