func main() {
// Initialize GLFW for window management
glfw.SetErrorCallback(glfwErrorCallback)
if !glfw.Init() {
panic("failed to initialize glfw")
}
defer glfw.Terminate()
glfw.WindowHint(glfw.Resizable, glfw.False)
glfw.WindowHint(glfw.ContextVersionMajor, 3)
glfw.WindowHint(glfw.ContextVersionMinor, 3)
glfw.WindowHint(glfw.OpenglForwardCompatible, glfw.True) // Necessary for OS X
glfw.WindowHint(glfw.OpenglProfile, glfw.OpenglCoreProfile) // Necessary for OS X
glfw.WindowHint(glfw.OpenglDebugContext, glfw.True)
window, err := glfw.CreateWindow(WindowWidth, WindowHeight, "Cube", nil, nil)
if err != nil {
panic(err)
}
window.MakeContextCurrent()
// Initialize Glow
if err := gl.Init(); err != nil {
panic(err)
}
// Note that it is possible to use GL functions spanning multiple versions
if err := gl4.Init(); err != nil {
fmt.Printf("Could not initialize GL 4.4 (non-fatal)")
}
if gl.ARB_debug_output {
gl.Enable(gl.DEBUG_OUTPUT_SYNCHRONOUS_ARB)
gl.DebugMessageCallbackARB(gl.DebugProc(glDebugCallback), gl.Ptr(nil))
// Trigger an error to demonstrate debug output
gl.Enable(gl.CONTEXT_FLAGS)
}
version := gl.GoStr(gl.GetString(gl.VERSION))
fmt.Println("OpenGL version", version)
// Configure the vertex and fragment shaders
program, err := newProgram(vertexShader, fragmentShader)
if err != nil {
panic(err)
}
gl.UseProgram(program)
projection := mgl32.Perspective(70.0, float32(WindowWidth)/WindowHeight, 0.1, 10.0)
projectionUniform := gl.GetUniformLocation(program, gl.Str("projection\x00"))
gl.UniformMatrix4fv(projectionUniform, 1, false, &projection[0])
camera := mgl32.LookAtV(mgl32.Vec3{3, 3, 3}, mgl32.Vec3{0, 0, 0}, mgl32.Vec3{0, 1, 0})
cameraUniform := gl.GetUniformLocation(program, gl.Str("camera\x00"))
gl.UniformMatrix4fv(cameraUniform, 1, false, &camera[0])
model := mgl32.Ident4()
modelUniform := gl.GetUniformLocation(program, gl.Str("model\x00"))
gl.UniformMatrix4fv(modelUniform, 1, false, &model[0])
textureUniform := gl.GetUniformLocation(program, gl.Str("tex\x00"))
gl.Uniform1i(textureUniform, 0)
gl.BindFragDataLocation(program, 0, gl.Str("outputColor\x00"))
// Load the texture
texture, err := newTexture("square.png")
if err != nil {
panic(err)
}
// Configure the vertex data
var vao uint32
gl.GenVertexArrays(1, &vao)
gl.BindVertexArray(vao)
var vbo uint32
gl.GenBuffers(1, &vbo)
gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
gl.BufferData(gl.ARRAY_BUFFER, len(cubeVertices)*4, gl.Ptr(cubeVertices), gl.STATIC_DRAW)
vertAttrib := uint32(gl.GetAttribLocation(program, gl.Str("vert\x00")))
gl.EnableVertexAttribArray(vertAttrib)
gl.VertexAttribPointer(vertAttrib, 3, gl.FLOAT, false, 5*4, gl.PtrOffset(0))
texCoordAttrib := uint32(gl.GetAttribLocation(program, gl.Str("vertTexCoord\x00")))
gl.EnableVertexAttribArray(texCoordAttrib)
gl.VertexAttribPointer(texCoordAttrib, 2, gl.FLOAT, false, 5*4, gl.PtrOffset(3*4))
// Configure global settings
gl.Enable(gl.DEPTH_TEST)
gl.DepthFunc(gl.LESS)
gl.ClearColor(1.0, 1.0, 1.0, 1.0)
angle := 0.0
previousTime := glfw.GetTime()
