fix(updateloop): face rect algorithm

internal/pkg/arkprocessor/processor_character.go

@@ -150,9 +150,43 @@ func mergeCharacterFace(body image.Image, face image.Image, faceRect image.Recta
 	// Because faceRect is based on body as if it is a square, we need to adjust it.
 	dx := body.Bounds().Dx()
 	dy := body.Bounds().Dy()
-	xOffset := (dx - max(dx, dy)) / 2
-	yOffset := (dy - max(dx, dy)) / 2
-	faceRect = faceRect.Add(image.Pt(xOffset, yOffset))
+
+	if dx == dy && dx < 1024 {
+		// If the body is square and the side is less than 1024px,
+		// it should be resized into 1024px.
+
+		// Example: avg_npc_457_1
+		// size of body = 512px, but the face parameters are as if the size of the body is 1024px (scale)
+
+		factor := float64(min(max(dx, dy), 1024.0)) / 1024.0
+		faceRect = image.Rect(
+			int(float64(faceRect.Min.X)*factor),
+			int(float64(faceRect.Min.Y)*factor),
+			int(float64(faceRect.Max.X)*factor),
+			int(float64(faceRect.Max.Y)*factor),
+		)
+	}
+
+	if dx != dy && max(dx, dy) < 1024 {
+		// If the body is not a square and both sides are less than 1024px,
+		// add paddings (top, left, right, but not bottom) to make it a square with both sides 1024px.
+
+		// Example: avgnew_147_shining_1:
+		// both sides of body < 1024px,
+
+		xOffset := (dx - 1024) / 2 // left + right
+		yOffset := dy - 1024       // top only
+		faceRect = faceRect.Add(image.Pt(xOffset, yOffset))
+	} else {
+		// If the body is not a square and either side is greater than (or equal to) 1024px,
+		// add paddings (left, right) to make it a square with both sides the longer side.
+
+		// Example: avg_npc_1303_1:
+		// one side of body > 1024px
+		xOffset := (dx - max(dx, dy)) / 2
+		yOffset := (dy - max(dx, dy)) / 2
+		faceRect = faceRect.Add(image.Pt(xOffset, yOffset))
+	}
 
 	if !faceRect.In(body.Bounds()) {
 		return nil, errors.Errorf("merge character face: face rectangle %v is not in the body's bounds %v", faceRect, body.Bounds())