Transmission of characters

If you draw a character with the code written as below, the surroundings of the character become black. Can I pass it through?

setup

  myFont.load("Futura.ttc",10,true,true,true,0.5,1000);
  mesh = myFont.getStringMesh("bd", 0, 0);

draw

    myFont.getFontTexture().bind();
    mesh.draw();
    myFont.getFontTexture().unbind();