More progress. Got up to 2.65

ex-2-40.rkt

@@ -133,6 +133,7 @@
   (make-vect (* (vect-xcoor v) n)
              (* (vect-ycoor v) n)))
 ;; 2.47
+;; a list-of-three representation
 (define (make-frame1 origin edge1 edge2)
   (list origin edge1 edge2))
 (define (frame-origin1 f)
@@ -142,8 +143,61 @@
 (define (frame-edge2-1 f)
   (list-ref f 2))
 
+; two cons representation
 (define (make-frame2 origin edge1 edge2)
   (cons origin (cons edge1 edge2)))
 (define frame-origin2 car)
 (define frame-edge1-2 cadr)
 (define frame-edge2-2 cddr)
+
+; choose one impl
+(define origin-frame frame-origin2)
+(define edge1-frame frame-edge1-2)
+(define edge2-frame frame-edge2-2)
+
+;; 2.48
+;; decided to stop using define-struct for this, as it kinda
+;; screws with the naming conventions
+(define make-segment cons)
+
+(define start-segment car)
+(define end-segment cdr)
+
+;; 2.49
+(define (draw-line x y) #f)
+(define (frame-coord-map frame)
+  (lambda (v)
+    (add-vect
+     (origin-frame frame)
+     (add-vect (scale-vect (xcoor-vect v) (edge1-frame frame))
+               (scale-vect (ycoor-vect v) (edge2-frame frame))))))
+(define (segments->painter segment-list)
+  (lambda (frame)
+    (for-each
+     (lambda (segment)
+       (draw-line
+        ((frame-coord-map frame)
+         (start-segment segment))
+        ((frame-coord-map frame)
+         (end-segment segment))))
+     segment-list)))
+
+; I really should have thought of making a better
+; notation for these things, it would have been super easy too.
+; but I've already written it, so it stays, I guess.
+(define outline-painter
+  (segments->painter
+   (list (make-segment (make-vect 0 0) (make-vect 0 1))
+         (make-segment (make-vect 0 0) (make-vect 1 0))
+         (make-segment (make-vect 1 0) (make-vect 1 1))
+         (make-segment (make-vect 0 1) (make-vect 1 1)))))
+(define x-painter
+  (segments->painter
+   (list (make-segment (make-vect 0 0) (make-vect 1 1))
+         (make-segment (make-vect 1 0) (make-vect 0 1)))))
+(define diamond
+  (segments->painter
+   (list (make-segment (make-vect 0.5 0) (make-vect 0 0.5))
+         (make-segment (make-vect 0.5 0) (make-vect 1 0.5))
+         (make-segment (make-vect 0 0.5) (make-vect 0.5 1))
+         (make-segment (make-vect 1 0.5) (make-vect 0.5 1)))))