From 13960cd6456bd3a488c81be4a6e789bc30723f58 Mon Sep 17 00:00:00 2001
From: barnold1953 <brb555@utk.edu>
Date: Mon, 14 Jul 2014 16:16:07 -0700
Subject: [PATCH] Basic falling sand script

---
 examples/fallingSand.js | 91 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 examples/fallingSand.js

diff --git a/examples/fallingSand.js b/examples/fallingSand.js
new file mode 100644
index 0000000000..015f9e23ff
--- /dev/null
+++ b/examples/fallingSand.js
@@ -0,0 +1,91 @@
+var SAND_LIFETIME = 100.0;
+var UPDATE_RATE = 1.0;
+var SAND_SIZE = 0.125;
+
+var sandArray = [];
+var numSand = 0;
+
+
+var red = 255;
+var green = 0;
+var blue = 0;
+
+var SOURCE_POSITION = MyAvatar.position;
+
+function update() {
+
+    for (var i = 0; i < numSand; i++) {
+        updateSand(i);
+    }
+    
+    var voxel = Voxels.getVoxelAt(SOURCE_POSITION.x, SOURCE_POSITION.y, SOURCE_POSITION.z, SAND_SIZE);
+    if (voxel.s == 0) {
+        sandArray[numSand] = {x: SOURCE_POSITION.x, y: SOURCE_POSITION.y, z: SOURCE_POSITION.z, s: SAND_SIZE, r: red, g: green, b: blue};
+        numSand++;
+        Voxels.setVoxel(SOURCE_POSITION.x, SOURCE_POSITION.y, SOURCE_POSITION.z, SAND_SIZE, red, green, blue);
+    }
+}
+
+function isVoxelEmpty(x, y, z) {
+    var adjacent = Voxels.getVoxelAt(x, y, z, SAND_SIZE);
+    return (adjacent.s == 0);
+}
+
+function tryMoveVoxel(voxel, x, y, z) {
+    //If the adjacent voxel is empty, we will move to it.
+    if (isVoxelEmpty(x, y, z)) {
+        moveVoxel(voxel, x, y, z);
+        return true;
+    }
+    return false;
+}
+
+function moveVoxel(voxel, x, y, z) {
+    Voxels.eraseVoxel(voxel.x, voxel.y, voxel.z, SAND_SIZE);
+    Voxels.setVoxel(x, y, z, SAND_SIZE, red, green, blue);
+    voxel.x = x;
+    voxel.y = y;
+    voxel.z = z;
+}
+
+function updateSand(i) {
+    var voxel = sandArray[i];
+    
+    //Down
+    if (tryMoveVoxel(voxel, voxel.x, voxel.y - SAND_SIZE, voxel.z)) return true;
+    //Left
+    if (isVoxelEmpty(voxel.x - SAND_SIZE, voxel.y, voxel.z) &&
+        isVoxelEmpty(voxel.x - SAND_SIZE, voxel.y - SAND_SIZE, voxel.z)) {
+        moveVoxel(voxel, voxel.x - SAND_SIZE, voxel.y, voxel.z);
+        return true;
+    }
+    //Back
+    if (isVoxelEmpty(voxel.x, voxel.y, voxel.z - SAND_SIZE) &&
+        isVoxelEmpty(voxel.x, voxel.y - SAND_SIZE, voxel.z - SAND_SIZE)) {
+        moveVoxel(voxel, voxel.x, voxel.y, voxel.z - SAND_SIZE);
+        return true;
+    }
+    //Right
+    if (isVoxelEmpty(voxel.x + SAND_SIZE, voxel.y, voxel.z) &&
+        isVoxelEmpty(voxel.x + SAND_SIZE, voxel.y - SAND_SIZE, voxel.z)) {
+        moveVoxel(voxel, voxel.x + SAND_SIZE, voxel.y, voxel.z);
+        return true;
+    }
+    //Front
+    if (isVoxelEmpty(voxel.x, voxel.y, voxel.z + SAND_SIZE) &&
+        isVoxelEmpty(voxel.x, voxel.y - SAND_SIZE, voxel.z + SAND_SIZE)) {
+        moveVoxel(voxel, voxel.x, voxel.y, voxel.z + SAND_SIZE);
+        return true;
+    }
+    return false;
+}
+
+function scriptEnding() {
+    for (var i = 0; i < numSand; i++) {
+        var voxel = sandArray[i];
+        Voxels.eraseVoxel(voxel.x, voxel.y, voxel.z, SAND_SIZE);
+    }
+}
+
+Script.update.connect(update);
+Script.scriptEnding.connect(scriptEnding);