Joystick won't work using SDL - events

Question

I'm building a simple game in SDL. I've been through countless tutorials and I've clearly missed something as it still ignoring my Joystick completely
In my constructor
SDL_JoystickEventState(SDL_ENABLE);
joystick = SDL_JoystickOpen(0);
In my update I'm calling a test to check I have actually initialized the joystick
if (SDL_NumJoysticks() <= 0)
{
done = true;
}
Here is my player update as well
void World::playerMovement()
{
SDL_Event event;
while (SDL_PollEvent (&event))
{
switch (event.type)
{
case SDL_QUIT:
done = true;
break;
case SDL_JOYAXISMOTION:
if ( ( event.jaxis.value < -3200 ) || (event.jaxis.value > 3200 ) )
{
test = true;
}
break;
}
}
}
Test is simply a bool which once true will mean my enemies start spawning. I also run a check in main
if (SDL_Init( SDL_INIT_VIDEO | SDL_INIT_JOYSTICK ) < 0)
{
fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
done = true;
}
When I run the game it loads as normal but no matter how much I move the joystick it won't set test to true.
I also tried using the following in the while poll event loop instead.
if (event.type == SDL_JOYAXISMOTION)
{
if(SDL_JoystickGetAxis(joystick, 1) > 0)
{
test = true;
}
}
Any idea's what I have missed?

Answer 1

I think emartel has the best answer to make sure SDL_joystick is working.
When does World::playerMovement() happen? The overall flow of your program is hard to determine from these snippets.
I'm happy to share with you my code for handling joysticks, which keeps track of: multiple joysticks, axes scaled [-1,1] with deadzone removed, and buttons held down.
http://www.raptor007.com/code/RaptorEngine_Joystick.zip
And here's a snippet of how that would be utilized as part of your main loop:
// FIXME: SDL needs to be initialized before we get here.
JoystickManager Joy;
Joy.Initialize();
double deadzone = 0.02;
// Main loop.
bool done = false;
while( ! done )
{
// Keep the list of joysticks up-to-date.
Joy.FindJoysticks();
// Handle all user input.
SDL_Event event;
while( SDL_PollEvent( &event ) )
{
// Let the JoystickManager track events relevant to it.
Joy.TrackEvent( &event );
// FIXME: Handle single-press events here (next target, etc).
// Don't handle button-held-down events like firing (see below).
if( event.type == SDL_QUIT )
done = true;
}
// Read joystick 0 analog axes.
double roll = Joy.Axis( 0, 0, deadzone );
double pitch = Joy.Axis( 0, 1, deadzone );
double yaw = Joy.Axis( 0, 3, deadzone );
double throttle = Joy.AxisScaled( 0, 2, 1., 0., 0., deadzone );
// Read joystick 0 buttons held down.
bool firing = Joy.ButtonDown( 0, 0 );
// FIXME: Update game objects and draw graphics.
}

Answer 2

I found a weird behaviour in SDL2:
If no events are put into the queue, try adding the following before the SDL_Init call:
SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS,"1");

Answer 3

Are you sure joystick points to a valid joystick?
You state that you're getting it in your Constructor... does that contructor happen to be called before you initialize SDL with SDL_INIT_JOYSTICK? This could happen if your player is a global variable.
Make sure that in order you:
Init the Joystick subsystem, either by adding it to your SDL_Init with | SDL_INIT_JOYSTICK or by calling SDL_InitSubSystem(SDL_INIT_JOYSTICK);
Check SDL_NumJoysticks() > 0
Get joystick 0: joystick = SDL_JoystickOpen(0);
Enable events: SDL_JoystickEventState(SDL_ENABLE);
Process your events with SDL_PollEvent
At the end of your program, close your joystick: SDL_JoystickClose(joystick);
Also, make sure the joystick is properly detected in Windows and reports its inputs properly.

Answer 4

Looks like your SDL isn't init proper.
replace
SDL_Init(SDL_INIT_VIDEO | SDL_INIT_JOYSTICK)
with
SDL_Init(SDL_INIT_EVERYTHING)

Answer 5

Is this SDL 1.2 or 2.0? In my case, on 2.0 SDL_PollEvent(&event) didn't actually put any data in the event struct. After that call, I had to use SDL_JoystickGetAxis(joystick_id, axis) and friends to get data.
So in your case, try to move the SDL_JoystickGetAxis call out of the if-test on event-type.

Answer 6

If you call SDL_NumJoysticks to get the number of controllers connected, then call SDL_JoystickOpen which returns a joystick identifier before your game loop then you will receive the SDL_JOYAXISMOTION events.
e.g.
int num_joy;
num_joy = SDL_NumJoysticks();
printf("%d joysticks found\n", num_joy);
for(int i = 0; i < num_joy; i++)
{
SDL_Joystick *joystick = SDL_JoystickOpen(i);
printf("Joystick name: %s\n", SDL_JoystickName(joystick));
}
SDL_Event event;
bool quit = false;
// Game loop
while(!quit)
{
// event loop
while(SDL_PollEvent(&event))
{
if (event.type == SDL_JOYAXISMOTION)
{
printf("Joystick______EVENT!\n");
}
// etc.....
See https://wiki.libsdl.org/SDL_JoystickName

Answer 7

I do not know how this can help you, but I do know that pygame supports joystick. And pygame is the python port of the SDL library. If everything fails, I guess you can always write that particular piece of code in python.