SDL allows us to poll for keyboard input. Whenever the user presses a key, a call to SDL_PollEvent( &event ) will return us an SDK_KEYDOWN SDL_Event. When a key is released, it will return an SDK_KEYUP event. We can look into the values in such a case to figure out which key has been pressed or released. We can use this information to set flags in our game to let us know when to move our spaceship, and in what direction. Later, we can add code that detects a space bar press that will fire our ship's weapons.
For now, we are going to go back to using the default Emscripten shell. For the rest of this section, we will be able to do everything from within the WebAssembly C code. I will walk you through creating a new keyboard.c file from scratch, which will handle keyboard events and print to the textarea in our default shell.
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