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Add gamepad support to woodeneye-008 #14167

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5db327a
Add gamepad support to woodeneye-008
ccawley2011 Oct 6, 2025
39c5dce
examples/demo/02-woodeneye-008: check gamepad sticks each frame, not …
icculus Nov 8, 2025
32563c2
examples/demo/02-woodeneye-008: use right stick for camera, not left.
icculus Nov 8, 2025
3e2ff3f
examples/demo/02-woodeneye-008: Minor coding style tweaks.
icculus Nov 8, 2025
90874fa
demo/02-woodeneye-008/woodeneye-008: ignore gamepad stick deadzones.
icculus Nov 8, 2025
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105 changes: 101 additions & 4 deletions examples/demo/02-woodeneye-008/woodeneye-008.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
typedef struct {
SDL_MouseID mouse;
SDL_KeyboardID keyboard;
SDL_Gamepad *gamepad;
double pos[3];
double vel[3];
unsigned int yaw;
Expand Down Expand Up @@ -46,7 +47,9 @@ static int whoseMouse(SDL_MouseID mouse, const Player players[], int players_len
{
int i;
for (i = 0; i < players_len; i++) {
if (players[i].mouse == mouse) return i;
if (players[i].mouse == mouse) {
return i;
}
}
return -1;
}
Expand All @@ -55,7 +58,20 @@ static int whoseKeyboard(SDL_KeyboardID keyboard, const Player players[], int pl
{
int i;
for (i = 0; i < players_len; i++) {
if (players[i].keyboard == keyboard) return i;
if (players[i].keyboard == keyboard) {
return i;
}
}
return -1;
}

static int whoseGamepad(SDL_JoystickID gamepad, const Player players[], int players_len)
{
int i;
for (i = 0; i < players_len; i++) {
if (SDL_GetGamepadID(players[i].gamepad) == gamepad) {
return i;
}
}
return -1;
}
Expand Down Expand Up @@ -101,9 +117,31 @@ static void shoot(int shooter, Player players[], int players_len)
}
}

static void updatePlayerGamepad(Player *player)
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@expikr expikr Nov 8, 2025

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I suggest have this function also handle the left stick to save a 2d direction as an extra field in the player struct representing the current frame’s intended joystick input, akin to how WASD is sampled each frame. It should then be combined with the normalized WASD vector to calculate the final X and Z acceleration

{
if (player->gamepad) {
const int rightx = (int)SDL_GetGamepadAxis(player->gamepad, SDL_GAMEPAD_AXIS_RIGHTX);
const int righty = (int)SDL_GetGamepadAxis(player->gamepad, SDL_GAMEPAD_AXIS_RIGHTY);
if ((SDL_abs(rightx) > 0x1000) || (SDL_abs(righty) > 0x1000)) { /* ignore if stick is near center, since it might be noise and the user is actually using the mouse, etc. */
player->yaw -= rightx * 0x00000800;
player->pitch = SDL_max(-0x40000000, SDL_min(0x40000000, player->pitch - righty * 0x00000800));
}
}
}

static void update(Player *players, int players_len, Uint64 dt_ns)
{
static int gamepad_update_ticks = 0;
const Uint64 now = SDL_GetTicks();
int i;

if ((now - gamepad_update_ticks) >= 16) { /* only update joysticks at about 60Hz so framerate doesn't matter. */
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@expikr expikr Nov 8, 2025 •
edited
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Should just forward dt_ns to the gamepad function which multiplies it by the desired angular velocity to get the targeted angular displacement in floats, and the function should return two floats representing residual angles to be carried over next frame, saved as extra fields in the player struct.

gamepad_update_ticks += 16;
for (i = 0; i < players_len; i++) {
updatePlayerGamepad(&players[i]); /* check current gamepad state before we do any processing. */
}
}

for (i = 0; i < players_len; i++) {
Player *player = &players[i];
double rate = 6.0;
Expand Down Expand Up @@ -288,6 +326,7 @@ static void initPlayers(Player *players, int len)
players[i].wasd = 0;
players[i].mouse = 0;
players[i].keyboard = 0;
players[i].gamepad = NULL;
players[i].color[0] = (1 << (i / 2)) & 2 ? 0 : 0xff;
players[i].color[1] = (1 << (i / 2)) & 1 ? 0 : 0xff;
players[i].color[2] = (1 << (i / 2)) & 4 ? 0 : 0xff;
Expand Down Expand Up @@ -344,7 +383,7 @@ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
*appstate = as;
}

