From 5311486a9ab56a6a5b03915e8834eade35924061 Mon Sep 17 00:00:00 2001
From: Nintorch <[EMAIL REDACTED]>
Date: Sat, 11 Jul 2026 11:49:03 +0500
Subject: [PATCH] Emscripten: Convert joystick axis 9 to a hat
(cherry picked from commit d11e3e087a2313369ce853268366df749ec805e4)
---
src/joystick/emscripten/SDL_sysjoystick.c | 73 ++++++++++++++++-----
src/joystick/emscripten/SDL_sysjoystick_c.h | 3 +-
2 files changed, 58 insertions(+), 18 deletions(-)
diff --git a/src/joystick/emscripten/SDL_sysjoystick.c b/src/joystick/emscripten/SDL_sysjoystick.c
index 3d8339c8aa43e..6e51cb65c6a4a 100644
--- a/src/joystick/emscripten/SDL_sysjoystick.c
+++ b/src/joystick/emscripten/SDL_sysjoystick.c
@@ -155,13 +155,38 @@ static void SDL_GetEmscriptenNormalizedName(int device_index, char *out, int len
}, device_index, out, length);
}
+#define IS_EQUAL_APPROX(a, b) (((a)-(b)) < 0.00001 && ((a)-(b)) > -0.00001)
+static Uint8 SDL_GetHatFromEmscriptenAxis(float hat_axis)
+{
+ if (IS_EQUAL_APPROX(hat_axis, -7.0/7)) {
+ return SDL_HAT_UP;
+ } else if (IS_EQUAL_APPROX(hat_axis, -5.0/7)) {
+ return SDL_HAT_UP | SDL_HAT_RIGHT;
+ } else if (IS_EQUAL_APPROX(hat_axis, -3.0/7)) {
+ return SDL_HAT_RIGHT;
+ } else if (IS_EQUAL_APPROX(hat_axis, -1.0/7)) {
+ return SDL_HAT_DOWN | SDL_HAT_RIGHT;
+ } else if (IS_EQUAL_APPROX(hat_axis, 1.0/7)) {
+ return SDL_HAT_DOWN;
+ } else if (IS_EQUAL_APPROX(hat_axis, 3.0/7)) {
+ return SDL_HAT_DOWN | SDL_HAT_LEFT;
+ } else if (IS_EQUAL_APPROX(hat_axis, 5.0/7)) {
+ return SDL_HAT_LEFT;
+ } else if (IS_EQUAL_APPROX(hat_axis, 7.0/7)) {
+ return SDL_HAT_UP | SDL_HAT_LEFT;
+ } else {
+ return SDL_HAT_CENTERED;
+ }
+}
+#undef IS_EQUAL_APPROX
+
static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamepadEvent *gamepadEvent, void *userData)
{
SDL_joylist_item *item;
int i;
Uint16 bus;
Uint16 vendor, product;
- Uint8 os_id;
+ Uint8 os_id, subtype;
bool is_xinput;
char name[128];
@@ -185,6 +210,7 @@ static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamep
is_xinput = SDL_IsEmscriptenJoystickXInput(gamepadEvent->index);
os_id = SDL_GetEmscriptenOSID();
+ subtype = os_id;
item->trigger_rumble_available = MAIN_THREAD_EM_ASM_INT({
let gamepad = navigator['getGamepads']()[$0];
@@ -220,7 +246,7 @@ static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamep
if (SDL_strcmp(gamepadEvent->mapping, "standard") == 0) {
// We should differentiate between devices that are mapped or unmapped by the browser.
- os_id += 0x80;
+ subtype += 0x80;
}
SDL_GetEmscriptenNormalizedName(gamepadEvent->index, name, sizeof(name));
@@ -231,10 +257,10 @@ static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamep
}
if (vendor && product) {
- item->guid = SDL_CreateJoystickGUID(bus, vendor, product, 0, NULL, name, 0, os_id);
+ item->guid = SDL_CreateJoystickGUID(bus, vendor, product, 0, NULL, name, 0, subtype);
} else {
item->guid = SDL_CreateJoystickGUIDForName(item->name);
- item->guid.data[15] = os_id;
+ item->guid.data[15] = subtype;
}
item->mapping = SDL_strdup(gamepadEvent->mapping);
@@ -263,12 +289,16 @@ static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamep
// dump the digital trigger buttons in any case.
first_trigger_button = 6;
num_buttons -= 2;
+ } else if ((SDL_strcmp(gamepadEvent->mapping, "standard") != 0) && (num_axes >= 10) && (os_id == 5)) {
+ // The browsers (Chromium and Firefox) on Windows usually convert the hat on unmapped controllers to axis 9
+ // We can't know for sure that this axis is a hat, but most of the time it is
+ item->hat_is_axis = true;
}
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->nhats = (first_hat_button >= 0 || item->hat_is_axis) ? 1 : 0;
item->naxes = num_axes;
item->nbuttons = num_buttons;
item->device_instance = SDL_GetNextObjectID();
@@ -295,7 +325,7 @@ static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamep
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.
