#!/usr/bin/python
# -*- coding: utf-8 -*-
"""Could you write most of a software rasterizer in SQL, or is it too slow?

<https://news.ycombinator.com/item?id=26417138> asks this question.
This program gets about 800–900 frames per second on one core of my
laptop so I think the answer is a qualified yes.  But I haven't
actually rendered the results.

"""

from __future__ import print_function, division
import sqlite3, random, time


def render_frame(db):
    cursor = db.cursor()
    cursor.execute('''select ycp - rp as ybegin, xcp, ycp, rp, z, r, g, b from (
        select x / z as xcp, y / z as ycp, r / z as rp, z, r, g, b from balls
    ) order by ybegin desc''')
    for ybegin, xcp, ycp, rp, z, r, g, b in cursor:
        pass


def main():
    db = sqlite3.Connection(':memory:')
    cursor = db.cursor()
    cursor.execute('''create table balls (
        x float, y float, z float, radius float, r float, g float, b float)''')
    for i in range(256):
        cursor.execute('''insert into balls (x, y, z, radius, r, g, b)
            values (?, ?, ?, ?, ?, ?, ?)''',
           (random.random(),
            random.random(),
            random.random(),
            random.random(),
            random.random(),
            random.random(),
            random.random()))

    prev = start = time.time()
    max_frame = 0
    for frame in range(60000):
        render_frame(db)
        db.cursor().execute('update balls set y = max(0, y - 0.001)')

        # Rotate the scene in SQL!
        sin = 0.05
        cos = (1 - sin**2)**(1/2)
        db.cursor().execute('update balls set x = x * ? + y * ?, y = x * ? + y * ?',
                            (cos, sin, -sin, cos))
        end = time.time()
        max_frame = max(max_frame, end - prev)
        prev = end

    print(end - start, 'seconds, frame', frame, 'fps', (frame+1)/(end-start), 'max frame time', max_frame)

if __name__ == '__main__':
    main()