From 792aa38d34fd033d527ac11c0b406f4cfb8e40f3 Mon Sep 17 00:00:00 2001
From: Flyinghead <raphael.jean@gmail.com>
Date: Tue, 26 Nov 2024 16:06:13 +0100
Subject: [PATCH] input: implement ramp up/down for analog axes mapped to
 buttons

Full analog axes now have a ramp up/down of 100 ms when the mapped
button is pressed/released. Works also for keyboards.
Issue #1017
---
 core/input/gamepad_device.cpp | 76 +++++++++++++++++++++++++++++++++++
 core/input/gamepad_device.h   | 22 +++++-----
 core/oslib/oslib.cpp          |  9 +++--
 3 files changed, 94 insertions(+), 13 deletions(-)

diff --git a/core/input/gamepad_device.cpp b/core/input/gamepad_device.cpp
index 7ca658414..5ddc72c6b 100644
--- a/core/input/gamepad_device.cpp
+++ b/core/input/gamepad_device.cpp
@@ -584,6 +584,82 @@ void GamepadDevice::SaveMaplePorts()
 	}
 }
 
+s16 (&GamepadDevice::getTargetArray(DigAnalog axis))[4]
+{
+	switch (axis)
+	{
+	case DIGANA_LEFT:
+	case DIGANA_RIGHT:
+		return joyx;
+	case DIGANA_UP:;
+	case DIGANA_DOWN:
+		return joyy;
+	case DIGANA2_LEFT:
+	case DIGANA2_RIGHT:
+		return joyrx;
+	case DIGANA2_UP:
+	case DIGANA2_DOWN:
+		return joyry;
+	case DIGANA3_LEFT:
+	case DIGANA3_RIGHT:
+		return joy3x;
+	case DIGANA3_UP:
+	case DIGANA3_DOWN:
+		return joy3y;
+	default:
+		die("unknown axis");
+	}
+}
+
+void GamepadDevice::rampAnalog()
+{
+	if (lastAnalogUpdate == 0)
+		// also used as a flag that no analog ramping is needed on this device (yet)
+		return;
+
+	const u64 now = getTimeMs();
+	const int delta = std::round(static_cast<float>(now - lastAnalogUpdate) * AnalogRamp);
+	lastAnalogUpdate = now;
+	for (unsigned port = 0; port < std::size(digitalToAnalogState); port++)
+	{
+		for (int axis = 0; axis < 12; axis += 2)	// 3 sticks with 2 axes each
+		{
+			DigAnalog negDir = static_cast<DigAnalog>(1 << axis);
+			if ((rampAnalogState[port] & negDir) == 0)
+				// axis not active
+				continue;
+			DigAnalog posDir = static_cast<DigAnalog>(1 << (axis + 1));
+			const int socd = digitalToAnalogState[port] & (negDir | posDir);
+			s16& axisValue = getTargetArray(negDir)[port];
+			if (socd != 0 && socd != (negDir | posDir))
+			{
+				// One axis is pressed => ramp up
+				if (socd == posDir)
+					axisValue = std::min(32767, axisValue + delta);
+				else
+					axisValue = std::max(-32768, axisValue - delta);
+			}
+			else
+			{
+				// No axis is pressed (or both) => ramp down
+				if (axisValue > 0)
+					axisValue = std::max(0, axisValue - delta);
+				else if (axisValue < 0)
+					axisValue = std::min(0, axisValue + delta);
+				else
+					rampAnalogState[port] &= ~negDir;
+			}
+		}
+	}
+}
+
+void GamepadDevice::RampAnalog()
+{
+	std::lock_guard<std::mutex> _(_gamepads_mutex);
+	for (auto& gamepad : _gamepads)
+		gamepad->rampAnalog();
+}
+
 #ifdef TEST_AUTOMATION
 #include "cfg/option.h"
 static bool replay_inited;
diff --git a/core/input/gamepad_device.h b/core/input/gamepad_device.h
index aef633870..6e94b70ad 100644
--- a/core/input/gamepad_device.h
+++ b/core/input/gamepad_device.h
@@ -20,6 +20,7 @@
 #pragma once
 #include "types.h"
 #include "mapping.h"
+#include "stdclass.h"
 
 #include <map>
 #include <memory>
@@ -98,6 +99,7 @@ class GamepadDevice
 	static int GetGamepadCount();
 	static std::shared_ptr<GamepadDevice> GetGamepad(int index);
 	static void SaveMaplePorts();
+	static void RampAnalog();
 
 	static void load_system_mappings();
 	bool find_mapping(int system = settings.platform.system);
@@ -163,16 +165,14 @@ class GamepadDevice
 			digitalToAnalogState[port] |= axis;
 		else
 			digitalToAnalogState[port] &= ~axis;
-		const u32 socd = digitalToAnalogState[port] & (NegDir | PosDir);
-		if (socd == 0 || socd == (NegDir | PosDir))
-			joystick = 0;
-		else if (socd == NegDir)
-			joystick = -32768;
-		else
-			joystick = 32767;
-
+		rampAnalogState[port] |= NegDir;
+		if (lastAnalogUpdate == 0)
+			lastAnalogUpdate = getTimeMs();
 	}
 
+	s16 (&getTargetArray(DigAnalog axis))[4];
+	void rampAnalog();
+
 	std::string _api_name;
 	int _maple_port;
 	bool _detecting_button = false;
@@ -184,7 +184,11 @@ class GamepadDevice
 	std::map<DreamcastKey, int> lastAxisValue[4];
 	bool perGameMapping = false;
 	bool instanceMapping = false;
-	
+
+	u64 lastAnalogUpdate = 0;
+	u32 rampAnalogState[4] {};
+	static constexpr float AnalogRamp = 32767.f / 100.f;		// 100 ms ramp time
+
 	static std::vector<std::shared_ptr<GamepadDevice>> _gamepads;
 	static std::mutex _gamepads_mutex;
 };
diff --git a/core/oslib/oslib.cpp b/core/oslib/oslib.cpp
index fa7a3793e..67bc3393b 100644
--- a/core/oslib/oslib.cpp
+++ b/core/oslib/oslib.cpp
@@ -40,6 +40,7 @@
 #include <shlobj.h>
 #endif
 #include "profiler/fc_profiler.h"
+#include "input/gamepad_device.h"
 
 namespace hostfs
 {
@@ -370,12 +371,12 @@ void os_UpdateInputState()
 {
 	FC_PROFILE_SCOPE;
 
+	// FIXME threading (android) this will be called on the render thread, events are on the main app thread
+	GamepadDevice::RampAnalog();
 #if defined(USE_SDL)
 	input_sdl_handle();
-#else
-	#if defined(USE_EVDEV)
-		input_evdev_handle();
-	#endif
+#elif defined(USE_EVDEV)
+	input_evdev_handle();
 #endif
 }