Drawings are special objects for MRIcroGL.

 1. The color reflects the voxel intensity (e.g. 1=red, 2=blue, 3 = green, etc). 

 2. The drawings are not shown in the renderings. The renderings require gradient information for volumes, which is computationally expensive and therefore incompatible with interactively modifying drawings. Once the dynamic drawing stage is completed, you can always load it as a static overlay (File/AddOverlay) to view it on the rendering.

Our nascent NiiVue does allow you to customize drawing colors, and does show them in the rendering (albeit the rendering view is blank while the drawing pen is being dragged).

You can see this by changing the palette in the draw menu here:

 https://niivue.github.io/niivue/features/draw.ui.html

and you can make your own custom palette by adjusting the script at the bottom of this web page:

  https://niivue.github.io/niivue/features...