Settings for gradient/normal thresholds (#208)

Settings for gradient/normal thresholds

Assets/Editor/VolumeRenderedObjectCustomInspector.cs

@@ -61,6 +61,19 @@ public override void OnInspectorGUI()
  EditorGUILayout.MinMaxSlider("Visible value range", ref visibilityWindow.x, ref visibilityWindow.y, 0.0f, 1.0f);
  volrendObj.SetVisibilityWindow(visibilityWindow);
 
+ if (newRenderMode == RenderMode.IsosurfaceRendering)
+ {
+ float oldThreshold = volrendObj.GetGradientVisibilityThreshold();
+ float oldThresholdSqrt = Mathf.Sqrt(oldThreshold); // Convert to square root scaling (=> more precision close to 0)
+ float newThreshold = EditorGUILayout.Slider(
+ new GUIContent("Gradient visibility threshold", "Minimum gradient maginitude value that will be visible"),
+ oldThresholdSqrt, 0.0f, 1.0f
+ );
+ newThreshold = newThreshold * newThreshold; // Convert back to linear scaling
+ if (newThreshold != oldThreshold)
+ volrendObj.SetGradientVisibilityThreshold(newThreshold);
+ }
+
  // Transfer function settings
  EditorGUILayout.Space();
  tfSettings = EditorGUILayout.Foldout(tfSettings, "Transfer function");
@@ -101,6 +114,19 @@ public override void OnInspectorGUI()
  LightSource newLightSource = (LightSource)EditorGUILayout.EnumPopup("Light source", oldLightSource);
  if (newLightSource != oldLightSource)
  volrendObj.SetLightSource(newLightSource);
+
+ // Gradient lighting threshold: Threshold for how low gradients can contribute to lighting.
+ Vector2 gradLightThreshold = volrendObj.GetGradientLightingThreshold();
+ // Convert to square root scaling (=> more precision close to 0)
+ gradLightThreshold = new Vector2(Mathf.Sqrt(gradLightThreshold.x), Mathf.Sqrt(gradLightThreshold.y));
+ EditorGUILayout.MinMaxSlider(
+ new GUIContent("Gradient lighting threshold",
+ "Minimum and maximum threshold for gradient contribution to lighting.\n"
+ + "Voxels with gradient less than min will be unlit, and with gradient >= max will fully shaded."),
+ ref gradLightThreshold.x, ref gradLightThreshold.y, 0.0f, 1.0f
+ );
+ // Convert back to linear scale, before setting updated value.
+ volrendObj.SetGradientLightingThreshold(new Vector2(gradLightThreshold.x * gradLightThreshold.x, gradLightThreshold.y * gradLightThreshold.y));
  }
  }
 

Assets/Scripts/VolumeObject/VolumeRenderedObject.cs

@@ -1,6 +1,5 @@
 using System.Threading;
 using System.Threading.Tasks;
-using UnityEditor;
 using UnityEngine;
 
 namespace UnityVolumeRendering
@@ -25,17 +24,33 @@ public class VolumeRenderedObject : MonoBehaviour
 
  [SerializeField, HideInInspector]
  private RenderMode renderMode;
+
  [SerializeField, HideInInspector]
  private TFRenderMode tfRenderMode;
+
  [SerializeField, HideInInspector]
  private bool lightingEnabled;
+
  [SerializeField, HideInInspector]
  private LightSource lightSource;
 
+ // Minimum and maximum gradient threshold for lighting contribution. Values below min will be unlit, and between min and max will be partly shaded.
+ [SerializeField, HideInInspector]
+ private Vector2 gradientLightingThreshold = new Vector2(0.02f, 0.15f);
+
+ // Gradient magnitude threshold. Voxels with gradient magnitude less than this will not be rendered in isosurface rendering mode.
+ [SerializeField, HideInInspector]
+ private float minGradient = 0.01f;
+
+ // Minimum/maximum data value threshold for rendering. Values outside of this range will not be rendered.
  [SerializeField, HideInInspector]
  private Vector2 visibilityWindow = new Vector2(0.0f, 1.0f);
+
+ // Early ray termination
  [SerializeField, HideInInspector]
  private bool rayTerminationEnabled = true;
+
+ // Tri-cubic interpolation of data texture (expensive, but looks better)
  [SerializeField, HideInInspector]
  private bool cubicInterpolationEnabled = false;
 
