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emscripten: Support analog gamepad triggers on both Firefox and Chrome.

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Fixes #13051.
This commit is contained in:
Ryan C. Gordon
2025-09-12 14:19:57 -04:00
parent 3c627390bb
commit 614ae1b115
3 changed files with 55 additions and 20 deletions
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2
src/joystick/SDL_gamepad_db.h
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@@ -897,7 +897,7 @@ static const char *s_GamepadMappings[] = {
"050000005e040000e0020000ff070000,Xbox Wireless Controller,a:b0,b:b1,back:b8,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,dpup:h0.1,guide:b9,leftshoulder:b4,leftstick:b6,lefttrigger:a2,leftx:a0,lefty:a1,rightshoulder:b5,rightstick:b7,righttrigger:a5,rightx:a3,righty:a4,start:b10,x:b2,y:b3,",
#endif
#ifdef SDL_JOYSTICK_EMSCRIPTEN
"default,Standard Gamepad,a:b0,b:b1,back:b8,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,dpup:h0.1,guide:b12,leftshoulder:b4,leftstick:b10,lefttrigger:b6,leftx:a0,lefty:a1,rightshoulder:b5,rightstick:b11,righttrigger:b7,rightx:a2,righty:a3,start:b9,x:b2,y:b3,",
"default,Standard Gamepad,a:b0,b:b1,back:b6,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,dpup:h0.1,guide:b10,leftshoulder:b4,leftstick:b8,lefttrigger:a4,leftx:a0,lefty:a1,rightshoulder:b5,rightstick:b9,righttrigger:a5,rightx:a2,righty:a3,start:b7,x:b2,y:b3,",
#endif
#ifdef SDL_JOYSTICK_PS2
"0000000050533220436f6e74726f6c00,PS2 Controller,crc:ed87,a:b14,b:b13,back:b0,dpdown:b6,dpleft:b7,dpright:b5,dpup:b4,leftshoulder:b10,leftstick:b1,lefttrigger:b8,leftx:a0,lefty:a1,rightshoulder:b11,rightstick:b2,righttrigger:b9,rightx:a2,righty:a3,start:b3,x:b15,y:b12,",

