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linux: Improve gamepad mapping heuristic to accept Android conventions #7797

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merged 2 commits into from
Jun 13, 2023
Merged

linux: Improve gamepad mapping heuristic to accept Android conventions #7797

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49cec22
linux: Reduce magic numbers when mapping gamepad axes
smcv Jun 9, 2023
5804fcd
linux: Improve gamepad mapping heuristic to accept Android conventions
smcv Jun 9, 2023
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97 changes: 80 additions & 17 deletions src/joystick/linux/SDL_sysjoystick.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1608,11 +1608,24 @@ static void LINUX_JoystickQuit(void)
/*
This is based on the Linux Gamepad Specification
available at: https://www.kernel.org/doc/html/v4.15/input/gamepad.html
and the Android gamepad documentation,
https://developer.android.com/develop/ui/views/touch-and-input/game-controllers/controller-input
*/
static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMapping *out)
{
SDL_Joystick *joystick;
SDL_joylist_item *item = GetJoystickByDevIndex(device_index);
enum {
MAPPED_TRIGGER_LEFT = 0x1,
MAPPED_TRIGGER_RIGHT = 0x2,
MAPPED_TRIGGER_BOTH = 0x3,

MAPPED_DPAD_UP = 0x1,
MAPPED_DPAD_DOWN = 0x2,
MAPPED_DPAD_LEFT = 0x4,
MAPPED_DPAD_RIGHT = 0x8,
MAPPED_DPAD_ALL = 0xF,
};
unsigned int mapped;

SDL_AssertJoysticksLocked();
Expand Down Expand Up @@ -1817,63 +1830,94 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
/* Prefer analog triggers, but settle for digital hat or buttons. */
mapped = 0;

/* Unfortunately there are several conventions for how analog triggers
* are represented as absolute axes:
*
* - Linux Gamepad Specification:
* LT = ABS_HAT2Y, RT = ABS_HAT2X
* - Android (and therefore many Bluetooth controllers):
* LT = ABS_BRAKE, RT = ABS_GAS
* - De facto standard for older Xbox and Playstation controllers:
* LT = ABS_Z, RT = ABS_RZ
*
* We try each one in turn. */
if (joystick->hwdata->has_abs[ABS_HAT2Y]) {
/* Linux Gamepad Specification */
out->lefttrigger.kind = EMappingKind_Axis;
out->lefttrigger.target = joystick->hwdata->abs_map[ABS_HAT2Y];
mapped |= 0x1;
mapped |= MAPPED_TRIGGER_LEFT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped LEFTTRIGGER to axis %d (ABS_HAT2Y)", out->lefttrigger.target);
#endif
} else if (joystick->hwdata->has_abs[ABS_BRAKE]) {
/* Android convention */
out->lefttrigger.kind = EMappingKind_Axis;
out->lefttrigger.target = joystick->hwdata->abs_map[ABS_BRAKE];
mapped |= MAPPED_TRIGGER_LEFT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped LEFTTRIGGER to axis %d (ABS_BRAKE)", out->lefttrigger.target);
#endif
} else if (joystick->hwdata->has_abs[ABS_Z]) {
/* De facto standard for Xbox 360 and Playstation gamepads */
out->lefttrigger.kind = EMappingKind_Axis;
out->lefttrigger.target = joystick->hwdata->abs_map[ABS_Z];
mapped |= 0x1;
mapped |= MAPPED_TRIGGER_LEFT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped LEFTTRIGGER to axis %d (ABS_Z)", out->lefttrigger.target);
#endif
}

if (joystick->hwdata->has_abs[ABS_HAT2X]) {
/* Linux Gamepad Specification */
out->righttrigger.kind = EMappingKind_Axis;
out->righttrigger.target = joystick->hwdata->abs_map[ABS_HAT2X];
mapped |= 0x2;
mapped |= MAPPED_TRIGGER_RIGHT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped RIGHTTRIGGER to axis %d (ABS_HAT2X)", out->righttrigger.target);
#endif
} else if (joystick->hwdata->has_abs[ABS_GAS]) {
/* Android convention */
out->righttrigger.kind = EMappingKind_Axis;
out->righttrigger.target = joystick->hwdata->abs_map[ABS_GAS];
mapped |= MAPPED_TRIGGER_RIGHT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped RIGHTTRIGGER to axis %d (ABS_GAS)", out->righttrigger.target);
#endif
} else if (joystick->hwdata->has_abs[ABS_RZ]) {
/* De facto standard for Xbox 360 and Playstation gamepads */
out->righttrigger.kind = EMappingKind_Axis;
out->righttrigger.target = joystick->hwdata->abs_map[ABS_RZ];
mapped |= 0x2;
mapped |= MAPPED_TRIGGER_RIGHT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped RIGHTTRIGGER to axis %d (ABS_RZ)", out->righttrigger.target);
#endif
}

if (mapped != 0x3 && joystick->hwdata->has_hat[2]) {
if (mapped != MAPPED_TRIGGER_BOTH && joystick->hwdata->has_hat[2]) {
int hat = joystick->hwdata->hats_indices[2] << 4;
out->lefttrigger.kind = EMappingKind_Hat;
out->righttrigger.kind = EMappingKind_Hat;
out->lefttrigger.target = hat | 0x4;
out->righttrigger.target = hat | 0x2;
mapped |= 0x3;
mapped |= MAPPED_TRIGGER_BOTH;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped LEFT+RIGHTTRIGGER to hat 2 (ABS_HAT2X, ABS_HAT2Y)");
#endif
}

