Merge pull request #70 from mlavik1/origin

Improved Generate2DHistogramTexture.

Assets/Editor/TransferFunction2DEditorWindow.cs

@@ -93,10 +93,10 @@ namespace UnityVolumeRendering
                 TransferFunction2D.TF2DBox box = tf2d.boxes[selectedBoxIndex];
                 float oldX = box.rect.x;
                 float oldY = box.rect.y;
-                box.rect.x = EditorGUI.Slider(new Rect(startX, startY, 200.0f, 20.0f), "x", box.rect.x, 0.0f, 0.99f);
+                box.rect.x = EditorGUI.Slider(new Rect(startX, startY, 200.0f, 20.0f), "min x", box.rect.x, 0.0f, 0.99f);
-                box.rect.width = EditorGUI.Slider(new Rect(startX + 220.0f, startY, 200.0f, 20.0f), "width", oldX + box.rect.width, box.rect.x + 0.01f, 1.0f) - box.rect.x;
+                box.rect.width = EditorGUI.Slider(new Rect(startX + 220.0f, startY, 200.0f, 20.0f), "max x", oldX + box.rect.width, box.rect.x + 0.01f, 1.0f) - box.rect.x;
-                box.rect.y = EditorGUI.Slider(new Rect(startX, startY + 50, 200.0f, 20.0f), "y", box.rect.y, 0.0f, 1.0f);
+                box.rect.y = EditorGUI.Slider(new Rect(startX, startY + 50, 200.0f, 20.0f), "min y", box.rect.y, 0.0f, 1.0f);
-                box.rect.height = EditorGUI.Slider(new Rect(startX + 220.0f, startY + 50, 200.0f, 20.0f), "height", oldY + box.rect.height, box.rect.y + 0.01f, 1.0f) - box.rect.y;
+                box.rect.height = EditorGUI.Slider(new Rect(startX + 220.0f, startY + 50, 200.0f, 20.0f), "max y", oldY + box.rect.height, box.rect.y + 0.01f, 1.0f) - box.rect.y;
                 box.colour = EditorGUI.ColorField(new Rect(startX + 450.0f, startY + 10, 100.0f, 20.0f), box.colour);
                 box.minAlpha = EditorGUI.Slider(new Rect(startX + 450.0f, startY + 30, 200.0f, 20.0f), "min alpha", box.minAlpha, 0.0f, 1.0f);
                 box.alpha = EditorGUI.Slider(new Rect(startX + 450.0f, startY + 60, 200.0f, 20.0f), "max alpha", box.alpha, 0.0f, 1.0f);
@@ -110,7 +110,7 @@ namespace UnityVolumeRendering
             }
 
             // Add new rectangle
-            if (GUI.Button(new Rect(startX, startY + 100, 110.0f, 30.0f), "Add rectangle"))
+            if (GUI.Button(new Rect(startX, startY + 100, 150.0f, 30.0f), "Add rectangle"))
             {
                 tf2d.AddBox(0.1f, 0.1f, 0.8f, 0.8f, Color.white, 0.5f);
                 needsRegenTexture = true;
@@ -118,20 +118,21 @@ namespace UnityVolumeRendering
             // Remove selected shape
             if (selectedBoxIndex != -1)
             {
-                if (GUI.Button(new Rect(startX, startY + 140, 110.0f, 30.0f), "Remove selected shape"))
+                if (GUI.Button(new Rect(startX, startY + 140, 150.0f, 30.0f), "Remove selected shape"))
                 {
                     tf2d.boxes.RemoveAt(selectedBoxIndex);
+                    selectedBoxIndex = -1;
                     needsRegenTexture = true;
                 }
             }
 
-            if(GUI.Button(new Rect(startX, startY + 180, 110.0f, 30.0f), "Save"))
+            if(GUI.Button(new Rect(startX, startY + 180, 150.0f, 30.0f), "Save"))
             {
                 string filepath = EditorUtility.SaveFilePanel("Save transfer function", "", "default.tf2d", "tf2d");
                 if(filepath != "")
                     TransferFunctionDatabase.SaveTransferFunction2D(tf2d, filepath);
             }
-            if(GUI.Button(new Rect(startX, startY + 220, 110.0f, 30.0f), "Load"))
+            if(GUI.Button(new Rect(startX, startY + 220, 150.0f, 30.0f), "Load"))
             {
                 string filepath = EditorUtility.OpenFilePanel("Save transfer function", "", "tf2d");
                 if(filepath != "")
@@ -151,8 +152,6 @@ namespace UnityVolumeRendering
                 tf2d.GenerateTexture();
                 needsRegenTexture = false;
             }
-
-            return;
         }
 
         private void OnSelectionChange()

Assets/Scripts/Utils/HistogramTextureGenerator.cs

@@ -110,11 +110,20 @@ namespace UnityVolumeRendering
         /// <returns></returns>
         public static Texture2D Generate2DHistogramTexture(VolumeDataset dataset)
         {
-            int numSamples = dataset.GetMaxDataValue() + 1;
+            int minValue = dataset.GetMinDataValue();
-            int numGradientSamples = 256;
+            int maxValue = dataset.GetMaxDataValue();
-            Color[] cols = new Color[numSamples * numGradientSamples];
-            Texture2D texture = new Texture2D(numSamples, numGradientSamples, TextureFormat.RGBAFloat, false);
 
+            // Value range of the density values.
+            int densityValRange = maxValue - minValue + 1;
+            float densityRangeRecip = 1.0f / (maxValue - minValue); // reciprocal
+            // Clamp density value samples.
+            int numDensitySamples = System.Math.Min(densityValRange, 512);
+            int numGradientSamples = 256;
+
+            Color[] cols = new Color[numDensitySamples * numGradientSamples];
+            Texture2D texture = new Texture2D(numDensitySamples, numGradientSamples, TextureFormat.RGBAFloat, false);
+
+            // Zero-initialise colours.
             for (int iCol = 0; iCol < cols.Length; iCol++)
                 cols[iCol] = new Color(0.0f, 0.0f, 0.0f, 0.0f);
 
@@ -137,8 +146,16 @@ namespace UnityVolumeRendering
                         int z1 = dataset.data[x + y * dataset.dimX + (z + 1) * (dataset.dimX * dataset.dimY)];
                         int z2 = dataset.data[x + y * dataset.dimX + (z - 1) * (dataset.dimX * dataset.dimY)];
 
+                        // Calculate gradient
                         Vector3 grad = new Vector3((x2 - x1) / (float)maxRange, (y2 - y1) / (float)maxRange, (z2 - z1) / (float)maxRange);
-                        cols[density + (int)(grad.magnitude * numGradientSamples / maxNormalisedMagnitude) * numSamples] = Color.white;
+
+                        // Calculate density and gradient value indices (in flattened 2D array)
+                        float tDensity = (density - minValue) * densityRangeRecip;
+                        int iDensity = Mathf.RoundToInt((numDensitySamples - 1) * tDensity);
+                        int iGrad = (int)(grad.magnitude * numGradientSamples / maxNormalisedMagnitude);
+
+                        // Assign a white colour to all samples (in a histogram where x = density and y = gradient magnitude).
+                        cols[iDensity + iGrad * numDensitySamples] = Color.white;
                     }
                 }
             }