if (!SDL_Init(SDL_INIT_VIDEO)) {
if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_GAMEPAD)) {
return SDL_APP_FAILURE;
}
if (!SDL_CreateWindowAndRenderer("examples/demo/woodeneye-008", 640, 480, SDL_WINDOW_RESIZABLE, &as->window, &as->renderer)) {
Expand Down Expand Up @@ -386,6 +425,25 @@ SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
}
}
break;
case SDL_EVENT_GAMEPAD_REMOVED:
for (i = 0; i < player_count; i++) {
if (players[i].gamepad && (SDL_GetGamepadID(players[i].gamepad) == event->gdevice.which)) {
SDL_CloseGamepad(players[i].gamepad);
players[i].gamepad = NULL;
}
}
break;
case SDL_EVENT_GAMEPAD_ADDED:
for (i = 0; i < player_count; i++) {
if (players[i].gamepad == NULL) {
players[i].gamepad = SDL_OpenGamepad(event->gdevice.which);
if (!players[i].gamepad)
SDL_Log("Failed to open gamepad ID %u: %s", (unsigned int) event->gdevice.which, SDL_GetError());
else
as->player_count = SDL_max(as->player_count, i + 1);
}
}
break;
case SDL_EVENT_MOUSE_MOTION: {
SDL_MouseID id = event->motion.which;
int index = whoseMouse(id, players, player_count);
Expand Down Expand Up @@ -446,6 +504,36 @@ SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
}
break;
}

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@expikr expikr Nov 8, 2025

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Just get rid of dpad events entirely, use the left stick for analog movement instead.

/* We query the gamepad sticks every frame, so we don't check for SDL_EVENT_GAMEPAD_AXIS_MOTION here. */

case SDL_EVENT_GAMEPAD_BUTTON_DOWN: {
Uint8 button = event->gbutton.button;
SDL_JoystickID id = event->gbutton.which;
int index = whoseGamepad(id, players, player_count);
if (index >= 0) {
if (button == SDL_GAMEPAD_BUTTON_DPAD_UP) players[index].wasd |= 1;
if (button == SDL_GAMEPAD_BUTTON_DPAD_LEFT) players[index].wasd |= 2;
if (button == SDL_GAMEPAD_BUTTON_DPAD_DOWN) players[index].wasd |= 4;
if (button == SDL_GAMEPAD_BUTTON_DPAD_RIGHT) players[index].wasd |= 8;
if (button == SDL_GAMEPAD_BUTTON_SOUTH) players[index].wasd |= 16;
if (button == SDL_GAMEPAD_BUTTON_EAST) shoot(index, players, player_count);
}
break;
}
case SDL_EVENT_GAMEPAD_BUTTON_UP: {
Uint8 button = event->gbutton.button;
SDL_JoystickID id = event->gbutton.which;
int index = whoseGamepad(id, players, player_count);
if (index >= 0) {
if (button == SDL_GAMEPAD_BUTTON_DPAD_UP) players[index].wasd &= 30;
if (button == SDL_GAMEPAD_BUTTON_DPAD_LEFT) players[index].wasd &= 29;
if (button == SDL_GAMEPAD_BUTTON_DPAD_DOWN) players[index].wasd &= 27;
if (button == SDL_GAMEPAD_BUTTON_DPAD_RIGHT) players[index].wasd &= 23;
if (button == SDL_GAMEPAD_BUTTON_SOUTH) players[index].wasd &= 15;
}
break;
}
}
return SDL_APP_CONTINUE;
}
Expand Down Expand Up @@ -476,5 +564,14 @@ SDL_AppResult SDL_AppIterate(void *appstate)

void SDL_AppQuit(void *appstate, SDL_AppResult result)
{
AppState *as = appstate;
Player *players = as->players;
int player_count = as->player_count;
int i;
for (i = 0; i < player_count; i++) {
if (players[i].gamepad) {
SDL_CloseGamepad(players[i].gamepad);
}
}
SDL_free(appstate); // just free the memory, SDL will clean up the window/renderer for us.
}
}
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