GSP 125 GSP/125 GSP 125 Week 5 iLab // INSTRUCTIONS // ———— // Compile this code. After pressing any key to clear the instructions, You // should see three rectangles labeled ‘#’, ‘b’, and ‘c’. You should also see // two triangles, labeled ‘d’ and ‘e’. Pressing ‘>’ and ‘<' will change which // shape is labeled '#'. Pressing 'w', 'a', 's', and 'd' will move the shape // labeled '#'. Pressing 'space' will randomize the selected shape. // // Read through this code! Try to understand it before starting the assignment. // Comment confusing lines with what you think code is doing, and experiment // with existing code to test your understanding. // Once you feel comfortable with this code, accomplish each of the following, // and make sure your code compiles and runs after each step is completed. // // 1. Getting comfortable with the code // a) Create a "makeRandom" method in both the Rect and Tri classes, based // on the "makeRandomRect" and "makeRandomTri" functions in // "application.cpp". The makeRandom function should take no parameters, // and instead make itself random. Removing the old "makeRandomRect" // and "makeRandomTri" functions as well. Be sure to consider what to do // about "screenMin" and "screenMax". // b) Create a print method for the Tri class, similar to the print method // for the Rect class. This method may come in very handy when debugging. // 2. Create Shape base class // a) Create a header file (without a .cpp file) for a Shape class. // b) Create the Shape class, which should have no member variables. // c) Make the Shape class an interface for the Rect and Tri classes. Shape // should have pure-virtual methods for each method that Rect and Tri have // in common. // d) Make sure Shape has a virtual destructor with an empty body. // 3. Make Rect and Triangle extend Shape // 4. Change selected // a) Change the type of "Application::selected" from "void *" to "Shape *". // b) Every piece of code that typecasts "selected" (and the logic around it) // can be removed now. Simply call functions using the "Shape" interface. // c) Remove the "selectedType" variable from Application. Logic that needs // some form of RunTime Type Information should use dynamic_cast instead. // 5. Merge all Shape objects into a single array // a) Create an array of Shape pointers in the Application called "shapes". // b) Making a complementary NUM_SHAPES variable would make sense. // b) Remove "rectangles" and "triangles" arrays. // c) Put each Tri and Rect object managed by the Application class into // the "shapes" array. This will require re-factoring in multiple files. // While removing references to "rectangles" and "triangles" arrays, it // may make sense to replace pairs of for-loops using each of the old // arrays with a single for-loop using just "shapes". // 6. Make "shapes" dynamic // a) Give Application::init() 2 parameters: int numRect, int numTri // b) Make "shapes" a pointer of type "Shape **", and allocate it to be // "numShapes" big, where "numShapes" is an int member of Application // equal to (numRect + numTri), defined in Application::init(). // c) When calling "app.init()" in main, pass valid arguments for numRect // and numTri. // d) De-allocate the "shapes" array in Application::Release(). // 7. Clean up old variables // a) Remove the TYPE_RECT and TYPE_TRI variables from Application. // b) Remove NUM_TRI and NUM_RECT, and any NUM_SHAPES variable as well. Use // numShapes where needed. // 8. Add Circle class // a) Create a header file AND a source file for a Circle class. // b) Use Rect and Tri as examples to create the Circle class with. // c) A Circle class should have at least a 2 dimensional position, and a // radius. // d) A simple algorithm for drawing a Circle will be similar to drawing a // Rect or Tri, thought it might include the following code: // float dx = center.x - col, dy = center.y - row; // if( dx*dx + dy*dy <= radius * radius ) { // moveCursor(col, row); // putchar(letter); // } // e) Add an additional parameter to Application::init(), "int numCircles". // Implement init to generate Circle objects along with Rect and Tri // objects. // 9. Implement add/remove for the shapes array // a) Add code that increases the size of the shapes array, adding a random // shape, whenever the '=' or '+' key is pressed. Take a look at the week // 5 lecture showing explicit constructors for help with this algorithm. // a) Add code that decreases the size of the shapes array, removing the last // shape, whenever the '-' or '_' key is pressed. End the program when the // last shape is removed. Removing a shape, like adding a shape, can be // done by allocating an array of a different size (smaller this time).
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