Compute Shader Error

Hi all. So this is my first time using compute shaders so to play it safe I decided to use one from the asset store. I'm trying to generate SImplex Noise. When I call the compute shader however it gives the following error :

Code (CSharp):

1. NullReferenceException: Object reference not set to an instance of an object
2. NoiseHandler.CreateNoise (Single x, Single y, Single z, Int32 iSize, Single Str, Single NoiseA, Single NoiseB, Single NoiseC) (at Assets/Scripts/Generation Scripts/Shader/NoiseHandler.cs:22)

I get that the the compute shader can't be found but I don't know where I'm going wrong. Here's the code below :
NoiseHandler :

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class NoiseHandler {
6.  
7.  
8.     ComputeShader perlin;
9.  
10.     public float CreateNoise(float x, float y, float z, int iSize = 32, float Str = 4.0f, float NoiseA = 0.000718f, float NoiseB = 0.000632f, float NoiseC = 0.000695f)
11.     {
12.  
13.         int mgen_id = perlin.FindKernel("Noise3d");
14.         float Volume = 0f;
15.         perlin.SetFloat("Result", Volume);
16.  
17.         perlin.SetFloats("_StartPos", new float[] {x, y, z});
18.         //perlin.SetFloat("_MyTime",Time.time*Speed);
19.         perlin.SetFloat("_Str", Str);
20.         perlin.SetFloat("_NoiseA", NoiseA);
21.         perlin.SetFloat("_NoiseB", NoiseB);
22.         perlin.SetFloat("_NoiseC", NoiseC);
23.  
24.         perlin.Dispatch(mgen_id, 1, 1, iSize);
25.  
26.         return Volume;
27.     }
28.  
29.  
30. }
31.  

Compute Shader :

Code (CSharp):

