2 files changed, 121 insertions, 6 deletions

diff --git a/src/simulation/senses.js b/src/simulation/senses.js
index 4fc96d6..0a882c9 100644
--- a/src/simulation/senses.js
+++ b/src/simulation/senses.js
@@ -3,7 +3,7 @@
 
 const frozen = {
   size: 1,
-  read: (lattice, agent) => {
+  read: (world, agent) => {
     if (agent.flags.frozen === true) {
       return [ 1 ];
     } else {
@@ -13,6 +13,39 @@ const frozen = {
 };
 
 
+// add two arrays together element-wise with a scaling factor
+function array_scalesum(a, s, b) {
+  return a.map((x, i) => x + (s*b[i]));
+}
+// determine the square of the distance between two cells
+function lattice_dist2(x0, y0, x1, y1) {
+  if (x0 === x1 && y0 === y1) { return 1; } // not proper distance but avoids divide-by-zero errors c:
+  return ((x0-x1)**2) + ((y0-y1)**2);
+}
+const hear = {
+  size: 8,
+  read: (world, agent) => {
+    const {x, y} = agent;
+    const lattice_sounds = world.lattice
+      .map((row, cy) => row.map((cell, cx) => [ 1/lattice_dist2(x, y, cx, cy), cell ]))
+      .flat()
+      .filter(([scale, cell]) => cell.flags.emit !== undefined)
+      .reduce(
+        (acc, [scale, cell]) => array_scalesum(acc, scale, cell.flags.emit),
+        [0, 0, 0, 0, 0, 0, 0, 0]
+      );
+    const agent_sounds = world.agents
+      .filter(a => a.flags.emit !== undefined)
+      .reduce(
+        (acc, a) => array_scalesum(acc, 1/lattice_dist2(x, y, a.x, a.y), a.flags.emit),
+        [0, 0, 0, 0, 0, 0, 0, 0]
+      );
+
+    return array_scalesum(lattice_sounds, 1, agent_sounds).map(ch => Math.tanh(ch));
+  },
+};
+
+
 export const senses = [
-  frozen,
+  frozen, hear,
 ];
diff --git a/src/simulation/senses.test.js b/src/simulation/senses.test.js
index 1caed52..b54ada2 100644
--- a/src/simulation/senses.test.js
+++ b/src/simulation/senses.test.js
@@ -2,7 +2,7 @@
 
 import { senses } from './senses.js';
 
-const [ frozen, ...rest ] = senses;
+const [ frozen, hear, ...rest ] = senses;
 
 
 test("frozen sense", () => {
@@ -10,9 +10,91 @@ test("frozen sense", () => {
     id: 0, x: 0, y: 0,
     flags: { frozen: true, },
   };
-  const lattice = null;
 
-  expect(frozen.read(lattice, agent)).toEqual([1]);
+  expect(frozen.read(null, agent)).toEqual([1]);
   agent.flags.frozen = false;
-  expect(frozen.read(lattice, agent)).toEqual([0]);
+  expect(frozen.read(null, agent)).toEqual([0]);
+});
+
+
+test("hear nothing", () => {
+  const agent = { id: 4, x: 1, y: 1, flags: {} };
+  const o = { type: 'empty', flags: {} };
+  const world = {
+    lattice: [
+      [ o, o, o ],
+      [ o, o, o ],
+      [ o, o, o ],
+    ],
+    agents: [agent],
+  };
+
+  expect(hear.read(world, agent)).toEqual([
+    Math.tanh(0), Math.tanh(0), Math.tanh(0), Math.tanh(0),
+    Math.tanh(0), Math.tanh(0), Math.tanh(0), Math.tanh(0),
+  ]);
+});
+
+
+test("hear self", () => {
+  const agent = { id: 4, x: 1, y: 1, flags: { emit: [1, 0, 0.5, 0, 0, 0, 0, 1] } };
+  const o = { type: 'empty', flags: {} };
+  const world = {
+    lattice: [
+      [ o, o, o ],
+      [ o, o, o ],
+      [ o, o, o ],
+    ],
+    agents: [agent],
+  };
+
+  expect(hear.read(world, agent)).toEqual([
+    Math.tanh(1), Math.tanh(0), Math.tanh(0.5), Math.tanh(0),
+    Math.tanh(0), Math.tanh(0), Math.tanh(0), Math.tanh(1),
+  ]);
+});
+
+
+test("hear cells", () => {
+  const agent = { id: 4, x: 2, y: 2, flags: {} };
+  const o = { type: 'empty', flags: {} };
+  const s = { type: 'empty', flags: { emit: [1, 0.5, 0.25, 0.125, 0, 0, 0, 0] } };
+  const world = {
+    lattice: [
+      [ o, o, s, o, o ],
+      [ o, o, o, o, o ],
+      [ o, s, o, o, o ],
+      [ o, o, o, o, o ],
+      [ o, o, o, o, o ],
+    ],
+    agents: [agent],
+  };
+
+  expect(hear.read(world, agent)).toEqual([
+    Math.tanh(1.25), Math.tanh(0.625), Math.tanh(0.3125), Math.tanh(0.15625), 
+    Math.tanh(0), Math.tanh(0), Math.tanh(0), Math.tanh(0),
+  ]);
+});
+
+
+test("hear cells & agents", () => {
+  const agent = { id: 4, x: 2, y: 2, flags: {} };
+  const agent2 = { id: 0, x: 2, y: 4, flags: { emit: [0, 0, 0, 0, 1, 1, 1, 1] } };
+  const o = { type: 'empty', flags: {} };
+  const s = { type: 'empty', flags: { emit: [1, 0.5, 0.25, 0.125, 0, 0, 0, 0] } };
+  const world = {
+    lattice: [
+      [ o, o, s, o, o ],
+      [ o, o, o, o, o ],
+      [ o, s, o, o, o ],
+      [ o, o, o, o, o ],
+      [ o, o, o, o, o ],
+    ],
+    agents: [agent, agent2],
+  };
+
+  expect(hear.read(world, agent)).toEqual([
+    Math.tanh(1.25), Math.tanh(0.625), Math.tanh(0.3125), Math.tanh(0.15625), 
+    Math.tanh(0.25), Math.tanh(0.25), Math.tanh(0.25), Math.tanh(0.25),
+  ]);
 });