Name : glfont Library
Author : Noah Shibley, http://socialhardware.net
Date : June 16th 2016
Notes : A modern opengl text rendering library for golang
Dependencies: freetype, go-gl, glfw
Function List:
func LoadFont
func LoadFont(file string, scale int32, windowWidth int, windowHeight int) (*Font, error)LoadFont loads the specified font at the given scale. The default character set is ASCII (codepoints 32 to 127).
func LoadTrueTypeFont
func LoadTrueTypeFont(program uint32, r io.Reader, scale int32, low, high rune, dir Direction) (*Font, error)LoadTrueTypeFont builds buffers and textures based on a ttf files gylphs.
func (*Font) GenerateGlyphs
func (f *Font) GenerateGlyphs(low, high rune) errorGenerateGlyphs builds additional glyphs for non-ASCII Unicode codepoints.
func (*Font) Printf
func (f *Font) Printf(x, y float32, scale float32, fs string, argv ...interface{}) errorPrintf draws a string to the screen, takes a list of arguments like printf
func (*Font) SetColor
func (f *Font) SetColor(red float32, green float32, blue float32, alpha float32)SetColor allows you to set the text color to be used when you draw the text
func (f *Font) UpdateResolution
func (f *Font) UpdateResolution(windowWidth int, windowHeight int)UpdateResolution is needed when the viewport is resized
func (f *Font) Width
func (f *Font) Width(scale float32, fs string, argv ...interface{}) float32Width returns the width of a piece of text in pixels
Example:
package main
import (
"fmt"
"log"
"runtime"
"github.com/go-gl/gl/all-core/gl"
"github.com/go-gl/glfw/v3.1/glfw"
"github.com/nullboundary/glfont"
)
const windowWidth = 1920
const windowHeight = 1080
func init() {
runtime.LockOSThread()
}
func main() {
if err := glfw.Init(); err != nil {
log.Fatalln("failed to initialize glfw:", err)
}
defer glfw.Terminate()
glfw.WindowHint(glfw.Resizable, glfw.True)
glfw.WindowHint(glfw.ContextVersionMajor, 3)
glfw.WindowHint(glfw.ContextVersionMinor, 2)
glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)
window, _ := glfw.CreateWindow(int(windowWidth), int(windowHeight), "glfontExample", glfw.GetPrimaryMonitor(), nil)
window.MakeContextCurrent()
glfw.SwapInterval(1)
if err := gl.Init(); err != nil {
panic(err)
}
//load font (fontfile, font scale, window width, window height
font, err := glfont.LoadFont("Roboto-Light.ttf", int32(52), windowWidth, windowHeight)
if err != nil {
log.Panicf("LoadFont: %v", err)
}
gl.Enable(gl.DEPTH_TEST)
gl.DepthFunc(gl.LESS)
gl.ClearColor(0.0, 0.0, 0.0, 0.0)
for !window.ShouldClose() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
//set color and draw text
font.SetColor(1.0, 1.0, 1.0, 1.0) //r,g,b,a font color
font.Printf(100, 100, 1.0, "Lorem ipsum dolor sit amet, consectetur adipiscing elit.") //x,y,scale,string,printf args
window.SwapBuffers()
glfw.PollEvents()
}
}