Transfer Functions (WIP - TODO: Make GUI)

Assets/Editor.meta

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Assets/Editor/TransferFunctionEditorWindow.cs

@@ -0,0 +1,6 @@
+using UnityEngine;
+using UnityEditor;
+
+public class TransferFunctionEditorWindow : EditorWindow
+{
+}

Assets/Editor/TransferFunctionEditorWindow.cs.meta

@@ -0,0 +1,11 @@
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Assets/Scenes/TestScene.unity

@@ -328,10 +328,10 @@ Transform:
   m_PrefabParentObject: {fileID: 0}
   m_PrefabInternal: {fileID: 0}
   m_GameObject: {fileID: 326583332}
-  m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
+  m_LocalRotation: {x: 0, y: -0.7071068, z: -0.7071068, w: 0}
   m_LocalPosition: {x: 0, y: 0, z: 0}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_Children: []
   m_Father: {fileID: 0}
   m_RootOrder: 2
-  m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+  m_LocalEulerAnglesHint: {x: 270, y: 0, z: 180}

Assets/Scripts/VolumeRenderer.cs

@@ -47,28 +47,20 @@ public class VolumeRenderer : MonoBehaviour
                 noiseCols[iX + iY * noiseDimX] = new Color(pixVal, pixVal, pixVal);
             }
         }
+        
+        TransferFunction tf = new TransferFunction();
+        tf.AddControlPoint(new TFColourControlPoint(0.0f, Color.black));
+        tf.AddControlPoint(new TFColourControlPoint(0.055f, Color.yellow));
+        tf.AddControlPoint(new TFColourControlPoint(0.11f, Color.red));
+        tf.AddControlPoint(new TFColourControlPoint(1.0f, Color.white));
 
-        const int tfDimX = 1024;
-        const int tfDimY = 1024;
+        tf.AddControlPoint(new TFAlphaControlPoint(0.0f, 0.0f));
+        tf.AddControlPoint(new TFAlphaControlPoint(0.01f, 0.0f));
+        tf.AddControlPoint(new TFAlphaControlPoint(0.6f, 0.2f));
+        tf.AddControlPoint(new TFAlphaControlPoint(1.0f, 1.0f));
 
-        Texture2D tfTexture = new Texture2D(tfDimX, tfDimY, TextureFormat.RGBAFloat, false);
-        Color[] tfCols = new Color[tfDimX * tfDimY];
-        for (int iX = 0; iX < tfDimX; iX++)
-        {
-            float t = (float)iX / tfDimX;
-            Color col = t > 0.28f ? Color.white : (t > 0.026f && t < 0.103f ? Color.green : Color.red);
-            float alpha = Mathf.Lerp(0.0f, 1.0f, t > 0.01f ? t : 0.0f);
-            Color tfVal = new Color(col.r, col.g, col.b, alpha);
-            for (int iY = 0; iY < tfDimY; iY++)
-            {
-                tfCols[iX + iY * tfDimX] = tfVal;
-            }
-        }
+        Texture2D tfTexture = tf.GetTexture();
 
-        // Copy the pixel data to the texture and load it into the GPU.
-        tfTexture.wrapMode = TextureWrapMode.Clamp;
-        tfTexture.SetPixels(tfCols);
-        tfTexture.Apply();
 
         GetComponent<MeshRenderer>().sharedMaterial.SetTexture("_DataTex", tex);
         GetComponent<MeshRenderer>().sharedMaterial.SetTexture("_NoiseTex", noiseTexture);

Assets/Shaders/DirectVolumeRenderingShader.shader

@@ -23,7 +23,7 @@
 			#pragma fragment frag
 			// make fog work
 			#pragma multi_compile_fog
-			
+
 			#include "UnityCG.cginc"
 
 			struct appdata
@@ -61,7 +61,7 @@
 			
 			fixed4 frag (v2f i) : SV_Target
 			{
-                #define NUM_STEPS 40//200
+                #define NUM_STEPS 500//200
                 const float stepSize = 1.732f/*greatest distance in box*/ / NUM_STEPS;
 
                 float4 col = float4(i.vertexLocal.x, i.vertexLocal.y, i.vertexLocal.z, 1.0f);
@@ -75,7 +75,7 @@
 
                 col = float4(0.0f, 0.0f, 0.0f, 0.0f);
                 float maxDensity = 0.0f;
-                [unroll]
+                //[unroll(NUM_STEPS)]
                 for (uint iStep = 0; iStep < NUM_STEPS; iStep++)
                 {
                     const float t = iStep * stepSize + stepSize * 0.5f;
@@ -83,9 +83,10 @@
                     if (currPos.x < 0.0f || currPos.x >= 1.0f || currPos.y < 0.0f || currPos.y > 1.0f || currPos.z < 0.0f || currPos.z > 1.0f) // TODO: avoid branch?
                         break;
                     
-                    float density = tex3D(_DataTex, currPos).r / 4095.0f;
+                    //const float density = tex3D(_DataTex, currPos).r / 4095.0f;
+                    const float density = tex3Dlod(_DataTex, float4(currPos.x, currPos.y, currPos.z, 0.0f)).r / 4095.0f;
 
-                    float4 src = tex2D(_TFTex, float2(density, 0.0f));
+                    float4 src = tex2Dlod(_TFTex, float4(density, 0.0f, 0.0f, 0.0f));// tex2D(_TFTex, float2(density, 0.0f));
 
                     if (density < _MinVal || density > _MaxVal)
                         src.a = 0.0f;

