New example : Window letterbox

examples/core/window_letterbox/main.go

@@ -0,0 +1,115 @@
+package main
+
+import (
+	"fmt"
+	"image/color"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+const (
+	screenWidth  = 800
+	screenHeight = 450
+)
+
+func main() {
+	// Enable config flags for resizable window and vertical synchro
+	rl.SetConfigFlags(rl.FlagWindowResizable | rl.FlagVsyncHint)
+	rl.InitWindow(screenWidth, screenHeight, "raylib [core] example - Window Scale Letterbox")
+	rl.SetWindowMinSize(320, 240)
+
+	gameScreenWidth, gameScreenHeight := int32(640), int32(480)
+
+	// Render texture initialization, used to hold the rendering result so we can easily resize it
+	target := rl.LoadRenderTexture(gameScreenWidth, gameScreenHeight)
+	rl.SetTextureFilter(target.Texture, rl.FilterBilinear) // Texture scale filter to use
+
+	colors := getRandomColors()
+
+	rl.SetTargetFPS(60) // Set our game to run at 60 frames-per-second
+
+	for !rl.WindowShouldClose() { // Detect window close button or ESC key
+		// Compute required frame buffer scaling
+		scale := min(float32(rl.GetScreenWidth())/float32(gameScreenWidth),
+			float32(rl.GetScreenHeight())/float32(gameScreenHeight))
+
+		if rl.IsKeyPressed(rl.KeySpace) {
+			// Recalculate random colors for the bars
+			colors = getRandomColors()
+		}
+
+		// Update virtual mouse (clamped mouse value behind game screen)
+		mouse := rl.GetMousePosition()
+		virtualMouse := rl.Vector2{
+			X: (mouse.X - (float32(rl.GetScreenWidth())-(float32(gameScreenWidth)*scale))*0.5) / scale,
+			Y: (mouse.Y - (float32(rl.GetScreenHeight())-(float32(gameScreenHeight)*scale))*0.5) / scale,
+		}
+		virtualMouse = rl.Vector2Clamp(
+			virtualMouse,
+			rl.Vector2{},
+			rl.Vector2{X: float32(gameScreenWidth), Y: float32(gameScreenHeight)},
+		)
+
+		// Apply the same transformation as the virtual mouse to the real mouse (i.e. to work with raygui)
+		//rl.SetMouseOffset(
+		//	int(-(float32(rl.GetScreenWidth())-(float32(gameScreenWidth)*scale))*0.5),
+		//	int(-(float32(rl.GetScreenHeight())-(float32(gameScreenHeight)*scale))*0.5),
+		//)
+		//rl.SetMouseScale(1/scale, 1/scale)
+
+		// Draw everything in the render texture, note this will not be rendered on screen, yet
+		rl.BeginTextureMode(target)
+
+		rl.ClearBackground(rl.White)
+		for i := int32(0); i < 10; i++ {
+			rl.DrawRectangle(0, (gameScreenHeight/10)*i, gameScreenWidth, gameScreenHeight/10, colors[i])
+		}
+
+		text := "If executed inside a window,\nyou can resize the window,\nand see the screen scaling!"
+		rl.DrawText(text, 10, 25, 20, rl.White)
+		text = fmt.Sprintf("Default Mouse: [%.0f , %.0f]", mouse.X, mouse.Y)
+		rl.DrawText(text, 350, 25, 20, rl.Green)
+		text = fmt.Sprintf("Virtual Mouse: [%.0f , %.0f]", virtualMouse.X, virtualMouse.Y)
+		rl.DrawText(text, 350, 55, 20, rl.Yellow)
+
+		rl.EndTextureMode()
+
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.Black)
+		// Draw render texture to screen, properly scaled
+		rl.DrawTexturePro(
+			target.Texture,
+			rl.Rectangle{Width: float32(target.Texture.Width), Height: float32(-target.Texture.Height)},
+			rl.Rectangle{
+				X:      (float32(rl.GetScreenWidth()) - float32(gameScreenWidth)*scale) * 0.5,
+				Y:      (float32(rl.GetScreenHeight()) - float32(gameScreenHeight)*scale) * 0.5,
+				Width:  float32(gameScreenWidth) * scale,
+				Height: float32(gameScreenHeight) * scale,
+			},
+			rl.Vector2{X: 0, Y: 0}, 0, rl.White,
+		)
+		rl.EndDrawing()
+	}
+	rl.UnloadRenderTexture(target)
+	rl.CloseWindow() // Close window and OpenGL context
+}
+
+func getRandomColors() []color.RGBA {
+	var colors []color.RGBA
+
+	for i := 0; i < 10; i++ {
+		randomColor := color.RGBA{
+			R: rndUint8(100, 250),
+			G: rndUint8(50, 150),
+			B: rndUint8(10, 100),
+			A: 255,
+		}
+		colors = append(colors, randomColor)
+	}
+
+	return colors
+}
+
+func rndUint8(min, max int32) uint8 {
+	return uint8(rl.GetRandomValue(min, max))
+}