for !window.ShouldClose() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
// Update
time := glfw.GetTime()
elapsed := time - previousTime
previousTime = time
angle += elapsed
model = mgl32.HomogRotate3D(float32(angle), mgl32.Vec3{0, 1, 0})
// Render
gl.UseProgram(program)
gl.UniformMatrix4fv(modelUniform, 1, false, &model[0])
gl.BindVertexArray(vao)
gl.ActiveTexture(gl.TEXTURE0)
gl.BindTexture(gl.TEXTURE_2D, texture)
gl.DrawArrays(gl.TRIANGLES, 0, 6*2*3)
// Maintenance
window.SwapBuffers()
glfw.PollEvents()
}
}
func newTexture(file string) (uint32, error) {
imgFile, err := os.Open(file)
if err != nil {
return 0, err
}
img, _, err := image.Decode(imgFile)
if err != nil {
return 0, err
}
rgba := image.NewRGBA(img.Bounds())
if rgba.Stride != rgba.Rect.Size().X*4 {
return 0, fmt.Errorf("unsupported stride")
}
draw.Draw(rgba, rgba.Bounds(), img, image.Point{0, 0}, draw.Src)
var texture uint32
gl.GenTextures(1, &texture)
gl.ActiveTexture(gl.TEXTURE0)
gl.BindTexture(gl.TEXTURE_2D, texture)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
gl.TexImage2D(
gl.TEXTURE_2D,
0,
gl.RGBA,
int32(rgba.Rect.Size().X),
int32(rgba.Rect.Size().Y),
0,
gl.RGBA,
gl.UNSIGNED_BYTE,
gl.Ptr(rgba.Pix))
return texture, nil
}
// bindString generates all of the vertex buffers and vertex arrays for a single constant line of
// text. No error checking is done.
func (d *Dictionary) bindString(str string) strData {
var data strData
gl.GenVertexArrays(1, &data.varrays[0])
gl.BindVertexArray(data.varrays[0])
gl.GenBuffers(2, &data.vbuffers[0])
var positions, texcoords []float32
var pen pos
var prev rune
for _, r := range str {
ri := d.Runes[r]
var scale float32 = 1.0 / float32(d.GlyphMax.Dy())
var posMin, posMax pos
posMin.x = pen.x + float32(ri.GlyphBounds.Min.X)*scale
posMin.y = pen.y + float32(ri.GlyphBounds.Min.Y)*scale
posMax.x = pen.x + float32(ri.GlyphBounds.Max.X)*scale
posMax.y = pen.y + float32(ri.GlyphBounds.Max.Y)*scale
var texMin, texMax pos
texMin.x = float32(ri.PixBounds.Min.X) / float32(d.Dx)
texMin.y = float32(ri.PixBounds.Min.Y) / float32(d.Dy)
texMax.x = float32(ri.PixBounds.Max.X) / float32(d.Dx)
texMax.y = float32(ri.PixBounds.Max.Y) / float32(d.Dy)
pen.x += float32(ri.AdvanceWidth) * scale
pen.x += float32(d.Kerning[RunePair{prev, r}]) * scale
// pen.x -= float32(d.Kerning[RunePair{prev, r}]) * scale
positions = append(positions, posMin.x) // lower left
positions = append(positions, posMin.y)
positions = append(positions, posMin.x) // upper left
positions = append(positions, posMax.y)
positions = append(positions, posMax.x) // upper right
positions = append(positions, posMax.y)
positions = append(positions, posMin.x) // lower left
positions = append(positions, posMin.y)
positions = append(positions, posMax.x) // upper right
positions = append(positions, posMax.y)
positions = append(positions, posMax.x) // lower right
positions = append(positions, posMin.y)
texcoords = append(texcoords, texMin.x) // lower left
texcoords = append(texcoords, texMax.y)
texcoords = append(texcoords, texMin.x) // upper left
