[orx-noise] Add hash functions

orx-mesh-noise/src/commonMain/kotlin/MeshNoise.kt

@@ -3,6 +3,9 @@ package org.openrndr.extra.mesh.noise
 import org.openrndr.extra.mesh.IIndexedPolygon
 import org.openrndr.extra.mesh.IMeshData
 import org.openrndr.extra.mesh.IVertexData
+import org.openrndr.extra.noise.fhash1D
+import org.openrndr.extra.noise.uhash11
+import org.openrndr.extra.noise.uhash1D
 import org.openrndr.math.Vector3
 import kotlin.math.sqrt
 import kotlin.random.Random
@@ -20,6 +23,23 @@ fun uniformBarycentric(random: Random = Random.Default): Vector3 {
     return Vector3(b0, b1, 1.0 - b0 - b1)
 }
 
+/**
+ * Generate a uniformly distributed barycentric coordinate
+ * @param random a random number generator
+ */
+fun hashBarycentric(seed: Int, x: Int): Vector3 {
+    val u = fhash1D(seed, x)
+    val v = fhash1D(seed, u.toRawBits().toInt() - x)
+
+
+
+    val su0 = sqrt(u)
+    val b0 = 1.0 - su0
+    val b1 = v * su0
+    return Vector3(b0, b1, 1.0 - b0 - b1)
+}
+
+
 /**
  * Generate a uniformly distributed point that lies inside this [IIndexedPolygon]
  * @param vertexData vertex data used to resolve positions
@@ -33,6 +53,19 @@ fun IIndexedPolygon.uniform(vertexData: IVertexData, random: Random = Random.Def
     return x[0] * b.x + x[1] * b.y + x[2] * b.z
 }
 
+/**
+ * Generate a uniformly distributed point that lies inside this [IIndexedPolygon]
+ * @param vertexData vertex data used to resolve positions
+ * @param random a random number generator
+ */
+fun IIndexedPolygon.hash(vertexData: IVertexData, seed:Int, x: Int): Vector3 {
+    require(positions.size == 3) { "polygon must be a triangle"}
+
+    val s = vertexData.positions.slice(positions)
+    val b = hashBarycentric(seed, x)
+    return s[0] * b.x + s[1] * b.y + s[2] * b.z
+}
+
 internal fun IIndexedPolygon.area(vertexData: IVertexData): Double {
     require(positions.size == 3) { "polygon must be a triangle"}
     val x = vertexData.positions.slice(positions)
@@ -62,4 +95,27 @@ fun IMeshData.uniform(count: Int, random: Random = Random.Default): List<Vector3
         }
     }
     return result
+}
+
+/**
+ * Generate points on the surface described by the mesh data
+ */
+fun IMeshData.hash(count: Int, seed:Int, x: Int): List<Vector3> {
+    val triangulated = triangulate()
+    val result = mutableListOf<Vector3>()
+    val totalArea = triangulated.polygons.sumOf { it.area(vertexData) }
+    val randoms = (0 until count).map {
+        Pair(x + it, fhash1D(seed, x + it) * totalArea)
+    }.sortedBy { it.second }
+
+    var idx = 0
+    var sum = 0.0
+    for (t in triangulated.polygons) {
+        sum += t.area(vertexData)
+        while (idx <= randoms.lastIndex && sum > randoms[idx].second) {
+            result.add(t.hash(vertexData, seed xor 0x7f7f7f, randoms[idx].first))
+            idx++
+        }
+    }
+    return result
 }