Computer Science I Looking at code: "Where did Prof. - PowerPoint Presentation

Computer Science I Looking at code: "Where did Prof. Shablinsky go?” Reprise on Add to 15 implementation Classwork/homework: Catch up: classy project. Propose midterm project.

Feedback on error messages While programming in Processing Some you can ignore because you haven’t gotten to code something yet. BUT look at them because maybe the message indicates a mistake. For example, methods (aka functions) are defined to take specific arguments. void calculate(float v, float w) {…} is not the same as void calculate( int v) { }

Feedback You need to zip the FOLDER, containing the . pde file and, possibly, a data file, and, possibly, other things… USE THE NAMING CONVENTION: jMeyerBouncingThingsWClasses You may have problems in re-using names. Download may produce jMeyerBouncingThings (1).zip which could produce folder NOT matching . pde file name. Solution: erase old stuff or change name.

Why classes Like functions and variables, classes are a way to extend the language to [better] suit your application. Bouncing things used classes so The same code used when possible Different code used when necessary. The different code was defined in a structured way. Classes are not especially abstract. Think about what are the entities (things) in your application? Look at the Slingshot sketch later in the class.

Class A class definition is the template for any number of distinct objects. An object is set up using the new operator and invoking the constructor. So if Thingee is the name of a class Thingee myThingee = new Thingee ( ); Builds of object of datatype Thingee , setting values. The methods of the class can be invoked for each object using dot notation. The variables can be set or accessed using dot notation.

Arrays and Classes You can use one or both for your particular project. Except sometimes I required one or the other for an assignment! The Add to 15 has a more or less intricate use of arrays Values in certain arrays are indices into other arrays.

Feedback Consider use of array in place of Box1, Box2, … Then you can use loops for ( int i <0;i< boxes.length;i ++) { … } Do use distinct names for things that have specific roles Thing badguy = new Thing(…); Thing goodguy = new Thing(...); Things[] stuffToDisplay = { badguy,goodguy ,…}

Idea for game Display world map Player attempts to guess where Prof. Shablinsky went during a summer a couple of years ago? Answers are: Iceland St. Petersberg While player is thinking, a shrinking image travels towards mouse position. Elapsed time shown. If player clicks the screen, flyer appears where the mouse was clicked. Two possibilities for message: Positive message Distance in pixels from closest of two answers If alloted time runs out, Time ran out

Processing features The background function can take an image as an argument. This is how I make the map be the background: background( bg ); The nf function formats floats. So if secs has the value 5.100101, then nf (secs,1,2); will produce the string "5.10"

Planning Manage two phases: inmotion Boolean variable (aka flag) Define setup Draw If inmotion : move flyer image towards mouse Else: give response mouseClicked checkanswer giveresponse

Planning, cont. Move (animate) the flyer (the Irina image) towards the mouse position. Animation stops at the end of a fixed time duration set to 5 seconds OR if player clicks on the map. If player clicks on the map, a computation is done using the dist function to see if the player's location is near enough to one of the answer. Appropriate response given. If time runs out, a response is given.

Examine program Notice comments, including commented out code: used for debugging. The world map displayed using Pimage bg ; In setup: bg = loadImage ( filename ); In draw: background( bg ); The distance in pixels is calculated by builtin function dist . A for-loop calculates what of the two places is closer and then compares that number to 10, the tolerance allowed. This may be too strict. The function nf is used to format the elapsed time to display 2 decimal places. The flyer image dimensions are continuously changed, but kept in proportion using wdel , fw , and fh variables. fw -= wdel ; fh = fw *( origh / origw );

PImage bg ; PImage flyer; boolean inmotion = true; boolean clicked = false; float duration = 5; // 5 seconds float framer = 50; float interval = 1/framer; //frame interval in time float x,y,fw,fh, wdel ; float origw,origh,smallw ; PFont font; String question = "Where did Professor Shablinsky travel this summer?"; int [][] answers = {{452,90},{367,77}}; String[] answertexts = {"St. Petersberg , Russia", "Iceland"}; String responsetext ;

Functions setup draw mouseClicked checkAnswer (float cx , float cy) giveresponse

Reprise on Add to 15 Rules of the game Implementation Prepare data ahead of time No addition to 15 Example of use of arrays Arrays with pointers (indices) into other arrays

Starting position

After first moves

Finish of a game

Similar to … tic tac toe In fact, equivalent What does that mean? Examine game

Characteristics 9 moves What are winning combinations? 9 5 1 ?

Number of combinations 8 Same as number of rows + columns + diagonals!!! Suggestion for the proof Assign the numbers to the 9 locations on the tic tac toe grid to make valid combination in each row, column and diagonal Try to do it

Here is a way For each number, count up presence in winning combinations. 5 is present in 4, so….it goes in the middle. There are 4 numbers that are present in 3, so they go in the corners, First placement is arbitrary….keep going.

My approach to smartmove Check for immediate win Check for immediate need to block Check for group with 1 computer move and no player move Take the 5, if available Take a corner, if available Late addition. May not be needed Make random move

Implementation HTML, CSS, JavaScript Processing Continually re-drawing window AND checking for mouse clicks Both implementations use arrays to hold the information on winning combinations No adding up values Some use of place holder for first slot

[Some] variables int [] player = {}; int [] computer = {}; int [] board = {1,2,3,4,5,6,7,8,9};

String[] groups = { " ", //place holder, not used "3 4 8", "1 5 9", "2 6 7", "1 6 8", "3 5 7", "2 4 9", "2 5 8", "4 5 6" }; int [][] occupied = { //indexed subtracting 1 {2, 4}, {3, 6, 7}, {1, 5}, {1, 6, 8}, {2, 5, 7, 8}, {3, 4, 8}, {3, 5}, {1, 4, 7}, {2, 6} }; int [] pgroupcount = {0,0,0,0,0,0,0,0,0}; //unused first slot int [] cgroupcount = {0,0,0,0,0,0,0,0,0}; //unused first slot

Tracking progress The pgroupcount array indicates what the player has with respect to each of the 8 possible winning combinations. So given winning combinations String[] groups = { " ", //place holder, not used "3 4 8", "1 5 9", "2 6 7", "1 6 8", "3 5 7", "2 4 9", "2 5 8", "4 5 6" }; If computer is {1,2,5} then c groupcount will be {0, 0, 2, 1, 1, 1, 1, 2, 1} Computer wins if the 9 or the 8 is available to be taken, that is, still on the board.

int smartChoice () { //first check for immediate win int boardl = board.length ; for ( int i =0;i< boardl;i ++) { int possible = board[ i ]; for ( int j=0;j<occupied[possible-1]. length;j ++) { if ( cgroupcount [occupied[possible-1][j]]==2) { return ( i ); } } } ….

General comments Repeat: My code never adds up numbers. Sometimes, let your program do the work, and sometimes … no. O nly 8 valid combinations. Keeping track of progress towards satisfying each combination works. The human, even expert, approach may not be the best approach for a program. Reference: chess programs.

Challenges Play game and design and implement a perfect strategy for "the computer" Always wins or, at worse case, ties Make it possible for computer to start. Make computer skill adjustable (levels) Perhaps random, takes any win, my strategy, yours? Improve "look and feel" of game. Adding pause before computer move Add feature to keep record of moves. Add keeping score feature. ?

Classwork / Homework Catch up on classy project. Propose midterm project Wait for my approval and/or feedback. Study for midterm Check out midterm guide Prepare questions for second half of class