texcoords = append(texcoords, texMin.y)
texcoords = append(texcoords, texMax.x) // upper right
texcoords = append(texcoords, texMin.y)
texcoords = append(texcoords, texMin.x) // lower left
texcoords = append(texcoords, texMax.y)
texcoords = append(texcoords, texMax.x) // upper right
texcoords = append(texcoords, texMin.y)
texcoords = append(texcoords, texMax.x) // lower right
texcoords = append(texcoords, texMax.y)
prev = r
}
data.count = int32(len(positions))
gl.BindBuffer(gl.ARRAY_BUFFER, data.vbuffers[0])
gl.BufferData(gl.ARRAY_BUFFER, len(positions)*int(unsafe.Sizeof(positions[0])), gl.Ptr(&positions[0]), gl.STATIC_DRAW)
location, _ := render.GetAttribLocation("glop.font", "position")
gl.EnableVertexAttribArray(uint32(location))
gl.VertexAttribPointer(uint32(location), 2, gl.FLOAT, false, 0, gl.PtrOffset(0))
gl.BindBuffer(gl.ARRAY_BUFFER, data.vbuffers[1])
gl.BufferData(gl.ARRAY_BUFFER, len(texcoords)*int(unsafe.Sizeof(texcoords[0])), gl.Ptr(&texcoords[0]), gl.STATIC_DRAW)
location, _ = render.GetAttribLocation("glop.font", "texCoord")
gl.EnableVertexAttribArray(uint32(location))
gl.VertexAttribPointer(uint32(location), 2, gl.FLOAT, false, 0, gl.PtrOffset(0))
return data
}
// LoadDictionary reads a gobbed Dictionary object from r, registers its atlas texture with opengl,
// and returns a Dictionary that is ready to render text.
func LoadDictionary(r io.Reader) (*Dictionary, error) {
errChan := make(chan error)
initOnce.Do(func() {
render.Queue(func() {
// errChan <- render.RegisterShader("glop.font", []byte(font_vertex_shader), []byte(font_fragment_shader))
errChan <- render.RegisterShader("glop.font", []byte(font_vshader), []byte(font_fshader))
})
})
err := <-errChan
if err != nil {
return nil, err
}
var dict Dictionary
dec := gob.NewDecoder(r)
err = dec.Decode(&dict)
if err != nil {
return nil, err
}
render.Queue(func() {
// Create the gl texture for the atlas
gl.GenTextures(1, &dict.atlas.texture)
glerr := gl.GetError()
if glerr != 0 {
errChan <- fmt.Errorf("Gl Error on gl.GenTextures: %v", glerr)
return
}
// Send the atlas to opengl
gl.BindTexture(gl.TEXTURE_2D, dict.atlas.texture)
gl.PixelStorei(gl.UNPACK_ALIGNMENT, 1)
gl.TexImage2D(
gl.TEXTURE_2D,
0,
gl.RED,
dict.Dx,
dict.Dy,
0,
gl.RED,
gl.UNSIGNED_BYTE,
gl.Ptr(&dict.Pix[0]))
glerr = gl.GetError()
if glerr != 0 {
errChan <- fmt.Errorf("Gl Error on creating texture: %v", glerr)
return
}
// Create the atlas sampler and set the parameters we want for it
gl.GenSamplers(1, &dict.atlas.sampler)
gl.SamplerParameteri(dict.atlas.sampler, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
gl.SamplerParameteri(dict.atlas.sampler, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.SamplerParameteri(dict.atlas.sampler, gl.TEXTURE_WRAP_S, gl.REPEAT)
gl.SamplerParameteri(dict.atlas.sampler, gl.TEXTURE_WRAP_T, gl.REPEAT)
glerr = gl.GetError()
if glerr != 0 {
errChan <- fmt.Errorf("Gl Error on creating sampler: %v", glerr)
return
}
errChan <- nil
})
err = <-errChan
if err != nil {
return nil, err
}
return &dict, nil
}