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* add BouncingBalls example to falling-balls-mpp * add new bouncing balls at click position instead of a random coordinates * review improvements Co-authored-by: Oleksandr Karpovich <oleksandr.karpovich@jetbrains.com>pull/1703/head
Oleksandr Karpovich
3 years ago
committed by
GitHub
3 changed files with 249 additions and 3 deletions
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/* |
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* Copyright 2020-2022 JetBrains s.r.o. and respective authors and developers. |
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* Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE.txt file. |
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*/ |
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package bouncingBalls |
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import androidx.compose.foundation.background |
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import androidx.compose.foundation.border |
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import androidx.compose.foundation.clickable |
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import androidx.compose.foundation.gestures.detectTapGestures |
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import androidx.compose.foundation.interaction.MutableInteractionSource |
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import androidx.compose.foundation.layout.* |
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import androidx.compose.foundation.shape.CircleShape |
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import androidx.compose.runtime.* |
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import androidx.compose.ui.Modifier |
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import androidx.compose.ui.composed |
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import androidx.compose.ui.geometry.Offset |
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import androidx.compose.ui.graphics.Color |
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import androidx.compose.ui.input.pointer.pointerInput |
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import androidx.compose.ui.layout.onSizeChanged |
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import androidx.compose.ui.unit.dp |
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import kotlin.math.PI |
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import kotlin.math.cos |
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import kotlin.math.max |
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import kotlin.math.sin |
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import kotlin.random.Random |
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private inline fun Modifier.noRippleClickable(crossinline onClick: (Offset) -> Unit): Modifier = |
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composed { |
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clickable( |
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indication = null, |
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interactionSource = remember { MutableInteractionSource() }) { |
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}.pointerInput(Unit) { |
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detectTapGestures(onTap = { |
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println("tap offset = $it") |
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onClick(it) |
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}) |
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} |
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} |
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private var areaWidth = 0 |
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private var areaHeight = 0 |
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@Composable |
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fun BouncingBallsApp(initialBallsCount: Int = 5) { |
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val items = remember { |
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val list = mutableStateListOf<BouncingBall>() |
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list.addAll(generateSequence { |
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BouncingBall.createBouncingBall() |
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}.take(initialBallsCount)) |
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list |
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} |
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Box( |
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modifier = Modifier.fillMaxWidth() |
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.fillMaxHeight() |
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.border(width = 1.dp, color = Color.Black) |
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.noRippleClickable { |
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items += BouncingBall.createBouncingBall(offset = it) |
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}.onSizeChanged { |
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areaWidth = it.width |
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areaHeight = it.height |
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} |
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) { |
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Balls(items) |
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} |
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LaunchedEffect(Unit) { |
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var lastTime = 0L |
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var dt = 0L |
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while (true) { |
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withFrameNanos { time -> |
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dt = time - lastTime |
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if (lastTime == 0L) { |
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dt = 0 |
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} |
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lastTime = time |
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items.forEach { |
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it.recalculate(areaWidth, areaHeight, dt.toFloat()) |
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} |
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} |
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} |
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} |
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} |
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@Composable |
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private fun Balls(items: List<BouncingBall>) { |
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items.forEachIndexed { ix, ball -> |
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key(ix) { |
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Box( |
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modifier = Modifier |
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.offset( |
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x = (ball.circle.x.value - ball.circle.r).dp, |
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y = (ball.circle.y.value - ball.circle.r).dp |
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).size((2 * ball.circle.r).dp) |
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.background(ball.color, CircleShape) |
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) |
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} |
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} |
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} |
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private class Circle( |
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var x: MutableState<Float>, |
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var y: MutableState<Float>, |
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val r: Float |
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) { |
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constructor(x: Float, y: Float, r: Float) : this( |
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mutableStateOf(x), mutableStateOf(y), r |
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) |
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fun moveCircle(s: Float, angle: Float, width: Int, height: Int, r: Float) { |
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x.value = (x.value + s * sin(angle)).coerceAtLeast(r).coerceAtMost(width.toFloat() - r) |
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y.value = (y.value + s * cos(angle)).coerceAtLeast(r).coerceAtMost(height.toFloat() - r) |
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} |
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} |
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private fun calculatePosition(circle: Circle, boundingWidth: Int, boundingHeight: Int): Position { |
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val southmost = circle.y.value + circle.r |
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val northmost = circle.y.value - circle.r |
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val westmost = circle.x.value - circle.r |
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val eastmost = circle.x.value + circle.r |
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return when { |
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southmost >= boundingHeight -> Position.TOUCHES_SOUTH |
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northmost <= 0 -> Position.TOUCHES_NORTH |
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eastmost >= boundingWidth -> Position.TOUCHES_EAST |
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westmost <= 0 -> Position.TOUCHES_WEST |
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else -> Position.INSIDE |
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} |
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} |
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private enum class Position { |
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INSIDE, |
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TOUCHES_SOUTH, |
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TOUCHES_NORTH, |
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TOUCHES_WEST, |
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TOUCHES_EAST |
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} |
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private class BouncingBall( |
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val circle: Circle, |
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val velocity: Float, |
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var angle: Double, |
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val color: Color = Color.Red |
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) { |
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fun recalculate(width: Int, height: Int, dt: Float) { |
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val position = calculatePosition(circle, width, height) |
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val dtMillis = dt / 1000000 |
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when (position) { |
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Position.TOUCHES_SOUTH -> angle = PI - angle |
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Position.TOUCHES_EAST -> angle = -angle |
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Position.TOUCHES_WEST -> angle = -angle |
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Position.TOUCHES_NORTH -> angle = PI - angle |
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Position.INSIDE -> angle |
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} |
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circle.moveCircle( |
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velocity * (dtMillis.coerceAtMost(500f) / 1000), |
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angle.toFloat(), |
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width, |
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height, |
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circle.r |
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) |
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} |
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companion object { |
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private val random = Random(100) |
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private val angles = listOf(PI / 4, -PI / 3, 3 * PI / 4, -PI / 6, -1.1 * PI) |
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private val colors = listOf(Color.Red, Color.Black, Color.Green, Color.Magenta) |
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private fun randomOffset(): Offset { |
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return Offset( |
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x = random.nextInt(100, 700).toFloat(), |
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y = random.nextInt(100, 500).toFloat() |
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) |
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} |
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fun createBouncingBall(offset: Offset = randomOffset()): BouncingBall { |
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return BouncingBall( |
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circle = Circle(x = offset.x, y = offset.y, r = random.nextInt(10, 50).toFloat()), |
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velocity = random.nextInt(100, 200).toFloat(), |
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angle = angles.random(), |
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color = colors.random().copy(alpha = max(0.3f, random.nextFloat())) |
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) |
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} |
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} |
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} |
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