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elrsman: Use SDL Gamepad API instead of Joystick API
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The SDL Joystick API was being used incorrectly prior, it doesn't have consistent mappings for across different controllers. The SDL Gamepad API on the other hand is designed to be consistent across different controllers and platforms.
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@PixelyIon
PixelyIon committed Aug 2, 2024
1 parent f1eabbd commit da31414
Showing 1 changed file with 41 additions and 40 deletions.
81 changes: 41 additions & 40 deletions src/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -36,13 +36,13 @@ class ElrsManager {
std::optional<crsf::RcChannelsFrame> channelFrame{};
std::optional<crsf::BatterySensorData> batteryData{};

SDL_Joystick* joystick{};
SDL_Gamepad* gamepad{};
SDL_JoystickID joystickId{};
struct ButtonState {
bool pressed{}; //!< Whether the button is currently pressed, this is necessary to track releases for toggling.
bool toggled{}; //!< Turns true when the button is pressed and false when it is pressed again.
};
std::vector<ButtonState> buttonStates;
std::array<ButtonState, SDL_GAMEPAD_BUTTON_MAX> buttonStates{};
bool showJoystickData{}; //!< Whether to show the joystick input data.

crsf::Device* FindDevice(crsf::Address address) {
Expand Down Expand Up @@ -235,47 +235,46 @@ class ElrsManager {
ImGui::Indent();

SDL_LockJoysticks();
if (joystick && !SDL_JoystickConnected(joystick)) {
SDL_CloseJoystick(joystick);
joystick = nullptr;
if (gamepad && !SDL_GamepadConnected(gamepad)) {
SDL_CloseGamepad(gamepad);
gamepad = nullptr;
}

if (SDL_HasJoystick()) {
int joystickCount{};
auto joysticks{SDL_GetJoysticks(&joystickCount)};
auto joysticks{SDL_GetGamepads(&joystickCount)};

if (joystickId == 0)
joystickId = joysticks[0];

if (ImGui::BeginCombo("Joystick", SDL_GetJoystickName(joystick))) {
if (ImGui::BeginCombo("Gamepad", SDL_GetGamepadName(gamepad))) {
for (int i{}; i < joystickCount; i++) {
SDL_JoystickID id{joysticks[i]};
if (ImGui::Selectable(SDL_GetJoystickNameForID(id), id == joystickId)) {
if (ImGui::Selectable(SDL_GetGamepadNameForID(id), id == joystickId)) {
if (joystickId != id) {
SDL_CloseJoystick(joystick);
joystick = nullptr;
SDL_CloseGamepad(gamepad);
gamepad = nullptr;
joystickId = id;
}
}
}
ImGui::EndCombo();
}

if (!joystick) {
joystick = SDL_OpenJoystick(joystickId);
if (joystick != nullptr) {
fmt::print("Opened joystick: {}\n", SDL_GetJoystickName(joystick));
buttonStates.clear();
buttonStates.resize(SDL_GetNumJoystickButtons(joystick));
if (!gamepad) {
gamepad = SDL_OpenGamepad(joystickId);
if (gamepad != nullptr) {
fmt::print("Opened gamepad: {}\n", SDL_GetGamepadName(gamepad));
buttonStates = {};
} else {
fmt::print("Failed to open joystick: {}\n", SDL_GetError());
fmt::print("Failed to open gamepad: {}\n", SDL_GetError());
}
}
}

if (joystick) {
for (int i{}; i < SDL_GetNumJoystickButtons(joystick); i++) {
bool pressed{static_cast<bool>(SDL_GetJoystickButton(joystick, i))};
if (gamepad) {
for (size_t i{}; i < buttonStates.size(); i++) {
bool pressed{static_cast<bool>(SDL_GetGamepadButton(gamepad, static_cast<SDL_GamepadButton>(i)))};
ButtonState& buttonState{buttonStates[i]};
if (pressed && !buttonState.pressed) {
buttonState.pressed = true;
Expand All @@ -286,17 +285,17 @@ class ElrsManager {
}

constexpr u16 CrsfChannelMin{172 + 5}, CrsfChannelMid{992}, CrsfChannelMax{1811 - 5}, CrsfChannelDiff{CrsfChannelMax - CrsfChannelMin};
constexpr u16 JoystickDeadzone{2000};
constexpr u16 StickDeadzone{2000}, TriggerDeadzone{100};

auto getAxisValue{[&](int axis, bool invert = false) -> u16 {
i16 inputValue{SDL_GetJoystickAxis(joystick, axis)};
auto getAxisValue{[&](SDL_GamepadAxis axis, bool invert = false) -> u16 {
i16 inputValue{SDL_GetGamepadAxis(gamepad, axis)};
if (invert) {
if (inputValue == INT16_MIN)
inputValue = INT16_MAX;
else
inputValue *= -1;
}
if (abs(inputValue) < JoystickDeadzone)
if (abs(inputValue) < StickDeadzone)
return CrsfChannelMid;

// Shift the input value from -32768 to 32767 (signed 16-bit) to 0 to 65535 (unsigned 16-bit)
Expand All @@ -308,26 +307,27 @@ class ElrsManager {
return static_cast<uint16_t>(crsfValue);
}};

