Assignment 1: Turtle Graphics

Assignment 1 
Objectives • Review structures, loops and functions • Introduction to input and output in C++ • Practice reading a specification and implementing a specification • Introduction to Scalable Vector Graphics (SVG) • Introduction to software testing and debugging techniques
Introduction In this assignment you will implement a simplified version of Turtle Graphics. More information about Turtle Graphics can be found here: https://en.wikipedia.org/wiki/Turtle_graphics A turtle has three basic attributes: • a location • an orientation • a pen, which is either up or down In our implementation we will generate Scalable Vector Graphics (SVG) as output. SVG files can be viewed with many image programs and most web browsers.
Quick Start:
1. Read this entire document 2. Download all the provided files into a new directory 3. Read turtle.h carefully 4. Compile and run the test program part1_tester.cpp 5. If no errors reported by test program move on to Part 2 6. Implement one of the functions in turtle.cpp 7. goto 4

Multi-file Programs Most non-trivial programs contain more than one source code file. By convention, .h files contain function prototypes and type definitions1 and the implementation of the functions is contained in a .cpp file of the same name. While there are more complicated tools for dealing with building multi-file programs (like Make, scons, Eclipse projects etc), the simplest way to build a multi-file program is to specify all the .cpp files on the command line to the compiler. For example: % g++ ­Wall part1_tester.cpp turtle.cpp svg_file.cpp ­o part1 Will compile all the files used for Part 1 and create an executable called part1_test (part1_test.exe on Windows), which can be run to see if your implementation passes the test cases. Run the resulting program by typing: % part1 The output you should see is: Testing turtle_init:  Test 0 failed at line: 42 in file: part1_tester.cpp 
0 tests passed.  Because you haven't implemented anything yet, none of the test cases will pass.
1 C++ puts no restriction on what goes in .h files.

Part 1 In Part 1, you are implementing a set of functions that implement turtle graphics. The only code you have to write for Part 1 is in the file turtle.cpp. The specifications for what you are to write in Part 1 are fully contained in the file turtle.h. Be sure to read this specification carefully. You've been supplied with a test program that will give you feedback on your progress on Part 1. When you've finished Part 1, the output of the test program will be: Testing turtle_init:  Test 0 passed.  Test 1 passed. 
Testing turtle_pen_up and turtle_pen_down:  Test 2 passed.  Test 3 passed. 
Testing turtle_rotate_left and turtle_rotate_right:  Test 4 passed.  Test 5 passed.  Test 6 passed.  Test 7 passed. 
Testing turtle_move_forward and rounding:  Test 8 passed. 
Testing svg output.  You need to validate this test by hand.  View the file part1.svg.  It should contain a star. 
9 tests passed. 
In the directory you ran Part 1, you should find a file named “part1.svg”. If you open this file in a web browser, you should see the following image:

Compiling and running Part 1: To compile Part 1, type: % g++ ­Wall part1_tester.cpp svg_file.cpp turtle.cpp ­o part1 To run Part 1 type: % part1

Part 2 In Part 2, you will use what you completed in Part 1 to write a program that reads a text file and that text file will describe actions the turtle will take. This will allow us to draw interesting images without having to recompile. Most real programs use files as input in this way. See the section below on “Turtle Input Files” for details on the content of the input files. Note that in Part 2, you do not have to implement the repeat command.
When you've finished Part 2, and you run it like this: % part2 ex1.txt Your program will create a file named ex1.txt.svg which contains the following image:
To compile Part 2, type: % g++ ­Wall part2.cpp svg_file.cpp turtle.cpp ­o part2

Part 3 When you have finished Part 2, copy your part2.cpp file to a new file named part3.cpp. In Part 3, you will implement the repeat command. Again see the section on “Turtle Input Files” below for details on the repeat command. In Part 3, repeat commands cannot be nested. That is, you can't have a repeat command inside a repeat command. For Part 3, you need to create your own input file that draws a unique image. You should create this in the file creation.txt. You need to submit your creation and the resulting .svg file produced by your Part 3. When you've finished Part 3, and you run it like this: % part3 ex2.txt Your program will create a file named ex2.txt.svg which contains the following image:
To compile Part 3, type: % g++ ­Wall part3.cpp svg_file.cpp turtle.cpp ­o part3

Bonus Copy your part3.cpp file to bonus.cpp. For the bonus, you should change your code so that it handles nested loops. To keep it simple, you may assume that loops will be nested no more than 100 deep. When you've finished your bonus and you run it like: % bonus bonus.txt Your program will create a file named bonus.txt.svg which contains the following image:
To compile the bonus, type: % g++ ­Wall bonus.cpp svg_file.cpp turtle.cpp ­o bonus

Turtle Input files Part 2 and Part 3 of the assignment take text files as input to control the turtle. You may assume that any text files used for testing follow these specifications exactly. Your program is not responsible for detecting errors in the input files. The result of providing an invalid input file to your program is undefined. You are not responsible for handling the case where the input file causes the turtle to move outside the boundaries of the canvas. The properties of the text file is as follows: • Each line of the input file contains exactly one command • There are no blank lines in the input file • Where a command contains more than one item on the line, the items are separated by exactly one space The possible commands that may be included are: Command Parameters Desciption Example pen up or down Set the pen to be either up or down pen up right an integer between 0 and 360 Rotate the turtle to the right right 180 left an integer between 0 and 360 Rotate the turtle to the left left 90 forward a positive integer Move the turtle forward forward 100 repeat a positive integer Repeat a set of commands See below
An example input file and the output it produces: pen down  forward 100  right 144  forward 100  left 90  forward 100  left 90 forward 100 

Loops Loops provide the ability for commands to be repeated, which allows for more complex pictures to be generated. The loop command itself takes up three lines, and has the following format: repeat 4 { } This loop will repeat the commands four (4) times. The commands to be repeated are placed on new lines between the { and the }. A reminder that each command must be on its own line and that commands inside the loop cannot be indented. Loops are only implemented in Part 3 and the Bonus parts of the assignment. For Part 3, loops cannot be nested. For bonus marks, loops can be nested.
Submission Submit your turtle.cpp, part2.cpp, part3.cpp, creation.txt and  creation.svg files using Connex. If you completed the bonus, submit your bonus.cpp file.