Add repellent pheromone channel with per-channel blur parameters

src/Config.ts

@@ -11,4 +11,9 @@ export default {
     antSpeed: 1,
     antRotationAngle: Math.PI / 30,
     brushRadius: 20,
+    // per-channel pheromone params
+    repellentFadeOutFactor: 0.0005,
+    repellentBlurRadius: 0.05,
+    repellentMaxPerCell: 10,
+    repellentThreshold: 0.01,
 };

src/Renderer.ts

@@ -195,6 +195,18 @@ export default class Renderer {
             ANT_ROTATION_ANGLE: Renderer.convertNumberToFloatString(
                 Config.antRotationAngle,
             ),
+            REPELLENT_FADE_OUT_FACTOR: Renderer.convertNumberToFloatString(
+                Config.repellentFadeOutFactor,
+            ),
+            REPELLENT_BLUR_RADIUS: Renderer.convertNumberToFloatString(
+                Config.repellentBlurRadius,
+            ),
+            REPELLENT_MAX_PER_CELL: Renderer.convertNumberToFloatString(
+                Config.repellentMaxPerCell,
+            ),
+            REPELLENT_THRESHOLD: Renderer.convertNumberToFloatString(
+                Config.repellentThreshold,
+            ),
         };
     }
 

src/shaders/world.frag

@@ -10,7 +10,7 @@ uniform sampler2D tDiscreteAnts;
 
 void main()	{
     vec4 lastState = texture(tLastState, vUv);
-    vec3 discreteAnts = texture(tDiscreteAnts, vUv).xyz;
+    vec4 discreteAnts = texture(tDiscreteAnts, vUv);
 
     int cellData = int(lastState.x);
     int isFood = cellData & 1;
@@ -18,10 +18,11 @@ void main()	{
     int isObstacle = (cellData & 4) >> 2;
     float scentToHome = min(SCENT_MAX_PER_CELL, lastState.y + discreteAnts.x);
     float scentToFood =  min(SCENT_MAX_PER_CELL, lastState.z + discreteAnts.y);
+    float repellent = min(REPELLENT_MAX_PER_CELL, lastState.w);
 
     if (discreteAnts.z == 1.) {
         isFood = 0;
     }
 
-    FragColor = vec4(float(isFood + (isHome << 1) + (isObstacle << 2)), scentToHome, scentToFood, 0);
+    FragColor = vec4(float(isFood + (isHome << 1) + (isObstacle << 2)), scentToHome, scentToFood, repellent);
 }

src/shaders/worldBlur.frag

@@ -8,6 +8,7 @@ out vec4 FragColor;
 uniform sampler2D tWorld;
 
 const float offset = 1. / WORLD_SIZE * SCENT_BLUR_RADIUS;
+const float repellentOffset = 1. / WORLD_SIZE * REPELLENT_BLUR_RADIUS;
 
 void main()	{
     vec4 s0 = texture(tWorld, vUv);
@@ -19,10 +20,18 @@ void main()	{
     float scentToHome = (s0.y + s1.y + s2.y + s3.y + s4.y) / 5. * (1. - SCENT_FADE_OUT_FACTOR);
     float scentToFood = (s0.z + s1.z + s2.z + s3.z + s4.z) / 5. * (1. - SCENT_FADE_OUT_FACTOR);
 
+    // repellent channel uses its own diffusion radius and decay rate
+    vec4 rr0 = texture(tWorld, vUv);
+    vec4 rr1 = texture(tWorld, vUv + vec2(1, 1) * repellentOffset);
+    vec4 rr2 = texture(tWorld, vUv + vec2(-1, -1) * repellentOffset);
+    vec4 rr3 = texture(tWorld, vUv + vec2(-1, 1) * repellentOffset);
+    vec4 rr4 = texture(tWorld, vUv + vec2(1, -1) * repellentOffset);
+    float repellent = (rr0.w + rr1.w + rr2.w + rr3.w + rr4.w) / 5. * (1. - REPELLENT_FADE_OUT_FACTOR);
+
     FragColor = vec4(
         s0.x,
         scentToHome < SCENT_THRESHOLD ? 0. : scentToHome,
         scentToFood < SCENT_THRESHOLD ? 0. : scentToFood,
-        0
+        repellent < REPELLENT_THRESHOLD ? 0. : repellent
     );
 }