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Fixed binding the D-pad on some Super NES style controllers

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Fixed a case where partial trigger pull could be bound to another button

There is a fundamental problem not resolved by this commit:

Some controllers have axes (triggers, pedals, etc.) that don't start at zero, but we're guaranteed that if we get a value that it's correct. For these controllers, the current code works, where we take the first value we get and use that as the zero point and generate axis motion starting from that point on.

Other controllers have digital axes (D-pad) that assume a zero starting point, and the first value we get is the min or max axis value when the D-pad is moved. For these controllers, the current code thinks that the zero point is the axis value after the D-pad motion and this doesn't work.

My hypothesis is that the first class of devices is more common and that we should solve for that, and add an exception to SDL_JoystickAxesCenteredAtZero() as needed for the second class of devices.
This commit is contained in:
Sam Lantinga 2017-01-03 23:39:28 -08:00
parent d359180040
commit 082132a70c
8 changed files with 110 additions and 77 deletions
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67
src/joystick/SDL_joystick.c
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@ -113,6 +113,34 @@ SDL_JoystickNameForIndex(int device_index)
return (SDL_SYS_JoystickNameForDeviceIndex(device_index));
}
/*
* Return true if this joystick is known to have all axes centered at zero
* This isn't generally needed unless the joystick never generates an initial axis value near zero,
* e.g. it's emulating axes with digital buttons
*/
static SDL_bool
SDL_JoystickAxesCenteredAtZero(SDL_Joystick *joystick)
{
struct {
Uint16 vendor;
Uint16 product;
} zero_centered_joysticks[] = {
{ 0x0e8f, 0x3013 }, /* Unknown Super NES USB adapter */
};
int i;
Uint16 vendor = SDL_JoystickGetVendor(joystick);
Uint16 product = SDL_JoystickGetProduct(joystick);
for (i = 0; i < SDL_arraysize(zero_centered_joysticks); ++i) {
if (vendor == zero_centered_joysticks[i].vendor &&
product == zero_centered_joysticks[i].product) {
return SDL_TRUE;
}
}
return SDL_FALSE;
}
/*
* Open a joystick for use - the index passed as an argument refers to
* the N'th joystick on the system. This index is the value which will
@ -192,6 +220,15 @@ SDL_JoystickOpen(int device_index)
}
joystick->epowerlevel = SDL_JOYSTICK_POWER_UNKNOWN;
/* If this joystick is known to have all zero centered axes, skip the auto-centering code */
if (SDL_JoystickAxesCenteredAtZero(joystick)) {
int i;
for (i = 0; i < joystick->naxes; ++i) {
joystick->axes[i].has_initial_value = SDL_TRUE;
}
}
/* Add joystick to list */
++joystick->ref_count;
/* Link the joystick in the list */
@ -597,25 +634,25 @@ int
SDL_PrivateJoystickAxis(SDL_Joystick * joystick, Uint8 axis, Sint16 value)
{
int posted;
const int MAX_ALLOWED_JITTER = SDL_JOYSTICK_AXIS_MAX / 256;
/* Make sure we're not getting garbage or duplicate events */
if (axis >= joystick->naxes) {
return 0;
}
if (value == joystick->axes[axis].value) {
if (!joystick->axes[axis].has_initial_value) {
joystick->axes[axis].value = value;
joystick->axes[axis].zero = value;
joystick->axes[axis].has_initial_value = SDL_TRUE;
}
if (SDL_abs(value - joystick->axes[axis].value) <= MAX_ALLOWED_JITTER) {
return 0;
}
if (!joystick->axes[axis].moved) {
if (joystick->axes[axis].intial_value == 0) {
joystick->axes[axis].intial_value = value;
return 0;
}
if (value == joystick->axes[axis].intial_value) {
return 0;
}
/* We got more than 0 and the initial value from the joystick, consider it as having actually moved */
joystick->axes[axis].moved = SDL_TRUE;
if (!joystick->axes[axis].sent_initial_value) {
int initial_value = joystick->axes[axis].value;
joystick->axes[axis].sent_initial_value = SDL_TRUE;
joystick->axes[axis].value = value; /* Just so we pass the check above */
SDL_PrivateJoystickAxis(joystick, axis, initial_value);
}
/* We ignore events if we don't have keyboard focus, except for centering
@ -798,9 +835,11 @@ SDL_JoystickUpdate(void)
if (joystick->force_recentering) {
int i;
/* Tell the app that everything is centered/unpressed... */
/* Tell the app that everything is centered/unpressed... */
for (i = 0; i < joystick->naxes; i++) {
SDL_PrivateJoystickAxis(joystick, i, joystick->axes[i].zero);
if (joystick->axes[i].has_initial_value) {
SDL_PrivateJoystickAxis(joystick, i, joystick->axes[i].zero);
}
}
for (i = 0; i < joystick->nbuttons; i++) {