Snake Updates

The Snake project has changed a little bit from Saturday. I had to add another Sprite to get the “touching colour” code to work. So now there are 3 Sprites that move around.

1. The one that you move around with the Arrow keys.
2. One that follows 0.2 seconds behind, this one now draws the tail and is not touching the first one.
3. This one follows 2 seconds behind and erases the tail.

I also changed the first Sprite to Move “2” steps not one, this speeds it up a little. I have uploaded the completed project to the AthenryAdvancers account on http://www.scratch.mit.edu so you can take a look and have a go.

My challenge to you is to beat my high score of 1200

Magnify Updates

I have uploaded a Gravity project with one single Sprite to the AthenryAdvancers account on http://www.scratch.mit.edu.

You can use this Template project to create your own Magnify project, think of an idea and draw out the Sprites you will need on a bit of paper, give the Sprites Names on this bit of paper, it doesn’t have to be a masterpiece, any rough old picture will do.

Then you need to get one Image for each of your Sprites, save them all to the same Folder on your Computer.

Once you have your diagram and all your images you can download a copy of the Magnify Project and save it to the same folder as all the images.

The steps (process) to follow to use this Project are:

1. Rename the StartSprite to the Level 1 Sprite in your diagram
2. Update the Variables, for this one you only need to update the MyName variable
3. Change the Costume by uploading your image for this Sprite, delete the original costume

And then to add More Levels and Sprites use these steps:

1. Copy the Level 1 Sprite
2. Update the new Sprites name
3. Update the new Sprites variables, the MyParent needs to match the MyName of the Sprite from the level above
4. Update the MyX and MyY variables to where you want this Sprite to appear on the screen, you may have to test a few different places to get it right
5. Change the Costume by uploading your image for this Sprite, delete the original costume

Don’t forget to Save and Test often.

http://www.scratch.mit.edu

To access the Scratch website use the following details:

Username : athenryadvancers
Password : Advancers

This will be an interactive Christmas Card.

1. A nice background with Snow, Christmas Trees, a house.
   1. We might use different Sprites for the Trees.
2. Flashing lights on the House and the Tree.
3. Falling snow.
4. Snow building up on the ground.
5. An animated Snowman.

Snowflakes

To make it even more interesting, we are going to make the snowflakes different sizes and fall at different rates depending on how big they are.

We will use the clone functionality to make the snowflakes.

Each clone will pick a random size and will glide to the bottom of the screen, how fast if glides will be related to how big or small it is.

The snowflake is going to be quite hard to draw as it will be a small white dot on a white background, so we will be careful.

The building up on the ground part, is quite easy, we just pick a random Y value to stop at, as long as it is close to the bottom of the screen we should be ok.

Flashing Lights or Tree Sprites

Again, these might be quite difficult to draw as we have to draw them over the background and get them to be over the Trees?

If we draw the complete Tree in the Sprite I think it is going to be a lot easier.

Snowflake code

Flashing light code

I know Windows has a Calculator, but we are going to build our own. This will give you an idea of how real Calculators actually work.

The Calculator should be able to:

1. Add, Subtract, Multiply and Divide 2 numbers.

2. Be able to work with decimal points (2.5 for example).

3. Display the sum and the result on the screen.

4. Have a “clear” button to reset everything ready for the next calculation.

Let’s look at the steps that you need for a calculation

1. Clear the variables.

2. Click on the numbers for the first number.

3. Click on the operator you want to use.

4. Click on the numbers for the second number.

5. Click on the equals button.

6. Display the result.

Hint: When you click on the Operator, this indicates we have got the first number and need to start storing the second number. See variable 6.

It sounds like there is a lot to do, but if we are smart with the way we work, there is a lot of code that is very similar and we can copy and paste it and then modify it slightly.

You will need 6 variables (for all Sprites) to share:

1. The first number in the calculation (NumberOne), not visible.

2. The second number in the calcualtion (NumberTwo), not visible.

3. The complete sum (Question), visible.

4. The operator (+,-,x,/) for the calculation (Operator), not visible.

5. The result of the calculation (Result), visible.

6. A variable to indicate what number we are working with (SecondNumber). not visible.

Hint: When you press clear, all the variables should be set to blank, except the SecondNumber which should be 0

You will need 17 Sprites, don’t panic! Remember copy and paste is your friend:

11 Number Sprites 0,1,2,3,4,5,6,7,8,9 and the decimal point.

4 Operator Sprite +,-,x and /.

1 Equals (=) Sprite.

1 Clear Sprite.

Scratch code blocks that will be used:

Operators, we will use the join operator a lot as well as the +,-,x and /.

If Else block with variable 6 to decide what number to update.

set variable blocks – lots of these!

Hint:

Start by creating the variables.

Start with just 4 Sprites, 1, +, clear and Equals

Once you can get 1 + 1 working, the rest is quite easy.

The answer is 2 (not 11) by the way, just in case.

Coding Tips:

Here is some of the code that we will be using:

This is the code when you click on a number Sprite, this example is for the number 1, can you see what needs to change if this was the number 2 sprite?

This is the code for the + Sprite

And this is the code in the = Sprite

And finally, the CLR sprite

This weeks challenge is to build a working clock.

This is not just an ordinary clock though, we are going to build a clock that works in the same way as the Railway clocks works in Switzerland.

These clocks work in the following way:

• The Clock waits for a signal from the master clock
• When it gets the signal, it moves the minute hand on by one minute (and the hour hand if necessary)
• then the second hand moves round once in about 58 seconds
• It then waits for the signal again from the master clock.

