Can't figure out how to create this particular BoxShadow design - flutter

Question

I'm trying to make this particular UI and I can't figure out how to create that specific BoxShadow design in the image above. The BoxShadow that I have created is a bit near the center but, the UI that I want to create is more leaned diagonally.
This is my main.dart file.
import 'package:flutter/material.dart';
import 'package:secondlife_mobile/PageViewHolder.dart';
import 'package:provider/provider.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Perspective PageView',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key});
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
late PageViewHolder holder;
late PageController _controller;
double fraction =
0.57; // By using this fraction, we're telling the PageView to show the 50% of the previous and the next page area along with the main page
#override
void initState() {
super.initState();
holder = PageViewHolder(value: 2.0);
_controller = PageController(initialPage: 2, viewportFraction: fraction);
_controller.addListener(() {
holder.setValue(_controller.page);
});
}
#override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
appBar: AppBar(
title: const Text("Perspective PageView"),
),
body: Container(
child: Center(
child: AspectRatio(
aspectRatio: 1,
child: ChangeNotifierProvider<PageViewHolder>.value(
value: holder,
child: PageView.builder(
controller: _controller,
itemCount: 4,
physics: const BouncingScrollPhysics(),
itemBuilder: (context, index) {
return MyPage(
number: index.toDouble(),
fraction: fraction,
);
}),
),
),
),
),
));
}
}
class MyPage extends StatelessWidget {
final number;
final double? fraction;
const MyPage({super.key, this.number, this.fraction});
#override
Widget build(BuildContext context) {
double? value = Provider.of<PageViewHolder>(context).value;
double diff = (number - value);
// diff is negative = left page
// diff is 0 = current page
// diff is positive = next page
//Matrix for Elements
final Matrix4 pvMatrix = Matrix4.identity()
..setEntry(3, 2, 1 / 0.9) //Increasing Scale by 90%
..setEntry(1, 1, fraction!) //Changing Scale Along Y Axis
..setEntry(3, 0, 0.004 * -diff); //Changing Perspective Along X Axis
return Stack(
fit: StackFit.expand,
alignment: FractionalOffset.center,
children: [
Transform(
transform: pvMatrix,
alignment: FractionalOffset.center,
child: Container(
decoration: const BoxDecoration(boxShadow: [
BoxShadow(
color: Colors.grey,
blurRadius: 2.0,
spreadRadius: 4.0,
offset: Offset(8.0, 20.0), // shadow direction: bottom right
)
]),
child: Image.asset("assets/images/image_${number.toInt() + 1}.jpg",
fit: BoxFit.fill),
),
),
],
);
}
}
And this is how it looks like on the emulator.