How would one "lock" the mouse to a certain OpenGL window. Sort of like how it is done in Minecraft.
Is GameDev a better place to ask?
Like Robert said in the comment, OpenGL doesn't actually do user input.
However, there are libraries that can abstract the platform dependent part away, such as LibSDL. You can use it to grab the mouse to your window.
A similar question has been asked here, where a programmer used a class called robot to change the mouse position.
Code: Robot.moveMouse(x,y)
This code was written in java, however, There are several classes like robot that can do the trick!
One option is to constantly move the mouse to the center of the screen or wherever you want it.
Related
I am on an Ubuntu 19.10 64 bit system
Source files:
https://drive.google.com/open?id=1I4ejOHNXqbAOkTbIyJR0lvldsAwiPPqI
Problem:
I am working on a simple drawing program using gtk and glade with c. Right now I am stuck into implementing undoing behavior. I have two problems. There are cases for when I press the undo button.
1)
When I have one stroke or one dot on the canvas, it works perfect as I experienced. Canvas clears itself.
2)
When I have two strokes or two dots on the canvas, if I click undo once, canvas does not redraw itself, unless I draw again; if I click twice, it works perfect like in the first case, canvas clears.
3)
When I have more than two strokes or two dots on the canvas, if I click undo twice, the program stops working waiting me to force quit.
I am a beginner at using glade, gtk3, and cairo libraries. I have been searching about the issue for days. However, the resources are scarce compared to trending frameworks and libraries. Furthermore, I couldn't match the problem I need. I appreciate any help.
EDIT I forgot to add that the halting problem occurs after the function , on_undo_clicked exits the second time (twice undo click).
I solved the problem.
In the function, addPoint I forgot that the next struct pointer's pre pointer may be a dangling pointer. It creates the problem.
The Gtk+ 3 migration guide shows how the GdkEventExpose.region field can be used to provide a fine-grained area for re-rendering widgets. We already do something like this in Inkscape to avoid rendering excessive amounts of complicated stuff on our drawing canvas.
However, the example in the guide shows how to do this for the old Gtk+ 2 expose_event handler.
How do I do the equivalent in a new Gtk+ 3 draw handler, which receives a "ready-clipped" Cairo context as a parameter, rather than a GdkEventExpose?
I guess one possibility is to use cairo_copy_clip_rectangle_list on the "ready-clipped" cairo context to obtain a list of rectangles that make up the region to draw. Does anyone have any experience of using this? Does it seem like a sensible approach?
Yes, you should use cairo_copy_clip_rectangle_list() on the cairo_t that you get in your widget's ::draw() signal handler. See this commit for an example:
http://git.gnome.org/browse/vte/commit/?id=21a064ac8b5925108b0ab9bd6516664c8cd3e268
Since I have not much clue, I decided to check the source code. GDK emits a GDK_EXPOSE event on a window and creates the GdkEventExpose instance for this.
This event is then handled in gtk/gtkmain.c via gtk_widget_send_expose():
http://git.gnome.org/browse/gtk+/tree/gtk/gtkwidget.c?id=eecb9607a5c0ee38eadb446545beccd0922cb0b8#n6104
This function clips the cairo_t to GdkEventExpose.region, as you already learned in the docs.
This then calls _gtk_widget_draw_internal() which emits the actual draw signal:
http://git.gnome.org/browse/gtk+/tree/gtk/gtkwidget.c?id=eecb9607a5c0ee38eadb446545beccd0922cb0b8#n5726
As far as I can see, nothing here let's you access the clip region directly. In gtk_widget_send_expose() the GdkEvent is added as userdata to the cairo context. However, this is not accessible, because all the involved functions and variables are static. So you'll have to use cairo_copy_clip_rectangle_list().
However, this sounds quite inefficent. First gdk_cairo_region transforms the region into a number of calls to cairo_rectangle and then cairo transforms this from its internal representation into a cairo_rectangle_list_t (which may fail if the clip is, for some reason, not a region). If you see this being slow, it might make sense to have some shortcut for this added to gtk directly.
I am new to Gtk and want to do simple drawing of shapes like circles and rectangles. I was looking at the gnome tutorial and the hello word example. However the curves section is undocumented. I was wondering if someone could point me in the right direction as to what should I look at, and maybe if I need to include some other supplementary library to draw?
The preferred drawing API in GTK 2 and 3 is Cairo. But if you need to develop a diagram program, with nodes that can react to events, you will need also to use a canvas, like GooCanvas.
Check out http://developer.gnome.org/gtk3/3.2/GtkDrawingArea.html about the GtkDrawingArea, plus http://developer.gnome.org/gdk/stable/gdk-Drawing-Primitives.html about Gdk-Drawing-Primitives and you are on the go.
You might also go a bit further by using this link and check out Cairo directly http://www.cairographics.org
I am trying to implement a text box where a user can type, use arrow keys, backspace, delete, etc. I would like to be able to know what is in this text box without the user needing to submit anything. I suppose I could catch keypress events, find a way to display a cursor, and basically build a min-text-editor by hand--but maybe that would be reinventing the wheel?
What I am after is rather scrabble-like. You have several letters in the top part of a window and a text box in the bottom. Each time you type a letter it disappears from the top pane so that you know when you've used them all up. I want to be able to edit that text with the arrow keys, 'cause rather than the 7 letters scrabble would give me I hope to be doing this with paragraphs.
I have the window displaying, and the source file processed and displayed as a list of allowable letters... I just want to update the list of allowable letters while the user types in their sentence. Can Xlib do this? Is there something else that might be more suitable? Thanks!
Can Xlib do this?Why yes, Xlib can do a lot of things. What you describe seems simple enough by using X's event processing and drawing functions.
Xlib is pretty crufty, though, and IMO you should only use it if you need closeness to the X protocol. (Even then there are newer replacements like XCB. But I digress.)
You might find it easier to work with a modern toolkit, like GTK+ or Qt.
For example, this might be expressed as a GtkEntry with a "key-press-event" handler.
Hey Guys, I am building a cards game which displays a stack of Cards( Some thing like Solitaire). I was wondering you give me some advise regarding it? Also if you could direct me to a tutorial for stuff like these( I am already going through the gtk doc).
You should check what have already be done in GnomeGames :
Aisleriot
Blackjack
Get the code and see how they have done it. It seems that they render each and every card :
For example, in Aisleriot source code, in game.h, you have the definition of an ArSlot struct which stores all the cards of one slot. In there, you can see that they define the 'expansion' union which is just defining the offset between the cards.
So if you wish to create a heap of cards, you can draw each one of them, or if you consider it's too slow, just draw a few cards with a random offset of one or two pixels, and then draw the last card on the top : with this algorithm, your heap of cards looks like a heap, and it's quick to render on screen.
Unfortunately, there's no widget included in GTK+ that displays stack of cards, so yu have to write one yourself. You should use GtkDrawingArea (preferably by subclassing it), and in handler for expose_event signal do your drawing stuff. To draw you can use either plain GDK which is more basic, or use Cairo, which is more flexible drawing library (nb. Cairo is used by GTK+ anyway, so it's not additional dependency. If you want more, you can even use OpenGL (then you have to use GtkGlExt library).
GTK Tutorial has a chapter dedicated for creating own widgets.