Animating a nice backbuffer. Thank you Casey Muratori of Handmade Hero fame (https://www.youtube.com/watch?v=hNKU8Jiza2g)

ui/controller.go

@@ -1,25 +1,37 @@
 package ui
 
 import (
-	"gb-player/gb"
+	"fmt"
+	"log"
 
 	"github.com/veandco/go-sdl2/sdl"
+	"github.com/veandco/go-sdl2/ttf"
+
+	"gb-player/gb"
 )
 
 type Controller struct {
+	window    *sdl.Window
 	renderer  *sdl.Renderer
+	font      *ttf.Font
 	view      *View
 	timestamp uint64
 }
 
-func NewController(renderer *sdl.Renderer) *Controller {
+func NewController(window *sdl.Window, renderer *sdl.Renderer, font *ttf.Font) *Controller {
 	controller := Controller{}
+	controller.window = window
 	controller.renderer = renderer
+	controller.font = font
 	return &controller
 }
 
 func (c *Controller) Start(path string) {
-	console := gb.NewConsole(path)
+	console, err := gb.NewConsole(path)
+	if err != nil {
+		log.Fatal(err)
+	}
+
 	c.view = NewView(c, console)
 	c.Run()
 }
@@ -27,17 +39,14 @@ func (c *Controller) Start(path string) {
 func (c *Controller) Step() {
 	timestamp := sdl.GetTicks64()
 	dt := timestamp - c.timestamp
-	c.view.Update(timestamp, dt)
+	c.timestamp = timestamp
+	c.view.Update(dt)
 }
 
 func (c *Controller) Run() {
 	var fps float64
 	var frameCount uint32
-	var startTicks = sdl.GetTicks64()
-	var now, last uint64
-
-	// cartridge := gb.Insert(romPath)
-	// fmt.Println(cartridge)
+	var frameStart = sdl.GetTicks64()
 
 	running := true
 	for running {
@@ -49,38 +58,49 @@ func (c *Controller) Run() {
 			}
 		}
 
-		last = now
-		now = sdl.GetPerformanceCounter()
-		deltaTime := float64((now - last) * 1000.0 / sdl.GetPerformanceFrequency())
-		_ = deltaTime
-
 		// Clear screen
-		renderer.SetDrawColor(0x63, 0x94, 0xED, 0xff)
-		renderer.Clear()
+		c.renderer.SetDrawColor(0x63, 0x94, 0xED, 0xff)
+		c.renderer.Clear()
 
 		// Update state
 		c.Step()
-		rect := sdl.Rect{X: 100, Y: 100, W: 200, H: 150}
-		renderer.SetDrawColor(0, 0, 255, 255)
-		renderer.FillRect(&rect)
-
-		drawDebugWindow(fps)
+		c.drawDebugWindow(fps)
 
 		// Present to screen
-		renderer.Present()
+		c.renderer.Present()
 
 		// Calculate framerate
 		frameCount++
-		currentTicks := sdl.GetTicks64()
-		elapsed := currentTicks - startTicks
+		frameEnd := sdl.GetTicks64()
+		elapsed := frameEnd - frameStart
 
 		if elapsed >= 1000 {
 			fps = float64(frameCount) / (float64(elapsed) / 1000.0)
 
-			// Reset counters
+			// Reset framerate counters
 			frameCount = 0
-			startTicks = currentTicks
+			frameStart = frameEnd
 		}
 	}
-
+}
+
+func (c *Controller) drawDebugWindow(fps float64) {
+	renderer := c.renderer
+	font := c.font
+
+	// FPS
+	textSurface, err := font.RenderUTF8Blended(fmt.Sprintf("FPS: %.2f", fps), sdl.Color{R: 0, G: 0, B: 0, A: 255})
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer textSurface.Free()
+
+	textTexture, err := renderer.CreateTextureFromSurface(textSurface)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer textTexture.Destroy()
+
+	textRect := sdl.Rect{X: 0, Y: 0, W: textSurface.W, H: textSurface.H}
+	renderer.Copy(textTexture, nil, &textRect)
 }