REPL
Scheme as calculator
--------------------
(+ 1 2)
(+ 1 2 3)
nesting:
(+ 1 (* 2 3))
    
Naming values
-------------
(define size 2)
size
(* size 2)

Naming functions
----------------

(define (square x) (* x x))
(square 10)
(square 2)

Aruments names don't matter to the computer:
(define (square apple) (* apple apple))
Important to name them properly for humans

New functions expanding scheme's vocabulary

Functions within functions:

(define (sum-of-squares x y)
    (+ (square x) (square y)))
	
(sum-of-squares 10 2)

Comments and printing
---------------------
; I am a comment

Display and newline command:

(display "hello")(newline)


Graphics programming
--------------------

Functions which are defined as part of fluxus 
Describe a 3D scene to the renderer

Workspace : ctrl-1 

ctrl-d : save as - prompts you for a filename to save to
ctrl-s : saves over the current filename
ctrl-l : load screen, use the cursor keys and return to navigate and select a script

My first cube
-------------

(define (render)
    (draw-cube))

(every-frame (render))

(draw-cube) : draws a cube in the current state for one frame
(every-frame (funcname)) : registers a function to be called every frame

Press F5
Drag mouse for camera

State
-----

Allows us to change how things are drawn

(define (render)
    (colour (vector 1 0 0))
    (draw-cube))
    
(every-frame (render))

(colour) : sets the current colour state
(vector) : makes a new vector (a standard Scheme command)

RGB 0->1

Animation
---------

(define (render)
    (colour (vector (flxrnd) (flxrnd) (flxrnd)))
    (draw-cube))
    
(every-frame (render))

(flxrnd) : a fluxus command which returns a random number between 0 and 1

Sound
-----

Jack setup

(define (render)
    (colour (vector (gh 1) (gh 2) (gh 3)))
    (draw-cube))
    
(every-frame (render))

(gh) : Short for "get harmonic". The audio is processed and split into 16 frequency bands, this command gets the level for the band specified.

More about state
----------------

State stack

(push) : copies the current state and adds it to the top of the stack to become our new current state
(pop) : removes the top of the stack, and sets the current state to the next one down

'sandwich' between push and pop pairs

(define (render)
    (push)                     ; push a new state
    (colour (vector 1 0 0))    ; set the current colour
    (draw-cube)                ; draw a cube
    (translate (vector 2 0 0)) ; move a bit in X
    (draw-cube)                ; draw another cube
    (pop))                     ; pop the current state
    
(every-frame (render))

New command:

(translate) : translates the current transform
Translate, rotate and scale.

State Hierachy
--------------

(define (render)
    (push)                         ; push a top level state
      (colour (vector 1 0 0))      ; set the top level colour (you can think of this like a default)
      (push)                       ; push a new state
        (colour (vector 0 1 0))    ; override the current colour
        (draw-cube)                ; draws a green cube
      (pop)                        ; pops the green colour state and forgets it
      (push)                       ; push a new state
        (translate (vector 2 0 0)) ; move a bit (just so we can actually see it)
        (draw-cube)                ; draws a red cube (we haven't specified a colour in this state, so we take the top level colour)
      (pop)                        ; pops the current state
    (pop))                         ; pops the top level state
    
(every-frame (render))

Making descisions
-----------------

(define (abs n) ; returns the absolute value of n
    (if (< n 0) ; if n is less than 0
        (- n)   ; return the positive n
        n))     ; else return n as is

Recursion
---------

        Escher
        Defining a function in terms of itself
        Always needs an exit condition

    Cube row
    Cube tree