Raycasting in python

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#!/usr/bin/python
# This code is public domain.
# By init. initd5@gmail.com
 
import sys # For terminal output
 
W = 24 # Width/Height
H = 79
 
RAYS = 360 # Should be 360!
 
STEP = 3 # The step of for cycle. More = Faster, but large steps may
         # cause artifacts. Step 3 is great for radius 10.
 
RAD = 10 # FOV radius.
 
# Tables of precalculated values of sin(x / (180 / pi)) and cos(x / (180 / pi))
 
sintable = [
    0.00000, 0.01745, 0.03490, 0.05234, 0.06976, 0.08716, 0.10453,
    0.12187, 0.13917, 0.15643, 0.17365, 0.19081, 0.20791, 0.22495, 0.24192,
    0.25882, 0.27564, 0.29237, 0.30902, 0.32557, 0.34202, 0.35837, 0.37461,
    0.39073, 0.40674, 0.42262, 0.43837, 0.45399, 0.46947, 0.48481, 0.50000,
    0.51504, 0.52992, 0.54464, 0.55919, 0.57358, 0.58779, 0.60182, 0.61566,
    0.62932, 0.64279, 0.65606, 0.66913, 0.68200, 0.69466, 0.70711, 0.71934,
    0.73135, 0.74314, 0.75471, 0.76604, 0.77715, 0.78801, 0.79864, 0.80902,
    0.81915, 0.82904, 0.83867, 0.84805, 0.85717, 0.86603, 0.87462, 0.88295,
    0.89101, 0.89879, 0.90631, 0.91355, 0.92050, 0.92718, 0.93358, 0.93969,
    0.94552, 0.95106, 0.95630, 0.96126, 0.96593, 0.97030, 0.97437, 0.97815,
    0.98163, 0.98481, 0.98769, 0.99027, 0.99255, 0.99452, 0.99619, 0.99756,
    0.99863, 0.99939, 0.99985, 1.00000, 0.99985, 0.99939, 0.99863, 0.99756,
    0.99619, 0.99452, 0.99255, 0.99027, 0.98769, 0.98481, 0.98163, 0.97815,
    0.97437, 0.97030, 0.96593, 0.96126, 0.95630, 0.95106, 0.94552, 0.93969,
    0.93358, 0.92718, 0.92050, 0.91355, 0.90631, 0.89879, 0.89101, 0.88295,
    0.87462, 0.86603, 0.85717, 0.84805, 0.83867, 0.82904, 0.81915, 0.80902,
    0.79864, 0.78801, 0.77715, 0.76604, 0.75471, 0.74314, 0.73135, 0.71934,
    0.70711, 0.69466, 0.68200, 0.66913, 0.65606, 0.64279, 0.62932, 0.61566,
    0.60182, 0.58779, 0.57358, 0.55919, 0.54464, 0.52992, 0.51504, 0.50000,
    0.48481, 0.46947, 0.45399, 0.43837, 0.42262, 0.40674, 0.39073, 0.37461,
    0.35837, 0.34202, 0.32557, 0.30902, 0.29237, 0.27564, 0.25882, 0.24192,
    0.22495, 0.20791, 0.19081, 0.17365, 0.15643, 0.13917, 0.12187, 0.10453,
    0.08716, 0.06976, 0.05234, 0.03490, 0.01745, 0.00000, -0.01745, -0.03490,
    -0.05234, -0.06976, -0.08716, -0.10453, -0.12187, -0.13917, -0.15643,
    -0.17365, -0.19081, -0.20791, -0.22495, -0.24192, -0.25882, -0.27564,
    -0.29237, -0.30902, -0.32557, -0.34202, -0.35837, -0.37461, -0.39073,
    -0.40674, -0.42262, -0.43837, -0.45399, -0.46947, -0.48481, -0.50000,
    -0.51504, -0.52992, -0.54464, -0.55919, -0.57358, -0.58779, -0.60182,
    -0.61566, -0.62932, -0.64279, -0.65606, -0.66913, -0.68200, -0.69466,
    -0.70711, -0.71934, -0.73135, -0.74314, -0.75471, -0.76604, -0.77715,
    -0.78801, -0.79864, -0.80902, -0.81915, -0.82904, -0.83867, -0.84805,
    -0.85717, -0.86603, -0.87462, -0.88295, -0.89101, -0.89879, -0.90631,
    -0.91355, -0.92050, -0.92718, -0.93358, -0.93969, -0.94552, -0.95106,
    -0.95630, -0.96126, -0.96593, -0.97030, -0.97437, -0.97815, -0.98163,
    -0.98481, -0.98769, -0.99027, -0.99255, -0.99452, -0.99619, -0.99756,
    -0.99863, -0.99939, -0.99985, -1.00000, -0.99985, -0.99939, -0.99863,
    -0.99756, -0.99619, -0.99452, -0.99255, -0.99027, -0.98769, -0.98481,
    -0.98163, -0.97815, -0.97437, -0.97030, -0.96593, -0.96126, -0.95630,
    -0.95106, -0.94552, -0.93969, -0.93358, -0.92718, -0.92050, -0.91355,
    -0.90631, -0.89879, -0.89101, -0.88295, -0.87462, -0.86603, -0.85717,
    -0.84805, -0.83867, -0.82904, -0.81915, -0.80902, -0.79864, -0.78801,
    -0.77715, -0.76604, -0.75471, -0.74314, -0.73135, -0.71934, -0.70711,
    -0.69466, -0.68200, -0.66913, -0.65606, -0.64279, -0.62932, -0.61566,
    -0.60182, -0.58779, -0.57358, -0.55919, -0.54464, -0.52992, -0.51504,
    -0.50000, -0.48481, -0.46947, -0.45399, -0.43837, -0.42262, -0.40674,
    -0.39073, -0.37461, -0.35837, -0.34202, -0.32557, -0.30902, -0.29237,
    -0.27564, -0.25882, -0.24192, -0.22495, -0.20791, -0.19081, -0.17365,
    -0.15643, -0.13917, -0.12187, -0.10453, -0.08716, -0.06976, -0.05234,
    -0.03490, -0.01745, -0.00000
]
 
