intern/ghost/GHOST_Types.h

@@ -142,6 +142,7 @@ typedef struct GHOST_TabletData {
   float Pressure;           /* range 0.0 (not touching) to 1.0 (full pressure) */
   float Xtilt; /* range 0.0 (upright) to 1.0 (tilted fully against the tablet surface) */
   float Ytilt; /* as above */
+  float Twist; /* range (-pi,pi), stylus button side towards left is 0.0. */
 } GHOST_TabletData;
 
 static const GHOST_TabletData GHOST_TABLET_DATA_NONE = {

intern/ghost/intern/GHOST_SystemX11.cc

@@ -59,6 +59,9 @@
 #include <sys/time.h>
 #include <unistd.h>
 
+/* M_PI */
+#include <math.h>
+
 #include <cstdio>  /* for fprintf only */
 #include <cstdlib> /* for exit */
 #include <iostream>
@@ -1558,6 +1561,13 @@ void GHOST_SystemX11::processEvent(XEvent *xe)
             window->GetTabletData().Ytilt = short(axis_value & 0xffff) /
                                             float(xtablet.YtiltLevels);
           }
+          if (AXIS_VALUE_GET(5, axis_value)) {
+            window->GetTabletData().Twist = short(axis_value & 0xffff) /
+                                            float(xtablet.TwistLevels) * M_PI;
+#  ifdef WITH_GHOST_DEBUG
+            printf("Twist: %f\n", window->GetTabletData().Twist);
+#  endif
+          }
 
 #  undef AXIS_VALUE_GET
         }
@@ -2721,6 +2731,12 @@ void GHOST_SystemX11::refreshXInputDevices()
                     xtablet.XtiltLevels = 0;
                     xtablet.YtiltLevels = 0;
                   }
+                  if (xvi->num_axes > 5) {
+                    xtablet.TwistLevels = xvi->axes[5].max_value;
+                  }
+                  else {
+                    xtablet.TwistLevels = 0;
+                  }
 
                   break;
                 }

intern/ghost/intern/GHOST_SystemX11.hh

@@ -271,6 +271,7 @@ class GHOST_SystemX11 : public GHOST_System {
 
     int PressureLevels;
     int XtiltLevels, YtiltLevels;
+    int TwistLevels;
   } GHOST_TabletX11;
 
   std::vector<GHOST_TabletX11> &GetXTablets()

intern/ghost/intern/GHOST_WindowWin32.cc

@@ -5,6 +5,8 @@
  * \ingroup GHOST
  */
 
+#define _USE_MATH_DEFINES
+
 #include "GHOST_WindowWin32.hh"
 #include "GHOST_ContextD3D.hh"
 #include "GHOST_ContextNone.hh"
@@ -953,6 +955,7 @@ GHOST_TSuccess GHOST_WindowWin32::getPointerInfo(
     outPointerInfo[i].tabletData.Pressure = 1.0f;
     outPointerInfo[i].tabletData.Xtilt = 0.0f;
     outPointerInfo[i].tabletData.Ytilt = 0.0f;
+    outPointerInfo[i].tabletData.Twist = 0.0f;
     outPointerInfo[i].time = system->performanceCounterToMillis(pointerApiInfo.PerformanceCount);
 
     if (pointerPenInfo[i].penMask & PEN_MASK_PRESSURE) {
@@ -970,6 +973,13 @@ GHOST_TSuccess GHOST_WindowWin32::getPointerInfo(
     if (pointerPenInfo[i].penMask & PEN_MASK_TILT_Y) {
       outPointerInfo[i].tabletData.Ytilt = fmin(fabs(pointerPenInfo[i].tiltY / 90.0f), 1.0f);
     }
+
+    if (pointerPenInfo[i].penMask & PEN_MASK_ROTATION) {
+      /* POINTER_PEN_INFO specifies rotation range to be [0,359], convert to radiant here. */
+      outPointerInfo[i].tabletData.Twist = ((float)pointerPenInfo[i].rotation / 360.0f) * M_PI * 2;
+      /* Debug only. */
+      printf("Twist (ink): %f\n", outPointerInfo[i].tabletData.Twist);
+    }
   }
 
