I am using texture fonts in FTGL to render fonts into multiple canvases as labels for axis and such. My first plot comes out fine. However all subsequent canvases render my texture fonts as simply black squares. I've also noticed that some numbers do not display on the canvas which actually renders. The "Center Time" should display 8.3956 but displays the following instead.
The font rendering is as follows:
glTranslatef(pixelX, pixelY, 0.0);
glRotatef(ang, 0.0, 0.0, 1.0);
It seems alpha blending is disabled when you draw your subsequent plots. Make sure you have enabled it, before you render texts: