Problem Set: Sprite Overlap

This section contains a number of selected problems for the Sprite Overlap section.

It is recommended that you review the problems, and complete a few before moving on to the next section.

Problem #1: Hidden Treasure

Create two ||sprites:sprites||: a ||sprites:sprite|| of kind Player and a ||sprites:sprite|| of kind Treasure. Design the Player ||sprites:sprite|| so that it looks like a pirate, and make it ||controller:move with buttons||.

The Treasure ||sprites:sprite|| should be filled with the color the background, so that it is hard to see. Place the Treasure at a ||math:random|| position on the screen.

Create an ||sprites:overlap|| event between Player and Treasure ||sprites:sprites|| to represent the pirate finding the treasure.

In the ||sprites:overlap|| event, use ||sprites:sprite.setImage|| to change the ||images:image|| of the Treasure ||sprites:sprite|| to a treasure chest. After changing the ||images:image||, ||loops:pause|| for one second, and then end the game with ||game:game.over(true)||.

Problem #2: Dodge Ball

Create two ||sprites:sprites||: a ||sprites:sprite|| of kind Player and a ||sprites:sprite|| of kind Ball. Design the Player ||sprites:sprite|| so that it looks like a student in gym class, and make it ||controller:move with buttons||.

Give the Ball a ||math:random|| initial ||sprites:x|| and ||sprites:y|| velocities. Set the ||sprites:BounceOnWall|| SpriteFlag to ||logic:true||, so that the Ball will bounce around the screen. Draw a ball for the ||images:image|| of the Ball ||sprites:sprite||.

Create an ||sprites:overlap|| event between Player and Ball ||sprites:sprites|| to represent the player getting hit by the ball.

In the ||sprites:overlap|| event, ||game:splash|| “ouch!” to the screen, and then ends the game with ||game:game.over(false)||

Problem #3: Stay Out of the Fire

Create two ||sprites:sprites||: a ||sprites:sprite|| of kind Food and a ||sprites:sprite|| of kind Fire. Design the Food ||sprites:sprite|| so that it looks like a small burger, and make it ||controller:move with buttons|| at about half speed (that is, using 50 as the ||variables:vx|| and ||variables:vy|| parameters for ||controller:moveSprite||).

Set the Fire ||sprites:sprite||‘s ||images:image|| to look like a fire.

Create an ||sprites:overlap|| event between Food and Fire ||sprites:sprites|| to represent the player getting hit by the ball.

In the ||sprites:overlap|| event, move the ||sprites:Food|| up and to the left 1 pixel, and move the ||sprites:Fire|| down and to the right 1 pixel.

Now, the Food and Fire will repel each other when they touch.

Problem #4: Pushing the Food

Start with a solution to problem #3; this problem will extend from that code.

The previous problem resulted in the Fire and Food moving away from each other on contact, but they always moved in the same direction. Another option would be to have the Food move away from the Fire depending on where it is on the screen; that way, if the burger moves on top of the fire from the bottom right, the burger moves back in the direction it came from.

In the ||sprites:overlap|| event, remove the portion that makes the Fire move. Next, use ||logic:if|| conditions to control the direction the Food is moved.

||logic:If|| the ||sprites:x position|| of the Food ||sprites:sprite|| is less than the ||sprites:x position|| of the Fire ||sprites:sprite||, increment the Food ||sprites:sprite||‘s ||sprites:x position||; otherwise (||logic:else||), decrement the ||sprites:x position||.

Finally, do the same comparison and updates for the ||sprites:y position||. With that, the Food ||sprites:sprite|| will stay away from the Fire ||sprites:sprite||, moving away no matter the direction it comes from.