2.13 GAME - Shooting

Have you seen those shooting games on TV? The closer a contestant shoots a bullet on the target to the bullseye, the higher his score.

Today we are also doing a shooting game in Scratch. In the game, let the Crosshair shoot as far as possible to the bullseye to get a higher score.

Click on the green flag to start. Use the Obstacle Avoidance module to shoot an bullet.

../_images/14_shooting.png

You Will Learn

  • How the Obstacle Avoidance module works and the angle range

  • Paint different sprites

  • Touch colors

Build the Circuit

The obstacle avoidance module is a distance-adjustable infrared proximity sensor whose output is normally high and low when an obstacle is detected.

Now build the circuit according to the diagram below.

../_images/avoid_circuit.png

Programming

1. Paint the Crosshair sprite

Delete the default sprite, select the Sprite button and click Paint, a blank sprite Sprite1 will appear and name it Crosshair.

../_images/14_shooting0.png

Go to the Crosshair sprite’s Costumes page. Click on the Circle tool, remove the fill color, and set the color and width of the outline.

../_images/14_shooting02.png

Now draw a circle with the Circle tool. After drawing, you can click to the Select tool and move the circle so that the original point is aligned with the center of the canvas.

../_images/14_shooting03.png

Using the Line tool, draw a cross inside the circle.

../_images/14_shooting033.png

Paint the Target sprite

Create a new sprite called Target sprite.

../_images/14_shooting01.png

Go to the Costumes page of the Target sprite, click on the Circle tool, select a fill color and remove the Outline and paint a large circle.

../_images/14_shooting05.png

Use the same method to draw additional circles, each with a different color, and you can use the Forward or Backbard tool to change the position of the overlapping circles. Note that you also need to select the tool to move the circles, so that the origin of all the circles and the center of the canvas are aligned.

../_images/14_shooting04.png

3. Add a backdrop

Add a suitable background which preferably does not have too many colors and does not match the colors in the Target sprite. Here I have chosen Wall1 backdrop.

../_images/14_shooting06.png

4. Script the Crosshair sprite

Set the random position and size of the Crosshair sprite, and let it move randomly.

../_images/14_shooting4.png

When a hand is placed in front of the obstacle avoidance module, it will output a low level as a transmit signal.

../_images/14_shooting5.png

When the shooting message is received, the sprite stops moving and slowly shrinks, thus simulating the effect of a bullet being shot.

../_images/14_shooting6.png

Use the [Touch color ()] block to determine the position of the shot.

../_images/14_shooting7.png

When the shot is inside the yellow circle, 10 is reported.

../_images/14_shooting8.png

Use the same method to determine the position of the bullet shot, if it is not set on the Target sprite, it means it is out of the circle.

../_images/14_shooting9.png