This means that all the clocks on all the Stations are synchronised exactly.

In Computer speak this is called Event Driven Programming, where the code simply waits for an Event before doing anything.

So what’s the plan?

We need 4 Sprites

1. For the Clock Face
2. For the Hour Hand
3. For the Minute Hand
4. For the Second Hand

You can create them however you want but this is what the Swiss railway clocks look like and I will try and create something similar.

Remember one thing, when creating the Sprites make sure they are centred correctly.

So, the clock face should be perfectly centred and then the hands should be centred near one end something like this, I have highlighted where the centre is, with the green circle.

The code

Remember this will be event driven, so we will be using Broadcasts a lot. We will also have to calculate how far to move each hand, this means we will be using the number 360 a lot as that is one complete circle.

So just to let you know how far each hand should move:

• The Second hand will move 360 degrees for each event.
• The Minute hand will move 6 degrees for each event (360/60 minutes)
• The Hour hand will move 0.5 degree for each event (360/60 minutes/ 12 hours)

The first event will be broadcast from the Stage:

The Minute hand will receive this broadcast and move 6 degrees it will then broadcast another 2 events, one to the Hour hand and one to the second hand so they can move.

This is the code for the Minute hand which should be enough to work out the rest of the code as well.

The extra code above is to make sure the Minute hand starts in the correct position.

And one final thing which might be a little tricky, but I’ll leave it as a challenge for you, the Second hand should only take 58 seconds to go all the way around.

Introduction

This week we built a Mad House with different rooms that you could go into and if you found the right place to click something would happen.

The coding for this project shows how you can re-use code, this has 2 benefits, it makes coding quicker and it also makes all the code consistent, so it all looks the same.

The Plan

As always, it’s best to have a little bit of a plan.

We decided on the following:

• 4 Rooms – each room would have 2 Sprites
• Clicking a room would make it large
• Clicking the Space key would make the room small again
• We would build one room first so we could copy the code.

The Code

The first room we created was the Kitchen, the plan was when you clicked on the saucepan, it would boil over.

The Sprites need to fill the whole screen and also need a coloured background to ensure that the Mouse Click is recognised by the code.

These are the 2 Sprites that I built:

 

 

 

 

It’s not easy to see, but the “On” Sprite has some flames coming out of the pot.

 

 

 

 

Because we are having 4 Sprites, when the program starts we need to make the Sprite a quarter of it’s full size and move it to one of the corners of the Screen. We also discovered that we would need a variable (a flag) to indicate if the room was Large (1) or Small (0). We did this in the GreenFlag code like this:

We moved to top left corner.
we set the size to 50% (this makes it fill a quarter of the screen
We set the variable to 0 (0 = small, 1 = large)
We set the start costume to the Off costume.

 

 

Next step was to write the code for when the Sprite was clicked, this would make the Sprite fill the screen, slowly! It would also set the flag to say that the Sprite was large.

The biggest piece of the code was making the Sprite grow slowly, we did it in 50 steps, changing the size was easy as it just changed by 1 each step, but the X and Y positions were a little trickier as we needed to make sure they were going in the right direction and also changing by the right amount to reach the full size in 50 steps.

Only run this code if we are small (0)
Make we can’t run again set the flag to 1.
Make sure we are in front of the other Sprites

X needed to go from -120 to 0, 2.4 each time
Y needed to go from 90 to 0, so -1.8 each time
Size was simple, 1 each time
And to make it nice and smooth, we wait for .1 of a second in each step.

 

We then moved on to the code that should run when the Space key is pressed, this would reverse what happened when the Sprite was clicked.

Again, we only run if we are large (1)

The X and Y changes are the reverse of the ones above.

And finally we set the size back to small again (0)

 

Now we can move on to the code that changes the costume if the user clicked on a certain spot on the screen.

We decided that the user should click on the pan for the costume to change, so first we needed to work out where the pan is on the screen (It’s X and Y positions). This is easy in Scratch 2, when you move the mouse across the Stage the X and Y position is shown at the bottom of the screen, so you just need to place the Mouse on the 4 sides of the Pan and make a note of the X and Y values. X values for the min and max left/right positions, Y values for the min and max up/down positions. Hopefully this picture will help:

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We needed to place the Mouse on each of the positions indicated, which then gave use the correct values to place in the code.

The code then looked like this:

 

We loop forever
Only check X and Y if we are large (1) and the Mouse is clicked. Then check where the Mouse is. This where we use the values we got when checking where the Pan was on the screen.

 

And that is it for the first Room.

The Second Room.

Now that all the code is written for the first Room, the second Room becomes a lot easier, we simply duplicate the first Room Sprite and then make the following changes to the code:

• Change the 2 Costumes to something else for this new Room.
• Add a new Variable for this Room
• Update all the places where the Variable is set to this new one.
• Update the starting X and Y positions to one of the other corners of the Stage.
• Update the X and Y changes when the Room grows and shrinks to make sure it is going to the centre of the screen correctly and also back to it’s own corner.
• Update the X and Y values to a new location on the Screen, depending on what you have drawn on your new Costumes.

The Finished Program

I only got 3 Rooms finished and this what it looked like at the end:

Next Steps

If you want to improve the program you can look at adding the following:

• The final Room to make it 4 rooms.
• Extra code change the Costume back to normal if the item is clicked again, this would check what Costume is currently, this can be done using the “costume #” from the Looks blocks.

Notes

The one I did in the class is available on the Scratch Web Site:

Project Name : ClassVersion-MadHouse

UserId : cdadvancers1819

Password : advancers