PGraphics3D, ignore alpha channel information when rendering to screen

Is it possible to update a PGraphics (P2D, P3D) element so that the alpha channel information is ignored and the element is rendered fully opaque (I have tried filter(OPAQUE); but this drives my CPU crazy)? 

For example, when I draw a couple of shapes with a semi-transparent color into a PGraphics3D element I want to retain the semi-transparent alpha behavior when they overlap, but the PGraphics element as a whole should be rendered fully opaque when drawing it onto the screen with image(pg3D, 0 , 0 ); ?