Caustics was backwards on Z-axis. Working on cube now.

Materials/Cube.mat

@@ -88,5 +88,5 @@ Material:
     m_Colors:
     - _Color: {r: 1, g: 1, b: 1, a: 1}
     - _EmissionColor: {r: 0, g: 0, b: 0, a: 1}
-    - light: {r: 0.3213938, g: 0.76604444, b: -0.5566705, a: 0}
-    - sphereCenter: {r: 0, g: -0.766, b: 0.423, a: 0}
+    - light: {r: 0.6562178, g: 0.69221956, b: 0.3003507, a: 0}
+    - sphereCenter: {r: -0.4, g: -0.75, b: 0.2, a: 0}

Materials/Unlit_Caustics.mat

@@ -38,5 +38,5 @@ Material:
     - poolHeight: 1
     - sphereRadius: 0.25
     m_Colors:
-    - light: {r: 0.3213938, g: 0.76604444, b: -0.5566705, a: 0}
-    - sphereCenter: {r: 0, g: -0.766, b: 0.423, a: 0}
+    - light: {r: 0.6562178, g: 0.69221956, b: 0.3003507, a: 0}
+    - sphereCenter: {r: -0.4, g: -0.75, b: 0.2, a: 0}

Materials/Unlit_Sphere.mat

@@ -34,5 +34,5 @@ Material:
     - poolHeight: 1
     - sphereRadius: 0.25
     m_Colors:
-    - light: {r: 0.3213938, g: 0.76604444, b: -0.5566705, a: 0}
-    - sphereCenter: {r: 0, g: -0.766, b: 0.423, a: 0}
+    - light: {r: 0.6562178, g: 0.69221956, b: 0.3003507, a: 0}
+    - sphereCenter: {r: -0.4, g: -0.75, b: 0.2, a: 0}

Materials/Unlit_Water Above.mat

@@ -41,6 +41,6 @@ Material:
     - poolHeight: 1
     - sphereRadius: 0.25
     m_Colors:
-    - eye: {r: 2.53948, g: 1.8776947, b: -3.4477127, a: 0}
-    - light: {r: 0.3213938, g: 0.76604444, b: -0.5566705, a: 0}
-    - sphereCenter: {r: 0, g: -0.766, b: 0.423, a: 0}
+    - eye: {r: 1.3820654, g: 1.0016792, b: 3.6965032, a: 0}
+    - light: {r: 0.6562178, g: 0.69221956, b: 0.3003507, a: 0}
+    - sphereCenter: {r: -0.4, g: -0.75, b: 0.2, a: 0}

Materials/Unlit_Water Below.mat

@@ -41,6 +41,6 @@ Material:
     - poolHeight: 1
     - sphereRadius: 0.25
     m_Colors:
-    - eye: {r: 2.53948, g: 1.8776947, b: -3.4477127, a: 0}
-    - light: {r: 0.3213938, g: 0.76604444, b: -0.5566705, a: 0}
-    - sphereCenter: {r: 0, g: -0.766, b: 0.423, a: 0}
+    - eye: {r: 1.3820654, g: 1.0016792, b: 3.6965032, a: 0}
+    - light: {r: 0.6562178, g: 0.69221956, b: 0.3003507, a: 0}
+    - sphereCenter: {r: -0.4, g: -0.75, b: 0.2, a: 0}

Scripts/CameraOrbit.cs

@@ -0,0 +1,19 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class CameraOrbit : MonoBehaviour {
+  public float rotationRate = 100f;
+
+	// Use this for initialization
+	void Start () {
+	}
+
+	// Update is called once per frame
+	void Update () {
+    if (Input.GetMouseButton(0)) {
+      transform.Rotate(-Input.GetAxis("Mouse Y") * rotationRate * Time.deltaTime, 0f, 0f, Space.Self);
+      transform.Rotate(0f, Input.GetAxis("Mouse X") * rotationRate * Time.deltaTime, 0f, Space.World);
+    }
+	}
+}

