ebiten: add DebugInfo.TotalGPUImageMemoryUsageInBytes

Updates #3205

examples/windowsize/main.go

@@ -353,6 +353,9 @@ func (g *game) Draw(screen *ebiten.Image) {
 		fg = "No"
 	}
 
+	var debug ebiten.DebugInfo
+	ebiten.ReadDebugInfo(&debug)
+
 	msg := fmt.Sprintf(`[Arrow keys] Move the window
 [Shift + Arrow keys] Change the window size
 %s
@@ -375,7 +378,8 @@ Window size limitation: (%d, %d) - (%d, %d)
 Cursor: (%d, %d)
 TPS: Current: %0.2f / Max: %s
 FPS: %0.2f
-Device Scale Factor: %0.2f`, msgM, msgR, fg, wx, wy, ww, wh, minw, minh, maxw, maxh, cx, cy, ebiten.ActualTPS(), tpsStr, ebiten.ActualFPS(), ebiten.Monitor().DeviceScaleFactor())
+Device Scale Factor: %0.2f
+GPU Memory Usage: %d`, msgM, msgR, fg, wx, wy, ww, wh, minw, minh, maxw, maxh, cx, cy, ebiten.ActualTPS(), tpsStr, ebiten.ActualFPS(), ebiten.Monitor().DeviceScaleFactor(), debug.TotalGPUImageMemoryUsageInBytes)
 	ebitenutil.DebugPrint(screen, msg)
 }
 

graphics.go

@@ -15,6 +15,7 @@
 package ebiten
 
 import (
+	"github.com/hajimehoshi/ebiten/v2/internal/atlas"
 	"github.com/hajimehoshi/ebiten/v2/internal/builtinshader"
 	"github.com/hajimehoshi/ebiten/v2/internal/ui"
 )
@@ -70,11 +71,18 @@ var _ [GraphicsLibraryAuto]int = [0]int{}
 type DebugInfo struct {
 	// GraphicsLibrary represents the graphics library currently in use.
 	GraphicsLibrary GraphicsLibrary
+
+	// TotalGPUImageMemoryUsageInBytes is the total image memory usage for GPU in bytes.
+	// TotalGPUImageMemoryUsageInBytes is approximately the total memory usage for GPU.
+	TotalGPUImageMemoryUsageInBytes int64
 }
 
 // ReadDebugInfo writes debug info (e.g. current graphics library) into a provided struct.
+//
+// ReadDebugInfo is concurrent-safe.
 func ReadDebugInfo(d *DebugInfo) {
 	d.GraphicsLibrary = GraphicsLibrary(ui.Get().GraphicsLibrary())
+	d.TotalGPUImageMemoryUsageInBytes = atlas.TotalGPUImageMemoryUsageInBytes()
 }
 
 // ColorSpace represents the color space of the screen.

internal/atlas/image.go

@@ -838,3 +838,18 @@ func DumpImages(graphicsDriver graphicsdriver.Graphics, dir string) (string, err
 
 	return restorable.DumpImages(graphicsDriver, dir)
 }
+
+func TotalGPUImageMemoryUsageInBytes() int64 {
+	backendsM.Lock()
+	defer backendsM.Unlock()
+
+	var sum int64
+	for _, b := range theBackends {
+		if b.restorable == nil {
+			continue
+		}
+		w, h := b.restorable.InternalSize()
+		sum += 4 * int64(w) * int64(h)
+	}
+	return sum
+}