if (!(mapped & 0x1) && joystick->hwdata->has_key[BTN_TL2]) {
if (!(mapped & MAPPED_TRIGGER_LEFT) && joystick->hwdata->has_key[BTN_TL2]) {
out->lefttrigger.kind = EMappingKind_Button;
out->lefttrigger.target = joystick->hwdata->key_map[BTN_TL2];
mapped |= 0x1;
mapped |= MAPPED_TRIGGER_LEFT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped LEFTTRIGGER to button %d (BTN_TL2)", out->lefttrigger.target);
#endif
}

if (!(mapped & 0x2) && joystick->hwdata->has_key[BTN_TR2]) {
if (!(mapped & MAPPED_TRIGGER_LEFT) && joystick->hwdata->has_key[BTN_TR2]) {
out->righttrigger.kind = EMappingKind_Button;
out->righttrigger.target = joystick->hwdata->key_map[BTN_TR2];
mapped |= 0x2;
mapped |= MAPPED_TRIGGER_RIGHT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped RIGHTTRIGGER to button %d (BTN_TR2)", out->righttrigger.target);
#endif
Expand All @@ -1885,7 +1929,7 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
if (joystick->hwdata->has_key[BTN_DPAD_UP]) {
out->dpup.kind = EMappingKind_Button;
out->dpup.target = joystick->hwdata->key_map[BTN_DPAD_UP];
mapped |= 0x1;
mapped |= MAPPED_DPAD_UP;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped DPUP to button %d (BTN_DPAD_UP)", out->dpup.target);
#endif
Expand All @@ -1894,7 +1938,7 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
if (joystick->hwdata->has_key[BTN_DPAD_DOWN]) {
out->dpdown.kind = EMappingKind_Button;
out->dpdown.target = joystick->hwdata->key_map[BTN_DPAD_DOWN];
mapped |= 0x2;
mapped |= MAPPED_DPAD_DOWN;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped DPDOWN to button %d (BTN_DPAD_DOWN)", out->dpdown.target);
#endif
Expand All @@ -1903,7 +1947,7 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
if (joystick->hwdata->has_key[BTN_DPAD_LEFT]) {
out->dpleft.kind = EMappingKind_Button;
out->dpleft.target = joystick->hwdata->key_map[BTN_DPAD_LEFT];
mapped |= 0x4;
mapped |= MAPPED_DPAD_LEFT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped DPLEFT to button %d (BTN_DPAD_LEFT)", out->dpleft.target);
#endif
Expand All @@ -1912,13 +1956,13 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
if (joystick->hwdata->has_key[BTN_DPAD_RIGHT]) {
out->dpright.kind = EMappingKind_Button;
out->dpright.target = joystick->hwdata->key_map[BTN_DPAD_RIGHT];
mapped |= 0x8;
mapped |= MAPPED_DPAD_RIGHT;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped DPRIGHT to button %d (BTN_DPAD_RIGHT)", out->dpright.target);
#endif
}

if (mapped != 0xF) {
if (mapped != MAPPED_DPAD_ALL) {
if (joystick->hwdata->has_hat[0]) {
int hat = joystick->hwdata->hats_indices[0] << 4;
out->dpleft.kind = EMappingKind_Hat;
Expand All @@ -1929,7 +1973,7 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
out->dpright.target = hat | 0x2;
out->dpup.target = hat | 0x1;
out->dpdown.target = hat | 0x4;
mapped |= 0xF;
mapped |= MAPPED_DPAD_ALL;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped DPUP+DOWN+LEFT+RIGHT to hat 0 (ABS_HAT0X, ABS_HAT0Y)");
#endif
Expand All @@ -1942,7 +1986,7 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
out->dpright.target = joystick->hwdata->abs_map[ABS_HAT0X];
out->dpup.target = joystick->hwdata->abs_map[ABS_HAT0Y];
out->dpdown.target = joystick->hwdata->abs_map[ABS_HAT0Y];
mapped |= 0xF;
mapped |= MAPPED_DPAD_ALL;
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped DPUP+DOWN to axis %d (ABS_HAT0Y)", out->dpup.target);
SDL_Log("Mapped DPLEFT+RIGHT to axis %d (ABS_HAT0X)", out->dpleft.target);
Expand All @@ -1961,14 +2005,33 @@ static SDL_bool LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMap
#endif
}

/* The Linux Gamepad Specification uses the RX and RY axes,
* originally intended to represent X and Y rotation, as a second
* joystick. This is common for USB gamepads, and also many Bluetooth
* gamepads, particularly older ones.
*
* The Android mapping convention used by many Bluetooth controllers
* instead uses the Z axis as a secondary X axis, and the RZ axis as
* a secondary Y axis. */
if (joystick->hwdata->has_abs[ABS_RX] && joystick->hwdata->has_abs[ABS_RY]) {
/* Linux Gamepad Specification, Xbox 360, Playstation etc. */
out->rightx.kind = EMappingKind_Axis;
out->righty.kind = EMappingKind_Axis;
out->rightx.target = joystick->hwdata->abs_map[ABS_RX];
out->righty.target = joystick->hwdata->abs_map[ABS_RY];
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped RIGHTX to axis %d (ABS_RX)", out->rightx.target);
SDL_Log("Mapped RIGHTY to axis %d (ABS_RY)", out->righty.target);
#endif
} else if (joystick->hwdata->has_abs[ABS_Z] && joystick->hwdata->has_abs[ABS_RZ]) {
/* Android convention */
out->rightx.kind = EMappingKind_Axis;
out->righty.kind = EMappingKind_Axis;
out->rightx.target = joystick->hwdata->abs_map[ABS_Z];
out->righty.target = joystick->hwdata->abs_map[ABS_RZ];
#ifdef DEBUG_GAMEPAD_MAPPING
SDL_Log("Mapped RIGHTX to axis %d (ABS_Z)", out->rightx.target);
SDL_Log("Mapped RIGHTY to axis %d (ABS_RZ)", out->righty.target);
#endif
}

Expand Down