In the easy-to-use WebGL-based GlowScript 3D programming environment ( you can now specify the opacity of an object (other than curve, ring, and helix). The following statement creates a cyan-colored cube that has low opacity (high transparency):

box( {color.cyan, opacity:0.2 } )

Here is a demo: ... ansparency

The technique used is "depth peeling" which correctly handles transparency at the pixel level. Simpler transparency schemes, in which objects are ordered back-to-front on the basis of their centers, fail to make the correct display if, for example, two transparent objects intersect each other.

The open source is at In the Source folder the key files are lib/glow/WebGLRenderer.js and the shader files which are found in the shader folder.