Scripts/WaterSimulation.cs

@@ -6,26 +6,27 @@
 // http://tips.hecomi.com/entry/2017/05/17/020037
 public class WaterSimulation : MonoBehaviour, IPointerClickHandler, IDragHandler {
   public CustomRenderTexture texture;
-  private CustomRenderTextureUpdateZone[] zones = null;
   public float dropRadius = 1f; // uv units [0, 1]
   public bool pause = false;
 
+  private CustomRenderTextureUpdateZone[] zones = null;
   private Collider collider;
   private CustomRenderTextureUpdateZone defaultZone, normalZone, clickZone;
+
   void Start() {
     texture.Initialize();
     collider = GetComponent<Collider>();
 
     defaultZone = new CustomRenderTextureUpdateZone();
     defaultZone.needSwap = true;
-    defaultZone.passIndex = 0;
+    defaultZone.passIndex = 0; // integrate
     defaultZone.rotation = 0f;
     defaultZone.updateZoneCenter = new Vector2(0.5f, 0.5f);
     defaultZone.updateZoneSize = new Vector2(1f, 1f);
 
     normalZone = new CustomRenderTextureUpdateZone();
     normalZone.needSwap = true;
-    normalZone.passIndex = 2;
+    normalZone.passIndex = 2; // update normals
     normalZone.rotation = 0f;
     normalZone.updateZoneCenter = new Vector2(0.5f, 0.5f);
     normalZone.updateZoneSize = new Vector2(1f, 1f);
@@ -39,8 +40,13 @@ void Start() {
     clickZone.updateZoneSize = new Vector2(dropRadius, dropRadius);
     // clickZone.updateZoneSize = new Vector2(1f, 1f);
 
-    texture.ClearUpdateZones();
-    texture.SetUpdateZones(new CustomRenderTextureUpdateZone[] { defaultZone, defaultZone, normalZone });
+    texture.SetUpdateZones(new CustomRenderTextureUpdateZone[] { clickZone, normalZone });
+    for (int i = 0; i < 20; i++) {
+      clickZone.updateZoneCenter = new Vector2(Random.Range(0f, 1f),
+                                               1f - Random.Range(0f, 1f));
+      texture.Update(1);
+    }
+    // texture.ClearUpdateZones();
   }
 
   public void OnDrag(PointerEventData ped) {
@@ -64,11 +70,12 @@ void AddWave(PointerEventData ped) {
     var leftClick = ped.button == PointerEventData.InputButton.Left;
 
     Debug.Log("We got a click " + localCursor + " uv " + uv);
-    AddWave(uv, leftClick ? 2 : 3); // 1 または -1 にバッファを塗るパス);
+    // AddWave(uv, leftClick ? 2 : 3); // 1 または -1 にバッファを塗るパス);
+    AddWave(uv);
   }
 
-  void AddWave(Vector2 uv, int passIndex) {
-    clickZone.updateZoneCenter = new Vector2(uv.x, 1 - uv.y);
+  void AddWave(Vector2 uv) {
+    clickZone.updateZoneCenter = new Vector2(uv.x, 1f - uv.y);
 
     if (pause) {
       zones = new CustomRenderTextureUpdateZone[] { clickZone, normalZone };
@@ -86,11 +93,10 @@ void Update() {
       texture.SetUpdateZones(zones);
       zones = null;
     } else {
-      // texture.ClearUpdateZones();
       texture.SetUpdateZones(new CustomRenderTextureUpdateZone[] { defaultZone, defaultZone, normalZone });
     }
-    // if (! pause
-    //     || Input.GetKeyDown(KeyCode.N))
+    if (! pause
+        || Input.GetKeyDown(KeyCode.N))
       texture.Update(1);
   }
 
@@ -109,7 +115,8 @@ void UpdateZones() {
 
     if (collider.Raycast(ray, out hit, 100f)) {
       Debug.Log("Clicked uv " + hit.textureCoord2);
-      AddWave(hit.textureCoord2, leftClick ? 2 : 3);
+      // AddWave(hit.textureCoord2, leftClick ? 2 : 3);
+      AddWave(hit.textureCoord2);
     }
   }
 }

