drs: hook down movement, adjust touch hooks (#898)

When Down Motion button is bound, install hooks into the game that
detects down movement via patches.

When Disable Touch option is enabled, don't install touch hooks.

src/spice2x/CMakeLists.txt

@@ -520,6 +520,7 @@ set(SOURCE_FILES ${SOURCE_FILES}
         games/scotto/io.cpp
         games/drs/drs.cpp
         games/drs/io.cpp
+        games/drs/motion_cam.cpp
         games/drs/rgb_cam.cpp
         games/we/we.cpp
         games/we/io.cpp

src/spice2x/games/drs/drs.cpp

@@ -9,6 +9,8 @@
 #include "util/logging.h"
 #include "util/precise_timer.h"
 #include "util/memutils.h"
+#include "io.h"
+#include "motion_cam.h"
 #include "rgb_cam.h"
 
 #pragma pack(push)
@@ -276,6 +278,7 @@ namespace games::drs {
     void DRSGame::attach() {
         Game::attach();
 
+        if (!DISABLE_TOUCH) {
             // TouchSDK hooks
             detour::iat("??0TouchSDK@@QEAA@XZ",
                     (void *) &TouchSDK_Constructor, avs::game::DLL_INSTANCE);
@@ -312,12 +315,13 @@ namespace games::drs {
             detour::iat("?InitTouch@TouchSDK@@QEAAHPEAU_DeviceInfo@@HP6AXU2@PEBU_TouchPointData@@HHPEBX@ZP6AX1_N3@ZPEAX@Z",
                     (void *) &TouchSDK_InitTouch, avs::game::DLL_INSTANCE);
 
-        if (!DISABLE_TOUCH) {
             start_touch();
         } else {
-            log_info("drs", "no native input method detected");
+            log_info("drs", "touch input for dance floor disabled");
         }
 
+        init_down_motion_hook();
+
         if (RGB_CAMERA_HOOK) {
             init_rgb_camera_hook();
         }

src/spice2x/games/drs/io.cpp

@@ -20,7 +20,8 @@ std::vector<Button> &games::drs::get_buttons() {
                 "P2 Up",
                 "P2 Down",
                 "P2 Left",
-                "P2 Right"
+                "P2 Right",
+                "Down Motion"
         );
     }
 
@@ -30,8 +31,8 @@ std::vector<Button> &games::drs::get_buttons() {
 std::string games::drs::get_buttons_help() {
     // keep to max 100 characters wide
     return
-        "Motion camera required for DOWN movement.\n"
+        "Touchscreen supported for dance floor.\n"
-        "Touchscreen supported for dance floor."
+        "Down Motion applies to both players."
         ;
 }
 

src/spice2x/games/drs/io.h

@@ -20,7 +20,8 @@ namespace games::drs {
             P2_Up,
             P2_Down,
             P2_Left,
-            P2_Right
+            P2_Right,
+            DownMotion
         };
     }
 

