Size of OPENGL context in SFML WINDOW - c++

i'm currently working on a voxel editor and everything is going fine.
I have my SFML windows and my model to work with. I was just wondering if it was possible with SFML to set the 3D context to a certain specefic size.
I'm asking this because my model is currently shown on the screen with not problem at all, except that now, I want to create some options settings with SFML and my button will on my 3D model. Like, I would like 75% of the left side of my window to be my 3D context and the 25% at the right to be blank with space to fill in my buttons.

To do what you want to do, I believe what you're looking for is this: http://www.sfml-dev.org/documentation/2.0/classsf_1_1View.php#details
I think the context is attached to the window in general. Also be aware that SFML is for 2D graphics. Once you want 3D rendering, you're going to need to use openGL directly. SFML is a wrapper for openGL calls so there's no problem with using SFML to help set up and manage things, and openGL directly for rendering needs.
http://www.sfml-dev.org/tutorials/2.0/window-opengl.php

try:
glViewport(x,y,width,height);
source: https://www.khronos.org/registry/OpenGL-Refpages/es2.0/xhtml/glViewport.xml

Related

QOpenGLWindow z-order issues

I am working on updating an application for a client.
They use Qt and currently use a QGLWidget to display a full-screen view of 1 of 4 possible cameras selected by clicking the appropriate radio button. They then use OpenGL to draw on the image being displayed. This works great, but they want to update the UI to include a quad-split view of all 4 cameras.
My first thought on how to accomplish this was to keep the one QGLWidget for the full-screen display, and have 4 small QGLWidgets for the quad-split. From the documentation I found that you can't overlap QGLWidgets or QOpenGLWidgets because they don't handle z-order appropriately, but that this can be accomplished by using QOpenGLWindows and QWidget::createWindowContainer.
So, I coded up an application that uses a QOpenGLWidget (trying to bring them up to date) for the full-screen view, and 4 smaller QOpenGLWindows using QWidget::createWindowContainer, but this isn't working either.
The widgets built from QOpenGLWindows are always on top even if I use lower() to try to get them behind the full screen QOpenGLWidget. I've also tried using hide() on the widgets built from QOpenGLWindows, however, this has had no effect.
Do this at a lower level. Keep the one QGLWidget -- in fact don't touch your Qt objects. Instead, change the lower-level rendering so that it makes 4 calls to glViewport.
After each call to glViewport, update the modelview and projection and matrices according to the camera of interest, then draw the 3D scene.
This is simple and performant, because the driver only needs to deal with a single OpenGL context. You might have some extra work to adjust mouse input, but I think it'll be worthwhile.

Qt Widget inside qt3d window

How to put a label or button into qt3d window? Is it possible? Havent seen any example... I was trying to simply put qt3d in windowcontainer, assign layout to it and layout->addWiget() but it just doesnt work.
I know this is a farily old question but I wanted to give a more detailed answer if anyone else stumbles across this.
I implemented a Qt3D widget which you can find here. Unfortunately it relies on a method to obtain the texture id from QAbstractTexture which is only available from Qt >= 5.13 so that's the minimum version you have to use.
createWindowContainer draws the respective window above everything else. So you'll never be able to draw any buttons inside the container.
You can of course have buttons and everything else around your containered 3D window. But that's specifically not what you wanted.
You can use Dear ImGui - and it's Qt3D integration. ImGui is used to draw GUI elements using vertices in 3D environments.
Of course you can always use QML - there you should be able to place buttons inside the 3D view.
you have both label and (radio)buttons on the first example for C++ into the QT3d documentation, refer to Qt 3D: Basic Shapes C++ Example
QExtrudedTextGeometry seems to be the class for 3D text

