Hey everyone! I’m Erik from the Scratch team, and today I’m going to show you how to use video sensing and color detection in Scratch to create some amazing projects. Let’s dive in and learn how these features work!
First, let’s talk about color detection. I’ve made a simple program where a cat sprite moves to the right when you press the right arrow key and to the left when you press the left arrow key. Now, let’s add some color sensing to make it more interesting!
To do this, I’ll go to the backdrop and draw a big red circle for the cat to interact with. Then, I’ll go back to the cat sprite and open the scripts. We want the cat to say “ow” when it touches the red circle. To make this happen, we’ll use a sensing block called “touching color.”
We’ll drag out the “touching color” block and use the color picker to select the red color. Next, we’ll create a script that says if the cat is touching the red color, it will say “ow.” But there’s a catch! This script only runs once when we click the green flag.
To fix this, we’ll put the script inside a forever loop, so it keeps checking if the cat is touching the color. Now, when we run the program, the cat says “ow” whenever it touches the red shape. Cool, right?
Now, let’s make it even cooler by using video sensing. This feature lets us use a webcam to interact with our Scratch projects. I’ll start with a white backdrop and turn on the video sensing using the “turn video on” block from the sensing category. This activates the webcam, and you can see the view on the screen.
Instead of drawing on the backdrop, I’ll use a red Lego piece. I’ll place it on the stage, and the webcam will detect its color. We’ll use the same “touching color” concept here. I’ll select the red color of the Lego, and now the webcam can detect it. This opens up many fun possibilities!
Let me show you some examples of what you can do with these features:
I created a music program where a black bar moves across the screen. When it touches a Lego of a certain color, it plays a specific note. For example, it plays a C note when touching green, an E note when touching orange, and an A note when touching red. You can make your own music with this idea!
In another project, you can juggle cats and dogs based on the color of balloons. I made a large black sprite that covers the screen and is transparent. It triggers sounds when touched, even though you can’t see it. It’s like magic!
I also made a simple platform game using video sensing. In this game, green acts as a bounce pad, red is lava, and black is the ground. I remixed an existing platform game, and you can see how the scripts use the “when touching color” block to interact with different elements. It’s super fun to play!
I encourage you to explore some platformer tutorials on YouTube and Scratch. The idea of having objects you can interact with in real-time is really exciting. I’ll share links to all the projects in the video description, so you can check them out and remix them. Have a great time creating and experimenting with video sensing and color detection. It’s amazing to see what you can make!
Design a simple game where you control a sprite using the arrow keys. Draw different colored shapes on the backdrop. Use the “touching color” block to make your sprite react differently to each color. For example, make the sprite say “ouch” when touching red and “yay” when touching green. Experiment with different reactions and colors!
Turn on the video sensing feature in Scratch and use your webcam to interact with your project. Place a colored object in front of the camera and program your sprite to react when it detects that color. Try using different objects and see how the sprite responds. Can you create a game where you score points by showing the right color?
Create a musical project where different colors play different notes. Use the “touching color” block to detect when a sprite touches a specific color and play a corresponding sound. Arrange colored objects on the screen and see if you can compose a song by moving your sprite over them!
Develop a story where the plot changes based on the colors your sprite touches. Use the “touching color” block to trigger different story events. For example, touching blue could lead to a rainy day scene, while touching yellow might bring out the sun. Get creative and see how colors can change your story!
Use video sensing to create a platform game where different colors represent different types of terrain. Program your sprite to jump on green platforms, avoid red lava, and walk on black ground. Experiment with different levels and challenges. Can you make a game that’s both fun and challenging?
Here’s a sanitized version of the provided YouTube transcript:
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[Music]
Hey everyone, it’s Erik here from the Scratch team! I’m excited to show you how to use video sensing and color detection in Scratch to create some remarkable programs.
Let’s start by familiarizing ourselves with the concept of color detection in Scratch. I’ve created a simple program where, as you can see, if I press the right arrow key, the cat moves to the right, and if I press the left arrow key, the cat moves to the left.
