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INSERT OR REPLACE INTO images (id, width, height) VALUES ('circle', 400, 400) RETURNING id;
WITH RECURSIVE
image AS (SELECT * FROM images WHERE id = 'circle'),
circle AS (SELECT width/2 AS cx, height/2 AS cy, 160 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 (x - cx)*(x - cx) + (y - cy)*(y - cy) - radius*radius 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;
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