+ SDL_assert(item->nhats <= 1); // there is (currently) only ever one of these, faked from the d-pad buttons or the axis 9.
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.
@@ -312,6 +342,9 @@ static EM_BOOL Emscripten_JoyStickConnected(int eventType, const EmscriptenGamep
value |= SDL_HAT_RIGHT;
}
item->hat = value;
+ } else if (item->hat_is_axis) {
+ item->hat = SDL_GetHatFromEmscriptenAxis(gamepadEvent->axis[9]);
+ item->axis[9] = 0.0;
}
if (!SDL_joylist_tail) {
@@ -617,6 +650,9 @@ static void EMSCRIPTEN_JoystickUpdate(SDL_Joystick *joystick)
}
for (i = 0; i < real_axis_count; i++) {
+ if (item->hat_is_axis && i == 9) {
+ continue; // this axis is a hat
+ }
if (item->axis[i] != gamepadState.axis[i]) {
SDL_SendJoystickAxis(timestamp, item->joystick, i, (Sint16)(32767.0f * gamepadState.axis[i]));
item->axis[i] = gamepadState.axis[i];
@@ -635,16 +671,20 @@ static void EMSCRIPTEN_JoystickUpdate(SDL_Joystick *joystick)
SDL_assert(item->nhats <= 1); // there is (currently) only ever one of these, faked from the d-pad buttons.
if (item->nhats) {
Uint8 value = SDL_HAT_CENTERED;
- // this currently expects the first button to be up, then down, then left, then right.
- if (gamepadState.digitalButton[first_hat_button + 0]) {
- value |= SDL_HAT_UP;
- } else if (gamepadState.digitalButton[first_hat_button + 1]) {
- value |= SDL_HAT_DOWN;
- }
- if (gamepadState.digitalButton[first_hat_button + 2]) {
- value |= SDL_HAT_LEFT;
- } else if (gamepadState.digitalButton[first_hat_button + 3]) {
- value |= SDL_HAT_RIGHT;
+ if (first_hat_button >= 0) {
+ // this currently expects the first button to be up, then down, then left, then right.
+ if (gamepadState.digitalButton[first_hat_button + 0]) {
+ value |= SDL_HAT_UP;
+ } else if (gamepadState.digitalButton[first_hat_button + 1]) {
+ value |= SDL_HAT_DOWN;
+ }
+ if (gamepadState.digitalButton[first_hat_button + 2]) {
+ value |= SDL_HAT_LEFT;
+ } else if (gamepadState.digitalButton[first_hat_button + 3]) {
+ value |= SDL_HAT_RIGHT;
+ }
+ } else if (item->hat_is_axis) {
+ value = SDL_GetHatFromEmscriptenAxis(gamepadState.axis[9]);
}
if (item->hat != value) {
item->hat = value;
@@ -652,7 +692,6 @@ static void EMSCRIPTEN_JoystickUpdate(SDL_Joystick *joystick)
}
}
-
item->timestamp = gamepadState.timestamp;
}
}
diff --git a/src/joystick/emscripten/SDL_sysjoystick_c.h b/src/joystick/emscripten/SDL_sysjoystick_c.h
index c23d544748e0f..86fafb0855701 100644
--- a/src/joystick/emscripten/SDL_sysjoystick_c.h
+++ b/src/joystick/emscripten/SDL_sysjoystick_c.h
@@ -37,6 +37,7 @@ typedef struct SDL_joylist_item
int first_hat_button;
int first_trigger_button;
bool triggers_are_buttons;
+ bool hat_is_axis;
int nhats;
SDL_GUID guid;
int nbuttons;
@@ -45,7 +46,7 @@ typedef struct SDL_joylist_item
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.
+ Uint8 hat; // there is (currently) only ever one of these, faked from the d-pad buttons or the axis 9.
bool rumble_available;
bool trigger_rumble_available;
Uint16 weak_magnitude_rumble;