layergl

README

LayerGL

OpenGL 3.3 abstraction layer (In other words, graphics library) for Go.

Installation

 $ go get -u github.com/iostapyshyn/layergl

Usage

Minimal Example

package main

import (
	"github.com/go-gl/glfw/v3.2/glfw"
	"github.com/iostapyshyn/layergl"
	"runtime"
)

var window *glfw.Window

const (
	width  = 640
	height = 480
)

func init() {
	runtime.LockOSThread()
}

func main() {
	var err error
	if err := glfw.Init(); err != nil {
		panic(err)
	}

	defer glfw.Terminate()

	// OpenGL version 3.3 Core.
	glfw.WindowHint(glfw.ContextVersionMajor, 3)
	glfw.WindowHint(glfw.ContextVersionMinor, 3)
	glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
	glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)

	// Required for MSAA anti-aliasing.
	glfw.WindowHint(glfw.Samples, 4)

	glfw.WindowHint(glfw.Resizable, glfw.False)
	glfw.WindowHint(glfw.Visible, glfw.False)

	window, err = glfw.CreateWindow(width, height, "Example", nil, nil)
	if err != nil {
		panic(err)
	}

	defer window.Destroy()

	// Center window on the screen.
	vidmode := glfw.GetPrimaryMonitor().GetVideoMode()
	window.SetPos((vidmode.Width-width)/2, (vidmode.Height-height)/2)

	window.MakeContextCurrent()
	glfw.SwapInterval(1)

	window.Show()

	loop()
}

func loop() {
	err := layergl.Init(width, height)
	if err != nil {
		panic(err)
	}

	for !window.ShouldClose() {
		layergl.Clear()

		layergl.DrawVertexObject(layergl.Triangles([]layergl.Point{
			{X: width/2 - 100, Y: height/2 - 100},
			{X: width/2 + 100, Y: height/2 - 100},
			{X: width / 2, Y: height/2 + 100},
		}), layergl.Color{1.0, 0.0, 1.0, 1.0})

		window.SwapBuffers()
		glfw.PollEvents()
	}
}

For more features, please refer to demo program source code included in the repository.

Libraries used:

• go-gl: Go bindings for OpenGL.

Documentation

Index

• func Clear()
• func ClearColor(color Color)
• func Distance(a, b Point) float64
• func DrawLines(points []Point, color Color)
• func DrawPoint(d Point, r float64, color Color)
• func DrawRect(rect Rect, color Color)
• func DrawTexture(d *Texture)
• func DrawVertexObject(d *VertexObject, color Color)
• func Init(width, height int) error
• type Color
• type Font
  • func LoadFont(file string, scale int32) (*Font, error)
  • func (f *Font) Printf(point Point, color Color, scale float64, fs string, argv ...interface{})
• type Point
• type Rect
  • func (rect Rect) Area() float64
  • func (rect Rect) Contains(p Point) bool
  • func (rect Rect) Height() float64
  • func (rect Rect) Intersects(r2 Rect) bool
  • func (rect Rect) Width() float64
• type Texture
  • func NewTexture(fileName string, width, height float64) (texture *Texture, err error)
• type VertexObject
  • func FromVertices(p []Point) (*VertexObject, error)
  • func Rectangle(rect Rect) (polygon *VertexObject)
  • func Triangles(vertices []Point) (polygon *VertexObject)
  • func (v VertexObject) Bounds() Rect
  • func (p *VertexObject) CenterAt(point Point)
  • func (v VertexObject) Centroid() (center Point)
  • func (p *VertexObject) Move(x, y float64)
  • func (v *VertexObject) RotateDeg(angle float64)
  • func (v *VertexObject) RotateRad(angle float64)
  • func (v *VertexObject) Scale(scale float64)
  • func (vo *VertexObject) Triangulate() error

Functions

func Clear

func Clear()

func ClearColor

func ClearColor(color Color)

func Distance

func Distance(a, b Point) float64

Return distance between two points.

func DrawLines

func DrawLines(points []Point, color Color)

func DrawPoint

func DrawPoint(d Point, r float64, color Color)

func DrawRect

func DrawRect(rect Rect, color Color)

func DrawTexture

func DrawTexture(d *Texture)

func DrawVertexObject

func DrawVertexObject(d *VertexObject, color Color)

func Init

func Init(width, height int) error

Types

type Color

type Color struct {
	R, G, B, A float64
}

type Font

type Font struct {
	// contains filtered or unexported fields
}

func LoadFont

func LoadFont(file string, scale int32) (*Font, error)

func (*Font) Printf

func (f *Font) Printf(point Point, color Color, scale float64, fs string, argv ...interface{})

type Point

type Point struct {
	X, Y float64
}

type Rect

type Rect struct {
	X1, Y1 float64
	X2, Y2 float64
}

func (Rect) Area

func (rect Rect) Area() float64

func (Rect) Contains

func (rect Rect) Contains(p Point) bool

func (Rect) Height

func (rect Rect) Height() float64

func (Rect) Intersects

func (rect Rect) Intersects(r2 Rect) bool

func (Rect) Width

func (rect Rect) Width() float64

type Texture

type Texture struct {
	*VertexObject
	// contains filtered or unexported fields
}

func NewTexture

func NewTexture(fileName string, width, height float64) (texture *Texture, err error)

Loads and creates new Texture object.

type VertexObject

type VertexObject struct {
	Vertices []Point
	Indices  []int
}

func FromVertices

func FromVertices(p []Point) (*VertexObject, error)

Performs triangulation creating new VertexObject.

func Rectangle

func Rectangle(rect Rect) (polygon *VertexObject)

func Triangles

func Triangles(vertices []Point) (polygon *VertexObject)

func (VertexObject) Bounds

func (v VertexObject) Bounds() Rect

Return rectangle approximating bounds of the polygon.

func (*VertexObject) CenterAt

func (p *VertexObject) CenterAt(point Point)

Centers VertexObject at exact point.

func (VertexObject) Centroid

func (v VertexObject) Centroid() (center Point)

Returns geometrical center, center of mass (centroid) of a polygon.

func (*VertexObject) Move

func (p *VertexObject) Move(x, y float64)

Translation of the VertexObject by x, y pixels in the respective directions.

func (*VertexObject) RotateDeg

func (v *VertexObject) RotateDeg(angle float64)

Rotation.

func (*VertexObject) RotateRad

func (v *VertexObject) RotateRad(angle float64)

func (*VertexObject) Scale

func (v *VertexObject) Scale(scale float64)

Scaling.

func (*VertexObject) Triangulate

func (vo *VertexObject) Triangulate() error

Performs triangulation of VertexObject, writing to the Indices field.