From 29710fb2ececee980e3923ed8f5f002ce219aa94 Mon Sep 17 00:00:00 2001
From: Joshua Ashton <joshua@froggi.es>
Date: Fri, 26 May 2023 17:06:33 +0100
Subject: [PATCH] vr_session: Support for trackpad scrolling

---
 src/main.cpp       |  2 ++
 src/vr_session.cpp | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/main.cpp b/src/main.cpp
index 14ce7c1..32a5209 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -89,6 +89,7 @@ const struct option *gamescope_options = (struct option[]){
 	{ "vr-overlay-physical-width", required_argument, nullptr, 0 },
 	{ "vr-overlay-physical-curvature", required_argument, nullptr, 0 },
 	{ "vr-overlay-physical-pre-curve-pitch", required_argument, nullptr, 0 },
+	{ "vr-scroll-speed", required_argument, nullptr, 0 },
 #endif
 
 	// wlserver options
@@ -195,6 +196,7 @@ const char usage[] =
 	"  --vr-overlay-physical-width              Sets the physical width of our VR overlay in metres\n"
 	"  --vr-overlay-physical-curvature          Sets the curvature of our VR overlay\n"
 	"  --vr-overlay-physical-pre-curve-pitch    Sets the pre-curve pitch of our VR overlay\n"
+	"  --vr-scrolls-speed    					Mouse scrolling speed of trackpad scroll in VR. Default: 8.0\n"
 	"\n"
 #endif
 	"Debug options:\n"
diff --git a/src/vr_session.cpp b/src/vr_session.cpp
index 2da4026..ac9ee20 100644
--- a/src/vr_session.cpp
+++ b/src/vr_session.cpp
@@ -31,6 +31,8 @@ struct OpenVRSession
     float flPhysicalWidth = 2.0f;
     float flPhysicalCurvature = 0.0f;
     float flPhysicalPreCurvePitch = 0.0f;
+    float flScrollSpeed = 8.0f;
+    float flScrollAccum[2] = { 0.0f, 0.0f };
     vr::VROverlayHandle_t hOverlay = vr::k_ulOverlayHandleInvalid;
     vr::VROverlayHandle_t hOverlayThumbnail = vr::k_ulOverlayHandleInvalid;
     struct wlserver_input_method *pIME = nullptr;
@@ -91,6 +93,8 @@ bool vr_init(int argc, char **argv)
 				    GetVR().flPhysicalCurvature = atof( optarg );
                 } else if (strcmp(opt_name, "vr-overlay-physical-pre-curve-pitch") == 0) {
 				    GetVR().flPhysicalPreCurvePitch = atof( optarg );
+                } else if (strcmp(opt_name, "vr-scroll-speed") == 0) {
+				    GetVR().flScrollSpeed = atof( optarg );
                 }
 				break;
 			case '?':
@@ -144,6 +148,7 @@ bool vrsession_init()
     vr::VROverlay()->SetOverlayFlag( GetVR().hOverlay, vr::VROverlayFlags_EnableControlBarKeyboard,	GetVR().bEnableControlBarKeyboard );
     vr::VROverlay()->SetOverlayFlag( GetVR().hOverlay, vr::VROverlayFlags_EnableControlBarClose,	GetVR().bEnableControlBarClose );
     vr::VROverlay()->SetOverlayFlag( GetVR().hOverlay, vr::VROverlayFlags_WantsModalBehavior,	    GetVR().bModal );
+    vr::VROverlay()->SetOverlayFlag( GetVR().hOverlay, vr::VROverlayFlags_SendVRSmoothScrollEvents, true );
     vrsession_update_touch_mode();
 
     vr::VROverlay()->SetOverlayWidthInMeters( GetVR().hOverlay,  GetVR().flPhysicalWidth );
@@ -315,6 +320,22 @@ static void vrsession_input_thread()
                     break;
                 }
 
+                case vr::VREvent_ScrollSmooth:
+                {
+                    wlserver_lock();
+
+                    GetVR().flScrollAccum[0] += -vrEvent.data.scroll.xdelta * GetVR().flScrollSpeed;
+                    GetVR().flScrollAccum[1] += -vrEvent.data.scroll.ydelta * GetVR().flScrollSpeed;
+
+                    float dx, dy;
+                    GetVR().flScrollAccum[0] = modf( GetVR().flScrollAccum[0], &dx );
+                    GetVR().flScrollAccum[1] = modf( GetVR().flScrollAccum[1], &dy );
+
+                    wlserver_mousewheel( dx, dy, timestamp );
+                    wlserver_unlock();
+                    break;
+                }
+
                 case vr::VREvent_ButtonPress:
                 {
                     vr::EVRButtonId button = (vr::EVRButtonId)vrEvent.data.controller.button;