Complete engine game loop+abstract imgui

engine/engine.go

@@ -1,8 +1,10 @@
 package engine
 
 import (
+	"github.com/bloeys/nmage/input"
 	"github.com/bloeys/nmage/timing"
 	"github.com/go-gl/gl/v4.1-core/gl"
+	"github.com/inkyblackness/imgui-go/v4"
 	"github.com/veandco/go-sdl2/sdl"
 )
 
@@ -11,6 +13,72 @@ type Window struct {
 	GlCtx  sdl.GLContext
 }
 
+func (w *Window) handleInputs() {
+
+	input.EventLoopStart()
+	imIO := imgui.CurrentIO()
+
+	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
+
+		switch e := event.(type) {
+
+		case *sdl.MouseWheelEvent:
+
+			input.HandleMouseWheelEvent(e)
+
+			xDelta, yDelta := input.GetMouseWheelMotion()
+			imIO.AddMouseWheelDelta(float32(xDelta), float32(yDelta))
+
+		case *sdl.KeyboardEvent:
+			input.HandleKeyboardEvent(e)
+
+			if e.Type == sdl.KEYDOWN {
+				imIO.KeyPress(int(e.Keysym.Scancode))
+			} else if e.Type == sdl.KEYUP {
+				imIO.KeyRelease(int(e.Keysym.Scancode))
+			}
+
+		case *sdl.TextInputEvent:
+			imIO.AddInputCharacters(string(e.Text[:]))
+
+		case *sdl.MouseButtonEvent:
+			input.HandleMouseBtnEvent(e)
+
+		case *sdl.MouseMotionEvent:
+			input.HandleMouseMotionEvent(e)
+
+		case *sdl.WindowEvent:
+			if e.Event == sdl.WINDOWEVENT_SIZE_CHANGED {
+				w.handleWindowResize()
+			}
+
+		case *sdl.QuitEvent:
+			input.HandleQuitEvent(e)
+		}
+	}
+
+	// If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
+	x, y, _ := sdl.GetMouseState()
+	imIO.SetMousePosition(imgui.Vec2{X: float32(x), Y: float32(y)})
+
+	imIO.SetMouseButtonDown(0, input.MouseDown(sdl.BUTTON_LEFT))
+	imIO.SetMouseButtonDown(1, input.MouseDown(sdl.BUTTON_RIGHT))
+	imIO.SetMouseButtonDown(2, input.MouseDown(sdl.BUTTON_MIDDLE))
+
+	imIO.KeyShift(sdl.SCANCODE_LSHIFT, sdl.SCANCODE_RSHIFT)
+	imIO.KeyCtrl(sdl.SCANCODE_LCTRL, sdl.SCANCODE_RCTRL)
+	imIO.KeyAlt(sdl.SCANCODE_LALT, sdl.SCANCODE_RALT)
+}
+
+func (w *Window) handleWindowResize() {
+
+	fbWidth, fbHeight := w.SDLWin.GLGetDrawableSize()
+	if fbWidth <= 0 || fbHeight <= 0 {
+		return
+	}
+	gl.Viewport(0, 0, fbWidth, fbHeight)
+}
+
 func (w *Window) Destroy() error {
 	return w.SDLWin.Destroy()
 }

engine/game.go

@@ -0,0 +1,53 @@
+package engine
+
+import (
+	"github.com/bloeys/nmage/timing"
+	nmageimgui "github.com/bloeys/nmage/ui/imgui"
+	"github.com/go-gl/gl/v4.1-core/gl"
+)
+
+type Game interface {
+	Init()
+
+	FrameStart()
+	Update()
+	Render()
+	FrameEnd()
+	ShouldRun() bool
+
+	GetWindow() *Window
+	GetImGUI() nmageimgui.ImguiInfo
+
+	Deinit()
+}
+
+func Run(g Game) {
+
+	g.Init()
+
+	w := g.GetWindow()
+	ui := g.GetImGUI()
+	for g.ShouldRun() {
+
+		width, height := w.SDLWin.GetSize()
+		fbWidth, fbHeight := w.SDLWin.GLGetDrawableSize()
+
+		timing.FrameStarted()
+		w.handleInputs()
+		ui.FrameStart(float32(width), float32(height))
+
+		g.FrameStart()
+
+		g.Update()
+
+		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
+		g.Render()
+		ui.Render(float32(width), float32(height), fbWidth, fbHeight)
+		w.SDLWin.GLSwap()
+
+		g.FrameEnd()
+		timing.FrameEnded()
+	}
+
+	g.Deinit()
+}