Now, what if we want to add some color sensing to this project? I’ll go to the backdrop and create something red for the cat to interact with. I’ve clicked on the backdrop and drawn a large red circle.
Next, I’ll return to my Scratch cat sprite and go to the scripts. We want to say that if the cat touches this red shape, it will say “ow.” To do this, we’ll use a sensing block. We’ll create a statement that uses the “touching color” block.
Let’s drag this out and select the color we want to interact with by clicking the button to use the color picker. I’ll select the red color. Now, we need to build a script around this.
When the green flag is clicked, we’ll create an if-then statement. If the Scratch cat is touching this color, it will say “ow.” However, this won’t work as expected because the if-then statement only gets asked once when the green flag is clicked.
To fix this, we need to wrap this question in a forever loop, so it continuously checks if the cat is touching the color. Let’s run it again. Great! Now we have a simple program where the Scratch cat says “ow” when it touches the red shape.
But let’s take this a step further. Wouldn’t it be cool if the Scratch cat could interact with objects in the physical world? We can do this using video sensing, which allows us to use the webcam to interact with Scratch projects.
I’ll start with a white backdrop. Now, let’s enable video sensing. In the sensing category, I’ll use the “turn video on” block. This will activate the webcam. You can see the webcam view here, pointing down at a sheet of white paper.
Now, instead of drawing on the backdrop, let’s use a red Lego piece. I’ll grab a Lego and place it on the stage. The same concept of “when touching” will work here.
I’ll select the red color of the Lego, which is a slightly darker shade. Now, the webcam and video sensing can detect the color. This opens up many possibilities for interaction.
Let me show you a few examples of what you can do with video sensing and color detection.
Here’s a music-making program I created. It features a black bar that moves across the screen, and when it touches a Lego of a certain color, it plays a specific note. For example, it plays a C note when touching green, an E note when touching orange, and an A note when touching red.
Another project allows you to juggle cats and dogs based on the color of balloons. I created a large black sprite that takes up the entire screen and made it transparent so it triggers sounds when touched, even though it’s hidden.
Finally, I made a simple platform game using video sensing. The green acts as a bounce pad, the red represents lava, and the black is the ground. I’ve remixed an existing platform game, and you can see how the scripts use the “when touching color” block to interact with the different elements.
I encourage you to check out some platformer tutorials available on YouTube and Scratch. The basic concept of having movable objects that you can interact with in real-time is really exciting.
I’ll provide links to all the projects I’ve shared in the description of the video, so you can check them out and remix them. I wish everyone a great time creating and experimenting with video sensing and color detection. It’s amazing to see what you can make!
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This version removes informal language and maintains a professional tone while preserving the instructional content.
Video – A moving picture that you can watch on a computer or other device. – We watched a video on how to create a simple game using coding.
Sensing – The ability of a computer or program to detect or feel something, like movement or sound. – The robot uses sensing technology to avoid obstacles in its path.
Color – A property of an object that can be seen, such as red, blue, or green, often used in computer graphics. – We changed the color of the sprite to make it more visible on the screen.
Detection – The process of finding or identifying something, often used in coding to find specific conditions or inputs. – The program includes motion detection to start recording when someone enters the room.
Sprite – A character or object in a computer game or animation that can be moved and controlled. – I created a sprite of a cat that can jump over obstacles in the game.
Program – A set of instructions that a computer follows to perform a task. – We wrote a program to calculate the average of our test scores.
Script – A list of commands in a program that tells the computer what to do. – The script we wrote makes the sprite move across the screen when we press the arrow keys.
Webcam – A camera that connects to a computer and is used to take pictures or videos. – We used the webcam to record our coding project presentation.
Projects – Activities or tasks that involve creating something, often using coding or technology. – Our class worked on projects to design our own video games using Scratch.
Interact – To communicate or work together with a computer program or device. – The game allows players to interact with different characters by clicking on them.
