Do notĪssume that SFML will implicitly activate a context or that SFML will preserve the currently active context when calling into the library. When debugging issues with OpenGL in SFML, the first step is always to make sure a context is active when OpenGL functions are called. Helper class can be written for this purpose. Following this advice, each batch of operations would be visibly wrapped between activation and deactivation calls. Generally however, it is recommended to simply deactivate the context every time you are done with a batch This is required if the context is to be activated In order to explicitly deactivate a window's context, use tActive(false). ActivatingĪ context while another is currently active will result in the currently active one being implicitly deactivated before the new one is activated. In order to activate a window's context, use tActive() which is the same as tActive(true). If a context is not active when an OpenGL function isĬalled, the function call will not result in the desired effects since there is no state for it to have an effect on. It is thus required that a context be active any time OpenGL functions are called. When calling any OpenGL functions, they operate on the currently activeĬontext. Most likely contain solutions to your problems.Įvery window created in SFML automatically comes with an OpenGL context. So that we still have a valid OpenGL context for the last iteration of the loop and the cleanup code.ĭon't hesitate to have a look at the "OpenGL" and "Window" examples in the SFML SDK if you have further problems, they are more complete and Here we don't use window.isOpen() as the condition of the main loop, because we need the window to remain open until the program ends, end the current frame (internally swaps the front and back buffers) GlClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) adjust the viewport when the window is resized Įlse if (event.type = sf::Event::Resized) load resources, initialize the OpenGL states. Sf::Window window(sf::VideoMode(800, 600), "OpenGL", sf::Style::Default, sf::ContextSettings(32)) Sf::ContextSettings settings = window.getSettings() In any case, you can check what settings SFML actually used with the getSettings function: Is too high, it tries 2x and then falls back to 0. If any of these settings is not supported by the graphics card, SFML tries to find the closest valid match. Sf::Window window(sf::VideoMode(800, 600), "OpenGL", sf::Style::Default, settings) majorVersion and minorVersion comprise the requested version of OpenGL.antialiasingLevel is the multisampling level.stencilBits is the number of bits per pixel to use for the stencil buffer (0 to disable it).depthBits is the number of bits per pixel to use for the depth buffer (0 to disable it).This argument is an instance of the sf::ContextSettings structure, it provides access to the following In case you think it is too automatic, sf::Window's constructor has an extra argument that allows you to change the settings Since SFML is based on OpenGL, its windows are ready for OpenGL calls without any extra effort. Remember this when you get linker errors, it will help you find which library you forgot to link. OpenGL functions start with the "gl" prefix. Therefore, you need to know which library to link to according to what operating system you're using ("opengl32" on Windows, "GL" on Linux, etc.). Unlike what it does with the headers, SFML can't provide a unified way of linking You will then need to link your program to the OpenGL library. From the user's point of view, OpenGL extension loading must be handled like any other external library. People sometimes think that SFML automatically includes OpenGL extension headers because SFML loadsĮxtensions itself, but it's an implementation detail. This header includes OpenGL functions, and nothing else. Therefore, SFML provides an "abstract" header that takes care of including the right file for you. OpenGL headers are not the same on every OS. Including and linking OpenGL to your application Let's see how it allows you to play with OpenGL. That's where the sfml-window module comes into play. You would have no choice but to write OS-specific code to handle this stuff on your own. But OpenGL alone won't be enough to create complete programs: you needĪ window, a rendering context, user input, etc. This tutorial is not about OpenGL itself, but rather how to use SFML as an environment for OpenGL, and how to mix them together.Īs you know, one of the most important features of OpenGL is portability. Using OpenGL in a SFML window Introduction
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