fix assembly symmetry cage alignement

src/extensions/rcsb/assembly-symmetry/representation.ts

@@ -225,6 +225,7 @@ function getSymbolScale(symbol: string) {
 function setSymbolTransform(t: Mat4, symbol: string, axes: AssemblySymmetry.RotationAxes, size: number, structure: Structure) {
     const eye = Vec3();
     const target = Vec3();
+    const dir = Vec3();
     const up = Vec3();
     let pair: Mutable<AssemblySymmetry.RotationAxes> | undefined = undefined;
 
@@ -246,8 +247,8 @@ function setSymbolTransform(t: Mat4, symbol: string, axes: AssemblySymmetry.Rota
         const a5dir = Vec3.sub(Vec3(), a5.end, a5.start);
         pair = [a5];
         for (const a of axes.filter(a => a.order === 3)) {
-            let d = radToDeg(Vec3.angle(Vec3.sub(up, a.end, a.start), a5dir));
-            if (equalEps(d, 100.81, 0.1) || equalEps(d, 79.19, 0.1)) {
+            const d = radToDeg(Vec3.angle(Vec3.sub(up, a.end, a.start), a5dir));
+            if (!pair[1] && (equalEps(d, 100.81, 0.1) || equalEps(d, 79.19, 0.1))) {
                 pair[1] = a;
                 break;
             }
@@ -263,8 +264,8 @@ function setSymbolTransform(t: Mat4, symbol: string, axes: AssemblySymmetry.Rota
         Vec3.copy(target, aA.end);
         if (aB) {
             Vec3.sub(up, aB.end, aB.start);
-            const d = Vec3.dot(eye, up);
-            if (d < 0) Vec3.negate(up, up);
+            Vec3.sub(dir, eye, target);
+            if (Vec3.dot(dir, up) < 0) Vec3.negate(up, up);
             Mat4.targetTo(t, eye, target, up);
             Mat4.scaleUniformly(t, t, size * getSymbolScale(symbol));
         } else {