fix(mapper.js): fix color texture coordinate mapping when using logarithmic scale

Scalars array was already mapped with log scaling but texture coordinates were incorrectly mapped
using the linear range and value. Log color mapping was working if scalar interpolation was off when
scalars were not directly mapped to textures.

Also added some missing types to ColorTransferFunction.

Author: Antti-Palola

Sources/Rendering/Core/ColorTransferFunction/index.d.ts

@@ -312,6 +312,30 @@ export interface vtkColorTransferFunction extends vtkScalarsToColors {
    * @param colorMap
    */
   applyColorMap(colorMap: any): void;
+
+  /**
+   * Get the color space of the color transfer function.
+   * @returns {ColorSpace}
+   */
+  getColorSpace(): ColorSpace;
+
+  /**
+   * Set the color space of the color transfer function.
+   * @param {ColorSpace} colorSpace
+   */
+  setColorSpace(colorSpace: ColorSpace): void;
+
+  /**
+   * Get the scale of the color transfer function.
+   * @returns {Scale}
+   */
+  getScale(): Scale;
+
+  /**
+   * Set the scale of the color transfer function.
+   * @param {Scale} scale
+   */
+  setScale(scale: Scale): void;
 }
 
 /**

Sources/Rendering/Core/Mapper/index.js

@@ -136,6 +136,7 @@ const colorTextureCoordinatesCache = new WeakMap();
  * @param {vtkDataArray} input The input data array used for coloring
  * @param {Number} component The component of the input data array that is used for coloring (-1 for magnitude of the vectors)
  * @param {Range} range The range of the scalars
+ * @param {boolean} useLogScale Should the values be transformed to logarithmic scale. When true, the range must already be in logarithmic scale.
  * @param {Number} numberOfColorsInRange The number of colors that are used in the range
  * @param {vec3} dimensions The dimensions of the texture
  * @param {boolean} useZigzagPattern If a zigzag pattern should be used. Otherwise 1 row for colors (including min and max) and 1 row for NaN are used.
@@ -145,6 +146,7 @@ function getOrCreateColorTextureCoordinates(
   input,
   component,
   range,
+  useLogScale,
   numberOfColorsInRange,
   dimensions,
   useZigzagPattern
@@ -219,6 +221,10 @@ function getOrCreateColorTextureCoordinates(
     } else {
       scalarValue = inputV[inputIdx + component];
     }
+    if (useLogScale) {
+      scalarValue = Math.log10(scalarValue);
+    }
+
     inputIdx += numComps;
 
     // Convert to texture coordinates and update output
@@ -446,6 +452,9 @@ function vtkMapper(publicAPI, model) {
     const range = model.lookupTable.getRange();
     const useLogScale = model.lookupTable.usingLogScale();
     const origAlpha = model.lookupTable.getAlpha();
+    const scaledRange = useLogScale
+      ? [Math.log10(range[0]), Math.log10(range[1])]
+      : range;
 
     // Get rid of vertex color array.  Only texture or vertex coloring
     // can be active at one time.  The existence of the array is the
@@ -518,9 +527,6 @@ function vtkMapper(publicAPI, model) {
       const numberOfNonNaNColors = numberOfNonSpecialColors + 2;
       const textureCoordinates = [0, 0, 0];
 
-      const scaledRange = useLogScale
-        ? [Math.log10(range[0]), Math.log10(range[1])]
-        : range;
       const rangeMin = scaledRange[0];
       const rangeDifference = scaledRange[1] - scaledRange[0];
       for (let i = 0; i < numberOfNonNaNColors; ++i) {
@@ -576,7 +582,8 @@ function vtkMapper(publicAPI, model) {
     model.colorCoordinates = getOrCreateColorTextureCoordinates(
       scalars,
       scalarComponent,
-      range,
+      scaledRange,
+      useLogScale,
       model.numberOfColorsInRange,
       model.colorTextureMap.getDimensions(),
       cellFlag