;;-*-Lisp-*-
(in-package goal)

;; name: draw-node-h.gc
;; name in dgo: draw-node-h
;; dgos: GAME, ENGINE

;; A "draw-node" is a way to group together a bunch of drawables (possibly other draw-nodes) in a BVH
;; This BVH is used for sphere-in-view culling and the broad phase collision detection.
;; _most_ uses of draw-node are in a special tree with these properties:
;; - between 1 and 8 roots.
;; - each child has between 1 and 8 children
;; - all leaves are stored at the same depth
;; - all nodes and leaves have visibility IDs

;; shrub does not have these properties

(deftype draw-node (drawable)
  ((child-count uint8          :offset 6)   ;; if our child requires a count
   (flags       uint8          :offset 7)   ;; is our children leaf or draw-node?
   (child       drawable       :offset 8)   ;; can be draw-node or any other drawable
   (distance    float          :offset 12)  ;; used in shrub...
   )
  :method-count-assert 18
  :size-assert         #x20
  :flag-assert         #x1200000020
  ;; field distance is a float printed as hex? 
  )


;; for non-shrub uses of draw-node, this is used to store all the draw-nodes at a given depth.
(deftype drawable-inline-array-node (drawable-inline-array)
  ((data draw-node 1 :inline)
   (pad uint32)
   )
  :method-count-assert 18
  :size-assert         #x44
  :flag-assert         #x1200000044
  ;;  too many basic blocks
  (:methods

    )
  )

;; the types of these fields are a guess for now.
;; used for draw-node-cull function
(deftype draw-node-dma (structure)
  ((banka draw-node 32 :inline :offset-assert 0)
   (bankb draw-node 32 :inline :offset-assert 1024)
   )
  :method-count-assert 9
  :size-assert         #x800
  :flag-assert         #x900000800
  )