1. August 30
Intro to CS

2. Today’s Objectives More Boolean Broadcast and Ask & Answer
Custom Blocks
Layers
Work on your project

3. Review: More Boolean (“AND”)
Lincoln Lion = Dana Ave AND grade AND In Intro CS
Which one(s) are true?
Condition #
School on Dana?
9-12?
In Intro CS?
Lion CS programmer! 1 2 3 4 5 6 7

4. Review: More Boolean (“AND”)
Lincoln Lions = Dana Ave AND grade AND In Intro CS
Which one(s) are true?
Condition #
School on Dana?
9-12
In Intro CS?
Lion CS programmer!
False 1
True 2 3 4 5 6 7

5. Review: More Boolean (“AND”)
Lincoln Lions = Dana Ave AND grade AND Intro to CS
Do you see a pattern in the table?
Condition #
School on Dana?
9-12?
In Intro CS?
Lion CS programmer!
False 1
True 2 3 4 5 6 7
TRUE

6. More Block use More Boolean Parallelism Broadcast Ask/Answer If/Else
Repeat
Forever
Broadcast
More Boolean
Parallelism
Broadcast
Ask/Answer
Ask/Answer

7. SNAP! Broadcast What does this do?
It puts the scripted value into “message” system variable

8. SNAP! Ask and Answer What does this do?
It puts the value typed by the keyboard into “answer” system variable

9. Constructing Boolean expressions
Condition A
Condition B
Condition C
Expression
Wednesday
Sunday
9-3
cVSFarmersMarketOpen
cVSFarmersMarketOpen = (Wednesday AND 9-3) OR (Sunday AND 9-3)

10. Constructing Boolean expressions
Condition A
Condition B
Condition C
Expression
Wednesday
Sunday
9-3
CVSFarmersMarketOpen
floorLamp
tableLamp
pgePowerPresent
ARoomLightOn
deadBattery
noGas
-----
CarWontStart
CVSFarmersMarketOpen = (Wednesday AND 9-3) OR (Sunday AND 9-3)
ARoomLightOn = (write this on your paper)
CarWontStart = (write this on your paper)

11. Constructing Boolean expressions - ANSWER
Condition A
Condition B
Condition C
Expression
Wednesday
Sunday
9-3
CVSFarmersMarketOpen
floorLamp
tableLamp
pgePowerPresent
ARoomLightOn
deadBattery
noGas
-----
CarWontStart
CVSFarmersMarketOpen = (Wednesday AND 9-3) OR (Sunday AND 9-3)
ARoomLightOn = (floorLamp AND pgePowerPresent) OR ( tableLamp AND pgePowerPresent)
= ( floorLamp OR tableLamp) AND pgePowerPresent
CarWontStart = deadBattery OR noGas

12. Class Assignment – Write Truth Tables
Wednesday
Sunday
9-3
CVSFarmersMarketOpen
Fill in with all the rows and combinations
Evaluate each combination
floorLamp
tableLamp
pgePowerPresent
ARoomLightOn
Fill in with all the rows and combinations
Evaluate each combination
deadBattery
noGas
CarWontStart
Fill in with all the rows and combinations
Evaluate each combination

13. Today’s Objectives Review More Boolean Custom Blocks
Stage Scripting and Layers
Work on your project

14. Make Block or Right click on empty space in Script Area
this dialog box will appear. or
Press “Make Block” button in Variables
and this dialog box will appear.

15. Make Block, continued Fill in the name of your block
Choose all Sprites or This Sprite only
Default choice is “Command”
Click OK

16. Make Block, continued After OK this Block Editor appears
Can write a script in the Editor
Can drag a script into the Editor
Click OK

17. Make Block, continued Write your code Click OK Done!
Look in Variables for your custom block

18. Make Block (with Reporter)
You can re-edit Block
Right Click on the block
The yellow menu pops up
Select “edit “ and make your changes

19. Make Block (with Reporter)
Right click on empty space in Script Area
this dialog box will appear. or
Press “Make Block” button in Variables
and this dialog box will appear.

20. Choose “Reporter” option
Fill in the desired Name
Choose “Reporter” option here
Click OK

21. Now make some inputs Click on the “+” on the right
and name your inputs
This is the “report” block

22. Now add your code I clicked the “+” sign 4 times
I named each input as shown

23. Done! Sum = num1 + num2 + num3 + num4
“report” the Sum back to the caller

24. How to use the “reporter” block
You now have a custom block
which adds 4 numbers and reports the Sum back to the caller/user
You can use with any 4 hard coded numbers you want or
The custom block can use the values in the variables.

25. Lab: Make a “HeroWalksRight” custom block
Only 7 instructions needed
Be sure and include comments
Does everything it needs to do!!

26. ANSWER: Make a “HeroWalksRight” custom block

27. Today’s Objectives Review More Boolean Custom Blocks
Stage Scripting and Layers
Work on your project

28. Two “Looks” commands – goto front , go back N layers
Front, -2 layers
Front, -1 layer
Front layer
With these 2 commands, you can control where the scenery resides.

