SDL_Controller design |
Ed Phillips
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Hello,
I think I'm missing something when it comes to the basic reasoning behind the design of the SDL_Controller stuff, and the documentation on the Wiki that I can see doesn't go into any discussion on the design decisions. When I first looked at the "mapping" capabilities of SDL_Controller, I thought, HEY!, this was a way to give names to each of the buttons/axes on any device, so you can pass them through to the application/game and it can present these names to the user when they are setting up their controller configuration. Cool! Oh look, they already have a database of these name mappings! Great! However, the more I started looking at it, I began to see that this is not the case at all. It seems to be a way to turn the raw button/axis numbers on a non-XInput device into an XInput control like "leftshoulder" or "righty"? So really, this is just a way to make every controller work like an XBox controller (even if it doesn't have the same physical controls or the same names on the buttons, etc.), and doesn't really address the issue of mapping the names of the actual physical controls on a particular device to the button/axis numbers normally received in SDL_Joystick calls? I guess if you don't want your game/application to treat every device like an XBox 360 Controller, then the SDL_Controller stuff is not for you? How does Steam's controller API play into things? There is mention of Steam here (and nowhere else I can find): http://wiki.libsdl.org/CategoryGameController It states: "If you are running your game from Steam, the game controller mapping is automatically provided for your game." I'm not sure what that means. Steam controller mappings take a list of "actions" defined for a game, and allow the developer and/or user to configure which controls on their devices will invoke these actions. A game using the controller API will see "actions" and not raw inputs... so I'm not sure how the SDL_Controller stuff plays into this. Also, in order to use the Steam controller API, you have to call functions in the Steam runtime, and I'm not sure if SDL can/would be doing that, and it won't provide an SDL_Controller mapping. Any help regarding these concepts would be greatly appreciated! Thanks, Ed Ed Phillips University of Delaware (302) 831-6082 Systems Programmer IV, Network and Systems Services _______________________________________________ SDL mailing list http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org |
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SDL_Controller design |
Daniel Gibson
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Hi Ed,
SDL_GameController is for game controllers aka gamepads, which tend to be similar to the xbox360 or PS2/3/4 pad (one DPAD on the left, two analog sticks, 4 buttons for the right thumb, 2 shoulder buttons on each side that may be trigger axes and those "back" and "start" buttons in the middle, maybe even an "xbox" button or similar). I think the main purposes are 1. making it easy(er) to port XInput code to SDL, esp. for Linux/Mac 2. allowing game developers to set default bindings for gamepads that make sense with most gamepads. Usually you use SDL_GameController with the corresponding events (SDL_CONTROLLER*), I think, but you *can* also use it to set the displayed names etc of normal SDL_Joystick buttons, if the joystick happens to be a known game controller. SDL_IsGameController(joystick) tells you if a joystick is a know game controller, SDL_GameControllerGetBindForAxis() and SDL_GameControllerGetBindForButton() tell you how things are mapped. (I've used it that way so I don't have to handle game controller events separately, but still get the mapping) Regarding Steam: The documentation is referring to the gamepad configuration in the Steam (Linux?) Big Picture settings, that lets you create a mapping from your gamepad's buttons/axes to the xbox controller model. I think Steam then sets the SDL_GAMECONTROLLERCONFIG environment variable with the mapping string, which SDL2 then uses for games that use SDL2 and are launched from Steam. So "mapping" refers to "Button 3 corresponds to SDL_CONTROLLER_BUTTON_A, Axis 2 corresponds to SDL_CONTROLLER_AXIS_RIGHTX" and so on, not to standard actions. No idea if standard action mappings are available on Steam/Linux, but if they are that's something provided by Steamworks SDK, not by SDL2. BTW: https://joostdevblog.blogspot.de/2012/08/the-craziness-that-is-joysticks-on-pc.html is an interesting read about how handling joysticks and similar input devices sucks (only difference is that now with SDL2 it's a a bit better for gamepads). Cheers, Daniel On 01.12.2016 18:22, Ed Phillips wrote:
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SDL_Controller design |
Alex Szpakowski
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The SDL_GameController API is so your code can determine that e.g. the left trigger on a controller is held down, no matter what controller-like device is used and no matter what OS or drivers are used (for example the button and axis indices reported by the Xbox 360 controller on Windows are different than those reported when using the Tattiebogle driver for the 360 on macOS).
The latest SDL source code has an API in SDL_Joystick to get the vendor and product IDs of a joystick. That’s what you’d want to use if you want to display different button prompts (images and text) depending on what controller is actually used. _______________________________________________ SDL mailing list http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org |
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