UMBC CMSC201, Computer Science I, Spring '97

Project 5: Oil Spill Simulation

Due: Monday, May 12, 1997

Your assignment is to write a program that simulates an oil spill and the movement of the oil over time under certain conditions. This project will give you practice using two-dimensional arrays, passing an array to a function, pointers, getting input from the user using scanf, and reading from a file using ansi C functions, rather than unix redirection.

You are not allowed to use any of the Roberts' libraries for this project

Description of the Oil Spill and Simulation

You must keep track of the number of gallons of oil that are present on the surface of each square mile. The number of gallons in a particular square-mile location will vary over time due to environmental factors, i.e. the tides, wind, etc. For this simulation we will be concerned only with the effects of the wind on the oil spill.

If the wind is from the west, then the oil in a particular location will be pushed primarily to the east, affecting the neighboring areas to the north, north-east, east, south-east and south. Some portion of the oil will stay within the original square-mile area. Obviously the area to the east will get the largest influx of oil. Over time, the spill will shift significantly to the east.

The initial number of gallons of oil per square-mile location are found in the file "oilspill.dat". Basically, the file contains 225 integer values separated by whitespace. This is the contents of the file. You may assume that none of the integers found in the file will be larger than 3 digits. I guarantee that there are 225 integers in the file, so checking for EOF is not necessary.

You will be reading the values found in the file into a two dimensional array. This array will then hold the original number of gallons found in each square- mile area at the time of the spill.

You will also be asking the user to say how many time intervals should pass between displaying the values for each square-mile area, and the total amount of time for the entire simulation, as well as the wind direction. We will assume a constant wind velocity so that you do not need to consider it in your calculations.

A Sample Run

More details

• To begin, you will need to read in the data from the data file, oilspill.dat You will NOT be able to use unix redirection for this program, since you will also need to ask the user to input information. You will need to open the file for reading using fopen, read the integers in the file using fscanf, placing them into a two-dimensional array of integers as you go, and then close the file.
• For each unit of time, the amount of oil in each square-mile area must be recalculated. I will chose the wind direction W for the explanation of the calculations. The original amount of oil in the square will be reduced by 50%, because that much will be pushed by the wind into some of it's neighboring easterly squares. At the same time, however, more oil will be pushed into the area from some of its more westerly neighbors.

  For a west wind, the square and its surrounding squares will be affected as follows:

  Percentage of original Example using # of gallons Time 0: Time 1: Time 0: Time 1: | | | 5% | 10% 0| 0| 0 0| 10| 20 ----+----+---- ----+----+---- ----+----+---- ----+----+---- |100%| | 50%| 20% 0| 200| 0 0| 100| 40 ----+----+---- ----+----+---- ----+----+---- ----+----+---- | | | 5% | 10% 0| 0| 0 0| 10| 20 Winds from other directions will cause similar effects on their neighboring squares using the same percentages.
• If you view the results of the simulation after each unit of time, the movement of the oil is less noticeable than if you wait for several time units before viewing. Since the user needs to see and interpret the results of the simulation, the user needs to have control over how often he views the results and over how long a period of time to run the simulation. The period of time between the printing of charts I will refer to as the time interval. The period of time for the entire simulation I will refer to as total time. You must ask the user to input both the time interval and the total time, as well as the wind direction.

  You are REQUIRED to have a function called GetInput which gets all three of these items from the user. Since this function has to "return" three pieces of data, the function must have pointers as arguments. Here is the function prototype you are to use for this function :

  void GetInput (int *intervalPtr, int *timePtr, char *dirPtr);

  Although no error checking is necessary for the data coming in from the file, error checking of the user input is required.

• Hints
  • Be aware that the diagrams of oil movement shown above are the simplest case, where there was no oil originally in any of the neighboring squares. Each square mile will lose oil in the fashion indicated, but each square mile will also have an influx of oil from its neighboring squares.
  • Since every square will be altered by its neighbors, and you must use the original values of each square for the calculations, you cannot just move through the array making changes as you go. This would give erroneous results. A second two-dimensional array needs to be made that will hold the new amounts of oil that are being calculated for each square, while the original array is still intact to provide the values needed for the calculations.

The data file

What to Turn In