This lesson adds a new feature to the game. You'll see the benefits of the millis() timer approach when you see how quickly your JumpMan reacts to a collision. All of the hard work in setting up the code structure in lessons 12 and 13 will pay off here.  You'll see a function: a coding fundamental that has a big impact on how code is written in almost all languages.

/* * This lesson is about adding in a new feature to the game- an obstacle * for JumpMan to jump over. This wall will become the basis for levels, * points, lives, and the rest of the game. * */ #include "MakerScreenXVI.h" MakerScreenXVI lcd; byte run0[8] = { //legs in partial stride 0b00000, 0b01100, 0b01100, 0b01100, 0b01110, 0b01100, 0b01010, 0b01010 }; byte run1[8] = { //legs in full stride 0b00000, 0b01100, 0b01100, 0b01111, 0b01100, 0b01100, 0b01010, 0b10001 }; //A new graphic for the wall element using createChar byte wall[8] = { //wall obstacle 0b11111, 0b10101, 0b11111, 0b10001, 0b11111, 0b10101, 0b11111, 0b10001 }; //A graphic for JumpMan when he runs into the wall-a splatted character byte crash[8] = { //crashed JumpMan 0b00000, 0b00011, 0b01011, 0b00111, 0b00011, 0b00011, 0b00001, 0b00001 }; int position = 0; //holds the changing position of the cursor bool runState = 0; //which running animation to draw (0 or 1). int jumpState = 0; //0 ='pre-jump', 1 ='mid jump', 2='post jump' bool buttonState = 0; //will equal 1 after press, 0 after jump completed long animationTimer; //tracks animation (custom character) updates long runTimer; //tracks position updates void setup() { lcd.begin(); lcd.backlightOn(); lcd.createChar(0, run0); //partial stride character lcd.createChar(1, run1); //full stride character lcd.createChar(2, wall); //wall character in 'slot' 2 of custom characters lcd.createChar(3, crash); //splatted character against the wall pinMode(6,INPUT_PULLUP); //button to trigger jump //Start both timers equal to millis() so that the difference between //millis and the variables is 0. animationTimer = millis(); runTimer = millis(); } void loop() { //Set the cursor depending on the state of the character if (jumpState == 0){ lcd.setCursor(position,1); } else if (jumpState == 1){ lcd.setCursor(position,0); } else if (jumpState == 2){ lcd.setCursor(position,1); } lcd.write(runState);//draw the run0 or run1 animation /* * After you've set the position for JumpMan and drawn * him, set the cursor to the bottom right of the screen and * draw the wall. Because of where it is positioned, you'll draw the * wall thousands of times a second- as fast as Maker Board can. */ lcd.setCursor(14,1); //cursor near right side, second row lcd.write(2);//char in slot 2 is the wall if ((digitalRead(6) == LOW)&&(jumpState == 0)){ buttonState = 1; //1 means a press is recorded } //Button is unpressed and a jump has been completed if ((digitalRead(6) == HIGH)&&(jumpState == 2)){ jumpState = 0; } if (millis() - animationTimer > 300){//Update animation every 300 ms runState = 1 - runState; //draw the next JumpMan animation animationTimer = millis(); lcd.clear(); //clear the LCD to draw a new character } if (millis() - runTimer > 600){ //Every 600 milliseconds, run this... position = position + 1; //move character one space to the right if (position == 16){//reset position to 0 when you reach the screen's edge position = 0; } //if button has been pressed and a jump hasn't been initiated... if ((buttonState == 1)&&(jumpState == 0)){ jumpState = 1; buttonState = 0; //reset button to 'unpressed' in the code } else if (jumpState == 1){//true if jumpState set to one in the last loop jumpState = 2; //jump is marked as complete } /* * Create a check to see if JumpMan cleared the wall. * If the 'position' = 14 (the location of the wall) and the * jumpState is NOT 1 (mid-jump) then JumpMan has hit the wall. */ /* * This 'if' statement introduces a new type of boolean operator: * the 'not' operator. You use this operator as an exclamation in * front of the equals sign when you want to test 'not equal to'. * * The logic feels reversed, but the 'if' statement is asking "is it * true that jumpState is NOT equal to one?". If that is true AND the * position variable equals 14, the 'if' statement executes. */ if ((position == 14)&&(jumpState != 1)){ drawCrash(); //function for drawing a crash } /* * drawCrash() is a function- a block of code that always executes * together. This function has one purpose: draw the crash event. * Rather than writing every line of code here that makes that happen, * you can create a function in your code and name it. Whenever you * 'call the function', that group of code all executes together. * * Functions exist outside of void setup and void loop, but when you * call them, the code still runs in the place where you called the * function. When it's complete, the code loop continues from just * below the function call. See this function around line 188. */ lcd.clear(); runTimer = millis(); } } /* * When you make a function, you name it. This function is named drawCrash. * Void is the type- it means the function does not produce any data, it * just runs its code. You can also send information to the function with\ * arguments, like you do with methods. drawCrash doesn't need any * arguments, it just needs to be told 'run'. * * Everything between the { and } of drawCrash is the function. */ void drawCrash(){ //draw JumpMan crashed into a wall lcd.clear(); //clear all the characters on the screen lcd.setCursor(13,1);//set cursor next to the wall lcd.write(3); //draw the 'crashed' icon from custom character slot 3 //Move the cursor to the location of the wall and draw it again. lcd.setCursor(14,1); //wall location lcd.write(2); //draw the wall delay(1000); //show the crash for one second // Reset the variables to put the JumpMan back at the starting point position = 0; buttonState = 0; jumpState = 0; } /* * This lesson showed how to use a function to insert a block of code * somewhere. Functions are useful when your code performs the same * set of actions over and over in the program. Rather than write the same * series of steps over and over, put all of the steps into a function * and call the function when you need those steps to run. * * Functions are also useful for inserting complete blocks of code * into pre-existing programs, as you did here. Adding in new blocks * can be difficult when you have many of code lines to work * through, and functions make it convenient to simplify your code. * * Try typing drawCrash(); just below the line position = position + 1. * The game won't be very fun, but you'll see how you can activate a * whole series of events with the function. * * This is starting to look like a real game- the character is moving * around and can jump and there is an obstacle to avoid. Now that you * have the basic machanics down, you can start adding in features like * points and difficulty or improve the look of the game. */ // (c) 2017 Let's Start Coding. License:

Now that you have a function in your program, you're seeing major concepts in code organization as well as function.  As your code grows, so does the importance of having good structure. Imagine organizing a small book shelf for yourself: not very difficult. Now imagine organizing a huge library used by thousands of people: you need to pay closer attention to the organization as well as the items.