fix mixer brush uv2 and tip visibility on touch

src/canvas.cpp

@@ -391,7 +391,10 @@ void Canvas::stroke_draw()
             vertex_t{ {0, 0, 1, 1}, {1, 0}, {1, 0} },
         };
         for (int j = 0; j < 4; j++)
+        {
             B[j].pos = glm::vec4(xy(s.pos) + off[j] * glm::orientate2(-s.angle), 1, 1);
+            B[j].uvs2 = UV2[j];
+        }
 
         glViewport(0, 0, m_width, m_height);
 
@@ -466,9 +469,9 @@ void Canvas::stroke_draw()
                     {
                         inside++;
                     }
+                    //P[j].uvs2 = xy(P[j].pos) / glm::vec2(App::I.width, App::I.height);
                     P[j].pos.x = -(plane_local.x * 0.5f - 0.5f) * m_width;
                     P[j].pos.y = (plane_local.y * 0.5f + 0.5f) * m_height;
-                    P[j].uvs2 = UV2[j];
 
                     // Black magic - BEWARE!
                     // interpolation perspective correction, use the current camera projection to correct the interpolation