3D font in OpenGL

Sample Image

In this article, I give a wrap class which encapsulate the OpenGL 3D Font
functions. With this class, you can design any 3D letter as a 3D geometry
object, translating, scaling, rotating, texture mapping, etc.

The key steps to display a 3D letter is:

1) Create a display list

2) Create and set a font to current windows context device,
wglUseFontOutlines
function can retrieve the 3d Font geometry data from the context device.

3) call
glListBase and
glCallLists to
display 3D font letters.

The
wglUseFontOutlines
function calculate the 3D font geometry data from the mathmatic module of
Windows system TrueType fonts library.

My 3D font class contain position, material color data and content
string. It can be used as a separate geometry object in a multiple 3D
objects scene.

Here is a small example:



class C3DFontView : public CView
{
  ...
  CGLFont  m_FontX; // Declare a font object in your view class
  ...
};

int CMy3DFontView::OnCreate(LPCREATESTRUCT lpCreateStruct) // Create view
{
  if (CView::OnCreate(lpCreateStruct) == -1)
    return -1;
/*
** Setup font attributes
*/
  m_FontX.SetXOffset(-0.4f);
  m_FontX.SetYOffset(-0.4f);
  m_FontX.SetXScale(1.4f);
  m_FontX.SetYScale(1.3f);
  m_FontX.SetZScale(0.8f);
  m_FontX.SetXRotate(-20.0f);
  m_FontX.SetYRotate(-6.0f);
  m_FontX.SetZRotate(90.0f);

  wglMakeCurrent(m_pDC->m_hDC,m_hRC);
  m_FontX.SetFontType(GL_FONT_SOLID); // Select font type
  m_FontX.CreateFont(m_pDC, "Arial Black"); // Create the font
  m_FontX.SetText("Xing"); // Select text to render

  wglMakeCurrent(NULL,NULL);

}

void CMy3DFontView::OnDraw(CDC* pDC) // Draw method
{
  CMy3DFontDoc* pDoc = GetDocument();
  ASSERT_VALID(pDoc);

  ...

  wglMakeCurrent(m_pDC->GetSafeHdc(), m_hRC);
  DrawGLFont(); // Render the text
  SwapBuffers(m_pDC->GetSafeHdc());
  wglMakeCurrent(m_pDC->GetSafeHdc(), NULL);

}


void CMy3DFontView::DrawGLFont(void) // The render method
{
  glShadeModel(GL_SMOOTH);
  glEnable(GL_DEPTH_TEST);

  //clear color buffer
  glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  //set light model
  glLightfv(GL_LIGHT0, GL_AMBIENT, m_Lightambient); //set light ambient
  glLightfv(GL_LIGHT0, GL_DIFFUSE, m_Lightdiffuse); //set light specular
  glLightfv(GL_LIGHT0, GL_SPECULAR, m_Lightspecular); //set light specular
  glLightfv(GL_LIGHT0, GL_POSITION, m_Lightposition); //set light position

  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  glTranslatef(-0.5f, 0.0f, -5.0f);

  m_FontX.GLDrawText(); // Render the text

  glFlush();

}

Downloads

Download demo project – 175 Kb

Download source – 3 Kb

History

More by Author

Must Read