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 RegisterShader(name string, vertex, fragment []byte) error {
if _, ok := shader_progs[name]; ok {
return fmt.Errorf("Tried to register a shader called '%s' twice", name)
}
vertex_id := gl.CreateShader(gl.VERTEX_SHADER)
pointer := &vertex[0]
length := int32(len(vertex))
gl.ShaderSource(vertex_id, 1, (**int8)(unsafe.Pointer(&pointer)), &length)
gl.CompileShader(vertex_id)
var param int32
gl.GetShaderiv(vertex_id, gl.COMPILE_STATUS, ¶m)
if param == 0 {
buf := make([]byte, 5*1024)
var length int32
gl.GetShaderInfoLog(vertex_id, int32(len(buf)), &length, (*int8)(unsafe.Pointer(&buf[0])))
if length > 0 {
length--
}
maxVersion := gl.GoStr(gl.GetString(gl.SHADING_LANGUAGE_VERSION))
return fmt.Errorf("Failed to compile vertex shader (max version supported: %q) %q: %q", maxVersion, name, buf[0:int(length)])
}
fragment_id := gl.CreateShader(gl.FRAGMENT_SHADER)
pointer = &fragment[0]
length = int32(len(fragment))
gl.ShaderSource(fragment_id, 1, (**int8)(unsafe.Pointer(&pointer)), &length)
gl.CompileShader(fragment_id)
gl.GetShaderiv(fragment_id, gl.COMPILE_STATUS, ¶m)
if param == 0 {
buf := make([]byte, 5*1024)
var length int32
gl.GetShaderInfoLog(fragment_id, int32(len(buf)), &length, (*int8)(unsafe.Pointer(&buf[0])))
if length > 0 {
length--
}
maxVersion := gl.GoStr(gl.GetString(gl.SHADING_LANGUAGE_VERSION))
return fmt.Errorf("Failed to compile fragment shader (max version supported: %q) %q: %q", maxVersion, name, buf[0:int(length)])
}
// shader successfully compiled - now link
program_id := gl.CreateProgram()
gl.AttachShader(program_id, vertex_id)
gl.AttachShader(program_id, fragment_id)
gl.LinkProgram(program_id)
gl.GetProgramiv(program_id, gl.LINK_STATUS, ¶m)
if param == 0 {
return fmt.Errorf("Failed to link shader '%s': %v", name, param)
}
shader_progs[name] = program_id
return nil
}