Shaders/Caustics.shader

@@ -69,8 +69,9 @@ Shader "Unlit/Caustics"
         o.ray = refract(-light, normal, IOR_AIR / IOR_WATER);
         o.oldPos = project(v.vertex.xzy, refractedLight, refractedLight);
         o.newPos = project(v.vertex.xzy + float3(0.0, info.r, 0.0), o.ray, refractedLight);
-
+        // o.vertex = float4(0.75 * (o.newPos.xz + refractedLight.xz / refractedLight.y), 0.0, 1.0);
         o.vertex = float4(0.75 * (o.newPos.xz + refractedLight.xz / refractedLight.y), 0.0, 1.0);
+        // o.vertex.y *= 1;
 
         // o.position = v.vertex.xyz;
         // // o.worldPos = mul (unity_ObjectToWorld, v.vertex);
@@ -99,7 +100,10 @@ Shader "Unlit/Caustics"
         float3 refractedLight = refract(-light, float3(0.0, 1.0, 0.0), IOR_AIR / IOR_WATER);
 
         /* compute a blob shadow and make sure we only draw a shadow if the player is blocking the light */
-        float3 dir = (sphereCenter - i.newPos) / sphereRadius;
+        // float3 dir = (float3(sphereCenter.xy, -sphereCenter.z) - i.newPos) / sphereRadius;
+        // float3 dir = (float3(sphereCenter.xy, sphereCenter.z) - i.newPos) / sphereRadius;
+        // float3 dir = (float3(sphereCenter.xy, -sphereCenter.z) - i.oldPos) / sphereRadius;
+        float3 dir = (sphereCenter - i.oldPos) / sphereRadius;
         float3 area = cross(dir, refractedLight);
         float shadow = dot(area, area);
         float dist = dot(dir, -refractedLight);

Shaders/HelperFunctions.cginc

@@ -58,6 +58,11 @@
     return color;
   }
 
+float2 flipY(float2 v) {
+  v.y = 1 - v.y;
+  return v;
+}
+
   float3 getWallColor(float3 _point) {
     float scale = 0.5;
 
@@ -82,7 +87,8 @@
     float diffuse = max(0.0, dot(refractedLight, normal));
     float4 info = tex2D(water, _point.xz * 0.5 + 0.5);
     if (_point.y < info.r) {
-      float4 caustic = tex2D(causticTex, 0.75 * (_point.xz - _point.y * refractedLight.xz / refractedLight.y) * 0.5 + 0.5);
+      // float4 caustic = tex2D(causticTex, 0.75 * (_point.xz - _point.y * refractedLight.xz / refractedLight.y) * 0.5 + 0.5);
+    float4 caustic = tex2D(causticTex, flipY(0.75 * (_point.xz - _point.y * refractedLight.xz / refractedLight.y) * 0.5 + 0.5));
       scale += diffuse * caustic.r * 2.0 * caustic.g;
     } else {
       /* shadow for the rim of the pool */

Shaders/Sphere.shader

@@ -46,10 +46,10 @@
       v2f vert (appdata v)
       {
         v2f o;
-        // o.position = sphereCenter + v.vertex.xyz * sphereRadius;
         o.position = sphereCenter + v.vertex.xyz * sphereRadius;
-        o.vertex = UnityObjectToClipPos(v.vertex * sphereRadius);
-        // o.vertex = UnityObjectToClipPos(o.position);
+        o.position = sphereCenter + v.vertex.xyz * sphereRadius;
+        // o.vertex = UnityObjectToClipPos(v.vertex * sphereRadius);
+        o.vertex = UnityObjectToClipPos(o.position);
         // o.vertex = mul(UNITY_MATRIX_MVP, float4(o.position, 1));
         o.uv = TRANSFORM_TEX(v.uv, _MainTex);
         // UNITY_TRANSFER_FOG(o,o.vertex);

todo.org

@@ -0,0 +1,6 @@
+* TODO
+  - [ ] Sphere shadow is not working.
+  - [ ] Make camera pivot-able.
+  - [ ] Add ripples
+  - [ ] Made sphere draggable.
+  - [ ] Add sphere physics.