Drawing really a lot of love hearts

lispmoo2 » Devlog

7 hours ago by screwtape

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So we drew and improved a heart once.

But what about drawing a lot of hearts?

1. A table of hearts

In this article we learn how to use lisp mcclim clim's tables

Graphically, you write something like this:

formatting-table
formatting-row	formatting-cell
formatting-row	formatting-cell	formatting-cell
formatting-row	formatting-cell	formatting-cell	formatting-cell

This will end up like:

♡
♡♡
♡♡♡

for example.

1.1. Complete set up from last time

So you don't have to go away and come back, here's everything from last time basically. It's not that long. Stay strong.

See the playlist in the comments if you don't know how to set up lisp. You can skim this if you read the articles it's refactored from and jump to SOMETHING-NEW

(progn
  (require :mcclim)
  (require :series)
  (in-package :clim-user)
  (series::install))

1.1.1. Draw one heart []

Heart-bottom outline

This was guess-and-checked into shape:

(defparameter *heart-bottom*
  (butlast 
   (let* ((x (scan-range :from (- pi 0.3)
                         :upto (* 2 pi)
                         :by 0.05))
          (x+h (#m+ x (series 0.01)))
          (cosx (#mcos x+h))
          (secx (#M/ x+h))
          (tanx (#mtan x+h))
          (+abs (#Mabs (#M+ secx tanx)))
          (lnx (#mlog +abs)))
     (collect (#Mlist x lnx)))
   3))

draw-heart-bottom

(defun draw-heart-bottom (pane)
  (funcall 'draw-lines* pane
         (apply 'append (butlast *heart-bottom*)))
  (funcall 'draw-lines* pane
       (apply 'append
              (cdr *heart-bottom*))))

draw-heart

This is just where we got to last time.

(defun draw-heart (pane &aux (rad 25))
    (with-translation (pane -45 120)
      (with-scaling (pane 28 15)
            (draw-heart-bottom pane)))
  (let ((x (* rad (cos (* pi 1/6))))
          (y (* rad (sin (* pi 1/6)))))
      (with-translation (pane 60 80)
        (draw-circle* pane 0 0 rad :filled nil
                                   :start-angle
                                   (/ pi 6)
                                   :end-angle
                                   (+ pi (/ pi 6))))

      (with-translation (pane (+ 60 40) 80)
      (draw-circle* pane 0 0 rad :filled nil
                                 :start-angle
                                 (* pi -1/6)
                                 :end-angle
                                 (- pi (/ pi 6))))))

define a frame

(progn
  (define-application-frame heart ()
  ((current-ink :initform +red+))
  (:pane :application :display-function 'display-function))
  (defun display-function (frame pane)
    (with-slots (current-ink) frame

      (With-drawing-options (pane :ink current-ink)
        (draw-heart pane))))
  (defparameter *heart* (make-application-frame 'heart)))

Start heart in another thread

remembering mcclim is thread-safe.

(bt:make-thread
 (lambda ()
   (run-frame-top-level *heart*)))

1.2. SOMETHING-NEW

1.2.1. Draw three hearts

(defun display-function (frame pane)
  (with-slots (current-ink) frame
    (With-drawing-options (pane :ink current-ink)
      (loop :for x :below 30 :by 10 :do
        (with-translation (pane x 0)
          (draw-heart pane))))))
(reinitialize-instance *heart*)

Well, withstanding that looks more evil than romantic.

1.2.2. A table of hearts

(defun heart-table (pane)
  (clim:formatting-table (pane)
    (clim:formatting-row (pane)
      (clim:formatting-cell (pane)
        (draw-heart pane)))
    (clim:formatting-row (pane)
      (clim:formatting-cell (pane)
        (draw-heart pane))
      (clim:formatting-cell (pane)
        (draw-heart pane)))
    (clim:formatting-row (pane)
      (clim:formatting-cell (pane)
        (draw-heart pane))
      (clim:formatting-cell (pane)
        (draw-heart pane))
      (clim:formatting-cell (pane)
        (draw-heart pane)))))
(defun display-function (frame pane)
  (with-slots (current-ink) frame
    (With-drawing-options (pane :ink current-ink)
      (heart-table pane))))
(reinitialize-instance *heart*)

You could write that more concisely, but I think seeing it not-compressed-by-loops makes it clear how the code draws the table. Stay tuned for next time

By the way, can you see how we are creeping up on a game-world-grid.

</div>

Author: screwlisp

Created: 2025-02-02 Sun 10:25

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