In this exercise you will develop a small 'Pop Game' in which the user will "pop" shapes that are drawn on the screen. The game will be time based, showing a shot clock at the top left of the screen. Figure 1 shows the final version of the program executing.
The screen shows four main elements:
1. Shapes that need to be "popped" (clicked) in the main area.
¦ Shapes randomly appear, with a random size, position, and color
¦ The shapes are either Circles, Rectangles, or Triangles
2. A shot clock showing the time (milliseconds) since the last shape was popped - top left
3. The score that shows the number of shapes popped so far - top right
This program will be implemented over a number of iterations. At the end of each iteration you should have a working program.
Iteration 1: Creating a shape
Perform the following steps to build the artefacts needed to be able to create and draw a single shape.
1. Create a new SwinGame project called PopGame in your Documents/Code/Lab6 directory.
2. Create a PopGame.pas in the src directory, code a basic program in this with an empty Main and uses of SwinGame and sgTypes. The program will include the following elements when this iteration is complete.
Program: Pop Game
uses: SwinGame, sgTypes
declare constant MIN_CIRCLE_WIDTH = 50
declare constant MAX_CIRCLE_WIDTH = 100
declare Shape record type
declare Place Shape procedure
declare Create Shape At function
declare Draw Shape procedure
declare Main procedure
Steps:
1: Call Main ( )
Listing 2: Structure of Pop Game in Iteration 1
3. Add the code to declare the two constants.
4. Implement the Shape record. Listing 3 contains a data dictionary that describes the fields of the Shape record/structure. Use the text to determine how these can be written, see the section titled "Pascal Record/Structure Declaration".
Record: Shape
Fields:
- clr (a Color) the color of the shape
- circleShape (a Circle) shape data (x, y, radius)
- visible (a Boolean) is the shape drawn?
Listing 3: The structure of the Shape record
5. Create functions and procedures for place shape, create shape at, and draw shape. See Figure 2 for the structure chart showing these functions and procedures.
6. Place Shape will set a Shape to a random size and place it on the screen at the indicated center point. The pseudocode follows in Listing 4.
1 To generate a random number between two value you can use MIN + (MAX - MIN) * Rnd(). The Rnd() function returns a random number between 0 and 1.
2 The CircleAt() function populates a Circle record, and returns the value.
7. Create Shape At create a new shape with a given color, and then place it at a point on the screen. The pseudocode for this is as follows:
8. Draw Shape draws a Shape to the screen. The shape is only drawn if its visible field is set to True. The pseudocode for this is as follows:
9. The last step for this iteration will be to create and draw one Shape in Main.
10. Compile the program, and correct any syntax errors.
11. Run the program and you should see something like: