I have been adding a transparent propeller to an aircraft using CircleGeometry and a Basic Material that includes a transparent texture. I have tried to do the same thing in Blender, which is exported to 3JS as a glb file. But the transparent propeller is much darker, especially when against a light background.
On the Blender version, is 3JS shading the side away from the light? If so, is there a way to prevent this? Otherwise, is there a good way to make the Blender texture look more like the 3JS texture?
EDIT: I downloaded the latest version of Blender (2.9) and same result.
Since I have received no response, I will inquire on the Blender discussion list. I suppose the question I should ask is how to create a Blender material that behaves like the Basic Material in 3JS. I definitely like the behavior of the 3JS material better.
ANSWER: Apparently my suspicion about the Blender texture being affected by light was correct. The description for Three.MeshBasicMaterial (which is what I was using) says that the material is not affected by lights. So I had to find a way to create a Blender material that was not affected by light. In the Principled BSDF shader (which we are supposed to use for transparent materials), the way to do this is to increase the value for emission. I found that I could get the correct result by reducing the opacity of the transparent object by about 50% and increasing the emission to about A0A0A0 (hex). You will need to juggle these values to make the prop dark enough when looking away from the sun and light enough when facing the sun.
One drawback with using these materials is that they probably also glow in the dark. However, I will probably not be flying much at night - or, if I do, I could create a special night time model that does not include a spinning prop.