/* getCombinedTriggerValue, combines anegative axis and the positive axis them into a single axis which is:
/* getCombinedTriggerValue, combines a negative axis and the positive axis them into a single axis which is:
* * Centered when both are at their minimum.
* * At the maximum value, if the positive axis is at its max.
* * At the minimum value, if the negative axis is at its max.
* Note: Both the axes must be triggers, that are in the range of 0 to 32767.
*/
auto getCombinedTriggerValue{[&](int negativeAxis, int positiveAxis, bool invert = false) -> u16 {
i16 negativeInputValue{SDL_GetJoystickAxis(joystick, negativeAxis)};
if (abs(negativeInputValue) < JoystickDeadzone)
auto getCombinedTriggerValue{[&](SDL_GamepadAxis negativeAxis, SDL_GamepadAxis positiveAxis, bool invert = false) -> u16 {
i16 negativeInputValue{SDL_GetGamepadAxis(gamepad, negativeAxis)};
if (negativeInputValue < TriggerDeadzone)
negativeInputValue = 0;
u32 negativeUnsignedValue{static_cast<u32>(negativeInputValue) + (INT16_MAX + 1)};
u32 negativeUnsignedValue{static_cast<u32>(negativeInputValue)};

i16 positiveInputValue{SDL_GetJoystickAxis(joystick, positiveAxis)};
if (abs(positiveInputValue) < JoystickDeadzone)
i16 positiveInputValue{SDL_GetGamepadAxis(gamepad, positiveAxis)};
if (positiveInputValue < TriggerDeadzone)
positiveInputValue = 0;
u32 positiveUnsignedValue{static_cast<u32>(positiveInputValue) + (INT16_MAX + 1)};
u32 positiveUnsignedValue{static_cast<u32>(positiveInputValue)};

// Shift the input value from -32768 to 32767 (signed 16-bit) to 0 to 65535 (unsigned 16-bit)
// Shift the input value from 0 to 32767 (signed 16-bit) to 0 to 65535 (unsigned 16-bit)
u32 unsignedValue{INT16_MAX};
unsignedValue += positiveUnsignedValue / 2;
unsignedValue -= negativeUnsignedValue / 2;
unsignedValue += positiveUnsignedValue;
unsignedValue -= negativeUnsignedValue;

// Scale the shifted value to the CRSF range
u32 crsfValue{((unsignedValue * CrsfChannelDiff) / UINT16_MAX) + CrsfChannelMin};
Expand All @@ -347,8 +347,9 @@ class ElrsManager {
crsfChannels.set(4, getButtonToggle(SDL_GAMEPAD_BUTTON_LEFT_SHOULDER));
crsfChannels.set(5, getButtonToggle(SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER));
crsfChannels.set(6, getButtonToggle(SDL_GAMEPAD_BUTTON_START));
crsfChannels.set(7, getButtonToggle(SDL_GAMEPAD_BUTTON_BACK));

constexpr std::array<const char*, 7> channelLabels{"Roll", "Pitch", "Throttle", "Yaw", "Aux 1", "Aux 2", "Aux 3"};
constexpr std::array<const char*, 8> channelLabels{"Roll", "Pitch", "Throttle", "Yaw", "Aux 1", "Aux 2", "Aux 3", "Aux 4"};
for (int i{}; i < channelLabels.size(); i++) {
float scaledValue{static_cast<float>(crsfChannels.get(i) - CrsfChannelMin) / CrsfChannelDiff};
ImGui::ProgressBar(scaledValue, ImVec2(0.0f, 0.0f), channelLabels[i]);
Expand All @@ -361,18 +362,18 @@ class ElrsManager {

ImGui::Checkbox("Show Joystick Input", &showJoystickData);
if (showJoystickData) {
ImGui::Text("Name: %s", SDL_GetJoystickName(joystick));
for (int i{}; i < SDL_GetNumJoystickAxes(joystick); i++) {
ImGui::Text("Name: %s", SDL_GetGamepadName(gamepad));
for (int i{}; i < SDL_GAMEPAD_AXIS_MAX; i++) {
ImGui::Text("Axis %d:", i);
ImGui::Indent();
i16 signedValue{SDL_GetJoystickAxis(joystick, i)};
i16 signedValue{SDL_GetGamepadAxis(gamepad, static_cast<SDL_GamepadAxis>(i))};
u32 unsignedValue{static_cast<u32>(i32{signedValue} - (std::numeric_limits<i16>::min)())};
float value{static_cast<float>(unsignedValue) / (std::numeric_limits<u16>::max)()};
ImGui::ProgressBar(value, ImVec2(-100, 0), fmt::format("Axis {}", i).c_str());
ImGui::Unindent();
}

for (int i{}; i < SDL_GetNumJoystickButtons(joystick); i++) {
for (int i{}; i < buttonStates.size(); i++) {
ButtonState& buttonState{buttonStates[i]};
ImGui::Text("Button %d:", i);
ImGui::Indent();
Expand Down

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