added curves

src/main/kotlin/com/bytedice/bde_particles/math/main.kt

@@ -156,3 +156,23 @@ fun transformOffsetByScale(offset: Vector3f, scale: Vector3f): Vector3f {
 fun lerp(x: Float, y: Float, t: Float) : Float {
   return x + (y - x) * t
 }
+
+
+fun interpolateCurve(curve: Array<Vector3f>, t: Float): Vector3f {
+  if (curve.size < 2) { return curve[0] }
+
+  val clampedT = t.coerceIn(0.0f, 1.0f)
+
+  val scaledT = clampedT * (curve.size - 1)
+  val segmentIndex = scaledT.toInt()
+  val segmentT = scaledT - segmentIndex
+
+  val start = curve[segmentIndex]
+  val end = curve[(segmentIndex + 1).coerceAtMost(curve.size - 1)] // Ensure bounds
+
+  return Vector3f(
+    start.x + (end.x - start.x) * segmentT,
+    start.y + (end.y - start.y) * segmentT,
+    start.z + (end.z - start.z) * segmentT
+  )
+}

src/main/kotlin/com/bytedice/bde_particles/particle/Particle.kt

@@ -18,8 +18,8 @@ class Particle(private val particleParams: ParticleParams) {
 
   private var rot    = randomBetweenVector3f(particleParams.rotRandom.first, particleParams.rotRandom.second)
   private val rotVel = randomBetweenVector3f(particleParams.rotVelRandom.first, particleParams.rotVelRandom.second)
-  private val scale  = randomBetweenVector3f(particleParams.sizeRandom.first, particleParams.sizeRandom.second)
   private var vel    = randomBetweenVector3f(particleParams.velRandom.first, particleParams.velRandom.second)
+  private var scale  = randomBetweenVector3f(particleParams.sizeRandom.first, particleParams.sizeRandom.second)
 
   private var blockDisplay: DisplayEntity? = null
 
@@ -32,6 +32,13 @@ class Particle(private val particleParams: ParticleParams) {
   fun init(pos: Vec3d) {
     this.pos = pos
 
+    if ( particleParams.uniformSize ) {
+      val randomUniform = randomFloatBetween(particleParams.sizeRandom.first.x, particleParams.sizeRandom.second.x)
+      scale.x = randomUniform
+      scale.y = randomUniform
+      scale.z = randomUniform
+    }
+
     val (quatRot, newOffset) = calcTransformOffset(rot, initOffset, scale)
 
     val properties = DisplayEntityProperties(
@@ -81,23 +88,20 @@ class Particle(private val particleParams: ParticleParams) {
   }
 
 
-  // TODO: rotVelRandom, rotVelCurve, sizeCurve, forceFields
+  // TODO: forceFields, shape
   private fun calcNewProperties() : DisplayEntityProperties {
-    fun calcBlockCurve() : String {
-      val newBlockIdx = round(
-        lerp(
-          0.0f,
-          particleParams.blockCurve.lastIndex.toFloat(),
-          (timeAlive.toFloat() / particleParams.lifeTime.toFloat()).coerceIn(0.0f, 1.0f)
-        )
-      ).toInt()
 
+    fun calcBlockCurve(timeAliveClamped: Float) : String {
+      val newBlockIdx = round(lerp(0.0f, particleParams.blockCurve.lastIndex.toFloat(), timeAliveClamped)).toInt()
       return particleParams.blockCurve[newBlockIdx]
     }
 
-    fun calcRot() : Vector3f {
+    fun calcRot(timeAliveClamped: Float) : Vector3f {
       val newRot = Vector3f(rot)
-      newRot.add(rotVel)
+      val newVel = Vector3f(rotVel)
+
+      newVel.mul(interpolateCurve(particleParams.sizeCurve, timeAliveClamped))
+      newRot.add(newVel)
       return newRot
     }
 
@@ -115,17 +119,24 @@ class Particle(private val particleParams: ParticleParams) {
       return Pair(vel, newOffset)
     }
 
+    fun calcSize(timeAliveClamped: Float) : Vector3f {
+      val scale = Vector3f(scale)
+      scale.mul(interpolateCurve(particleParams.sizeCurve, timeAliveClamped))
+      return scale
+    }
 
+    val timeAliveClamped = (timeAlive.toFloat() / particleParams.lifeTime.toFloat()).coerceIn(0.0f, 1.0f)
 
