The OS scheduler will then decide what else needs to be done about it, based on priority and complexity. Essiantly, the processor saves the info about the click event and passes it to the Operating Systems scheduler. So, part of the operation then is to do only the minimum amount to document the click, before continuing with the workload. Afterward, it goes back to the state it saved and continues as if nothing had happened.īecause every hardware event is completely pausing the processor, it's important to handle them as quickly as possible. This means the processor will pause in whatever function it is running, saving where it is at in the code, and handle the click right then. The Processor must then handle the signal, immediately. The mouse or hardware device will send a signal directly to the processor when an event occurs. And indeed, that is how our modern systems work. What would a system where the mouse is the primary mover look like? I suppose the mouse could send a signal directly to the processor. Well, in the case of polling, the mouse changes something and the processor reacts, but the processor doesn't react until it checks that bit on its schedule. Of course, its problems in our use case are apparent from what I listed above. This is a system that was used in the past and used for other things still. If we check it less often, to be more efficient, we risk a sluggish user interface, not noticing clicks until noticeably late. But how often would we want to check that file? In a game, we might want to know about clicks every microsecond, and checking a file that often is certainly going to waste energy and processing power. If it's been flipped from a 0 to a 1, we'd know that the mouse was clicked. And if we did that, we could have the computer (the processor) check that file every so often. The mouse, upon being clicked, could be wired to change a bit somewhere or file. Well, how might a computer listen for something like a mouse click. I mean, how does your computer even know the mouse was clicked in the first place? So, what does happen when a user clicks their mouse? It might go to the event loop or to a handler, but for that to happen first the OS would have to be aware. Today, I want to simplify while giving a still accurate account of what happens when someone clicks their mouse because as long as we're writing thousands of lines of code that depend on user interaction, it would probably nice to know how we're even allowed to interact with those events in the first place. But when you dive into computer architecture complexity spirals just as quickly as it does when learning code. To successfully code an application, we don't need to understand how a mouse click or keypress works, or we might assume we do know at a high level. Here is some example code:ĬontrollerEnvironment.getDefaultEnvironment() įor(Controller cur : ce.If You're coming from a coding background, a mouse click is something you might take for granted. Make a folder inside your sketch folder called code and drop every file from the zip in it. Download JInput from its build management thing here: Turns out you need to setup LWJGL's Display to get mouse input, but you can use the same library that LWJGL uses for input directly. /*for (int i = 0 i cursor.update(frame.getX(), this.getX(), frame.getY(), this.getY()).The program works the same regardless of these lines being commented out, so it isn't an issue regarding these lines. I've commented out unnecessary code, related to the next thing I want to put in (the class that will control where units are positioned on the screen, class Actor). Inside draw (), pmouseX and pmouseY update only. You may find that pmouseX and pmouseY have different values when referenced inside of draw () and inside of mouse events like mousePressed () and mouseMoved (). At the very least, it seems the screen limiter is working, the cursor does indeed stop at the top right of the screen and remain locked to the window. The system variable pmouseX always contains the horizontal position of the mouse in the frame previous to the current frame. Movement related to where the mouse moves seems to work, but while the mouse is stationary, the cursor continues to move up to the top right of the screen. The cursor is constantly moving up and to the right, and I can't see where the issue is. Okay, so I've used that sketch and put it into my own, it looks like it should be correct, but I'm getting an issue with the way the cursor draws on the screen.
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