• Eman2UsingFTGL

Compiling EMAN2 with FTGL support

To compile EMAN2 with FTGL support set ENABLE_FTGL to ON in cmake setup. This may also require you to install FTGL on your machine. For more information contact an EMAN2 developer.

Using FTGL in python

Programmers have to create an instance of an EMFTGL object. A platform independent solution to getting a font renderer is available and is the recommended approach

   1 from EMAN2 import get_3d_font_renderer
   2 self.font_renderer = get_3d_font_renderer() # loads a platform independent font file that is shipped with EMAN2 (except windows, were we use system font file)
   3 self.font_renderer.set_face_size(16) # etc

The longer way would involve using commands like this, and would require you to supply the font file.

   1 from EMAN2 import EMFTGL
   2 self.font_renderer = EMFTGL()
   3 self.font_renderer.set_face_size(16)
   4 self.font_renderer.set_using_display_lists(True)
   5 self.font_renderer.set_depth(32) # only useful if font mode is EXTRUDE
   6 self.font_renderer.set_font_mode(FTGLFontMode.TEXTURE) # or EXTRUDE, PIXMAP, BITMAP, POLYGON or OUTLINE
   7 self.font_renderer.set_font_file_name("/usr/share/fonts/dejavu/DejaVuSerif-Bold.ttf") # be wary of platform dependence

Note that the EMFTGL has default values for all of its parameters and that in general you want to limit the number of times you call the setter functions, because they cause FTGL to regenerate an FTFont class and this is not a trivial expense. However the EMFTGL uses a cache so any FTFonts (which are characterized by face size, depth, display list use, mode, and font file) which have previously been created will automatically be reused (if parameters match).

The EMFTGL cache is not static. This is related to OpenGL contexts and display lists...

Then to render text use a command similar to the following in your paint function:

   1 glPushMatrix() # FTGL does transformations - must push
   2 self.font_renderer.render_string("Important Information")
   3 glPopMatrix()

To get the bounding box of the string use:

   1 bbox = self.font_renderer.bounding_box("Important Information")

If you want to rotate the font as though it is centered on the origin you might use

   1 rotation = 45
   2 rot_axis = [1,0,0]
   3 bbox = self.font_renderer.bounding_box(message)
   4 
   5 glPushMatrix()
   6 glTranslate(-(bbox[0]-bbox[3])/2,-(bbox[1]-bbox[4])/2,-(bbox[2]-bbox[5])/2)
   7 glRotate(rotation,*rot_axis)
   8 glTranslate((bbox[0]-bbox[3])/2,(bbox[1]-bbox[4])/2,(bbox[2]-bbox[5])/2)
   9 self.font_renderer.render_string(message)
  10 glPopMatrix()

Recommendations

TEXTURE fonts are probably the most versatile types. They are fast, antialiased, and can be transformed just like any OpenGL primitive. See http://ftgl.sourceforge.net/docs/html/ftgl-tutorial.html

C++

Have a look at the C++ code here