@@ -150,8 +165,39 @@ public async Task SetLightingEnabledAsync(bool enable, IProgressHandler progress
 
  public void SetLightSource(LightSource source)
  {
- lightSource = source;
- UpdateMaterialProperties();
+ if (lightSource != source)
+ {
+ lightSource = source;
+ UpdateMaterialProperties();
+ }
+ }
+
+ public void SetGradientLightingThreshold(Vector2 threshold)
+ {
+ if (gradientLightingThreshold != threshold)
+ {
+ gradientLightingThreshold = threshold;
+ UpdateMaterialProperties();
+ }
+ }
+
+ public Vector2 GetGradientLightingThreshold()
+ {
+ return gradientLightingThreshold;
+ }
+
+ public void SetGradientVisibilityThreshold(float min)
+ {
+ if (minGradient != min)
+ {
+ minGradient = min;
+ UpdateMaterialProperties();
+ }
+ }
+
+ public float GetGradientVisibilityThreshold()
+ {
+ return minGradient;
  }
 
  public void SetVisibilityWindow(float min, float max)
@@ -307,6 +353,9 @@ private void UpdateMatInternal()
 
  meshRenderer.sharedMaterial.SetFloat("_MinVal", visibilityWindow.x);
  meshRenderer.sharedMaterial.SetFloat("_MaxVal", visibilityWindow.y);
+ meshRenderer.sharedMaterial.SetFloat("_MinGradient", minGradient);
+ meshRenderer.sharedMaterial.SetFloat("_LightingGradientThresholdStart", gradientLightingThreshold.x);
+ meshRenderer.sharedMaterial.SetFloat("_LightingGradientThresholdEnd", gradientLightingThreshold.y);
  meshRenderer.sharedMaterial.SetVector("_TextureSize", new Vector3(dataset.dimX, dataset.dimY, dataset.dimZ));
 
  if (rayTerminationEnabled)

Assets/Shaders/DirectVolumeRenderingShader.shader

@@ -8,6 +8,9 @@
  _TFTex("Transfer Function Texture (Generated)", 2D) = "" {}
  _MinVal("Min val", Range(0.0, 1.0)) = 0.0
  _MaxVal("Max val", Range(0.0, 1.0)) = 1.0
+ _MinGradient("Gradient visibility threshold", Range(0.0, 1.0)) = 0.0
+ _LightingGradientThresholdStart("Gradient threshold for lighting (end)", Range(0.0, 1.0)) = 0.0
+ _LightingGradientThresholdEnd("Gradient threshold for lighting (start)", Range(0.0, 1.0)) = 0.0
  [HideInInspector] _TextureSize("Dataset dimensions", Vector) = (1, 1, 1)
  }
  SubShader
@@ -73,6 +76,10 @@
  float _MaxVal;
  float3 _TextureSize;
 
+ float _MinGradient;
+ float _LightingGradientThresholdStart;
+ float _LightingGradientThresholdEnd;
+
 #if CROSS_SECTION_ON
 #define CROSS_SECTION_TYPE_PLANE 1 
 #define CROSS_SECTION_TYPE_BOX_INCL 2 
@@ -336,7 +343,9 @@
 
  // Apply lighting
 #if defined(LIGHTING_ON)
- src.rgb = calculateLighting(src.rgb, gradient / gradMag, getLightDirection(-ray.direction), -ray.direction, 0.3f);
+ float factor = smoothstep(_LightingGradientThresholdStart, _LightingGradientThresholdEnd, gradMag);
+ float3 shaded = calculateLighting(src.rgb, gradient / gradMag, getLightDirection(-ray.direction), -ray.direction, 0.3f);
+ src.rgb = lerp(src.rgb, shaded, factor);
 #endif
 
  src.rgb *= src.a;
@@ -428,11 +437,16 @@
  const float density = getDensity(currPos);
  if (density > _MinVal && density < _MaxVal)
  {
- float3 normal = normalize(getGradient(currPos));
- col = getTF1DColour(density);
- col.rgb = calculateLighting(col.rgb, normal, getLightDirection(-ray.direction), -ray.direction, 0.15);
- col.a = 1.0f;
- break;
+ float3 gradient = getGradient(currPos);
+ float gradMag = length(gradient);
+ if (gradMag > _MinGradient)
+ {
+ float3 normal = gradient / gradMag;
+ col = getTF1DColour(density);
+ col.rgb = calculateLighting(col.rgb, normal, getLightDirection(-ray.direction), -ray.direction, 0.15);
+ col.a = 1.0f;
+ break;
+ }
  }
  }