Example #1
5
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()
	}
}
Example #2
0
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, &param)
	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, &param)
	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, &param)
	if param == 0 {
		return fmt.Errorf("Failed to link shader '%s': %v", name, param)
	}

	shader_progs[name] = program_id
	return nil
}