God School: Lesson 6

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God School: Lesson 6

Postby thinkslogically » Sat Jun 29, 2013 2:07 am

Lesson 6: The Selection Tool

Ratha did this so well, I’ve decided to leave the lesson more or less just as it was, with just a couple of tweaks :D

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The selection tool is just so damn useful. With it you can separate parts of an image into new layers, paint/pencil over only what you want to or erase specific areas without affecting anything else.

The selection tools are great.

So, for this lesson, we'll be dealing with these tools:

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These buttons are in order: The rectangle select tool, the ellipse select tool, the free select tool, the fuzzy select tool, the select by colour tool, the scissors select tool, and the foreground select tool. I'll be going over each of them separately, but first, let’s look at a general overview of the selection tool and what it does, using the rectangle tool as an example.

Part 1: The selection tool

So, you've got a picture. Click on the rectangle select tool then click and drag to create a rectangle somewhere on your canvas.

Now, select the pencil/paintbrush tool and scribble over the canvas and the selected area. Notice how it's only the area inside that gets painted? Good. Now, try the eraser. Same effect!

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Okay, some other stuff with the selection tool...

If you use any of the copy commands, like copy or copy visible, only the stuff inside of the selection will be copied. This can be useful if you're trying to separate out a specific part of a layer you're on.

Now, there are some fancy cool things you can do with the selection tools. Say you want to select two areas at once. Select the first one, then hold shift and select the other.

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You can also remove some of the selection. Again, make your first selection, then hold down the control key and draw an overlapping selection box. The overlapping section will become unselected.

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Finally, you can select only the overlap between two areas. To do this, select the first area, then hold control and shift while selecting the second area. This is probably most useful if you’re doing this with the other shapes or with two different shaped selections (e.g. a rectangle and an ellipse) rather than with two rectangles, but you get the idea.

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Well, that should about cover what you can do with the selection tool. Now for how to select different types of areas:

Part 2: The rectangle select tool

As mentioned earlier, we're talking about this tool:

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This tool is pretty simple. It selects an area shaped like a rectangle. The area will have hard edges, kind of like the pencil tool.

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Now, if you look at the toolbox for the rectangle select, you have some more options available:

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You could select feather edges, which make the edges ‘graduated’. The bigger the radius, the larger the blurred area will be. Selecting ‘rounded corners’ does exactly what you’d expect:

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Be warned though, the corners of this version will be soft if you have antialiasing selected, so if you want hard edges (usually good for sprite games), be certain to unselect antialiasing.

Additionally, you must make sure your selection tool options are correct BEFORE you fill in the shape or draw in it otherwise they won’t take effect. You can’t colour in the selection first and then play with the edges afterwards for example which is a bit of a pain if you don’t know about it.

Part 3: The ellipse select tool

That's this tool:

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Exactly what it says it is. Just like the rectangle select tool, but for ellipses. Watch out for anti-aliasing again if you don’t want soft edges, but otherwise it works just the same as the rectangle tool, only it’s rounder.

So yeah, an ellipse:

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Part 4: The free select tool

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Basically, you just draw the shape you want selected, and that's the shape you get. Click and drag to get an edge along the path you're dragging along. Click once, then click somewhere else to get a straight line between the two points. Double click, drag to the starting point, or click on the starting point to close the loop and get the selected area.

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As before, antialiasing gives you a soft edge instead of a hard edge, and feather edges gives you a REALLY soft edge. Remember, you need to select/unselect these options BEFORE making the selected area for them to take effect.

Part 5: The fuzzy select tool

Ahh, finally we've reached my favourite tool. The fuzzy select tool.

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Click on a coloured region, and the tool will select the entire region, which is good for selecting large uniform objects!

Like this:

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This is, as you can imagine, great for some of the sprites I work with. Imagine you have a sprite, stuck in a png, and you want to seperate it into its own layer. But the sprite is made of many parts! What to do?

Try this! Select the area around the sprite with the rectangle select tool:

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Now, remember how holding the control key while selecting gets rid of areas? Use the fuzzy select tool while holding the control key, and select the areas that aren't the sprite.

