transparency control
 

I would like to embody gradient transparency.
Yes, I could set alpha or transparency by .alpha, but the alpha value is applied in all object.
Is there any method to control alpha values in pixel by pixel on screen or image?
Can I manage alpha map in Vizard? If it is possible, how can I handle it?

Regards.

You may want to try setting your alpha the following way:

.alpha(, op=viz.OP_OVERRIDE)

However, doing this may cause you to lose color values. It's likely that you will have to re-apply the color after you set your alpha this way.