Tutorial

• Start PureData
• Create Patches
• Nodes
• Node Arguments
• Options
• Inlets and Outlets
• Referencing Nodes
• Connecting Nodes
• Colors
• Images

Start PureData

PureData can be started by calling startup. (Make sure that the pd executable can be found in your PATH.) When started this way, it will automatically load a patch that establishes a connection to clj-puredata. You can then load patches by calling load-patches. If these patches are later updated / rewritten using write-patch-reload, they will automatically be reloaded in PureData as well.

(startup) ; Start PureData.

(startup "test.pd") ; When supplied with an argument, clj-puredata tries to load the patch immediately.
; This will fail when PureData takes longer than 3 seconds to start. Sorry!

(load-patches "test.pd")
(load-patches "one.pd" "two.pd")

Create Patches

Patches are created using write-patch or write-patch-reload. When a patch has previously been opened in PureData using load-patches, then evaluating write-patch-reload will reload that patch in PureData automatically. A number of options can be supplied to customize the patch itself - see the list of options.

(write-patch
  "filename.pd" ; First argument is the patch filename.
  {:width 300 :height 200}  ; The second argument can (optionally) be an options map.
  
  [:print [:float 0 [:loadbang {:name 'onLoad}]]] ; Any other arguments are treated as nodes.
  [:msg "loading" (other 'onLoad)]
  ...
  )

Nodes

Nodes are created from vectors like [:+ 1 2]. The first element must always be a keyword like :print or a string like "subpatch.pd". Signal nodes always end with a dash - (not a tilde ~), like [:osc- 440]. A list of supported nodes and their names can be found in Nodes.md

(write-patch "basics.pd"
                              ; Nodes are created from hiccup-inspired vectors.
                              ; (see https://github.com/weavejester/hiccup#syntax)
             [:-]             ; The first item is always the node name, as a keyword.

             [:+ 1 2]         ; Literals (numbers, strings) are passed as creation arguments.
             [:msg "bang"]

             [:* [:msg 3]]    ; Nesting nodes creates connections between them.

                              ; Note these special cases:
             ["subpatch.pd"]  ; If the first item is a string, it will render as a subpatch.
             [:*- 1 [:osc-]]) ; Signal nodes have a `-` (dash) (instead of a `~` (tilde)) appended to their name.
                              ; (This is because tilde has special meaning in Clojure.)

Node Arguments

Inside a node vector, everything that isn't the first item, or an options map as the second item, is treated as an argument. If the argument is a literal number or string, those are used verbatim. If the argument is another node, a connection is formed. For nodes, the position of arguments determines the target inlet (unless otherwise specified using inlet).

(write-patch "arguments.pd"
             [:pack \f \f ; Argument position determines the connection inlet:
              [:msg 1]    ; Connected to first inlet.
              nil         ; `nil` skips an inlet.
              \f          ; Literals don't influence inlet count and are concatenated regardless of position.
              [:msg 3]])  ; Connected to third inlet.

Options

Options can be passed as the second argument to both Nodes (through hiccup) and Patches (through write-patch etc.). You can find a list of supported options in the List of supported Options. These are relevant for UI nodes like Sliders, Toggles, Bangs etc., and also contain the graphing options for subpatches.

(write-patch "options.pd"
             {:width 200 :height 80} ; Set patch options as the second argument to `write-patch`.
             [:bng {:name 'b         ; Set node options as the second element in hiccup vectors.
                    :x 100 :y 5
                    :size 64
                    :label-text "red!"
                    :fg-color -258049}
              [:metro 500 [:loadbang]]])

Inlets and Outlets

To specify which inlet or outlet two nodes connect on, use the inlet and outlet functions.

(write-patch "inlet-and-outlet.pd"
             [:pack
              (inlet [:msg "second inlet"] 1)              ; Specify target inlet explicitly with `inlet` function.
              (inlet [:msg "first inlet"] 0)]
             [:print "over 9000" (outlet [:moses 9000] 1)] ; Specify target outlet explicitly with `outlet` function.
             [:+ 1 (inlet (outlet [:select 3] 1) 1)])      ; `inlet` and `outlet` can be combined.

Referencing Nodes

TODO: show how let and pd can be used to reference nodes.

(write-patch "other.pd"
             [:loadbang {:name 'lb}]                      ; Giving Nodes a `:name` allows them to be referenced by `other`.
             [:print "loaded!" (other 'lb)]
             [:print "zero" (other 'm)]                   ; The named Node can be defined later, too.
             [:print "one or more" (outlet (other 'm) 1)] ; `inlet` and `outlet` also work with `other`.
             [:moses {:name 'm} 1])

Connecting Nodes

(write-patch "connect.pd"
             (connect [:loadbang] [:print "hello world!"]) ; Use `connect` to connect nodes explicitly.
             (connect [:moses] 1 [:pack] 1)                ; Use 4 arguments to specify inlet and outlet ...
             (connect (-> [:select]                        ; ... or use `inlet` and `outlet` explicitly.
                          (inlet 1)                        ; Note: they are used on the originating node.
                          (outlet 1))
                      [:pack]) 

             [:msg {:name 'tik} "bang"]
             [:metro {:name 'tok} 200]
             (connect (other 'tik) (other 'tok)))          ; It works fine with `other` as well.

Colors

(let [hues 32
      size 18
      width (+ 32 (* hues size))]
  (write-patch
   "colors.pd"
   {:width width
    :view-width width
    :view-height 32 :graph-on-parent 1}
   [:msg "; all-bangs color $1 0 0"
    (inlet [:msg (color-runtime 255 0 0) [:msg "red"]] 0)       ; Use `color-runtime` for sending color values during runtime.
    (inlet [:msg (color-runtime 0 255 0) [:msg "green"]] 0)
    (inlet [:msg (color-runtime 0 0 255) [:msg "blue"]] 0)]
   (map #(vector :bng {:x (+ 16 (* % size)) :y 5
                       :receive-symbol "all-bangs"
                       :bg-color (color-file                    ; Use `color-file` for color values stored in the file.
                                  (hsl2rgb (/ % hues) 1 0.5))}) ; Helper function `hsl2rgb` is available.
        (range hues))))

Images

(write-patch "smilie.pd"
  (import-image "smilie.png" 32)) ; Turns a PNG image into colored canvasses.