Question How do I generate mipmaps for a Texture3D?

I have this script used for generating the area around 0,0,0 as a Texture3D volume.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEditor;
5.  
6.  
7.  
8. public class LBTraceArea : MonoBehaviour
9. {
10.     public Texture3D Volume;
11.     public float CubeScale;
12.     public int CubeQuality;
13.     public string SaveAs;
14.  
15.     //pre-define texel size so it can be used among all functions
16.     float texelSize = 1f;
17.  
18.     // Start is called before the first frame update
19.     void Start()
20.     {
21.         Debug.Log(Volume.mipmapCount);
22.         //define the size of 1 3d texel/volumetric cube pixel/voxel
23.         texelSize = CubeScale / CubeQuality;
24.         VoxelizeArea();
25.         AssetDatabase.CreateAsset(Volume, "Assets/" + SaveAs + ".asset");
26.         Debug.Log(Volume.mipmapCount);
27.     }
28.  
29.     // Update is called once per frame
30.     void Update()
31.     {
32.      
33.     }
34.  
35.     //function to create 3D texture AKA voxel image with scene objects.
36.     void VoxelizeArea(){
37.  
38.  
39.         //Setup a 3d Texture
40.      
41.         //Format
42.         TextureFormat form = TextureFormat.RGBA32;
43.         TextureWrapMode wrap = TextureWrapMode.Clamp;
44.      
45.         //Defining the Volume
46.         Volume = new Texture3D(CubeQuality, CubeQuality, CubeQuality, form, false);
47.         Volume.wrapMode = wrap;
48.         Volume.filterMode = FilterMode.Trilinear;
49.  
50.         //Create a volumetric color array.
51.         Color[] color = new Color[CubeQuality * CubeQuality * CubeQuality];
52.  
53.  
54.         //Loop to actually create the color volume
55.      
56.         //Define how offset the position of the object is from the center of the Volume.
57.         //object Offset
58.         Vector3 oOff = new Vector3(
59.             transform.position.x + (CubeScale * -0.5f),
60.             transform.position.x + (CubeScale * -0.5f),
61.             transform.position.x + (CubeScale * -0.5f)
62.         );
63.  
64.         //define "Real Tick"/rt or how many loops total of all 3 for loops
65.         int rt = 0;
66.  
67.         //tx ty and tz is a pun because they are short for texel+(the axis, for example x) and also short for tick+(the axis, for example y)
68.         for (int tx = 0; tx < CubeQuality; tx++){
69.             for (int ty = 0; ty < CubeQuality; ty++){
70.                 for (int tz = 0; tz < CubeQuality; tz++){
71.                     //tick area, ya have access to tx, ty, and tz all in here so you shouldn't need to be outsize of this when calculating coor math and stuff.
72.  
73.                     //Color at Real Tick AKA rt would define the exact pixel at the exact position.
74.                     //so Color[rt] would be Color at the pixel
75.                  
76.                     //color[rt] = new Color(tx, 1f, tz, ty);
77.                     color[rt] = GetColorAtPosition(new Vector3(tz * texelSize, ty * texelSize, tx * texelSize) + oOff);
78.                  
79.                     rt++;
80.                 }
81.             }
82.         }
83.  
84.         //Put the colors on the 3d bitmap volume and apply the changes so it gets resent to the GPU.
85.         Volume.SetPixels(color);
86.         Volume.Apply();
87.  
88.     }
89.  
90.     //function to get an objects surface color at an exact Vector3 location
91.     void GetColorAt(Vector3 cpos){
92.  
93.     }
94.  
95.     Color GetColorAtPosition(Vector3 position) {
96.         Vector4 grabber = Vector4.zero;
97.         grabber += GetColorAtPosAndRot(position, Vector3.up);
98.         grabber += GetColorAtPosAndRot(position, -Vector3.up);
99.         grabber += GetColorAtPosAndRot(position, Vector3.right);
100.         grabber += GetColorAtPosAndRot(position, -Vector3.right);
101.         grabber += GetColorAtPosAndRot(position, Vector3.forward);
102.         grabber += GetColorAtPosAndRot(position, -Vector3.forward);
103.         return grabber;
104.     }
105.  
106.     Vector4 GetColorAtPosAndRot(Vector3 position, Vector3 normal){
107.         RaycastHit hit;
108.         if (Physics.Raycast(position, normal, out hit, texelSize)){
109.             Renderer renderer = hit.collider.GetComponent<Renderer>();
110.          
111.             if (renderer != null){
112.                 Texture2D texture = renderer.material.mainTexture as Texture2D;
113.              
114.                 if (texture){
115.                     Vector2 pixelUV = hit.textureCoord;
116.                     pixelUV.x *= texture.width;
117.                     pixelUV.y *= texture.height;
118.  
119.                     return texture.GetPixel((int)pixelUV.x, (int)pixelUV.y);
120.                 } else {
121.                     return renderer.material.color;
122.                 }
123.             }
124.             return new Vector4(1f,1f,1f,1f);
125.         }
126.      
127.         return new Vector4(0f,0f,0f,0f);
128.     }
129. }
130.  

When using this I have noticed the LOD function of a Sample Texture3D node does not work (URP 16). I have deducted that the reason is because there are NO MIPMAPS on my generated Texture3D.
I have been trying to use this 3D Texture volume for smooth noise-free Global illumination using this raymarching script:

Code (CSharp):

1. Color = float4(0, 0, 0, 0);
2. Distance = 0;
3.  
4. float MarchSize = 1 / VolumeQuality;
5.  
6. float3 pos = float3(0,0,0);
7.  
8. //Define t and start 4 steps out
9. //4 because honestly it's the best I could do
10. float t = MarchSize * 4;
11. while (t < 1) {
12.  
13.  
14.  
15.     if (Color.a < 1) {
16.         pos = Position + (Normal * t);
17.         Color += SAMPLE_TEXTURE3D_LOD(Volume, Sampler, pos, Roughness * t);
18.         Distance = t;
19.     }
20.  
21.     //advance tick size
22.     t += MarchSize;      
23. }
24. Color.a = min(Color.a, 1.0);

When using this, my output looks like this:

When my output should look like this image(except without basically any of the noise in this image, this is stochastically sampled because I couldn't get LOD to work from the lack of Mipmaps):

 

Try setting the last parameter here to true as opposed to false.

 

Thank you so much! Where did you find that? I couldn't even find that on the docs website.

 

It's there: https://docs.unity3d.com/ScriptReference/Texture3D-ctor.html

 

Thank you!