Assets/TransferFunction.meta

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Assets/TransferFunction/TFControlPoints.cs

@@ -0,0 +1,25 @@
+using UnityEngine;
+
+public struct TFColourControlPoint
+{
+    public float dataValue;
+    public Color colourValue;
+
+    public TFColourControlPoint(float dataValue, Color colourValue)
+    {
+        this.dataValue = dataValue;
+        this.colourValue = colourValue;
+    }
+}
+
+public struct TFAlphaControlPoint
+{
+    public float dataValue;
+    public float alphaValue;
+
+    public TFAlphaControlPoint(float dataValue, float alphaValue)
+    {
+        this.dataValue = dataValue;
+        this.alphaValue = alphaValue;
+    }
+}

Assets/TransferFunction/TFControlPoints.cs.meta

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Assets/TransferFunction/TransferFunction.cs

@@ -0,0 +1,92 @@
+using UnityEngine;
+using System.Collections.Generic;
+
+public class TransferFunction
+{
+    private List<TFColourControlPoint> colourControlPoints = new List<TFColourControlPoint>();
+    private List<TFAlphaControlPoint> alphaControlPoints = new List<TFAlphaControlPoint>();
+
+    private Texture2D texture = null;
+
+    private const int TEXTURE_WIDTH = 1024;
+    private const int TEXTURE_HEIGHT = 1024;
+
+    public void AddControlPoint(TFColourControlPoint ctrlPoint)
+    {
+        colourControlPoints.Add(ctrlPoint);
+    }
+
+    public void AddControlPoint(TFAlphaControlPoint ctrlPoint)
+    {
+        alphaControlPoints.Add(ctrlPoint);
+    }
+
+    public Texture2D GetTexture()
+    {
+        if (texture == null)
+            GenerateTexture();
+
+        return texture;
+    }
+
+    public void GenerateTexture()
+    {
+        texture = new Texture2D(TEXTURE_WIDTH, TEXTURE_HEIGHT, TextureFormat.RGBAFloat, false);
+        Color[] tfCols = new Color[TEXTURE_WIDTH * TEXTURE_HEIGHT];
+
+        List<TFColourControlPoint> cols = colourControlPoints;
+        List<TFAlphaControlPoint> alphas = alphaControlPoints;
+
+        // Sort lists of control points
+        cols.Sort((a, b) => (a.dataValue.CompareTo(b.dataValue)));
+        alphas.Sort((a, b) => (a.dataValue.CompareTo(b.dataValue)));
+
+        // Add colour points at beginning and end
+        if (cols.Count == 0 || cols[cols.Count - 1].dataValue < 1.0f)
+            cols.Add(new TFColourControlPoint(1.0f, Color.white));
+        if(cols[0].dataValue > 0.0f)
+            cols.Insert(0, new TFColourControlPoint(0.0f, Color.white));
+
+        // Add alpha points at beginning and end
+        if (alphas.Count == 0 || alphas[alphas.Count - 1].dataValue < 1.0f)
+            alphas.Add(new TFAlphaControlPoint(1.0f, 1.0f));
+        if (alphas[0].dataValue > 0.0f)
+            alphas.Insert(0, new TFAlphaControlPoint(0.0f, 0.0f));
+
+        int numColours = cols.Count;
+        int numAlphas = alphas.Count;
+        int iCurrColour = 0;
+        int iCurrAlpha = 0;
+
+        for(int iX = 0; iX < TEXTURE_WIDTH; iX++)
+        {
+            float t = iX / (float)(TEXTURE_WIDTH - 1);
+            while (iCurrColour < numColours - 2 && cols[iCurrColour + 1].dataValue < t)
+                iCurrColour++;
+            while (iCurrAlpha < numAlphas - 2 && alphas[iCurrAlpha + 1].dataValue < t)
+                iCurrAlpha++;
+
+            TFColourControlPoint leftCol = cols[iCurrColour];
+            TFColourControlPoint rightCol = cols[iCurrColour + 1];
+            TFAlphaControlPoint leftAlpha = alphas[iCurrAlpha];
+            TFAlphaControlPoint rightAlpha = alphas[iCurrAlpha + 1];
+
+            float tCol = (Mathf.Clamp(t, leftCol.dataValue, rightCol.dataValue) - leftCol.dataValue) / (rightCol.dataValue - leftCol.dataValue);
+            float tAlpha = (Mathf.Clamp(t, leftAlpha.dataValue, rightAlpha.dataValue) - leftAlpha.dataValue) / (rightAlpha.dataValue - leftAlpha.dataValue);
+
+            Color pixCol = rightCol.colourValue * tCol + leftCol.colourValue * (1.0f - tCol);
+            pixCol.a = rightAlpha.alphaValue * tAlpha + leftAlpha.alphaValue * (1.0f - tAlpha);
+
+            for (int iY = 0; iY < TEXTURE_HEIGHT; iY++)
+            {
+                tfCols[iX + iY * TEXTURE_WIDTH] = pixCol;
+            }
+
+        }
+
+        texture.wrapMode = TextureWrapMode.Clamp;
+        texture.SetPixels(tfCols);
+        texture.Apply();
+    }
+}
+

Assets/TransferFunction/TransferFunction.cs.meta

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