Using SDL, OpenGL and Qt together

For a while I've been using SDL to write my 3D engine,and have recently been implementing an editor that can export an optimized format for the type of engine Im building. Right now the editor is fairly simple, objects can just be moved around and their textures and models can be changed. As of right now, I'm using SDL with OpenGL to render everything, but I want to use Qt for the GUI part of the editor, that way it looks native on every platform. I've got it working great so far, I'm running a QApplication inside of the SDL application, so it basically just opens 2 windows, one that uses SDL and OpenGL, and the other using Qt. Doing a bit of research, I've found that you can manually update a QApplication, which totally removes any threading problems, and everything works. Just in case you're having a hard time visualizing this, heres a picture:
What my goal is to merge these windows into one, because on smaller screens (like my laptop's) it makes it really hard to keep track of all the different windows that I would eventually have. I know theres a way to render to Qt with OpenGL, but can this be integrated with SDL? Am I going to need to move away from using an SDL window and use a QT one if the editor is enabled? Just to clarify, when the engine isn't in editor mode, it won't use and Qt, just SDL, so optimally I wouldn't need to do this.
Drop the SDL part. You have Qt, which does everything SDL does as well. Just subclass a QGLWidget and use that.
You can keep your game and editor separate processes and still make them part of the same app.
Just spawn the window where you want the game to run as part of Qt, and at least in windows, you can then pass the window handle to your game, and make sure when your game is setting up, instead of creating the window yourself in SDL and binding the opengl context to it, you can actually bind to the existing handle.
There are some gotchas with this technique to watch out for such as input focus I believe (I tested with directX, but it might be similar with SDL). The problem is that the foreground mode does some dumb checks on the "root" window which for me was not the window that owned the opengl context, so it failed to initialize. However background mode worked. I think that was for a joystick now that I think about it, but anyway, that's how you can merge everything together.

creating starting page for opengl game

I am working on a graphics game project in OpenGL and I want to make a front page of the game containing a image, few buttons and some text. Buttons on click perform different actions e.g. start button for starting the game , Can anyone please suggest me , How can I do it?
How can I do it?
Well, by implementing it. OpenGL is not a game engine, nor a scene graph, nor a UI toolkit. It's merely a drawing API providing you the means to draw nice pictures, and that's it. Anything beyond that is the task of either a 3rd party library/toolkit, or your own code, or a combination of both.
A usual approach to model this behaviour is by introducing application states. Here is a related question.
You could model your StartScreenState by drawing a plane with buttons using an orthogonal projection and not drawing (or not having initialized yet) the rest. When the player clicks on 'start', you can switch to perspective projection and display game contents.
I don't know that I would even use OpenGL for that. OpenGL is for rendering colored/textured triangles/quads so that you can do tons of stuff graphically. There's no such thing as "load an image to coordinate x,y on the screen". The equivalent would be "draw two triangles with these vertices that make up a rectangle and are textured with this image". Which is why I would probably stay away from OpenGL to do this, because you don't really need to use any of the awesome features that OpenGL has.
A very common UI framework that I believe nestles in with OpenGL well if you really want to use the two together is Qt. It should make your life easier in terms of UI stuff. See wiki and dev page.

Questions about OpenGL Settings and drawing over a mask in a window

I would like to know the OpenGL Rendering settings for having a program render OpenGL over top of any window on screen that has a specific color code (screen-level buffer?)
I.E. VLC Media Player and Media Player Classic both have rendering modes which allow you to full-screen then minimize player, but maintain watching media via allowing a specific color to act as a transparent mask. For example, you could set the background color of a terminal application to be 0x000010 for VLC 0x000001 for MPC and you could then type over the media using text (as it is in it's original color). When you try to do a "printscreen" all you get is the mask color, However, this is an acceptable side-effect.
Is it possible to do this as well with any OpenGL application with the right settings and hardware? If so, what are the settings or at least the terminology of this effect to further research it?
What you are trying to implement is called "overlay". You can try this angelcode tutorial. If I remember correctly, there was also a tutorial in DirectX SDK.
If you need to use OpenGL, you will need to perform offscreen rendering (using FBO or P-buffer), read the results using glReadPixels() and display using overlay.