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add ParticlePhysics
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  • Tutorial1-1Basics/src/main/java/com/smarttoolfactory/tutorial1_1basics/chapter6_graphics

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‎Tutorial1-1Basics/src/main/java/com/smarttoolfactory/tutorial1_1basics/chapter6_graphics/ParticlePhysics.kt‎

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package com.smarttoolfactory.tutorial1_1basics.chapter6_graphics
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import android.content.res.Resources
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import androidx.compose.foundation.Canvas
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import androidx.compose.foundation.border
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import androidx.compose.foundation.layout.Arrangement
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import androidx.compose.foundation.layout.BoxWithConstraints
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import androidx.compose.foundation.layout.Column
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import androidx.compose.foundation.layout.Spacer
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import androidx.compose.foundation.layout.fillMaxSize
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import androidx.compose.foundation.layout.fillMaxWidth
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import androidx.compose.foundation.layout.height
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import androidx.compose.foundation.layout.padding
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import androidx.compose.foundation.layout.size
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import androidx.compose.material.Slider
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import androidx.compose.material.Text
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import androidx.compose.runtime.Composable
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import androidx.compose.runtime.getValue
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import androidx.compose.runtime.mutableFloatStateOf
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import androidx.compose.runtime.remember
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import androidx.compose.runtime.setValue
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import androidx.compose.ui.Alignment
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import androidx.compose.ui.Modifier
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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.platform.LocalDensity
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import androidx.compose.ui.tooling.preview.Preview
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import androidx.compose.ui.unit.Dp
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import androidx.compose.ui.unit.dp
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import androidx.compose.ui.unit.sp
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import java.util.Random
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@Preview
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@Composable
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fun ControlledExplosion() {
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Column(
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modifier = Modifier.fillMaxSize().padding(16.dp),
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horizontalAlignment = Alignment.CenterHorizontally
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) {
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var progress by remember { mutableFloatStateOf(0f) }
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Explosion(progress)
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Spacer(Modifier.height(16.dp))
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Text(text = "Progress: $progress", fontSize = 18.sp)
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Slider(
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modifier = Modifier.fillMaxWidth(),
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value = progress,
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onValueChange = {
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progress = it
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}
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)
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Spacer(Modifier.height(16.dp))
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}
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}
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@Composable
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fun Explosion(
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progress: Float
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) {
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BoxWithConstraints {
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val sizeDp = maxWidth
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val density = LocalDensity.current
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val sizePx = with(density) {
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sizeDp.toPx()
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}
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val sizePxHalf = sizePx / 2
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val particles = remember {
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List(150) {
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ExplodingParticle(
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color = Color(listOf(0xffea4335, 0xff4285f4, 0xfffbbc05, 0xff34a853).random()),
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startXPosition = sizePxHalf.toInt(),
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startYPosition = sizePxHalf.toInt(),
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maxHorizontalDisplacement = sizePxHalf,
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maxVerticalDisplacement = sizePxHalf
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)
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}
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}
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particles.forEach { it.updateProgress(progress) }
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Canvas(
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modifier = Modifier
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.border(width = 1.dp, color = Color(0x26000000))
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.size(sizeDp)
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) {
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drawLine(
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color = Color.Black,
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start = Offset(sizePxHalf, 0f),
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end = Offset(sizePxHalf, sizePx),
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strokeWidth = 2.dp.toPx()
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)
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drawLine(
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color = Color.Black,
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start = Offset(0f, sizePxHalf),
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end = Offset(sizePx, sizePxHalf),
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strokeWidth = 2.dp.toPx()
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)
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particles.forEach { particle ->
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drawCircle(
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alpha = particle.alpha,
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color = particle.color,
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radius = 5.dp.toPx(),
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center = Offset(particle.currentXPosition, particle.currentYPosition),
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)
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}
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}
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}
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}
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class ExplodingParticle(
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val color: Color,
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val startXPosition: Int,
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val startYPosition: Int,
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val maxHorizontalDisplacement: Float,
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val maxVerticalDisplacement: Float
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) {
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private val velocity = 4 * maxVerticalDisplacement
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private val acceleration = -2 * velocity
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var currentXPosition = 0f
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var currentYPosition = 0f
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var alpha = 1f
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fun updateProgress(explosionProgress: Float) {
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val currentTime = explosionProgress * 1f
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val verticalDisplacement =
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currentTime * velocity + 0.5 * acceleration * currentTime * currentTime
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currentXPosition = startXPosition + maxHorizontalDisplacement * explosionProgress
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currentYPosition = (startYPosition - verticalDisplacement).toFloat()
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}
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}
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fun Float.mapInRange(inMin: Float, inMax: Float, outMin: Float, outMax: Float): Float {
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return outMin + (((this - inMin) / (inMax - inMin)) * (outMax - outMin))
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}
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fun Int.dpToPx() = toFloat().dpToPx()
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fun Dp.toPx() = value.dpToPx()
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fun Float.dpToPx() = this * Resources.getSystem().displayMetrics.density
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private val random = Random()
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fun Float.randomTillZero() = this * random.nextFloat()
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fun randomInRange(min: Float, max: Float) = min + (max - min).randomTillZero()
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fun randomBoolean(trueProbabilityPercentage: Int) =
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random.nextFloat() < trueProbabilityPercentage / 100f

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