geom-webgl mesh handling with & without vertex attributes (temp. workaround until fully implemented)

gistfile1.clj

(require
 '[thi.ng.geom.core :as g]
 '[thi.ng.geom.core.vector :as v :refer [vec2 vec3]]
 '[thi.ng.geom.core.matrix :refer [M44]]
 '[thi.ng.geom.core.utils :as gu]
 '[thi.ng.geom.aabb :as a]
 '[thi.ng.geom.plane :as pl]
 '[thi.ng.geom.quad :as q]
 '[thi.ng.geom.webgl.core :as gl]
 '[thi.ng.geom.webgl.buffers :as buf]
 '[thi.ng.math.core :as m]
 '[thi.ng.typedarrays.core :as ta])

;; create ground plane...
;; option 1 - create a 3d quad
(def ground (-> (q/quad3 100) (g/center) (g/as-mesh)))

;; or use (initially) infinite plane as basis
;; (def ground (g/as-mesh (pl/plane-with-point (vec3) v/V3Y) {:size 100}))

;; create 2 boxes of different sizes/positions/orientations
(def box1 (g/as-mesh (a/aabb 10)))

(def box2
  (-> (a/aabb 5)
      (g/as-mesh)
      (g/transform (-> M44 (g/translate -25 0 0) (g/rotate-y m/QUARTER_PI)))))

(defn scene-without-uvs
  {:ground (-> ground
               (gl/as-webgl-buffer-spec {:tessellate true :fnormals true})
               ;; TODO insert shader spec (see http://v.gd/ez7RHK )
               (buf/make-attribute-buffers-in-spec gl gl/static-draw))
   :boxes  (-> box1
               (g/into box2) ;; combine box meshes
               (gl/as-webgl-buffer-spec {:tessellate true :fnormals true})
               ;; TODO insert shader spec (see http://v.gd/ez7RHK )
               (buf/make-attribute-buffers-in-spec gl gl/static-draw))})

;; vertex attributes are planned, but not *yet* implemented by the geom mesh types...
;; the below is a hacky workaround (not v.usable for larger meshes)

;; calling g/faces on an AABB or Cuboid will always return faces (quadriliterals) in this order:
;; east, west, north, south, front, back (assuming +X as right & +Y as up axes)
;;
;;     +---+
;;     | 2 |
;; +---+---+---+
;; | 1 | 4 | 0 |
;; +---+---+---+
;;     | 3 |
;;     +---+
;;     | 5 |
;;     +---+

(defn vertex-attribs
  [attribs]
  (flatten (map gu/tessellate-3 attribs)))

(def box-faces (g/faces (a/aabb 10)))

(def webgl-box-spec
  (-> {:attribs      {:position {:data (ta/float32 (vertex-attribs box-faces))
                                 :size 3}
                      :uvs      {:data (->> [[0 0] [1 0] [1 1] [0 1]]
                                            (repeat 6) ;; use same UVs for all faces
                                            (vertex-attribs)
                                            (ta/float32))
                                 :size 2}
                      :normal   {:data (->> [[1 0 0] [-1 0 0] [0 1 0] [0 -1 0] [0 0 1] [0 0 -1]]
                                            (map #(repeat 4 %)) ;; repeat each normal 4x times (4 verts / face)
                                            (vertex-attribs)
                                            (ta/float32))
                                 :size 3}}
       :uniforms     {:model   M44
                      :view    (mat/look-at (vec3 0 25 100) (vec3) (vec3 0 1 0))
                      :proj    (gl/perspective 60 (/ 16 9) 0.1 100)}
       :mode         gl/triangles
       :num-vertices (* 6 2 3)
       :shader       your-shader-object ;; see make-shader-from-spec (http://v.gd/Rs3ieR )
       }
      ;; TODO insert shader spec (see http://v.gd/ez7RHK )
      (buf/make-attribute-buffers-in-spec gl gl/static-draw)))

;; this model spec can then be drawn via:
;; (buf/draw-arrays gl webgl-box-spec) or
;; (buf/draw-arrays-with-shader gl webgl-box-spec)
;;
;; If using the former, you can ignore the shader & uniforms keys in
;; the above spec map, but then are responsible for setting all this yourself...