29. Layers, continued -
SNAP! will put your Sprites somewhere. Don’t know where.
You must tell SNAP! which layer each Sprite belongs to.
Procedure –
Step 1. Each Sprite must be told goto front in order to start from a
known layer.
Step 2. Each Sprite is now commanded to the proper layer with
go back N layers.
In this way a mountain can be behind a tree, the tree can be behind Mario and Mario and the gremlin can occupy the front layer.

30. Stage scripting Click on Stage icon Scripts just like for Sprites
Broadcast messages

31. Stage scripting Click on Stage icon Scripts just like for Sprites
Broadcast messages
This runs Mario Sprite only which is useful for debug

32. Today’s Objectives Review More Boolean Custom Blocks Layers
Work on your project

33. Initialization Logic for the Hero Sprite (“Program is repeatable and initializes state correctly.”)
Code is executed BEFORE Game starts
Set the desired layer
Set desired position
Set the desired size
Set the desired costume

34. Rest In Peace (R.I.P.) – Game over Logic (“Program is repeatable and initializes state correctly.”)
Starts when the game starts
forever checking
if <Mario and Gremlin touching>
Game Over!

35. Open Lab: Work on your Project
Where should I start? Start with the project spec.
There are least two scenery sprites (example: a tree and a mountain)
Scenery sprites are layered with Mario (example: appropriate layering blocks are in your program)
Scenery sprites move based on Mario’s movement
Scenery sprites move at different speeds (e.g. the mountain far away moves slower than the nearby tree – just like when you look out a car window)
Scenery sprites roll over when the fall of the stage

36. Reminders Read Chapter 1 Quiz next week Test on Friday, Sept 4
on computer processing, abstraction Boolean operations, and SNAP!

37. Looking ahead … Monday Tues / Weds Thurs/Fri TODAY 8/25-26 8/27-28
BACK TO SCHOOL NIGHT
8/31
TEST #1
9/1-2
QUIZ #1
9/4
LABOR DAY – NO SCHOOL
9/8-9
PROJECT #1 DUE
9/11
PROJECT #1 6pm

38. Design first – small manageable sections
Mario
Initialize : costume, position
Right Arrow : costume, move right, costume change, move right, etc (check for Right Edge & wrap)
Left Arrow : costume, move left , costume change , move left , etc (check for Left Edge & wrap)
Up Arrow : move up, wait, move down
R.I.P. : Mario and Gremlin are touching

39. Design first – small manageable sections
Tree
Initialize: position
Right Arrow: point left , move left, check for left edge (wrap or bounce)
Left Arrow: point right, move right, check for right edge (wrap or bounce)

40. Lab Exercise: Design Gremlin and Mountain on paper – 10 min
All possible inputs are shown - but may not be relevant to the Sprite
What happens on RIP (Rest In Peace – the hero dies)
Mountain
Initialize: yy
Right Arrow: yy
Left Arrow: yy
Up Arrow: yy
RIP: yy
Gremlin
Initialize: yy
Right Arrow: yy

41. What does it mean? Same as going to MacDonalds…
Front counter where you give your order
Different orders - different input

42. What does it mean? Ann : Cheeseburger Water No (false)
Fries?
Ann : Cheeseburger Water No (false)
Jim : Fish Coffee No (false)
You : Big Mac Coke Yes (true)

43. Creating Broadcast messages
Step 1. Create a message by choosing “new”.
Step 2. SNAP! Opens a dialog box
where you invent the name of your
Message
Step 3. Click “OK”

44. Parallelism ( also called threads)
These are 5 different streams of instructions/code also called threads.
Program Counter can’t be in 5 different places at the same time!!
SNAP executes a few instructions in one stream and then moves to the next.
1 GHz = 1,000,000,000 instructions in 1 second
Makes it appear that each stream/thread is executed simultaneously.

45. Advanced Blocks – using inputs
We will write code together as a class
From the rubric, it says the Hero…
“ Must be able to walk anywhere - left,
right, up or down”
“Make Block” with inputs
You can write 6 or 7 lines of code
and use it for Gremlin, Tree
and Mountain.
Why not Mario?

46. Lab Exercise: Make Block, continued
Name your block - “FancyWalk”
Choose all Sprites, or , This Sprite only
Click OK

47. Lab Exercise: Make Block, continued
Block Editor appears with the
name of the block
Click on the “+” sign
Type the name of your input
LeftOrRight
Click OK

48. Lab Exercise: Make Block, continued
You now have a Block with an input
Click on the “+” sign again

49. Lab Exercise: Make Block, continued
Type the name of your
2nd input: UpOrDown
Click OK

50. Lab Exercise: Make Block, continued
Your Custom Block now has 2 inputs
Now add the script

51. Lab Exercise: Make Block, continued
After you have constructed
your script …
Drag the input names as shown in the figure
Now let’s run SNAP, initialize and see it work!!

52. Test Review SNAP! Broadcast Ask/Answer Variables System Global Local
Layers
Costumes
Terminology
Sprite, Script, Stage, Scripting Area, Blocks, Tabs
Custom Blocks

53. Test Review Computer Architecture Parallelism Boolean Logic
Main Memory
Program Memory
ALU
Variables
Program Counter
Parallelism
Definition
Boolean Logic
AND, OR, NOT
Truth Tables