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.
Related
I'm Using the SDL library in C to learn some game dev , however i'm quite confused as to what SDL_RenderClear does and when do we use it. I did check the SDL documentation about the same , however i still wasn't able to understand where exactly we would use it and what is its use.
It's like rendering background color to color you have set via another API namely SDL_SetRenderDrawColor as you already found on documentation online.
Imagine you have rendered several things on screen. To begin again, you need to clear it to start over. Underlying of SDL_RenderClear wraps specific native platform your application runs on top, it can be OpenGL, DirectX, etc. It helps in communicating with such specific function that platform provides in order for you to flexibly clear your screen without a need to know low level functions, and use SDL2 for other things else like windowing, inputs from keyboard/mouse/joysticks, sound, and even utility functions related to rendering to aid your own rendering implementation.
To add a few more, SDL2 provides minimal but optimized rendering capability. SDL_RenderClear is one of those several functions you can use in rendering category. Anyway, you can decide to go on integrating with what you prefer i.e. OpenGL, DirectX, Vulkan etc. yourself.
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.
I am trying to develop an 2D game using cocos2d library. I am still learning the framework.
Please understand that I am new to game development but not new to programming using objective c.
Here is the issue I am facing when it comes to my game development effort - I feel that I am missing the theoretical understanding of how to develop an infinite scrolling game. Is it possible for any of you to provide me some guidance on that ?
Here is my understanding of achieving infinite scrolling using cocos2d framework:
Cocos2d has a singleton director class which handles the current scene and scene transitions
In the current scene, I feel like I have to create an platform object consisting of several images and add them as a child to the current layer. And constantly run a move action to the platform sprite. So as and when I detect a particular image is off screen I have to replace it with another image. That way I will be able to create an infinite scrolling.
I am sorry if point 2 is not coherent. I just attempted to put my understanding of how to infinite scrolling.
Can you please help me with this ?
Thanks
I dissected how to implement scrolling with cocos2d-iphone in this article. What you probably want is the "fake scrolling" approach where two background images are moved and switch position after one completely left the screen.
You want to do this for the background layer only, not individual sprites. Your world isn't really moving, it's just the background panning that creates the illusion of movement. All sprites etc (player, enemies) movement is still relative to screen coordinates.
You'll find a working implementation in the code for my Learn Cocos2D 2 book in the Shoot'em Up project.
If you don't want to bother implementing this yourself, KoboldTouch supports endless/infinite scrolling for tilemaps. Here the game objects actually move along with the background infinitely (up to the maximum coordinates supported by float which is around +/- 16 million points).
Does someone know a fast way to add the ability to rotate and move a 3D model using Qt?
Obviously, I have to make changes to the world matrix based on the mouse and keyboard movements, and hence I should somehow handle the appropriate mouseEvents and keyboardEvens.
For a 3d camera this seems a bit tricky and although I could implement it myself, I'd better stick to something ready.
Does anyone know or have an example which handles this kind of actions and reflects them to the world matrix?
Thank you.
This might be what you're looking for. It is an example that loads .obj models and allows you to rotate them with the mouse. It also shows you how to render Qt dialogs within the OpenGL scene.
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