-    val newBlock            = calcBlockCurve()
+    val newBlock            = calcBlockCurve(timeAliveClamped)
     val (newVel, newOffset) = calcOffset()
-    val newRot              = calcRot()
+    val newRot              = calcRot(timeAliveClamped)
+    val newScale            = calcSize(timeAliveClamped)
 
     vel    = newVel
     offset = newOffset
     rot    = newRot
 
-    val (quatRot, transformOffset) = calcTransformOffset(newRot, initOffset, scale /* newScale */)
+    val (quatRot, transformOffset) = calcTransformOffset(newRot, initOffset, newScale)
     val combinedOffset = transformOffset.add(newOffset)
 
     val newProperties = DisplayEntityProperties(
@@ -133,7 +144,7 @@ class Particle(private val particleParams: ParticleParams) {
       blockType    = newBlock,
       translation  = combinedOffset,
       leftRotation = quatRot,
-      scale        = scale, //fix
+      scale        = newScale,
       tags         = arrayOf("BPS_Particle")
     )
 

src/main/kotlin/com/bytedice/bde_particles/particle/ParticleParams.kt

@@ -2,21 +2,24 @@ package com.bytedice.bde_particles.particle
 
 import org.joml.Vector3f
 
-// sizeRandom: set y and z on both vectors to -1 for uniform scale // not implemented
+// TODO: order these correctly, explain all
+// sizeRandom: if uniformSize is true then sizeRandom will be uniform (cubic) and the values are taken from X
 // lifeTime:   any value below 1 will result in a particle not spawning
-// minVel      values 0 or less mean the particle can travel however slow it wants
+// minVel:     values 0 or less mean the particle can travel however slow it wants
+// gravity:    Y being -0.025 is close to regular gravity
 data class ParticleParams (
   //val shape: Shape, // add later, start with single point
-  val blockCurve:   Array<String>            = arrayOf("minecraft:purple_concrete", "minecraft:purple_stained_glass"),
+  val blockCurve:   Array<String>            = arrayOf("minecraft:shroomlight", "minecraft:orange_concrete", "minecraft:orange_stained_glass", "minecraft:gray_stained_glass", "minecraft:light_gray_stained_glass"),
   val rotRandom:    Pair<Vector3f, Vector3f> = Pair(Vector3f(0.0f, 0.0f, 0.0f), Vector3f(360.0f, 360.0f, 360.0f)),
   val rotVelRandom: Pair<Vector3f, Vector3f> = Pair(Vector3f(-0.2f, -0.2f, -0.2f), Vector3f(0.2f, 0.2f, 0.2f)),
   val rotVelCurve:  Array<Vector3f>          = arrayOf(Vector3f(1.0f, 1.0f, 1.0f), Vector3f(0.0f, 0.0f, 0.0f)),
   val sizeRandom:   Pair<Vector3f, Vector3f> = Pair(Vector3f(0.5f, 0.5f, 0.5f), Vector3f(1.0f, 1.0f, 1.0f)),
-  val sizeCurve:    Array<Vector3f>          = arrayOf(Vector3f(1.0f, 1.0f, 1.0f), Vector3f(0.0f, 0.0f, 0.0f)),
-  val velRandom:    Pair<Vector3f, Vector3f> = Pair(Vector3f(-0.3f, 0.3f, -0.3f), Vector3f(0.3f, 0.6f, 0.3f)),
+  val uniformSize:  Boolean                  = true,
+  val sizeCurve:    Array<Vector3f>          = arrayOf(Vector3f(1.0f, 1.0f, 1.0f), Vector3f(0.5f, 0.5f, 0.5f)),
+  val velRandom:    Pair<Vector3f, Vector3f> = Pair(Vector3f(-0.1f, 0.4f, -0.1f), Vector3f(0.1f, 0.8f, 0.1f)),
   val forceFields:  ForceField               = ForceField(),
-  val gravity:      Vector3f                 = Vector3f(0.0f, -0.025f, 0.0f),
+  val gravity:      Vector3f                 = Vector3f(0.0f, -0.01f, 0.0f),
   val drag:         Float                    = 0.075f,
   val minVel:       Float                    = 0.0f,
-  val lifeTime:     Int                      = 20
+  val lifeTime:     Int                      = 30
 )