We can draw all kinds of 3D Models in OpenGL. But oftentimes we also need to draw Fonts in OpenGL. How can we make that?
Luckily there are a few open-source fonts rendering libraries out there. I'll guide you to make use of one of them: FTGL
.
I. Libraries we'll need to use.
- OpenGL
- FTGL
- freeglut
- freetype
II. Compile the libraries in Visual Studio 2022 / VC++
.
- freeglut
I downloaded freeglut v3.4.0
from Sourceforge. And use CMake to build VC++ project management files.
CMake has a very easy to use GUI on Windows platforms.
With the generated freeglut.sln
we can open the project. Select building options of x64 & release
.
As we don't need other external libraries, we can build it directly.
Then we'll have a freeglut.lib
or freeglut_static.lib
for later use.
- freetype
I downloaded freetype v2.13.2
from freetype.org.
I'll recommend you to get the sources packages from their official websites if they have. You'll encounter fewer building errors in stead of using the newest code from their GitHub repositories.
After all, tuning rendering effects are much more interesting than solving building blockers.
We can open the default freetype.sln
provided by this source package in VC++ to build it. Before start building, please select x64 & release
options first. After that, we'll get the binary freetype.lib
.
- FTGL
We can use default ftgl.sln
in source package to build. Please select x64 & release
first.
And we'll need to configure include paths
& library paths
to the project. We'll also need to add freeglut.lib
& freetype.lib
to the linker settings.
In the end, we'll get ftgl.lib
.
III. Write a FTGL demo. Sample code:
// Demo code
void Demo_code(void)
{
// Resolutions of the picture
const GLfloat width = 800;
const GLfloat height = 600;
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
// Load the Font
// Use any TTF font name you like here
font = (FTGLfont*)new FTGLPolygonFont("./Mona-Regular-2.ttf");
if (((FTGLPolygonFont*)font)->Error())
{
fprintf(stderr, "Failed to load font\n");
return;
}
// Clear all pixels
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Set perspective view
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 100.0f);
glPushMatrix();
// Place camera
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Adjust the position of the text
glTranslatef(-0.5f, 0.0f, -5.0f);
// Rotate the text to be vertically
glRotatef(55.0f, 0.0f, 1.0f, 0.0f);
glScalef(0.35f, 0.35f, 0.35f);
if (font)
{
// Render Fonts
((FTGLPolygonFont*)font)->FaceSize(0);
glTranslatef(-6.0f, 0.0f, 0.0f);
((FTGLPolygonFont*)font)->Render("You know Bill?");
glColor4d(0.0, 0.0f, 1.0f, 0.8f);
glTranslatef(0.0f, -1.0f, 0.0f);
((FTGLPolygonFont*)font)->Render("You know Bill?");
}
glPopMatrix();
// Render
glutSwapBuffers();
}
IV. Compile the sample code into executable binary.
We need to confifgure the VC++ project with include paths
, library paths
and libraries
prior building:
- ftgl.lib
- freeglut.lib
- freetype.lib
V. Rendering results.
The library can render fonts into multiple styles.
- Polygon mode
- Outline mode
- Extrude mode
And more!
Don't forget to copy the TTF font file and any DLL files you're leveraging to executable folder to try the Demo.
Hope you enjoy the FTGL 3D Fonts rendering library for OpenGL. It's a wonderful library! 😊
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