src/spice2x/games/drs/motion_cam.cpp

@@ -0,0 +1,109 @@
+#include "games/drs/motion_cam.h"
+
+#include <cstdint>
+
+#include "avs/game.h"
+#include "util/detour.h"
+#include "util/logging.h"
+#include "util/sigscan.h"
+#include "io.h"
+
+namespace games::drs {
+
+    // the game reads down movement from a depth camera whose driver is compiled into the game DLL,
+    // so there is no import to replace.
+    //
+    // with no camera the tracked height never changes, so the motion state never leaves "still"
+    // and DOWN notes can never be hit.
+    //
+    // rather than answer CInputManager::IsDown, the button drives the same state pair the camera
+    // would; that leaves the game's own edge test untouched and keeps every note in a frame seeing
+    // one answer.
+    static int32_t *MOTION_STATE = nullptr;
+    static int32_t *MOTION_STATE_PREV = nullptr;
+    static constexpr int32_t MOTION_STATE_STILL = 1;
+    static constexpr int32_t MOTION_STATE_DOWN = 2;
+
+    static void (*UpdateMotion_orig)() = nullptr;
+    static bool DOWN_MOTION_HELD = false;
+
+    static void InputManager_UpdateMotion() {
+        UpdateMotion_orig();
+
+        auto &buttons = get_buttons();
+        const bool held = GameAPI::Buttons::getState(RI_MGR, buttons.at(Buttons::DownMotion));
+
+        // a state of DOWN only counts as movement when the frame before it was something else
+        if (held) {
+            *MOTION_STATE_PREV = DOWN_MOTION_HELD ? MOTION_STATE_DOWN : MOTION_STATE_STILL;
+            *MOTION_STATE = MOTION_STATE_DOWN;
+        }
+
+        DOWN_MOTION_HELD = held;
+    }
+
+    void init_down_motion_hook() {
+        // only hook motion camera if the user has down motion button bound to something
+        auto &buttons = get_buttons();
+        if (!buttons.at(Buttons::DownMotion).isSet()) {
+            return;
+        }
+
+        // CInputManager::IsDown - read the state pair out of its two operands.
+        // Identical in game versions 2020121400 and 2022121400 / 2024120300:
+        //
+        //   83 3D xx xx xx xx 02   cmp dword [rip+prev], 2  ; state one frame ago
+        //   74 0C                  je  FALSE                ; already down, so no new edge
+        //   83 3D xx xx xx xx 02   cmp dword [rip+cur], 2   ; state this frame
+        //   75 03                  jne FALSE                ; not down
+        //   B0 01                  mov al, 1                ; went down on this frame
+        //   C3                     ret
+        //   32 C0           FALSE: xor al, al
+        //   C3                     ret
+        auto is_down = reinterpret_cast<uint8_t *>(find_pattern(
+                avs::game::DLL_INSTANCE,
+                "833D0000000002740C833D00000000027503B001C332C0C3",
+                "XX????XXXXX????XXXXXXXXX",
+                0, 0));
+
+        if (is_down == nullptr) {
+            log_warning("drs", "motion sensor state not found, DOWN motion button unavailable");
+            return;
+        }
+
+        // rip-relative displacements resolve against the end of their own instruction, and each
+        // cmp above is 7 bytes with its displacement 4 bytes in: the first ends at +7 with its
+        // displacement at +2, the second starts at +9 so it ends at +16 with its own at +11.
+        // read signed, since a target sitting below the instruction encodes as negative.
+        MOTION_STATE_PREV = (int32_t *) (is_down + 7 + *(int32_t *) (is_down + 2));
+        MOTION_STATE = (int32_t *) (is_down + 16 + *(int32_t *) (is_down + 11));
+
+        // CInputManager::UpdateMotion is hooked for the sole purpose of reading the Down Motion
+        // button mapping frequently enough so that the rising edge can be detected.
+        //
+        // Matched over the prologue up to the camera read; the wildcards are a float and a callee:
+        //
+        //   48 83 EC 38               sub    rsp, 0x38
+        //   0F 29 74 24 20            movaps [rsp+0x20], xmm6
+        //   F3 0F 10 35 xx xx xx xx   movss  xmm6, [rip+height]  ; reading as of last frame
+        //   E8 xx xx xx xx            call   GetPlayVideoProcess
+        //   48 8B C8                  mov    rcx, rax
+        //   48 8B 10                  mov    rdx, [rax]
+        //   FF 52 60                  call   [rdx+0x60]          ; reading off the newest frame
+        auto update = reinterpret_cast<void *>(find_pattern(
+                avs::game::DLL_INSTANCE,
+                "4883EC380F29742420F30F103500000000E800000000488BC8488B10FF5260",
+                "XXXXXXXXXXXXX????X????XXXXXXXXX",
+                0, 0));
+
+        if (update == nullptr ||
+            !detour::trampoline_try(
+                update, (void *) InputManager_UpdateMotion, (void **) &UpdateMotion_orig)) {
+            log_warning("drs", "motion update not hooked, DOWN motion button unavailable");
+            return;
+        }
+
+        log_info("drs", "hooked DOWN motion at +{:#x}",
+                (uintptr_t) ((uint8_t *) update - (uint8_t *) avs::game::DLL_INSTANCE));
+    }
+}

src/spice2x/games/drs/motion_cam.h

@@ -0,0 +1,5 @@
+#pragma once
+
+namespace games::drs {
+    void init_down_motion_hook();
+}

src/spice2x/sdk/include/spicesdk_io.h

@@ -1607,6 +1607,7 @@ typedef enum SPICE_SDK_DANCERUSH_BUTTONS {
     DRS_Button_P2_Down,
     DRS_Button_P2_Left,
     DRS_Button_P2_Right,
+    DRS_Button_DownMotion,
 } SPICE_SDK_DANCERUSH_BUTTONS;
 
 typedef enum SPICE_SDK_DANCERUSH_LIGHTS {