Infor Tech 10/11/12 March 12, 2018 FROGGER

LET'S MAKE A VIDEO GAME



In this unit, we'll cover:
We'll be building our own Frogger-style video game.

• positive & negative numbers
• X and Y coordinates
• loops and conditions
• variables and "broadcasts"
• object-oriented programming
• input devices (e.g. keyboard)
• event sequences
• ... and more

 _________________________________________________________________________________

Getting the Frog Moving We are going to build our Frogger video game will only accept input from the arrow keys on the keyboard. So, go ahead and change that cat into a frog. But then what? We need to build a block that:     if           a key is pressed     then            change the frog's location And so, that's exactly what we build. Make it look like this.

Now, you have the building blocks, so change the settings that:     if           the right arrow key is pressed     then            move the frog 3 steps to the right The answer to step one: Common Problem "I clicked the green flag and nothing happened!" Answer:  Did you press the arrow key on your keyboard? Your script is waiting for you to press the arrow key!  ___________________________________________________________________________________ Making all 4 arrow keys work correctly Can you figure out the other 3 arrows? If "move 3 spaces" moves right 3 spaces, then  how can you use a similar block to move left 3 spaces? Answer: Now, can you put it all together, so your script can sense and react to all 4 arrow keys:    up,   down,   left,   and   right. Answer: Test this out!     Does it work?  ___________________________________________________________________________________ Edit the Stage Background                       Next up, making a background!                   Select the Stage object.                 Select the Backgrounds tab.                Click the Edit button to modify the costume.       Next up, making a background!                   Select the Stage object.       Select the Backgrounds tab.                Click the Edit button to modify the costume. __________________________________________________________________________________ Create the Highway There are two choices below.They both show how to construct the highway image for the stage (background).What to do -- click image/link for animated GIF  -->  . Click this image for the full animation Instructions to make this highway are below in the YouTube video. __________________________________________________________________________________ Creating a moving car To make a car move, we use the same basic structure as when we wanted the cat to bounce around inside the fence. However, in this case, we have highway lanes that are perfectly horizontal.  So, to make sure that the cars stay in their lanes, instead of  "moving 10 steps", we're going to just "change x by 10". Trust me, this will keep everything nice and orderly! NEAT TRICK: Rather than making hundreds of cars, we're going to re-use our car so that (for now) only one car travels in each lane. To do this, we're going to make our car drive across the video game screen, and then "teleport" back to the beginning of the lane. Watch the above  video to get the idea. Common Problem The second car takes some thinking. Check out the video below. Duplicate the Second Car Object-oriented programming is great because everything is an object.  If you want another, just "duplicate" it. What did you say? You tried it, but it's all messed up? Ah ha!  The dreaded copy-and-paste error rears its ugly head! Watch this video to see where to make changes Duplicate the Third Car Yes, you're completely right.  After showing us how to do the second car, there is absolutely no need to make a video showing how to create a third car. So go ahead.  It'll be easy....     ...right? Ummmm.  Teacher!  Why is my car smashing into the wall? ... over and over and over again? Well, that's not really "bashing".  No, it's more like a "jiggly dance," and the car is doing exactly what you've programmed it to do. Maybe you should watch this video to discover the simple solutions to fix your problem. __________________________________________________________________________________ Killing the Frog Sadly, in a video game called "Frogger", the whole point is to see how long the frog lasts before it dies. Thankfully, no actual real live frogs were harmed in the making of this game. But today, you get to learn how to kill those pesky virtual frogs.  You need to start by thinking like the blue car.   Once you can get into the mind of the blue car, everything else is easy.      ________________________________________________________________________________ Frogger Lives Again! Now that you've killed the frog, it's time to bring the poor guy (or girl) back to life!So, here's a list of all the things that need to happen between the death and re-life of the frog. In ALL cars: Dead frog message sent (variable) In the frogger: Dead frog message received (variable) Frog stops moving Frog displays a message (looks = words) Frog makes dying sound Frog goes back to start (try glide!) Frog comes back to life (variable)