   if (!outPointerInfo.empty()) {

intern/ghost/intern/GHOST_Wintab.cc

@@ -263,7 +263,7 @@ void GHOST_Wintab::remapCoordinates()
 
 void GHOST_Wintab::updateCursorInfo()
 {
-  AXIS Pressure, Orientation[3];
+  AXIS Pressure, Orientation[3], Rotation;
 
   BOOL pressureSupport = m_fpInfo(WTI_DEVICES, DVC_NPRESSURE, &Pressure);
   m_maxPressure = pressureSupport ? Pressure.axMax : 0;
@@ -278,11 +278,23 @@ void GHOST_Wintab::updateCursorInfo()
   else {
     m_maxAzimuth = m_maxAltitude = 0;
   }
-  WINTAB_PRINTF("HCTX %p %s maxAzimuth: %d, maxAltitude: %d\n",
+
+  if (Orientation[2].axResolution) {
+    m_maxTwist = Orientation[2].axMax;
+  }
+  else {
+    BOOL rotationSupport = m_fpInfo(WTI_DEVICES, DVC_ROTATION, &Rotation);
+    if (rotationSupport && Rotation.axResolution) {
+      m_maxTwist = Rotation.axMax;
+    }
+  }
+
+  WINTAB_PRINTF("HCTX %p %s maxAzimuth: %d, maxAltitude: %d, maxTwist: %d\n",
                 m_context.get(),
                 __func__,
                 m_maxAzimuth,
-                m_maxAltitude);
+                m_maxAltitude,
+                m_maxTwist);
 }
 
 void GHOST_Wintab::processInfoChange(LPARAM lParam)
@@ -362,6 +374,11 @@ void GHOST_Wintab::getInput(std::vector<GHOST_WintabInfoWin32> &outWintabInfo)
       out.tabletData.Ytilt = float(sin(M_PI_2 - azmRad) * vecLen);
     }
 
+    if (m_maxTwist > 0) {
+      ORIENTATION ort = pkt.pkOrientation;
+      out.tabletData.Twist = float(float(ort.orTwist) / float(m_maxTwist) * M_PI);
+    }
+
     out.time = pkt.pkTime;
 
     /* Some Wintab libraries don't handle relative button input, so we track button presses

intern/ghost/intern/GHOST_Wintab.hh

@@ -214,6 +214,7 @@ class GHOST_Wintab {
   int m_maxPressure = 0;
   int m_maxAzimuth = 0;
   int m_maxAltitude = 0;
+  int m_maxTwist = 0;
 
   /** Number of connected Wintab devices. */
   UINT m_numDevices = 0;

source/blender/windowmanager/WM_types.h

@@ -639,6 +639,8 @@ typedef struct wmTabletData {
   float x_tilt;
   /** as above. */
   float y_tilt;
+  /** range (-pi,pi), with stylus button to the left side being 0. */
+  float twist;
   /** Interpret mouse motion as absolute as typical for tablets. */
   char is_motion_absolute;
 } wmTabletData;

source/blender/windowmanager/intern/wm_event_system.cc

@@ -5138,6 +5138,7 @@ void wm_tablet_data_from_ghost(const GHOST_TabletData *tablet_data, wmTabletData
     wmtab->pressure = wm_pressure_curve(tablet_data->Pressure);
     wmtab->x_tilt = tablet_data->Xtilt;
     wmtab->y_tilt = tablet_data->Ytilt;
+    wmtab->twist = tablet_data->Twist;
     /* We could have a preference to support relative tablet motion (we can't detect that). */
     wmtab->is_motion_absolute = true;
     // printf("%s: using tablet %.5f\n", __func__, wmtab->pressure);