Whenever I try to make a game or something that requires the rapid clearing of a screen, I've used system("CLS"). I now know that that is not good to use so I tried using a for loop to print new lines rapidly. While this works it looks really weird and less clear. I've seen people try to use STRING to clear a screen but whenever I try it it never works. How can I clear my screen efficiently and cleanly.
There's no standard way to clear the screen. But in any case, actually clearing the terminal and redrawing will be far too slow and glitchy for many games.
You should use either your OS's native terminal handling functions, or a cross-platform library that abstracts them.
I'd recommend ncurses, which is the latter. It basically provides an interface akin to a double-buffered graphics API, and handles all of the actual terminal twiddling so the frame swap is as fast as possible.
Related
I'm making a program to record a window that is obscured by another window via python and WIN32API library.
Through many searches, I succeeded in capturing the hidden window through hwnd and BitBlt, but the execution time of my code is not stable.
I tried to provide the recording function by selecting 30~60 fps, but the time required to capture the hidden window and write() it to the video object of cv2 is irregular, so I can't make a 60fps video.
So I thought of OBS and Discord. In the case of OBS, it is possible to enforce stable recording for obscured windows. For Discord, there is a feature that allows you to select a specific window and share it with multiple people in real time (this can also be done for hidden windows).
I'd like to know how these programs provide stable video for occluded windows. I'm a student, and I'm not elite. I am asking this question because it is difficult to analyze the vast Github source code of OBS. Can someone give me an explanation of how the above program captures the screen?
Last time I checked, OBS was doing it with low-level hacks instead of APIs.
Specifically, they have wrote a DLL which they inject into the target application using CreateRemoteThread WinAPI. Then, they patch application’s code to intercept calls to IDXGISwapChain.Present method. Once a call is intercepted, the injected code has access to D3D frame buffer texture. It can copy that texture into another texture on GPU, and then do something with the copy. One possibility is DXGI surface sharing to pass the copy from the target application into the capturing process. The APIs for that don’t require both sides of the sharing to be in the same process, textures can be shared across processes just fine.
Unfortunately for you, their approach is borderline impossible to re-implement in higher-level languages like Python. Such things are only doable in C++ or similar low-level languages, and relatively hard to implement and debug.
#dy.kim, don't be afraid of large codebases. window-capture.c and the OBS GUI fairly obviously list "bitblt" and "Windows Graphics Capture" as the two methods it uses to capture windows, with the preference going to WGC if neither is specified.
I had some issues in full-screen mode using OverlayContainer.
The solution is to use FullscreenOverlayContainer (which also works in full-screen mode)
The FullscreenOverlayContainer is an alternative to OverlayContainer that supports correct displaying of overlay elements in fullscreen mode.
Now, I wonder why OverlayContainer exists at all:
Are there any drawbacks in using FullscreenOverlayContainer?
In which situations would we use OverlayContainer instead of FullscreenOverlayContainer?
see comment in #19434
original reasoning was that handling full-screen mode was extra code that not everyone necessarily needed
So when you want to save some extra bytes and really don't need full-scrren you may use OverlayContainer.
My take on this is to always use FullscreenOverlayContainer.
I'm writing a video annotation application with Qt4 in which users need to be able to seek to various points in a video, putting markers on various objects and then setting keypoints for those markers so that they stay on the objects in the video as they move around. QGraphicsItemAnimation seems like a great place to start for these markers, however they need to be able to appear and disappear at specific times, which I can't figure out how to do with the QGraphicsItemAnimation. I could set the scale at 0 to make the objects disappear, but that seems like a pretty hacky solution, and I'm guessing that the paint engine would still waste cpu cycles trying to draw those invisible objects. Does anyone have a better solution than this? I'm using Qt 4.5.3 right now, but I'm willing to upgrade to 4.6 if it makes things easier. Thanks!!
It seems like the functionality you want of showing/hiding QGraphicsItem objects is beyond the scope of the simple "tweening" that the animation class performs. It is only for one object at a time, and any appearance or disappearance you have to write yourself.
