demos/py_simple/plot.py

   1 #!/usr/bin/env python
   2 import gfxprim.core as core
   3 import gfxprim.backends as backends
   4 import gfxprim.gfx as gfx
   5 import sys
   6 from math import *
   7
   8 W = 640
   9 H = 480
  10 EPS = 0.05
  11
  12 env = {}
  13 env['sin'] = sin
  14 env['cos'] = cos
  15 env['sqrt'] = sqrt
  16
  17 def compute(func, x, y_min, y_max):
  18   env['x'] = x
  19   try:
  20     ret = eval(func, env)
  21   except ZeroDivisionError:
  22     return -1
  23
  24   return - H * ret / (y_max - y_min) + (H * y_max) / (y_max - y_min)
  25
  26 def x_to_x(x, x_min, x_max):
  27   return  (x_max - x_min) * x / W + x_min
  28
  29 class plotter(object):
  30   def __init__(self, func, x_min, x_max, y_min, y_max):
  31     self.x = 0.0
  32     self.y = compute(func, x_to_x(self.x, x_min, x_max), y_min, y_max)
  33     self.y_min = y_min
  34     self.y_max = y_max
  35     self.x_min = x_min
  36     self.x_max = x_max
  37     self.func = func
  38   def next(self):
  39     x = x_to_x(self.x + 1, self.x_min, self.x_max)
  40     new_y = compute(self.func, x, self.y_min, self.y_max)
  41
  42     inc = 1.0
  43
  44     while (abs(new_y - self.y) > 1 and inc > EPS):
  45       x = x_to_x(self.x + inc, self.x_min, self.x_max)
  46       new_y = compute(self.func, x, self.y_min, self.y_max)
  47       inc /= 2
  48
  49     self.x += inc
  50     self.y = new_y
  51
  52     print(self.x, self.y)
  53
  54
  55 def main():
  56   bk = backends.BackendSDLInit(W, H, 0, 0, "Plot AA")
  57   assert bk
  58   print(bk)
  59   print("Modify source for parameters,")
  60   print("Kill to terminate ;-)")
  61   print("Usage: function x_min x_max y_min y_max")
  62   black = bk.context.RGBToPixel(0, 0, 0)
  63
  64   x_min = float(sys.argv[2])
  65   x_max = float(sys.argv[3])
  66   y_min = float(sys.argv[4])
  67   y_max = float(sys.argv[5])
  68   p = plotter(sys.argv[1], x_min, x_max, y_min, y_max)
  69
  70   r = 255
  71   g = 0
  72   b = 0
  73
  74   while p.x < W:
  75     x = int((p.x + 0.5) * 0x100)
  76     y = int((p.y + 0.5) * 0x100)
  77     gfx.PutPixelAA(bk.context, x, y, bk.context.RGBToPixel(int(r), int(g), int(b)))
  78     bk.Flip()
  79     p.next()
  80
  81   while True:
  82     pass
  83
  84 if __name__ == '__main__':
  85   main()