rawinput: distinguish between circular and linear analog input (#665)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Currently, all analogs are treated as circular values that wrap around.
This works for knobs and turntables, but can get weird for linear values
(like tilt sensors and sliders) especially once analog options are
enabled, such as sensitivity.

This PR groups analogs into 3 buckets: circular, linear (centered), and
linear (positive). Linear types get different algorithms applied to it
when options are set (e.g., sensitivity caps out at 0, 1 instead of
wrapping around).

In linear mode:
* Sensitivity value applies an exponential response curve (power curve)
to the original value.
* Multiplier/divisor serves as a linear cut-off.
* Relative mode works as you expect, but of course, values don't wrap
around.
* Invert and deadzone work as you expect (since they applied to the
controller input anyway)
* Smoothing is removed from the UI and has no effect.
* Delay is unaffected.

Also, fix a small bug with -/+ button not working for analog `Delay`
option.

## Testing
WIP

src/spice2x/cfg/analog.cpp

@@ -207,22 +207,38 @@ float Analog::applyMultiplier(float value) {
 }
 
 float Analog::normalizeAnalogValue(float value) {
-    // effectively the same as fmodf(value, 1.f)
-    // for small values, this is MUCH faster than fmodf.
-    float new_value = value;
-    while (new_value > 1.f) {
-        new_value -= 1.f;
+    if (getType() == GameAPI::Analogs::AnalogType::Circular) {
+        // effectively the same as fmodf(value, 1.f)
+        // for small values, this is MUCH faster than fmodf.
+        float new_value = value;
+        while (new_value > 1.f) {
+            new_value -= 1.f;
+        }
+        while (new_value < 0.f) {
+            new_value += 1.f;
+        }
+        return new_value;
+
+    } else {
+        // clamp to [0, 1] range
+        return std::clamp(value, 0.f, 1.f);
     }
-    while (new_value < 0.f) {
-        new_value += 1.f;
-    }
-    return new_value;
 }
 
 float Analog::applyDeadzone(float raw_value) {
     float value = raw_value;
-    const auto deadzone = this->getDeadzone();
-    if (deadzone > 0) {
+    auto deadzone = this->getDeadzone();
+
+    // in the past, positive deadzone applied in the center, negative deadzone applied to 0
+    // after each analog value received a type (circular/linear) this has been simpliifed to
+    // positive values only since we can figure out where the rest value is
+    // for back compat, treat negative value as positive
+    if (deadzone < 0.f) {
+        deadzone = -deadzone;
+    }
+
+    // relative mode assumes that user is using a stick, so center is neutral regardless of analog type
+    if (getType() != GameAPI::Analogs::AnalogType::LinearPositive || isRelativeMode()) {
 
         // calculate values
         const auto delta = value - 0.5f;
@@ -255,7 +271,7 @@ float Analog::applyDeadzone(float raw_value) {
             }
         }
 
-    } else if (deadzone < 0) {
+    } else {
 
         // invert for mirror
         if (this->getDeadzoneMirror()) {
@@ -263,8 +279,8 @@ float Analog::applyDeadzone(float raw_value) {
         }
 
         // deadzone from minimum value
-        if (deadzone > -1 && value > -deadzone) {
-            value = std::min(1.f, (value + deadzone) / (1.f + deadzone));
+        if (deadzone < 1.f && deadzone < value) {
+            value = std::max(0.f, (value - deadzone) / (1.f - deadzone));
         } else {
             value = 0.f;
         }

src/spice2x/cfg/analog.h

@@ -13,6 +13,21 @@ namespace rawinput {
     class RawInputManager;
 }
 
+namespace GameAPI::Analogs {
+    enum class AnalogType {
+        // default; values wrap around (below 0 turns into 1, over 1 is 0)
+        // knobs, turntables
+        Circular = 0,
+
+        // typical joystick that rests at the center and caps at [0, 1]
+        LinearCentered = 1,
+
+        // one-directional value (sliders and instruments like piano/drum velocity)
+        // starts at 0 and goes up to 1
+        LinearPositive = 2,
+    };
+}
+
 struct AnalogMovingAverage {
     double time_in_ms;
     float sine;
@@ -31,10 +46,11 @@ private:
     float last_state = 0.5f;
     bool sensitivity_set = false;
     bool deadzone_set = false;
+    GameAPI::Analogs::AnalogType type = GameAPI::Analogs::AnalogType::Circular;
     
     // smoothing function
     bool smoothing = false;
-    std::array<AnalogMovingAverage, ANALOG_HISTORY_CNT> vector_history;
+    std::array<AnalogMovingAverage, ANALOG_HISTORY_CNT> vector_history = {};
     int vector_history_index = 0;
     float smoothed_last_state = 0.f;
 
@@ -66,7 +82,8 @@ public:
     float override_state = 0.5f;
 
     explicit Analog(std::string name) : name(std::move(name)) {
-        vector_history.fill({0.0, 0.f, 0.f});
+    };
+    explicit Analog(std::string name, GameAPI::Analogs::AnalogType type) : name(std::move(name)), type(type) {
     };
 
     std::string getDisplayString(rawinput::RawInputManager* manager);
@@ -214,4 +231,12 @@ public:
     inline std::queue<float> &getDelayBuffer() {
         return this->delay_buffer;
     }
+
+    inline GameAPI::Analogs::AnalogType getType() const {
+        return this->type;
+    }
+
+    inline void setType(GameAPI::Analogs::AnalogType type) {
+        this->type = type;
+    }
 };

src/spice2x/cfg/api.cpp

@@ -679,7 +679,9 @@ float GameAPI::Analogs::getState(rawinput::RawInputManager *manager, rawinput::D
             }
 
