This buggy pattern ("something = parameter || nonzero value") exists at more places though elsewhere setting to zero doesn't make that much sense (e.g. in geometries).

Not sure if we should change it everywhere to proper pattern ("something = ( parameter !== undefined ) ? parameter : value").

Maybe it would be good for establishing habit. I remember fixing this buggy pattern long ago but it just keeps popping up.

Also shortened a life cycle for particles in shapes example. Still it gets about 10 fps slower with time :/

No need to computer Beckmann texture every frame, once is enough.

Added renderer.getClearAlpha. Extended RenderPass to be able to use custom alpha clear. Fixed UVs in UTF8Loader.

Committed deployment version by mistake.

Hope it works...

Fixed GeometryUtils.merge (normals and centroids weren't being multiplied)
Fixed misc_lookat and misc_ubiquity_test examples.

This allows, for example, better integration of additively blended materials with a regular scene.

Not to be confused with depthTest (which controls complete access to depth buffer, including reading).

Also messed up a bit with particle emitter example.

Simplified `Trident`.
Added `setX`, `setY`, `setZ` methods to `Vector3`. They're handy for oneliners (see `CylinderGeometry`).