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There you go! Now copy, and paste to new layer. You can now move the sprite around at will, to other pictures, without disturbing the layers behind it. This makes it much easier to manipulate as we discovered in lesson 2.

Now, if you’re struggling to select exactly the area you want (maybe the background colours are too similar and you’re getting a messy selection) you can adjust the Threshold level in the toolbox. This basically tells GIMP how picky to be when making its selection – the higher the threshold is set, the more colours will be included in the selection. You may want a high threshold if you’re trying to isolate a brightly coloured sprite from a gradient background for example, or a low threshold if your sprite’s colour is very similar to the background.

Part 6: The colour select tool

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This is kind of like the fuzzy select tool, but with an important difference. It selects ALL areas of the colour you click on. Let's say you have a pair of red circles. Here's what gets selected by the fuzzy select tool:

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And here's what gets selected by the colour select tool:

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Outside of that, it's pretty much identical to the fuzzy select.

Part7: The scissors select tool

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The scissors tool calls itself the intelligent edge fitting tool. If you use it, you'll notice that it does have a tendency towards travelling along edges. In fact, if you click and hold along a boundary, you'll notice that the point highlighted wanders along the boundary.

If the selection isn’t going where you want in big ‘chunks’, you can unclick the mouse to anchor the line as you go. Working in small segments like this is more likely to work than trying to make your whole selection in one go. Personally? I prefer the fuzzy select, but if you can make this work for you, go you!

Just remember, when you've made a complete shape with it, click inside that shape to select the region. The region will not be selected until then.

Part 8: The foreground select tool

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This tool is actually pretty smart. To use it, start by unchecking the ‘contiguous’ box in the toolbox. Then, select the area you’re interested in, the same as you would with the free select tool. You’ll notice that the cursor icon is a lasso at this point. Try to select as little of the surrounding area as possible. When you’re done, you'll notice that some of the area has a blue filter over it.

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But that’s a really rough selection and we don’t want that. Now you’ll notice that (without clicking on anything) the cursor has changed to a paintbrush. Now, paint roughly over the area you want to extract, being sure to paint over the different colours in the selection, but DO NOT paint over the background colour. You’ll notice your selection has been tidied up and the blue now tightly surrounds the part you wanted.

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Now, hit Enter and the selection is made! Note that until you hit enter, the whole process will be cancelled by clicking on a different tool or hitting escape so you need to do this in one go.

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And that’s it! It’s not perfect, but you might be able to make use of it.

The assignment will have you using the selection tools a lot so you should get plenty of practice and will be able to find the one you like using the best.
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Re: God School: Lesson 6

Postby M0rtimer » Mon Jul 01, 2013 11:25 am

Sorry, but I'm afraid I think I'm going to have to drop out for the assignments. I originally thought that, even with work, I should still have plenty of time left in the week to do said assignments- However, work today has left me drained. While I'm sure that once I get in the swing of things it won't be nearly as bad, I think it's going to be hard enough just to keep up with my own games- And I'd prefer to update my own games than spend that time working on these assignments, sorry.

I will keep following the lessons however- And if questions are raised, help if I can. I'll also try and make sure that gif lesson is done by the time it arrives.
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Re: God School: Lesson 6

Postby thinkslogically » Mon Jul 01, 2013 12:39 pm

No problem, thanks for letting me know m0rt :) Hope things calm down a bit for you!
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Re: God School: Lesson 6

Postby madmartin26 » Tue Jul 02, 2013 11:47 pm

Unfortunately, I'm going to have to join Mort on this one. I've been busy and my remaining free time has been taken up with other things. I'll still look at the lessons if i can, maybe even do some test drawings if i can find the time, but i won't be able to catch up with/keep up with the regular assignments. Good luck guys, the drawings i've seen from you guys so far are awesome. :)
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Re: God School: Lesson 6

Postby mucio77 » Wed Mar 05, 2014 6:23 am

I like the tutorial its quick and ellaborate :)
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