Add circle example

2 files changed, 22 insertions, 4 deletions

diff --git a/examples/circle.sql b/examples/circle.sql
new file mode 100644
index 0000000..46874cc
--- /dev/null
+++ b/examples/circle.sql
@@ -0,0 +1,18 @@
+DELETE FROM images WHERE id = 'circle';
+INSERT INTO images (id, width, height) VALUES ('circle', 200, 200) RETURNING id;
+
+WITH RECURSIVE
+  image AS (SELECT * FROM images WHERE id = 'circle'),
+  circle AS (SELECT width/2 AS cx, height/2 AS cy, 80 AS radius FROM image),
+  horizontal(x) AS
+    (SELECT width FROM image UNION ALL SELECT x - 1 FROM horizontal WHERE x > 1),
+  vertical(y) AS
+    (SELECT height FROM image UNION ALL SELECT y - 1 FROM vertical WHERE y > 1),
+  _pixels(x, y, r, g, b) AS (SELECT
+    x, y,
+    150,
+    255 * MAX(0, MIN(1, (SELECT POW(x - cx, 2) + POW(y - cy, 2) - POW(radius, 2) FROM circle))),
+    150
+    FROM vertical, horizontal
+  )
+INSERT INTO pixels (image_id, x, y, r, g, b) SELECT 'circle', x, y, r, g, b FROM _pixels;
diff --git a/examples/gradient.sql b/examples/gradient.sql
index 9aa9010..f04cdad 100644
--- a/examples/gradient.sql
+++ b/examples/gradient.sql
@@ -1,12 +1,12 @@
+DELETE FROM images WHERE id = 'gradient';
 INSERT INTO images (id, width, height) VALUES ('gradient', 200, 200) RETURNING id;
 
 WITH RECURSIVE
-  width AS (SELECT width FROM images WHERE id = 'gradient'),
-  height AS (SELECT height FROM images WHERE id = 'gradient'),
+  image AS (SELECT * FROM images WHERE id = 'gradient'),
   horizontal(x) AS
-    (SELECT * FROM width UNION ALL SELECT x - 1 FROM horizontal WHERE x > 1),
+    (SELECT width FROM image UNION ALL SELECT x - 1 FROM horizontal WHERE x > 1),
   vertical(y) AS
-    (SELECT * FROM height UNION ALL SELECT y - 1 FROM vertical WHERE y > 1),
+    (SELECT height FROM image UNION ALL SELECT y - 1 FROM vertical WHERE y > 1),
   _pixels(x, y, r, g, b) AS
     (SELECT x, y, mod(x, 255), mod(y, 255), 100 FROM vertical, horizontal)
 INSERT INTO pixels (image_id, x, y, r, g, b) SELECT 'gradient', x, y, r, g, b FROM _pixels;