1. //Boris Novikov (17.09.2013)
2. //Special thanks to Johannes Gotlén for shader example.
3.  
4. // Each #kernel tells which function to compile; you can have many kernels
5. #pragma kernel Simplex3D
6. #pragma kernel FillEmpty
7. #pragma kernel Plane
8. #pragma kernel Sphere
9.  
10. #define F3 1.0/3.0
11. #define G3 1.0/6.0
12.  
13. //Start position of this chunk
14. float3 _StartPos;
15.  
16. //Noise parameters
17. float _Str;
18. float _NoiseA;
19. float _NoiseB;
20. float _NoiseC;
21.  
22. // Create a RenderTexture with enableRandomWrite flag and set it
23. // with cs.SetTexture
24. RWTexture3D<float> Result;
25.  
26. float simplex3d(float3 ws) {
27. //thanks to Stefan Gustavson, Linköping University, Sweden
28.     float xin = ws.x;
29.     float yin = ws.y;
30.     float zin = ws.z;
31.       const float3 grad3[12] = {
32.           float3(1,1,0),float3(-1,1,0),float3(1,-1,0),float3(-1,-1,0),
33.          float3(1,0,1),float3(-1,0,1),float3(1,0,-1),float3(-1,0,-1),
34.         float3(0,1,1),float3(0,-1,1),float3(0,1,-1),float3(0,-1,-1)
35.     };
36.       const int perm[512] = {151,160,137,91,90,15,
37.       131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
38.       190,6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
39.       88,237,149,56,87,174,20,125,136,171,168,68,175,74,165,71,134,139,48,27,166,
40.       77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
41.       102,143,54,65,25,63,161,1,216,80,73,209,76,132,187,208,89,18,169,200,196,
42.       135,130,116,188,159,86,164,100,109,198,173,186,3,64,52,217,226,250,124,123,
43.       5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
44.       223,183,170,213,119,248,152,2,44,154,163,70,221,153,101,155,167,43,172,9,
45.       129,22,39,253,19,98,108,110,79,113,224,232,178,185,112,104,218,246,97,228,
46.       251,34,242,193,238,210,144,12,191,179,162,241,81,51,145,235,249,14,239,107,
47.       49,192,214,31,181,199,106,157,184,84,204,176,115,121,50,45,127,4,150,254,
48.       138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180,151,160,137,91,90,15,
49.       131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
50.       190,6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
51.       88,237,149,56,87,174,20,125,136,171,168,68,175,74,165,71,134,139,48,27,166,
52.       77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
53.       102,143,54,65,25,63,161,1,216,80,73,209,76,132,187,208,89,18,169,200,196,
54.       135,130,116,188,159,86,164,100,109,198,173,186,3,64,52,217,226,250,124,123,
55.       5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
56.       223,183,170,213,119,248,152,2,44,154,163,70,221,153,101,155,167,43,172,9,
57.       129,22,39,253,19,98,108,110,79,113,224,232,178,185,112,104,218,246,97,228,
58.       251,34,242,193,238,210,144,12,191,179,162,241,81,51,145,235,249,14,239,107,
59.       49,192,214,31,181,199,106,157,184,84,204,176,115,121,50,45,127,4,150,254,
60.       138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
61.     };
62.  
63.     const int permMod12[512] = {
64.         7,4,5,7,6,3,11,1,9,11,0,5,2,5,7,9,8,0,7,6,9,10,8,3,1,0,9,10,11,10,6,4,7,0,6,3,
65.         0,2,5,2,10,0,3,11,9,11,11,8,9,9,9,4,9,5,8,3,6,8,5,4,3,0,8,7,2,9,11,2,7,0,3,10,5
66.         ,2,2,3,11,3,1,2,0,7,1,2,4,9,8,5,7,10,5,4,4,6,11,6,5,1,3,5,1,0,8,1,5,4,0,7,4,5,
67.         6,1,8,4,3,10,8,8,3,2,8,4,1,6,5,6,3,4,4,1,10,10,4,3,5,10,2,3,10,6,3,10,1,8,3,2,
68.         11,11,11,4,10,5,2,9,4,6,7,3,2,9,11,8,8,2,8,10,7,10,5,9,5,11,11,7,4,9,9,10,3,1,7,
69.         2,0,2,7,5,8,4,10,5,4,8,2,6,1,0,11,10,2,1,10,6,0,0,11,11,6,1,9,3,1,7,9,2,11,11,1,
70.         0,10,7,1,7,10,1,4,0,0,8,7,1,2,9,7,4,6,2,6,8,1,9,6,6,7,5,0,0,3,9,8,3,6,6,11,1,
71.         0,0,7,4,5,7,6,3,11,1,9,11,0,5,2,5,7,9,8,0,7,6,9,10,8,3,1,0,9,10,11,10,6,4,7,0,6,3,
72.         0,2,5,2,10,0,3,11,9,11,11,8,9,9,9,4,9,5,8,3,6,8,5,4,3,0,8,7,2,9,11,2,7,0,3,10,5,
73.         2,2,3,11,3,1,2,0,7,1,2,4,9,8,5,7,10,5,4,4,6,11,6,5,1,3,5,1,0,8,1,5,4,0,7,4,5,
74.         6,1,8,4,3,10,8,8,3,2,8,4,1,6,5,6,3,4,4,1,10,10,4,3,5,10,2,3,10,6,3,10,1,8,3,2,
75.         11,11,11,4,10,5,2,9,4,6,7,3,2,9,11,8,8,2,8,10,7,10,5,9,5,11,11,7,4,9,9,10,3,1,7,
76.         2,0,2,7,5,8,4,10,5,4,8,2,6,1,0,11,10,2,1,10,6,0,0,11,11,6,1,9,3,1,7,9,2,11,11,1,
77.         0,10,7,1,7,10,1,4,0,0,8,7,1,2,9,7,4,6,2,6,8,1,9,6,6,7,5,0,0,3,9,8,3,6,6,11,1,0,0
78.     };
79.                         float n0,n1,n2,n3; // Noise contributions from the four corners
80.     // Skew the input space to determine which simplex cell we're in
81.     float s = (xin+yin+zin)*F3; // Very nice and simple skew factor for 3D
82.     int i = floor(xin+s);
83.     int j = floor(yin+s);
84.     int k = floor(zin+s);
85.     float t = (i+j+k)*G3;
86.     float X0 = i-t; // Unskew the cell origin back to (x,y,z) space
87.     float Y0 = j-t;
88.     float Z0 = k-t;
89.     float x0 = xin-X0; // The x,y,z distances from the cell origin
