Fix T95977: Point Info node radius wrong under rotation

intern/cycles/kernel/geom/point.h

@@ -141,9 +141,10 @@ ccl_device float point_radius(KernelGlobals kg, ccl_private const ShaderData *sd
       return r;
     }
     else {
-      float3 dir = make_float3(r, r, r);
+      const float normalized_r = r * (1.0f / M_SQRT3_F);
+      float3 dir = make_float3(normalized_r, normalized_r, normalized_r);
       object_dir_transform(kg, sd, &dir);
-      return average(dir);
+      return len(dir);
     }
   }
 

intern/cycles/util/math.h

@@ -80,6 +80,9 @@ CCL_NAMESPACE_BEGIN
 #ifndef M_SQRT2_F
 #  define M_SQRT2_F (1.4142135623730950f) /* sqrt(2) */
 #endif
+#ifndef M_SQRT3_F
+#  define M_SQRT3_F (1.7320508075688772f) /* sqrt(3) */
+#endif
 #ifndef M_LN2_F
 #  define M_LN2_F (0.6931471805599453f) /* ln(2) */
 #endif