add dual brush roundness property

src/canvas.cpp

@@ -921,6 +921,7 @@ void Canvas::stroke_start(glm::vec3 point, float pressure)
         dual_brush->m_jitter_scatter_bothaxis = m_current_brush->m_dual_scatter_bothaxis;
         dual_brush->m_jitter_angle = m_current_brush->m_dual_rotate;
         dual_brush->m_tip_texture = m_current_brush->m_dual_texture;
+        dual_brush->m_tip_aspect = m_current_brush->m_dual_aspect;
         m_dual_stroke = std::make_unique<Stroke>();
         m_dual_stroke->m_camera.rot = m_cam_rot;
         m_dual_stroke->m_camera.fov = m_cam_fov;