             // deadzone
-            if (analog.isDeadzoneSet()) {
+            // do not apply deadzone to circular analogs since it doesn't make sense (except in relative mode)
+            if (analog.isDeadzoneSet() &&
+                (analog.getType() != AnalogType::Circular || analog.isRelativeMode())) {
                 value = analog.applyDeadzone(value);
             }
 
@@ -704,7 +706,7 @@ float GameAPI::Analogs::getState(rawinput::RawInputManager *manager, rawinput::D
                 // translate relative movement to absolute value
                 value = analog.getAbsoluteValue(relative_delta);
 
-            } else {
+            } else if (analog.getType() == AnalogType::Circular) {
                 // integer multiplier
                 value = analog.applyMultiplier(value);
 
@@ -732,6 +734,53 @@ float GameAPI::Analogs::getState(rawinput::RawInputManager *manager, rawinput::D
                     // apply to value
                     value = rads * (float) M_1_TAU;
                 }
+            } else {
+                // sensitivity
+                if (analog.isSensitivitySet()) {
+                    // adjust curve
+                    // values < 1.f : less sensitive around neutral
+                    // values > 1.f : more sensitive around neutral
+                    float curve = analog.getSensitivity();
+                    if (curve <= 0.f) {
+                        curve = 0.01f;
+                    }
+                    curve = 1.f / curve;
+
+                    if (analog.getType() == AnalogType::LinearCentered) {
+                        // convert 0.0..1.0 to -1.0..+1.0
+                        float signed_raw = (value - 0.5f) * 2.0f;
+                        // apply curve
+                        float sign = signed_raw < 0.0f ? -1.0f : 1.0f;
+                        float magnitude = fabsf(signed_raw);
+                        float curved = sign * powf(magnitude, curve);
+                        // convert back to 0.0..1.0
+                        value = curved * 0.5f + 0.5f;
+                    } else {
+                        value = powf(value, curve);
+                    }
+
+                    value = std::clamp(value, 0.f, 1.f);
+                }
+
+                // multiplier / divisor
+                if (analog.getMultiplier() < -1) {
+                    if (analog.getType() == AnalogType::LinearCentered) {
+                        value = (value - 0.5f) / (-analog.getMultiplier()) + 0.5f;
+                    } else {
+                        value /= -analog.getMultiplier();
+                    }
+
+                    value = std::clamp(value, 0.f, 1.f);
+
+                } else if (analog.getMultiplier() > 1) {
+                    if (analog.getType() == AnalogType::LinearCentered) {
+                        value = (value - 0.5f) * analog.getMultiplier() + 0.5f;
+                    } else {
+                        value *= analog.getMultiplier();
+                    }
+
+                    value = std::clamp(value, 0.f, 1.f);
+                }
             }
 
             // delay
@@ -839,6 +888,42 @@ std::vector<Analog> GameAPI::Analogs::sortAnalogs(
     return sorted;
 }
 
+static std::vector<Analog> sortAnalogsWithTypeInternal(
+    std::vector<Analog> &analogs,
+    const std::initializer_list<GameAPI::Analogs::AnalogWithType> list) {
+
+    std::vector<Analog> sorted;
+
+    bool analog_found;
+    for (auto &a : list) {
+        analog_found = false;
+
+        for (auto &analog : analogs) {
+            if (a.name == analog.getName()) {
+                analog_found = true;
+                analog.setType(a.type);
+                sorted.push_back(analog);
+                break;
+            }
+        }
+
+        if (!analog_found) {
+            sorted.emplace_back(a.name, a.type);
+        }
+    }
+
+    return sorted;
+}
+
+void GameAPI::Analogs::sortAnalogsWithType(
+    std::vector<Analog> *analogs,
+    const std::initializer_list<AnalogWithType> list) {
+
+    if (analogs) {
+        *analogs = sortAnalogsWithTypeInternal(*analogs, list);
+    }
+}
+
 float GameAPI::Analogs::getState(rawinput::RawInputManager *manager, Analog &analog) {
 
     // check override

src/spice2x/cfg/api.h

@@ -85,14 +85,15 @@ namespace GameAPI {
                 const std::vector<Analog> &analogs,
                 const std::vector<std::string> &analog_names);
 
-        template<typename T>
-        void sortAnalogs(std::vector<Analog> *analogs, T t) {
-            const std::vector<std::string> analog_names { t };
+        struct AnalogWithType {
+            const std::string name;
+            const AnalogType type;
 
-            if (analogs) {
-                *analogs = GameAPI::Analogs::sortAnalogs(*analogs, analog_names);
-            }
-        }
+            AnalogWithType(std::string name, AnalogType type) :
+                name(std::move(name)), type(type) {}
+        };
+
+        void sortAnalogsWithType(std::vector<Analog> *analogs, const std::initializer_list<AnalogWithType> list);
 
         template<typename T, typename... Rest>
         void sortAnalogs(std::vector<Analog> *analogs, T t, Rest... rest) {