[Fluxus] commits

[Dave Griffiths]

Hi all,

A few more commits, motivated by some stuff I'm working on:

* It's possible to reparent objects in the scene hierachy. Previously
(parent) only had effect on the state stack, and couldn't be changed after
a primitive had been created. Now you can do something like this:

; make a cube
(define a (with-state
    (translate (vector -3 0 0))
    (build-cube))

; make another cube
(define b (with-state
    (translate (vector 3 0 0))
    (build-cube))

; make a torus
(define c (with-state
    (parent a) ; create the torus parented to cube a
    (build-torus 1 2 10 10))

(with-primitive c
    (parent b)) ; switch to b

Also, I need to add this to the docs I think, but there are some rules
regarding the primitive id's (which are really scene node id's).

0 = null scenenode (returned to represent nothing found, etc)
1 = root scenenode
anything else = a valid object

So - if you have a primitive parented to some other object, and you want
to detach it, call:

(with-primitive myprim
    (parent 1)) ; parent to the root node

I'll try and come up with an example to show this stuff more clearly.

* Bounding boxes are now created properly and actually useful for
something - (bb-intersect) returns #t if the bounding boxes of two
primitives intersect:

(with-primitive prim1
    (when (bb-intersect prim2 0)
        (display "collision!")(newline)))

The number is a threshold to expand (or shrink) the bounding box by to add
(or remove) some safety margin. Use (hint-box) to view the bounding box.

* More fluxa work, fixed some more buffer overflow errors, these are
getting rarer, but something is still up in the sampler. Asserts are
currently turned on in this code.

cheers,

dave