Allow transparent segmentations

Author: mlavik1

Assets/Scripts/VolumeObject/VolumeRenderedObject.cs

@@ -254,17 +254,19 @@ public void UpdateSegmentationLabels()
  float minDataValue = secondaryDataset.GetMinDataValue();
  float maxDataValue = secondaryDataset.GetMaxDataValue();
  secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(0.0f, 0.0f));
- secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(1.0f, 1.0f));
  for (int i = 0; i < segmentationLabels.Count; i++)
  {
  SegmentationLabel segmentationLabel = segmentationLabels[i];
  float t = segmentationLabel.id / maxDataValue;
+ float segmAlpha = segmentationLabel.colour.a;
  secondaryTransferFunction.colourControlPoints.Add(new TFColourControlPoint(t, segmentationLabel.colour));
- if (i == 0)
- {
- secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(t - 0.01f, 0.0f));
- secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(t, 1.0f));
- }
+ if (t > 0.0f)
+ secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(Mathf.Max(t - 0.001f, 0.0f), segmAlpha));
+ secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(t, segmAlpha));
+ if (i == segmentationLabels.Count - 1)
+ secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(1.0f, segmAlpha));
+ else
+ secondaryTransferFunction.alphaControlPoints.Add(new TFAlphaControlPoint(t + 0.001f, segmAlpha));
  }
  secondaryTransferFunction.GenerateTexture();
  secondaryTransferFunction.GetTexture().filterMode = FilterMode.Point;

Assets/Shaders/DirectVolumeRenderingShader.shader

@@ -476,13 +476,17 @@
  const float secondaryDensity = getSecondaryDensity(currPos);
  if (secondaryDensity > 0.0)
  {
- col = getSecondaryTF1DColour(secondaryDensity);
- float3 gradient = getGradient(currPos);
- float gradMag = length(gradient);
- float3 normal = gradient / gradMag;
- col.rgb = calculateLighting(col.rgb, normal, getLightDirection(-ray.direction), -ray.direction, 0.15);
- col.a = 1.0;
- break;
+ float4 secondaryColour = getSecondaryTF1DColour(secondaryDensity);
+ if (secondaryColour.a > 0.0)
+ {
+ col = secondaryColour;
+ float3 gradient = getGradient(currPos);
+ float gradMag = length(gradient);
+ float3 normal = gradient / gradMag;
+ col.rgb = calculateLighting(col.rgb, normal, getLightDirection(-ray.direction), -ray.direction, 0.15);
+ col.a = 1.0;
+ break;
+ }
  }
 #endif
  if (density > _MinVal && density < _MaxVal)