update_data_points   xtlang

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;; helpers for opengl rendering of fluidsym
(bind-func update_data_points
  (lambda () ;;cube:fluidcube* point_data:float* color_data:float*)
    (let ((vao DataVAO)
          (cube (get_fluid_cube))
          (vert_vbo (get_vbo vao 0))
          (verts (data vert_vbo))
          (vertsf (cast verts float*))
          (colour_vbo (get_vbo vao 3))
          (colours (data colour_vbo))
          (coloursf (cast colours float*))
          (densities (tref cube 5))
          (ii:i64 0)
          (jj:i64 0)
          (Vx (tref cube 6))
          (Vy (tref cube 7))
          (size_x (tref cube 0))
          (size_y (tref cube 10))
          (cvar:float 0.0)
          (cnt 0:i64)
          (idx 0)
          (red (dtof 1.0)) ;(dtof 0.3))
          (blue (dtof 0.8))
          (green (dtof 0.4))) ;(dtof .2)))
      (dotimes (ii (- size_x 2))
        (dotimes (jj (- size_y 2))
          (set! idx (+ (+ ii 1) (* (+ jj 1) size_x)))
          (pset! vertsf (+ 0 (* 4 cnt)) (- (* 2.0 (/ (i64tof ii) (i64tof CUBE_W))) 1.0))
          (pset! vertsf (+ 1 (* 4 cnt)) (- (* 2.0 (/ (i64tof jj) (i64tof CUBE_H))) 1.0))
          (pset! vertsf (+ 2 (* 4 cnt)) (* cvar 0.05))
          (pset! vertsf (+ 3 (* 4 cnt)) 1.0)
          (set! cvar (dtof (* 1.0 (pref densities idx))))
          (pset! coloursf (+ 0 (* 4 cnt)) (* cvar red))
          (pset! coloursf (+ 1 (* 4 cnt)) (* cvar green))
          (pset! coloursf (+ 2 (* 4 cnt)) (* cvar blue))
          ;; (pset! coloursf (+ 2 (* 4 cnt)) (* cvar blue)) ;(* cvar (- 1.0 blue)))
          (pset! coloursf (+ 3 (* 4 cnt)) cvar) ;1.0)
          (set! cnt (+ cnt 1))))
      (update vert_vbo)
      (update colour_vbo))
    void))