69
src/joystick/emscripten/SDL_sysjoystick.c
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@@ -66,36 +66,59 @@ static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamep
goto done;
}
const int real_button_count = gamepadEvent->numButtons;
const int real_axis_count = gamepadEvent->numAxes;
int first_trigger_button = -1;
int first_hat_button = -1;
int num_buttons = gamepadEvent->numButtons;
if ((SDL_strcmp(gamepadEvent->mapping, "standard") == 0) && (num_buttons >= 16)) { // maps to a game console gamepad layout, turn the d-pad into a hat.
num_buttons -= 4;
int num_axes = gamepadEvent->numAxes;
bool triggers_are_buttons = false;
if ((SDL_strcmp(gamepadEvent->mapping, "standard") == 0) && (num_buttons >= 16)) { // maps to a game console gamepad layout, turn the d-pad into a hat, treat triggers as analog.
num_buttons -= 4; // 4 dpad buttons become a hat.
first_hat_button = 12;
if (num_axes == 4) { // Chrome gives the triggers analog button values, Firefox exposes them as extra axes. Both have the digital buttons.
num_axes += 2; // the two trigger "buttons"
triggers_are_buttons = true;
}
// dump the digital trigger buttons in any case.
first_trigger_button = 6;
num_buttons -= 2;
}
item->first_hat_button = first_hat_button;
item->first_trigger_button = first_trigger_button;
item->triggers_are_buttons = triggers_are_buttons;
item->nhats = (first_hat_button >= 0) ? 1 : 0;
item->naxes = gamepadEvent->numAxes;
item->naxes = num_axes;
item->nbuttons = num_buttons;
item->device_instance = SDL_GetNextObjectID();
item->timestamp = gamepadEvent->timestamp;
for (i = 0; i < item->naxes; i++) {
item->axis[i] = gamepadEvent->axis[i];
}
int buttonidx = 0;
for (i = 0; i < item->nbuttons; i++, buttonidx++) {
for (i = 0; i < real_button_count; i++, buttonidx++) {
if (buttonidx == first_hat_button) {
buttonidx += 3; // skip these buttons, we're treating them as hat input.
buttonidx += 4; // skip these buttons, we're treating them as hat input.
} else if (buttonidx == first_trigger_button) {
buttonidx += 2; // skip these buttons, we're treating them as axes.
}
item->analogButton[i] = gamepadEvent->analogButton[buttonidx];
item->digitalButton[i] = gamepadEvent->digitalButton[buttonidx];
}
for (i = 0; i < real_axis_count; i++) {
item->axis[i] = gamepadEvent->axis[i];
}
if (item->triggers_are_buttons) {
item->axis[real_axis_count] = (gamepadEvent->analogButton[first_trigger_button] * 2.0f) - 1.0f;
item->axis[real_axis_count+1] = (gamepadEvent->analogButton[first_trigger_button+1] * 2.0f) - 1.0f;
}
SDL_assert(item->nhats <= 1); // there is (currently) only ever one of these, faked from the d-pad buttons.
if (item->nhats) {
if (first_hat_button != -1) {
Uint8 value = SDL_HAT_CENTERED;
// this currently expects the first button to be up, then down, then left, then right.
if (gamepadEvent->digitalButton[first_hat_button + 0]) {
@@ -393,14 +416,19 @@ static void EMSCRIPTEN_JoystickUpdate(SDL_Joystick *joystick)
if (result == EMSCRIPTEN_RESULT_SUCCESS) {
if (gamepadState.timestamp == 0 || gamepadState.timestamp != item->timestamp) {
const int first_hat_button = item->first_hat_button;
const int first_trigger_button = item->first_trigger_button;
const int real_button_count = gamepadState.numButtons;
const int real_axis_count = gamepadState.numAxes;
int buttonidx = 0;
for (i = 0; i < item->nbuttons; i++, buttonidx++) {
for (i = 0; i < real_button_count; i++, buttonidx++) {
if (buttonidx == first_hat_button) {
buttonidx += 4; // skip these buttons, we're treating them as hat input.
} else if (buttonidx == first_trigger_button) {
buttonidx += 2; // skip these buttons, we're treating them as axes.
}
if (item->digitalButton[i] != gamepadState.digitalButton[buttonidx]) {
bool down = (gamepadState.digitalButton[buttonidx] != 0);
const bool down = (gamepadState.digitalButton[buttonidx] != 0);
SDL_SendJoystickButton(timestamp, item->joystick, i, down);
}
@@ -409,15 +437,20 @@ static void EMSCRIPTEN_JoystickUpdate(SDL_Joystick *joystick)
item->digitalButton[i] = gamepadState.digitalButton[buttonidx];
}
for (i = 0; i < item->naxes; i++) {
for (i = 0; i < real_axis_count; i++) {
if (item->axis[i] != gamepadState.axis[i]) {
// do we need to do conversion?
SDL_SendJoystickAxis(timestamp, item->joystick, i,
(Sint16)(32767. * gamepadState.axis[i]));
SDL_SendJoystickAxis(timestamp, item->joystick, i, (Sint16)(32767.0f * gamepadState.axis[i]));
item->axis[i] = gamepadState.axis[i];
}
}
// store to compare in next update
item->axis[i] = gamepadState.axis[i];
if (item->triggers_are_buttons) {
for (i = 0; i < 2; i++) {
if (item->axis[real_axis_count+i] != gamepadState.analogButton[first_trigger_button+i]) {
SDL_SendJoystickAxis(timestamp, item->joystick, real_axis_count+i, (Sint16)(32767.0f * ((gamepadState.analogButton[first_trigger_button+i] * 2.0f) - 1.0f)));
item->axis[real_axis_count+i] = gamepadState.analogButton[first_trigger_button+i];
}
}
}
SDL_assert(item->nhats <= 1); // there is (currently) only ever one of these, faked from the d-pad buttons.

4
src/joystick/emscripten/SDL_sysjoystick_c.h
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@@ -35,11 +35,13 @@ typedef struct SDL_joylist_item
SDL_JoystickID device_instance;
SDL_Joystick *joystick;
int first_hat_button;
int first_trigger_button;
bool triggers_are_buttons;
int nhats;
int nbuttons;
int naxes;
double timestamp;
double axis[64];
double axis[64]; // !!! FIXME: don't hardcode 64 on all of these.
double analogButton[64];
EM_BOOL digitalButton[64];
Uint8 hat; // there is (currently) only ever one of these, faked from the d-pad buttons.