You still might get some mileage out of QGraphicsItemAnimation (although the fact that it uses its own timer instead of being locked to the frame clock of your video is a little dodgy).
Neglecting "seeking" for a moment, there is a QTimeLine::finished() signal. If you let the end of an annotation's active animation timeline represent the point where you want it to disappear, you can trigger QGraphicsItem::hide() at that point. When it comes time to turn it back on, you would construct a new QGraphicsItemAnimation (based on the next run of keyframe data for that object) and call QGraphicsItem::show().
Note that one of the headlining features of Qt 4.6 is the QtAnimation framework, which is more sophisticated but also rather complex. I've not used it yet, but looking over the examples it seems like you might be able to "animate" a visibility or opacity property.
Im trying to write an ascii game for an assignment. The program must be written entirely in c, no c++.
How can i get the program to open a window capable of rendering ascii art? I want to create a window of a certain size, that is capable of printing in multiple colors. A simple console window is insufficient.
Also, on a related note, can anyone show me a function that will write directly to the buffer? printf is too slow, and doesnt seem to be versatile enough for the graphics i want to produce.
Any help will be greatly appreciated.
Thanks in advance.
A simple console window is insufficient.
I disagree. A console window is perfectly fine for anything you seem to want to do. Colours, full ascii range, highlighting...
Also, on a related note, can anyone show me a function that will write directly to the buffer? printf is too slow,
How fast do you need to write? If you're forming the strings yourself and calling printf, it essentially just copies it into the buffer for you.
try ncurses
altho i dont think it works for windows at this time (v5.7)
or even AAlib
You want the Windows Console API there are functions in there to do exactly what you are asking. For example use SetConsoleDisplayMode to change the console size.
See here: http://code.google.com/p/ie7-js/
Does anyone have any experience or remarks about this javascript? Is it worth including? Do you recommend it?
I know many people, myself included that are using various IE hacks to get transparent PNG support. THis looks like a little bit more help, and as long as it works, and the size is fairly small, I wouldn't see much against using it.
I've used it before, and my results are mixed. Those scripts cause IE to churn for a bit on page load. Basically, you have to think of it as iterating through Elements and stylesheet rules to apply "fixes" for areas that are deficient in that particular rendering engine. In some cases, depending on how complicated your markup or stylesheets are, that can take a bit of time and you will see the browser hang.
That said, if you can trade off that performance cost, you will save development time as you'll spend less time hacking around IE6 quirks; IE7/IE8 will provide enough missing functionality that you can avoid certain edge cases, can develop using standards better (min-width/min-height, multiple className selectors, etc.), and certain rendering issues will disappear.
However, if you just need 24-bit transparent PNG support, use a tool built for that. Including IE7/IE8.js for PNG support alone is like pounding in a nail with a tank. Use DD_belatedPNG for that.
It works, but its worth keeping in mind that ie7.js and ie8.js do much more than provide transparent PNG support. Even with the transparent PNG support, its worth keeping in mind that transparent background images cannot be tiled (repeated) using background-repeat or positioned using background-position. This hinders any ability to use CSS rollovers using background-position. I've only used it on one site I've done, and now that I'm updating the site I can't remove the ie8.js because if I do the entire website breaks layout in IE. I don't believe I'll be using it in the future, and instead rely on simple CSS hacks or simply allow my sites to "degrade gracefully" in IE6.
I know that there are some tools for fixing the transparent PNG problem which are more flexible than this. For instance, the jQuery plugin ifixpng2 will support background position, which ie7-js doesn't do.
As long as you are aware of exactly what it fixes, I would say go for it. I'm not sure about this lib exactly, but some libs get very expensive if you have a large DOM, as they tend to hook in HTC file base behaviors on EVERY DOM Element. This causes the dreaded "Loading x of y" status bar message to flash constantly on the initial load, and any newly generated DOM content.
well its beautiful and works grate way u can use cs3 features like li:hover. we did lost of project last time using ie8.js and it works great way.