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()
}
}
// RenderString must be called on the render thread. x and y are the initial position of the pen,
// in screen coordinates, and height is the height of a full line of text, in screen coordinates.
func (d *Dictionary) RenderString(str string, x, y, height float64) {
if str == "" {
return
}
// No synchronization necessary because everything is run serially on the render thread anyway.
if d.strs == nil {
d.strs = make(map[string]strData)
}
data, ok := d.strs[str]
if !ok {
data = d.bindString(str)
d.strs[str] = data
}
render.EnableShader("glop.font")
defer render.EnableShader("")
gl.ActiveTexture(gl.TEXTURE0)
gl.BindTexture(gl.TEXTURE_2D, d.atlas.texture)
location, _ := render.GetUniformLocation("glop.font", "tex")
gl.Uniform1i(location, 0)
gl.BindSampler(0, d.atlas.sampler)
location, _ = render.GetUniformLocation("glop.font", "height")
gl.Uniform1f(location, float32(height))
var viewport [4]int32
gl.GetIntegerv(gl.VIEWPORT, &viewport[0])
location, _ = render.GetUniformLocation("glop.font", "screen")
gl.Uniform2f(location, float32(viewport[2]), float32(viewport[3]))
location, _ = render.GetUniformLocation("glop.font", "pen")
gl.Uniform2f(location, float32(x)+float32(viewport[0]), float32(y)+float32(viewport[1]))
location, _ = render.GetUniformLocation("glop.font", "textColor")
gl.Uniform3f(location, d.color[0], d.color[1], d.color[2])
gl.Enable(gl.BLEND)
gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
gl.BindVertexArray(data.varrays[0])
gl.DrawArrays(gl.TRIANGLES, 0, data.count)
}
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
}