From 29f3729df7e1f946d08326558f13e19112fa7687 Mon Sep 17 00:00:00 2001
From: baketnk <baketnk@protonmail.com>
Date: Thu, 24 Sep 2026 14:54:13 -0400
Subject: [PATCH] Face right-wrist panel inward without mirroring text

---
 docs/overlay.md      |  6 ++++--
 src/mount.cpp        |  6 ++++++
 tests/mount_test.cpp | 26 ++++++++++++++++++++++++--
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/docs/overlay.md b/docs/overlay.md
index 2f7a3f7..9d302e2 100644
--- a/docs/overlay.md
+++ b/docs/overlay.md
@@ -173,10 +173,12 @@ rather than placing a menu at the world origin. A tracking-origin reset requests
 a fresh placement. Settings → Recenter in front deliberately resamples the pose.
 
 Settings offers World space, Left wrist, Right wrist and Head on that same canvas.
-World/head width is 0.85 m; wrist width defaults to 0.30 m. Both wrists use
+World/head width is 0.85 m; wrist width defaults to 0.30 m. The left wrist uses
 VR Workspace's fallback watch-face axes: panel-right points toward the fingers
 (controller -Z), panel-up points out of the back of the hand (controller +Y),
-and panel-front points toward controller +X. Its controller-relative center is
+and panel-front points toward controller +X. The right wrist reverses panel-right
+and panel-front (controller +Z and -X), keeping panel-up unchanged so it faces
+inward with upright, unmirrored text. The controller-relative center is
 (0, 0.18, 0.089) m, approximating the compact HUD's surface center: its
 0.12 m wrist lift, 0.09 m bottom anchor and ~0.03 m panel-center correction;
 Z combines the fallback 0.054 m wrist calibration and 0.035 m finger-back offset. This copies placement geometry, not
diff --git a/src/mount.cpp b/src/mount.cpp
index 9244c61..b9bbcc5 100644
--- a/src/mount.cpp
+++ b/src/mount.cpp
@@ -78,6 +78,12 @@ Matrix34 relative_mount_pose(Mount mount, const WristPlacement& wrist) {
         pose[0] = {0.f, s, c, c * wrist.x + s * wrist.y};
         pose[1] = {0.f, c, -s, -s * wrist.x + c * wrist.y};
         pose[2] = {-1.f, 0.f, 0.f, wrist.z};
+        if (mount == Mount::RightWrist) {
+            // The wearer views the right wrist from the opposite side. Rotate
+            // 180 degrees about panel-up, not a reflection or upside-down roll:
+            // both right and front reverse, while up and center stay unchanged.
+            for (auto& row : pose) { row[0] = -row[0]; row[2] = -row[2]; }
+        }
         break;
     }
     case Mount::World: break;
diff --git a/tests/mount_test.cpp b/tests/mount_test.cpp
index 79b8b02..3366249 100644
--- a/tests/mount_test.cpp
+++ b/tests/mount_test.cpp
@@ -66,7 +66,13 @@ int main() {
     check_basis(head, 1, 0, 0, 1);
     CHECK(near(head[0][3], 0)); CHECK(near(head[1][3], -.16f)); CHECK(near(head[2][3], -1.05f));
     const auto left = relative_mount_pose(Mount::LeftWrist), right = relative_mount_pose(Mount::RightWrist);
-    CHECK(left == right); // VR Workspace fallback calibration uses the same controller-local axes for both hands.
+    check_basis(right, 0, 1, -1, 0); // right wrist faces inward, not away from wearer
+    for (int r = 0; r < 3; ++r) {
+        CHECK(near(right[r][3], left[r][3])); // position and up unchanged
+        CHECK(near(right[r][1], left[r][1]));
+        CHECK(near(right[r][0], -left[r][0]));
+        CHECK(near(right[r][2], -left[r][2]));
+    }
     CHECK(near(left[0][0], 0)); CHECK(near(left[1][0], 0)); CHECK(near(left[2][0], -1));
     CHECK(near(left[0][1], 0)); CHECK(near(left[1][1], 1)); CHECK(near(left[2][1], 0));
     CHECK(near(left[0][2], 1)); CHECK(near(left[1][2], 0)); CHECK(near(left[2][2], 0));
@@ -74,7 +80,23 @@ int main() {
     WristPlacement tuned{.02f, .1f, .07f, .25f, 90.f};
     const auto rotated = relative_mount_pose(Mount::RightWrist, tuned);
     CHECK(near(rotated[0][1], 1)); CHECK(near(rotated[1][1], 0));
-    CHECK(near(rotated[0][2], 0)); CHECK(near(rotated[1][2], -1));
+    CHECK(near(rotated[0][2], 0)); CHECK(near(rotated[1][2], 1));
+    // Every roll remains an orthonormal, positive-determinant rotation: no mirror.
+    for (float roll : {-180.f, -90.f, -35.f, 0.f, 90.f, 180.f}) {
+        tuned.roll_degrees = roll;
+        for (auto hand : {Mount::LeftWrist, Mount::RightWrist}) {
+            const auto m = relative_mount_pose(hand, tuned);
+            for (int a = 0; a < 3; ++a) for (int b = 0; b < 3; ++b) {
+                float dot = 0;
+                for (int r = 0; r < 3; ++r) dot += m[r][a] * m[r][b];
+                CHECK(near(dot, a == b ? 1.f : 0.f));
+            }
+            for (int r = 0; r < 3; ++r) {
+                const int a = (r + 1) % 3, b = (r + 2) % 3;
+                CHECK(near(m[a][0] * m[b][1] - m[b][0] * m[a][1], m[r][2]));
+            }
+        }
+    }
     CHECK(near(rotated[0][3], .1f)); CHECK(near(rotated[1][3], -.02f));
     CHECK(near(rotated[2][3], .07f)); CHECK(near(mount_width(Mount::RightWrist, tuned), .25f));
     CHECK(relative_mount_pose(Mount::Head, tuned) == head);