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98 lines
2.9 KiB
98 lines
2.9 KiB
import 'package:flame/extensions.dart';
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import 'package:flame_forge2d/flame_forge2d.dart';
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import 'package:flutter/material.dart';
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import 'package:geometry/geometry.dart' show centroid;
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import 'package:pinball/game/game.dart';
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/// {@template sling_shot}
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/// Triangular [BodyType.static] body that propels the [Ball] towards the
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/// opposite side.
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///
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/// [SlingShot]s are usually positioned above each [Flipper].
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/// {@endtemplate sling_shot}
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class SlingShot extends BodyComponent {
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/// {@macro sling_shot}
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SlingShot({
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required Vector2 position,
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required BoardSide side,
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}) : _position = position,
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_side = side {
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// TODO(alestiago): Use sprite instead of color when provided.
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paint = Paint()
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..color = const Color(0xFF00FF00)
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..style = PaintingStyle.fill;
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}
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/// The initial position of the [SlingShot] body.
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final Vector2 _position;
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/// Whether the [SlingShot] is on the left or right side of the board.
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///
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/// A [SlingShot] with [BoardSide.left] propels the [Ball] to the right,
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/// whereas a [SlingShot] with [BoardSide.right] propels the [Ball] to the
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/// left.
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final BoardSide _side;
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/// The size of the [SlingShot] body.
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// TODO(alestiago): Use size from PositionedBodyComponent instead,
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// once a sprite is given.
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static final Vector2 size = Vector2(6, 8);
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List<FixtureDef> _createFixtureDefs() {
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final fixtures = <FixtureDef>[];
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// TODO(alestiago): This magic number can be deduced by specifying the
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// angle and using polar coordinate system to place the bottom right
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// vertex.
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// Something as: y = -size.y * math.cos(angle)
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const additionalIncrement = 3;
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final triangleVertices = _side.isLeft
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? [
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Vector2(0, 0),
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Vector2(0, -size.y),
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Vector2(
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size.x,
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-size.y - additionalIncrement,
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),
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]
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: [
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Vector2(size.x, 0),
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Vector2(size.x, -size.y),
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Vector2(
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0,
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-size.y - additionalIncrement,
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),
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];
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final triangleCentroid = centroid(triangleVertices);
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for (final vertex in triangleVertices) {
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vertex.setFrom(vertex - triangleCentroid);
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}
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final triangle = PolygonShape()..set(triangleVertices);
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final triangleFixtureDef = FixtureDef(triangle)..friction = 0;
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fixtures.add(triangleFixtureDef);
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final kicker = EdgeShape()
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..set(
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triangleVertices.first,
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triangleVertices.last,
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);
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// TODO(alestiago): Play with restitution value once game is bundled.
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final kickerFixtureDef = FixtureDef(kicker)
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..restitution = 10.0
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..friction = 0;
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fixtures.add(kickerFixtureDef);
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return fixtures;
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}
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@override
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Body createBody() {
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final bodyDef = BodyDef()..position = _position;
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final body = world.createBody(bodyDef);
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_createFixtureDefs().forEach(body.createFixture);
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return body;
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}
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}
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