This is to be able to skip redundant updates in multipass rendering (like for shadow maps or dynamic cube maps).
Also reshuffled initWebGLObjects calls to have just a single update in a basic scenario of shadow map pass followed by scene render.
Still need to solve somehow potential redundant updates in EffectComposer (which can mix multiple scenes).
Noticeable difference: can't anymore assign Material references to faces directly - "face.materials" became "face.materialIndex". Materials have to go to "geometry.materials" array (to which "face.materialIndex" points). This is necessary to allow run-time changing of face materials (this indirection used to be done by arrays).
Some casualties:
- multi-materials example, this functionality isn't possible anymore
- had to simplify LOD Text examples as LODs don't handle groups (used to fake multi-materials)
- multi-materials sphere in materials example can't have faces with undefined materials (this may be fixable I guess, when there'll be some real use-case)
- scene format still has materials arrays, only the last material will be used (except when there are face materials, then materials from JSON will be used, as before)
Other renderers and their corresponding examples were not touched yet.
WebGLRenderer still needs some prettification, some things don't make sense anymore without arrays, code can be cleaned up further.
New per-pixel Phong code is enabled by setting `perPixel` parameter in Phong material.
This version is able to light single untesselated quad correctly.
Also it doesn't have point lights number limitation caused by varyings, all lights pass just through uniforms.
Performance wise it seems surprisingly quite similar to old version (stress test is ~6 fps faster with new version, though I guess for different use cases / GPUs it can differ).
Metal makes specular term multiplicative (default is additive). This is to be able to have textured materials that do not have diffuse color, just a specular one, to get metallic look (additive specular gives plastic look).
Removed diffuse color influence on ambient term in Phong. This was causing texture disappearance when diffuse color was black.
Made Lambert more similar to Phong: now it also has ambient color parameter. Before ambient light was affecting Lambert as if ambient color was always 0xffffff.
Lots of code got cleaner with seconds, seems we used them before all around.
Also changed examples that didn't need deltas to simple Date.now() plus some more examples cleaning, trying to get rid of obsolescence warnings.
Apparently iterating over object properties is dangerous even if that code path is not executed.
Stress-testing particles buffers setting showed 60% performance increase (in Chrome) even when there were no custom attributes (and thus custom attributes handling code behind "if ( customAttributes )" was never executed).
I suspect this may be caused by some V8 optimization heuristics.
Got tired of redoing deltas all the time. Not sure about API or implementation details, but so far seems to be useful.
In future, we could for example have clocks that are slower / faster than realtime, or fixed step based.
This is for being able to render shadowmap just once per frame - all dynamic cubemap faces and full scene can share the same shadowmap (at least until we don't have camera-specific fine-tuned shadowmaps).