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  • [BELL RINGING]

  • Hello again.

  • It's me from the future inserting myself

  • into your play list of videos.

  • I am making a video to go right here in between 7.7 and 7.8.

  • I don't know how you ended up here,

  • but that's the intended point of watching between these two

  • in this tutorial series.

  • So what I'm going to show you-- but you could also just

  • be here because you want to know how to add images to the P5 Web

  • Editor.

  • So this is in a series about object-oriented programming

  • in 7.8.

  • This next video, I look at how to use an image and an object

  • and then have multiple objects each showing a different image.

  • All sorts of fun.

  • But in both of these videos, I'm using the Atom text editor

  • And just opening up my JavaScript P5 sketch

  • in the Chrome browser directly.

  • And now, I want to show you how to do this-- oh and here--

  • in the P5 Web Editor.

  • So I'm going to create a new sketch.

  • Well, let me just save this and create a new sketch.

  • I'm going to hit OK because that's something else going on.

  • And, OK, so what I want to do is just look at let's say,

  • I've made this beautiful sketch.

  • It is this beautiful rectangle.

  • It is this lovely shade of gray.

  • But what I really want is a kitten to appear there.

  • Oh, I just so happen to have this nice directory

  • of little tiny kitten images.

  • I like this one.

  • And what I want to do is load this kitten

  • JPEG into my sketch.

  • So code-wise, there are two functions

  • that I need to know about.

  • One is a function called load image,

  • and another is a function called image.

  • So I might as well talk about those two

  • while I'm here, although I think I probably talk about those

  • in the next video as well.

  • But more importantly, the purpose of this video

  • is how do I actually get this image--

  • this image-- into this sketch.

  • So once again, this is a time for me

  • to go over here and reveal, pull back the curtain

  • of the P5 Web Editor.

  • I've done this before when I made a second JavaScript file.

  • We can see that there's also an html file and a style.css file.

  • What goes on in these files are things

  • that I get into in a future playlist about the P5 Dom

  • library.

  • So I want to look for that little arrow

  • again and click Add File, just like what

  • I did before when I added a new JavaScript

  • file, like bubble.js.

  • but now instead of typing in a new file,

  • I actually am just going to drag a file over here

  • into this region.

  • I could also click here, and it's

  • going to open up a kind of like finder thing.

  • But I'm just going to come over here.

  • I'm going to grab my kitten--

  • this lovely little kitten.

  • I'm going to drag it over here.

  • And then it's going to upload.

  • It is done, and we can see kitten2.jpg is now

  • part of this project.

  • You should realize though there is a limit.

  • I can't remember if it's 5 megabytes or 10 megabytes.

  • You can't upload really big files to the Web Editor

  • at present.

  • Maybe in the future, we'll figure out

  • ways of managing the data so that you can.

  • So now, just to finish this off, I

  • said I want to have a variable called image.

  • And that's the image where I want

  • to-- that's the variable where I want to load the file into.

  • And then, once I have that, I want

  • to draw that image to the canvas.

  • Of course, it's giving me an error now--

  • cannot read property width of undefined--

  • cannot read property width of undefined because the image is

  • not there.

  • So I need to actually load the image.

  • And you might think, OK, well, there's a load image function.

  • So why not just use load image and in quotes reference

  • the name of that JPEG?

  • Well, this doesn't work because I cannot call P5 functions

  • outside of setup or draw.

  • It doesn't actually know what a P5 function is.

  • So what I could do is then say, all right,

  • well, image needs to be a global variable.

  • I'm over explaining this, but I think

  • it's worth noting all this.

  • So let me put load image in setup.

  • And ther, it worked.

  • There's the image of the kitten.

  • Why did this work though?

  • Weird.

  • Let me draw on this again.

  • Did you see how the kitten wasn't there at

  • first for like a little bit?

  • What if I say here no loop?

  • The kitten doesn't appear.

  • The kitten's being loaded in setup

  • and then being drawn in draw.

  • So one of the things you have to start getting used to

  • is the asynchronous nature of JavaScript.

  • And this will come more and more as you go into the videos

  • about working with data and the DOM library.

  • But when we asked to load an image,

  • it's not going to be immediately ready.

  • It takes some time for it to go and grab those pixels

  • and load them into memory.

  • And there's ways of using something

  • called a callback, which I will get to in a future video.

  • But the best way for you to do this right now

  • is to use a function called preload.

  • And preload is a special function.

  • It's kind of like the prequel to setup.

  • Setup is where everything begins.

  • But before setup, we have preload.

  • And what preload does is it is a place where

  • you can load any media or data assets

  • and make sure they are already before setup and draw happen.

  • So, in this case, even with no loop,

  • that kitten's always going to be there.

  • And just incidentally while we're here,

  • we should note that the image function

  • drawing this particular image, which maybe I

  • should be more clear about my variable naming

  • and name it kitten, this is exactly

  • like the rectangle function.

  • I am drawing a rectangle at 0, 0.

  • The only difference is I'm filling that rectangle

  • with the pixels from that image.

  • But I can do things like give it a width and height.

  • And you can see I have stretched the kitten.

  • These could be variables.

  • And you can see now it's going to resize.

  • It's just a rectangle.

  • I could do things like say x and have a variable called x.

  • And I could say x plus plus.

  • And now the kitten is slowly moving.

  • I could change the y-value.

  • So it's just another thing to draw that you can rotate

  • and twist and color and turn and all that.

  • And in the next video, if you are here,

  • if you happen to be watching this

  • as part of this playlist, what I'm actually going to show you

  • in the next video--

  • you can sort of see it in the thumbnail--

  • is to make a whole bunch of objects that are images

  • and animate them around the window.

  • So I hope to help this clarify a little bit

  • about using the P5 Web Editor with all

  • these other surrounding videos.

  • And if I didn't get it right here or you're confused,

  • please let me know in the comments.

  • And I look forward to seeing you in a future video.

  • [BELL RINGING]

  • [MUSIC PLAYING]

[BELL RINGING]

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A2 初級

p5.js ウェブエディタ。メディアファイルのアップロード - p5.jsチュートリアル (p5.js Web Editor: Uploading Media Files - p5.js Tutorial)

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    林宜悉 に公開 2021 年 01 月 14 日
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