WIP: Scale and fit mesh into viewport

src/heyarne/all_my_friends/core.cljc

@@ -5,6 +5,8 @@
             [cheshire.core :as json]
             [thi.ng.geom.vector :as v]
             [thi.ng.geom.core :as g]
+            [thi.ng.geom.matrix :as mat]
+            [thi.ng.geom.rect :as r]
             [thi.ng.math.core :as m]
             [clojure.java.io :as io]
             [clojure.string :as str]))
@@ -33,23 +35,70 @@
 
 ;; "most-recent" now contains a seq of all faces detected in the most recently
 ;; uploaded picture
+;; next we calculate a matrix to fit each point in the mesh into our
+;; bounding box.
+
+(def max-number #?(:clj Float/MAX_VALUE :cljs js/Infinity))
+(def min-number #?(:clj Float/MIN_VALUE :cljs js/-Infinity))
+
+(defn points->bounds [pts]
+  (let [[x1 y1 x2 y2] (reduce (fn [[x1 y1 x2 y2] [x y]]
+                                [(min x x1) (min y y1)
+                                 (max x x2) (max y y2)])
+                              [max-number max-number min-number min-number] pts)]
+    (r/rect (v/vec2 x1 y1) (v/vec2 x2 y2))))
+
+(def face-bounds
+  (points->bounds (:scaled-mesh (first most-recent)))
+  #_(let [bbox (:bounding-box (first most-recent))]
+    (-> (concat (:top-left bbox) (:bottom-right bbox))
+        (points->bounds))))
+
+(def bounds (r/rect 0 0 500 500))
+
+(defn center-matrix [dst-bounds src-bounds]
+  (let [delta (m/- (m/+ (:p dst-bounds) (m/* (:size dst-bounds) 0.5))
+                   (m/+ (:p src-bounds) (m/* (:size src-bounds) 0.5)))]
+    (g/translate (mat/matrix32) delta)))
+
+(defn fit-matrix
+  "Returns an affine matrix than can be used to fit and center all points
+  described by the bounding box `src-bounds` into `dst-bounds`."
+  [dst-bounds src-bounds]
+  (let [factor (min (/ (-> dst-bounds :size :x) (-> src-bounds :size :x))
+                    (/ (-> dst-bounds :size :y) (-> src-bounds :size :y)))]
+    (mat/matrix32 factor 0 0
+                  0 factor 0)))
+
+;; TODO: Combine matrices
+(def transform-matrix (center-matrix bounds face-bounds))
 
 (defn setup []
-  (q/frame-rate 60)
+  (q/frame-rate 1)
+  (q/ellipse-mode :center)
   (q/color-mode :hsb))
 
+(def debug true)
+
 (defn draw []
   (q/clear)
   (q/background 40 80 255)
-  (q/stroke 240 100 255)
+  (q/stroke 4 120 255)
-  (q/stroke-weight 1)
   (q/no-fill)
+  (q/stroke-weight 1)
+
+  (when debug
+    (doseq [[a b] (->> (g/vertices face-bounds)
+                       (cycle)
+                       (partition-all 2 1)
+                       (take 4))]
+      (q/line (g/transform a transform-matrix) (g/transform b transform-matrix))))
 
   (doseq [face most-recent
-          :let [mesh (:mesh face)]]
+          p (:scaled-mesh face)
-    (doseq [[[x1 y1 z1] pt2] (partition 2 mesh)]
+          :let [p (g/transform (v/vec2 p) transform-matrix)]]
-      (q/line x1 y1 (+ (q/random -2 2) x1) (+ (q/random -2 2) y1))
+    (q/ellipse (p :x) (p :y) 6 6)
-      #_(apply q/line pt1 pt2))))
+    #_(apply q/line pt1 pt2)))
 
 #_:clj-kondo/ignore
 (q/defsketch all-my-friends
@@ -58,4 +107,4 @@
   :middleware [pause-on-error]
   :setup setup
   :draw draw
-  :size [500 500])
+  :size (:size bounds))