65 lines
3.2 KiB
Markdown
65 lines
3.2 KiB
Markdown
|
# blocks - rendering graphics
|
|||
|
|
|
|||
|
|
An introduction to graphics for the Block Editor. #docs
|
|||
|
|
|
|||
|
|
## Before we get started
|
|||
|
|
|
|||
|
|
Ensure you have completed the 'Hello, world!' and Loop tutorials and tested them on a simulator or on BBC micro:bit.
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The BBC micro:bit has a grid of 25 LEDs, so we can use these to display images.
|
|||
|
|
|
|||
|
|
We’ve already experimented with the `show string` block that displays a string (some text) that we program it to. However we can use more blocks from the **Images** drawer to render or display images in different ways.
|
|||
|
|
|
|||
|
|
### Pixel Art
|
|||
|
|
|
|||
|
|
We can draw little images from the LEDs by ticking boxes. Drag a `show image` block from the **Images** drawer and connect in a `create image` block. You can customize this image by clicking boxes to tick whether the LED will turn on or off. For example, if we were creating a music player we may want to the show the `play` block:
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
### Plotting points
|
|||
|
|
|
|||
|
|
We can also code our bug to plot a point by giving an x (horizontal) and y (vertical) coordinates, from 0 to 4. Click the **LED** drawer and drag a `plot` block. Try changing the coordinates and see the effect this has on the BBC micro:bit.
|
|||
|
|
|
|||
|
|
We can also unplot a point (turn the LED off again) using the `unplot` block. So we could create a flashing LED program, using the `pause` block to create a delay.
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
We can also use the `clear screen` block to turn off all LEDs.
|
|||
|
|
|
|||
|
|
## Tip
|
|||
|
|
|
|||
|
|
The pause block is in milliseconds, so setting it to 1000 will have a pause of a single second.
|
|||
|
|
|
|||
|
|
### Devising algorithms for shapes
|
|||
|
|
|
|||
|
|
An algorithm is a set of steps to follow to solve a problem. We can begin to draw shapes on the BBC micro:bit using an algorithm. For example, we could draw a straight line with this code:
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
Our algorithm is: increase **i** by 1 **from 0** to **4**, and **plot** the point **x=i**, **y=0**. The pause block allows this line to be animated (drawn frame by frame).
|
|||
|
|
|
|||
|
|
Try devising an algorithm for a diagonal line using the code above and the variable **i**. Your code should look like this; as our variable increases, so does the location that the BBC micro:bit is plotting at:
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
We can create more complex algorithms for more complex shapes, too. See the [challenges](/microbit/lessons/challenges) section for additional graphical challenges and solutions.
|
|||
|
|
|
|||
|
|
### Animations
|
|||
|
|
|
|||
|
|
Animations are changes happening at a certain rate. For example, we could add the `delay` block from the **Basic** drawer with our square algorithm – this will slowly draw a square (as an animation).
|
|||
|
|
|
|||
|
|
We could create more complex animations, for example we could make our BBC micro:bit display an explosion or fireworks.
|
|||
|
|
|
|||
|
|
See the [challenges](/microbit/lessons/challenges) section for some animation tasks.
|
|||
|
|
|
|||
|
|
### Image variables
|
|||
|
|
|
|||
|
|
We can create image variables so we can easily display an image at a later point. For example:
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
This uses the blocks from the **Variable** drawer, and the **create image** block from the **Image** drawer. This means our image can be displayed without having to replicate the `create image` block each time.
|
|||
|
|
|