improve raycaster component (fixes #829)

[ngokevin]

Description: Improve overall cursor + raycaster components with respect to performance, configuration, and code quality. This is a stepping stone for more complex cursor/interactions later on.

DEMO

Changes proposed:

• Don't use requestInterval which adds an additional requestAnimationFrame call. Work off of the existing tick handler.
• Generalize raycaster component for general use rather than just the cursor. Allow specifying the near, far, recursive. Thus decoupling raycaster and cursor, and having cursor be an abstraction of the raycaster.
• Raycaster origin/direction can be set with position/rotation of entities
• Allow passing in a list of entities (via selector) that the raycaster should intersect rather than intersecting everything
• Allow passing in a list of entities to ignore
• Return full intersection data in events
• Move intersectioncleared/mouseleave logic to the cursor component to remove cursor/raycaster coupling
• Be able to update the raycaster
• Prefix event/state names with respective component (cursor-/raycaster-)
• Removed cursor.maxDistance as it was redundant with raycaster.far
• Fully unit test the raycaster and cursor components

[amberroy]

Cool, I was also thinking it would be useful to get the full intersection data in events. I got it working in my cursor-hitpoint branch, with an example: amberroy@593ab4c

[ngokevin]

Yeah, returning full intersection data is part of the changes in that huge list.

[dmarcos]

Why are you replacing color names with hex values?

[ngokevin]

Color palette.

[ngokevin]

@dmarcos r?

• Example
• Example Code

[dmarcos]

we should not be using primitives here.

[ngokevin]

This is gonna be the boilerplate. <a-cursor> is one of the times i prefer the primitive because manually configuring the inner/outer radius of the ring is hard.

[dmarcos]

I would still make directionHelper, originVec3 and scaleDummy private to this function so no other method relies on it to store any state. Like in this example:
https://github.com/aframevr/aframe/blob/master/src/components/look-controls.js#L111

[dmarcos]

We should wrap directionHelper, originVec3 and scaleDummy in a closure of the method so they're not allocated on every frame. Like the example I had pointed out:
https://github.com/aframevr/aframe/blob/master/src/components/look-controls.js#L111

[dmarcos]

You can add scaleDummy to the closure as well.

[ngokevin]

I'm not actually using scaleDummy. I just pass it because decompose will expect it.