Launcher: the trackpad pointer measures from where the stick rests, so it does not creep

Launcher/Test/gamepad_input_tests.cpp

@@ -5,6 +5,7 @@
 #include <imgui.h>
 #include <imgui_internal.h>
 
+#include <cmath>
 #include <iostream>
 #include <map>
 #include <optional>
@@ -432,13 +433,13 @@ int main() {
         PadFeed stick;
         PadFeed trackpad(true);
         ImGui::GetIO().AddMousePosEvent(400, 300);
-        frame(trackpad, pad());
+        for (int i = 0; i < 20; ++i) frame(trackpad, pad());   // it settles first
         for (int i = 0; i < 10; ++i) frame(trackpad, pad(0, 3300, 0));   // a slow swipe
         frame(trackpad, pad());
         check(ImGui::GetIO().MousePos.x > 405, "A slow swipe on the trackpad moves the pointer");
         fresh();
         ImGui::GetIO().AddMousePosEvent(400, 300);
-        frame(stick, pad());
+        for (int i = 0; i < 20; ++i) frame(stick, pad());
         for (int i = 0; i < 10; ++i) frame(stick, pad(0, 3300, 0));
         frame(stick, pad());
         check(!stick.pointing() && ImGui::GetIO().MousePos.x == 400, "The same small tilt of a thumbstick does not");
@@ -446,7 +447,7 @@ int main() {
         fresh();
         PadFeed slowing(true);
         ImGui::GetIO().AddMousePosEvent(100, 300);
-        frame(slowing, pad());
+        for (int i = 0; i < 20; ++i) frame(slowing, pad());
         for (int i = 0; i < 5; ++i) frame(slowing, pad(0, 20000, 0));   // the swipe
         const float swiped = ImGui::GetIO().MousePos.x;
         float tilt = 20000;
@@ -459,6 +460,21 @@ int main() {
         frame(slowing, pad(0, -900, -1200));
         check(slowed > swiped + 60, "A swipe that slows down moves the pointer to its end");
         check(ImGui::GetIO().MousePos.x == slowed, "The pointer stops when the thumb lifts");
+
+        fresh();
+        PadFeed drifting(true);
+        ImGui::GetIO().AddMousePosEvent(400, 300);
+        for (int i = 0; i < 60; ++i) frame(drifting, pad(0, -2600, -2600));   // resting off the middle
+        check(!drifting.pointing() && ImGui::GetIO().MousePos.x == 400 && ImGui::GetIO().MousePos.y == 300,
+              "A trackpad resting off the middle does not move the pointer");
+        for (int i = 0; i < 10; ++i) frame(drifting, pad(0, 9000, -2600));
+        check(drifting.pointing() && ImGui::GetIO().MousePos.x > 420 && std::abs(ImGui::GetIO().MousePos.y - 300) < 1,
+              "A swipe moves it from where the trackpad rests");
+        for (int i = 0; i < 60; ++i) frame(drifting, pad(0, -1000, 1500));   // lifted: resting somewhere new
+        const ImVec2 rested = ImGui::GetIO().MousePos;
+        for (int i = 0; i < 60; ++i) frame(drifting, pad(0, -1000, 1500));
+        check(ImGui::GetIO().MousePos.x == rested.x && ImGui::GetIO().MousePos.y == rested.y,
+              "After a touch it rests again without the pointer creeping");
     }
 
     // ------------------------------------------------ trackpad pointer
@@ -468,7 +484,7 @@ int main() {
         auto& io = ImGui::GetIO();
         io.AddMousePosEvent(400, 300);
         feed.mouse_moved(ImVec2(400, 300));
-        frame(feed, pad());
+        for (int i = 0; i < 20; ++i) frame(feed, pad());
         frame(feed, pad(0, 3000, 0));
         check(!feed.pointing() && io.MousePos.x == 400, "A thumb resting near the middle does not move the pointer");
 

Launcher/gamepad_input.cpp

@@ -41,6 +41,12 @@ constexpr PointerFeel stick_feel{0.2f, 1400.0f, true};
 // tilt drops back to rest the moment the thumb lifts. Small swipes must move
 // the pointer and a quick one must cross the window.
 constexpr PointerFeel trackpad_feel{0.06f, 2600.0f, false};
+// The right stick never rests quite at the middle, and Steam's trackpad rests
+// a little off it too, somewhere new after each touch. A reading that holds
+// this still, this near the middle, for this long is where it rests.
+constexpr float rest_jitter = 0.01f;
+constexpr float rest_limit = 0.12f;
+constexpr float rest_seconds = 0.3f;
 // A mouse move this close to the last one is the same place reported again.
 constexpr float pointer_slack = 2.0f;
 
@@ -105,9 +111,24 @@ void PadFeed::update(ImGuiIO& io, const PadState& input, float scale) {
     if (pressed & focus_bits) pointing_ = false;
 
     const PointerFeel& feel = trackpad_ ? trackpad_feel : stick_feel;
-    const float x = axis(pad.right_x), y = -axis(pad.right_y);   // screen Y grows downward
+    const float raw_x = axis(pad.right_x), raw_y = -axis(pad.right_y);   // screen Y grows downward
+    if (std::abs(raw_x - last_x_) < rest_jitter && std::abs(raw_y - last_y_) < rest_jitter &&
+        std::sqrt(raw_x * raw_x + raw_y * raw_y) < rest_limit) {
+        steady_ += io.DeltaTime;
+        if (steady_ >= rest_seconds) {
+            rest_ = ImVec2(raw_x, raw_y);
+            rest_known_ = true;
+        }
+    } else {
+        steady_ = 0;
+    }
+    last_x_ = raw_x;
+    last_y_ = raw_y;
+    // Measured from where it rests, and not at all until that is known: a
+    // pointer creeping off on its own would take the screen from the focus.
+    const float x = raw_x - rest_.x, y = raw_y - rest_.y;
     const float tilt = std::min(1.0f, std::sqrt(x * x + y * y));
-    const bool steering = tilt > feel.dead_zone;
+    const bool steering = rest_known_ && tilt > feel.dead_zone;
     // The first R3 only shows the pointer: a stray click must not press
     // whatever the mouse last rested on.
     const bool click = pointing_ && (pressed & right_thumb);

Launcher/gamepad_input.h

@@ -54,6 +54,10 @@ private:
     ImGuiKey back_key_{ImGuiKey_Escape};
     bool pointing_{};
     bool clicking_{};   // R3 holds the left button
+    ImVec2 rest_{};     // where the right stick rests
+    bool rest_known_{};
+    float steady_{};    // seconds the right stick held still
+    float last_x_{}, last_y_{};
     ImVec2 pointer_{};
     ImVec2 mouse_{-1, -1};   // where the last mouse move was
 };