90.     float y0 = yin-Y0;
91.     float z0 = zin-Z0;
92.     // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
93.     // Determine which simplex we are in.
94.     int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
95.     int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
96.     if(x0>=y0) {
97.       if(y0>=z0)
98.         { i1=1; j1=0; k1=0; i2=1; j2=1; k2=0; } // X Y Z order
99.         else if(x0>=z0) { i1=1; j1=0; k1=0; i2=1; j2=0; k2=1; } // X Z Y order
100.         else { i1=0; j1=0; k1=1; i2=1; j2=0; k2=1; } // Z X Y order
101.       }
102.     else { // x0<y0
103.       if(y0<z0) { i1=0; j1=0; k1=1; i2=0; j2=1; k2=1; } // Z Y X order
104.       else if(x0<z0) { i1=0; j1=1; k1=0; i2=0; j2=1; k2=1; } // Y Z X order
105.       else { i1=0; j1=1; k1=0; i2=1; j2=1; k2=0; } // Y X Z order
106.     }
107.     // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
108.     // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
109.     // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
110.     // c = 1/6.
111.     float x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
112.     float y1 = y0 - j1 + G3;
113.     float z1 = z0 - k1 + G3;
114.     float x2 = x0 - i2 + 2.0*G3; // Offsets for third corner in (x,y,z) coords
115.     float y2 = y0 - j2 + 2.0*G3;
116.     float z2 = z0 - k2 + 2.0*G3;
117.     float x3 = x0 - 1.0 + 3.0*G3; // Offsets for last corner in (x,y,z) coords
118.     float y3 = y0 - 1.0 + 3.0*G3;
119.     float z3 = z0 - 1.0 + 3.0*G3;
120.     // Work out the hashed gradient indices of the four simplex corners
121.     int ii = i & 255;
122.     int jj = j & 255;
123.     int kk = k & 255;
124.     int gi0 = permMod12[ii+perm[jj+perm[kk]]];
125.     int gi1 = permMod12[ii+i1+perm[jj+j1+perm[kk+k1]]];
126.     int gi2 = permMod12[ii+i2+perm[jj+j2+perm[kk+k2]]];
127.     int gi3 = permMod12[ii+1+perm[jj+1+perm[kk+1]]];
128.     // Calculate the contribution from the four corners
129.     float t0 = 0.6 - x0*x0 - y0*y0 - z0*z0;
130.     if(t0<0){
131.         n0 = 0.0;
132.     }
133.     else {
134.       t0 *= t0;
135.       n0 = t0 * t0 * dot(grad3[gi0], float3(x0, y0, z0));
136.     }
137.     float t1 = 0.6 - x1*x1 - y1*y1 - z1*z1;
138.     if(t1<0){
139.      n1 = 0.0;
140.      } else {
141.       t1 *= t1;
142.       n1 = t1 * t1 * dot(grad3[gi1],float3(x1, y1, z1));
143.     }
144.     float t2 = 0.6 - x2*x2 - y2*y2 - z2*z2;
145.     if(t2<0){
146.         n2 = 0.0;
147.     } else {
148.       t2 *= t2;
149.       n2 = t2 * t2 * dot(grad3[gi2],float3(x2,y2,z2));
150.     }
151.     float t3 = 0.6 - x3*x3 - y3*y3 - z3*z3;
152.     if(t3<0){
153.      n3 = 0.0;
154.      } else {
155.       t3 *= t3;
156.       n3 = t3 * t3 * dot(grad3[gi3],float3( x3,y3,z3));
157.     }
158.  
159.    
160.     // Add contributions from each corner to get the final noise value.
161.     // The result is scaled to stay just inside [-1,1]
162.     return 32.0*(n0 + n1 + n2 + n3);
163.     //return 0;
164. }
165.  
166. [numthreads(32,32,1)]
167. void Simplex3d(uint3 id : SV_DispatchThreadID)
168. {
169.     int x,y,z;
170.  
171.     //20 UUnits in 1 voxel I assume
172.     x=id.x*20;y=id.y*20;z=id.z*20;
173.    
174.     x += _StartPos.x*20.0;y += _StartPos.y*20.0; z+=_StartPos.z*20.0;
175.    
176.     float3 ws = float3(x,y,z);
177.  
178.     float density = 1.0;
179.  
180.     float noiseA =  simplex3d(float3(x, y, z)* _NoiseA*_Str)*2 - 0.5;
181.     float noiseB =  simplex3d(float3(x, y, z)* _NoiseB*_Str);
182.     float noiseC =  simplex3d(float3(x, y, z)* _NoiseC*_Str);
183.  
184.     Result[float3(id.x,id.y,id.z)] = clamp(saturate(density+noiseA+ noiseB + noiseC / 5),-1.0,1.0);
185.  
186. }
187.  
188. [numthreads(32,32,1)]
189. void Plane (uint3 id : SV_DispatchThreadID)
190. {
191.     float Density = -1.0;
192.     if (id.y > 1)
193.         Density = 1.0;
194.     Result[float3(id.x,id.y,id.z)] = Density;
195. }
196.  
197. [numthreads(32,32,1)]
198. void Sphere (uint3 id : SV_DispatchThreadID)
199. {
200.     float _Brush_Size = 25.0;
201.      float3 v_center = float3(27,27,27);
202.     float3 pPosition = _StartPos+id.xyz; //*20.0
203.     float dist = distance(pPosition,v_center);
204.     float density = _Brush_Size-dist;
205.     clamp(density,-1.0,1.0);
206.  
207.     Result[id.xyz]=lerp(Result[id.xyz], max(density,Result[id.xyz]), 0.9);
208. }
209.  
210. [numthreads(32,32,1)]
211. void FillEmpty (uint3 id : SV_DispatchThreadID)
212. {
213.     Result[id.xyz]=0;
214. }

 

I wouldn't call a simplex noise algorithm playing it safe for your first attempt, but I salute you for trying to jump in at the deep-end.

It's evident however that you've yet to grasp the basics of compute shaders and how they work in Unity. For this reason I strongly suggest taking a step back and going over some tutorials. Click here and follow the links.