glText

glText is a simple cross-platform single header text rendering
library for OpenGL. glText requires no additional files
(such as fonts or textures) for drawing text, everything comes pre-packed
in the header.

The above screenshot is of the simple.c example.

Example

// Initialize glText
gltInit();
// Creating text
GLTtext *text = gltCreateText();
gltSetText(text, "Hello World!");
// Begin text drawing (this for instance calls glUseProgram)
gltBeginDraw();
// Draw any amount of text between begin and end
gltColor(1.0f, 1.0f, 1.0f, 1.0f);
gltDrawText2D(text, x, y, scale);
// Finish drawing text
gltEndDraw();
// Deleting text
gltDeleteText(text);
// Destroy glText
gltTerminate();

Implementation

In one C or C++ file, define GLT_IMPLEMENTATION prior to inclusion to create the implementation.

#define GLT_IMPLEMENTATION
#include "gltext.h"

Optimization

Each time gltDraw*() functions are called, glGetIntegerv(GL_VIEWPORT, ...)
is called. To avoid this and optimize that call away, define GLT_MANUAL_VIEWPORT
before including gltext.h.

#define GLT_MANUAL_VIEWPORT
#include "gltext.h"

Then when the viewport is resized manually call:

gltViewport(width, height)

Manual Model, View, Projection Matrix

The example uses LinearAlgebra.

GLfloat fontScale = 0.01f;
GLfloat x = 0.0f;
GLfloat y = 0.0f;
x -= gltGetTextWidth(text, fontScale) * 0.5f;
y -= gltGetTextHeight(text, fontScale) * 0.5f;
mat4 proj = mat4::perspective(70.0f, viewportWidth, viewportHeight, 0.1f, 10.0f);
mat4 view = ...;
mat4 model = mat4::identity;
model.translate(x, y + gltGetTextHeight(text, fontScale));
model.scale(fontScale, -fontScale);
mat4 mvp = proj * view * model;
gltDrawText(text, (GLfloat*)&mvp);

Aligned Text

// Where horizontal is either:
// - GLT_LEFT (default)
// - GLT_CENTER
// - GLT_RIGHT
// Where vertical is either:
// - GLT_TOP (default)
// - GLT_CENTER
// - GLT_BOTTOM
gltDrawText2DAligned(text, x, y, scale, horizontal, vertical);

No Dependencies

glText has no external dependencies besides OpenGL and the standard C libraries.
By default glText uses stdlib.h, string.h and stdint.h.

If GLT_DEBUG is defined assert.h is needed. If GLT_DEBUG_PRINT is defined stdio.h is needed.

Reporting Bugs & Requests

Feel free to use the issue tracker,
for reporting bugs, submitting patches or requesting features.

Before submitting bugs, make sure that you’re using the latest version of glText.