For color-coded rendering, unlit seems most sensible.

b20f7e9f · Martin Heistermann · 4f3009d1 · b20f7e9f
Commit b20f7e9f authored Feb 19, 2019 by Martin Heistermann
--- a/ObjectTypes/VolumeMeshObject/VolumeMeshNodeT_impl.hh
+++ b/ObjectTypes/VolumeMeshObject/VolumeMeshNodeT_impl.hh
@@ -765,8 +765,7 @@ void VolumeMeshNodeT<VolumeMeshT>::getCellRenderObjects(IRenderer* _renderer, GL
    {
        ro.shaderDesc.vertexColors = true;
        ro.shaderDesc.numLights = -1;
-        ro.shaderDesc.shadeMode = SG_SHADE_GOURAUD;
-
+        ro.shaderDesc.shadeMode = SG_SHADE_UNLIT;
    }
    else if (_drawMode & drawModes_.cellsSmoothShaded)
    {