Fix CV->GL pose conversion in updateTrackable()

Stop negating rotation columns 1 and 2 in updateTrackable(). The previous
behavior applied a partial CV->GL conversion (rotation columns flipped,
translation untouched), which left consumers with an inconsistent pose:
the rotation was neither raw OpenCV nor a clean GL right-handed modelview,
and the translation Z stayed positive — causing tracked objects to render
behind the camera in OpenGL/three.js scenes (clip.w < 0, ndc.z > 1).

After this change, getPoseMatrix2() / trans returns the raw OpenCV pose
(rotation unmodified, translation kept at the existing 0.001 * 1.64 scale).
The CV->GL handedness flip (negate Y and Z rows including translation) is
applied downstream by arglCameraViewRHf when building the GL right-handed
modelview (matrixGL_RH on the JS side, getGLViewMatrix() in WebARKitManager
on the C++ side). Both downstream paths are now mathematically clean
diag(1, -1, -1, 1) * pose conversions and produce a correct modelview that
places the tracked object in front of the GL camera.

Note: this is a semantic change to `pose` / `trans` for any consumer that
relied on the previous partially-converted shape. Downstream consumers
should use matrixGL_RH (or getGLViewMatrix) for OpenGL rendering and treat
`pose` as the raw OpenCV camera pose.

Refs: #34, webarkit/webarkit-testing#31

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: kalwalt

WebARKit/WebARKitPattern.cpp

@@ -55,12 +55,18 @@ void WebARKitPatternTrackingInfo::getTrackablePose(cv::Mat& pose) {
 
 void WebARKitPatternTrackingInfo::updateTrackable() {
     if (transMat) {
-        //visible = true;
+        // Keep `trans` as the raw OpenCV pose (rotation unmodified, translation
+        // scaled). The CV->GL handedness conversion (negate Y and Z rows incl.
+        // translation) is applied downstream by arglCameraViewRHf when building
+        // the GL right-handed modelview (matrixGL_RH / getGLViewMatrix).
+        // Previously, rotation columns 1 and 2 were negated here but the
+        // translation was not, producing an inconsistent partial conversion
+        // that left tracked objects behind the camera in OpenGL renderers.
         for (int j = 0; j < 3; j++) {
-            trans[j][0] =  transMat[j][0];
-            trans[j][1] = -transMat[j][1];
-            trans[j][2] = -transMat[j][2];
-            trans[j][3] = (transMat[j][3] * m_scale * 0.001f * 1.64f );
+            trans[j][0] = transMat[j][0];
+            trans[j][1] = transMat[j][1];
+            trans[j][2] = transMat[j][2];
+            trans[j][3] = (transMat[j][3] * m_scale * 0.001f * 1.64f);
         }
     }
 }