costable = [
    1.00000, 0.99985, 0.99939, 0.99863, 0.99756, 0.99619, 0.99452,
    0.99255, 0.99027, 0.98769, 0.98481, 0.98163, 0.97815, 0.97437, 0.97030,
    0.96593, 0.96126, 0.95630, 0.95106, 0.94552, 0.93969, 0.93358, 0.92718,
    0.92050, 0.91355, 0.90631, 0.89879, 0.89101, 0.88295, 0.87462, 0.86603,
    0.85717, 0.84805, 0.83867, 0.82904, 0.81915, 0.80902, 0.79864, 0.78801,
    0.77715, 0.76604, 0.75471, 0.74314, 0.73135, 0.71934, 0.70711, 0.69466,
    0.68200, 0.66913, 0.65606, 0.64279, 0.62932, 0.61566, 0.60182, 0.58779,
    0.57358, 0.55919, 0.54464, 0.52992, 0.51504, 0.50000, 0.48481, 0.46947,
    0.45399, 0.43837, 0.42262, 0.40674, 0.39073, 0.37461, 0.35837, 0.34202,
    0.32557, 0.30902, 0.29237, 0.27564, 0.25882, 0.24192, 0.22495, 0.20791,
    0.19081, 0.17365, 0.15643, 0.13917, 0.12187, 0.10453, 0.08716, 0.06976,
    0.05234, 0.03490, 0.01745, 0.00000, -0.01745, -0.03490, -0.05234, -0.06976,
    -0.08716, -0.10453, -0.12187, -0.13917, -0.15643, -0.17365, -0.19081,
    -0.20791, -0.22495, -0.24192, -0.25882, -0.27564, -0.29237, -0.30902,
    -0.32557, -0.34202, -0.35837, -0.37461, -0.39073, -0.40674, -0.42262,
    -0.43837, -0.45399, -0.46947, -0.48481, -0.50000, -0.51504, -0.52992,
    -0.54464, -0.55919, -0.57358, -0.58779, -0.60182, -0.61566, -0.62932,
    -0.64279, -0.65606, -0.66913, -0.68200, -0.69466, -0.70711, -0.71934,
    -0.73135, -0.74314, -0.75471, -0.76604, -0.77715, -0.78801, -0.79864,
    -0.80902, -0.81915, -0.82904, -0.83867, -0.84805, -0.85717, -0.86603, 
    -0.87462, -0.88295, -0.89101, -0.89879, -0.90631, -0.91355, -0.92050,
    -0.92718, -0.93358, -0.93969, -0.94552, -0.95106, -0.95630, -0.96126,
    -0.96593, -0.97030, -0.97437, -0.97815, -0.98163, -0.98481, -0.98769,
    -0.99027, -0.99255, -0.99452, -0.99619, -0.99756, -0.99863, -0.99939,
    -0.99985, -1.00000, -0.99985, -0.99939, -0.99863, -0.99756, -0.99619,
    -0.99452, -0.99255, -0.99027, -0.98769, -0.98481, -0.98163, -0.97815,
    -0.97437, -0.97030, -0.96593, -0.96126, -0.95630, -0.95106, -0.94552,
    -0.93969, -0.93358, -0.92718, -0.92050, -0.91355, -0.90631, -0.89879,
    -0.89101, -0.88295, -0.87462, -0.86603, -0.85717, -0.84805, -0.83867,
    -0.82904, -0.81915, -0.80902, -0.79864, -0.78801, -0.77715, -0.76604,
    -0.75471, -0.74314, -0.73135, -0.71934, -0.70711, -0.69466, -0.68200,
    -0.66913, -0.65606, -0.64279, -0.62932, -0.61566, -0.60182, -0.58779,
    -0.57358, -0.55919, -0.54464, -0.52992, -0.51504, -0.50000, -0.48481,
    -0.46947, -0.45399, -0.43837, -0.42262, -0.40674, -0.39073, -0.37461,
    -0.35837, -0.34202, -0.32557, -0.30902, -0.29237, -0.27564, -0.25882,
    -0.24192, -0.22495, -0.20791, -0.19081, -0.17365, -0.15643, -0.13917,
    -0.12187, -0.10453, -0.08716, -0.06976, -0.05234, -0.03490, -0.01745,
    -0.00000, 0.01745, 0.03490, 0.05234, 0.06976, 0.08716, 0.10453, 0.12187,
    0.13917, 0.15643, 0.17365, 0.19081, 0.20791, 0.22495, 0.24192, 0.25882,
    0.27564, 0.29237, 0.30902, 0.32557, 0.34202, 0.35837, 0.37461, 0.39073,
    0.40674, 0.42262, 0.43837, 0.45399, 0.46947, 0.48481, 0.50000, 0.51504,
    0.52992, 0.54464, 0.55919, 0.57358, 0.58779, 0.60182, 0.61566, 0.62932,
    0.64279, 0.65606, 0.66913, 0.68200, 0.69466, 0.70711, 0.71934, 0.73135,
    0.74314, 0.75471, 0.76604, 0.77715, 0.78801, 0.79864, 0.80902, 0.81915,
    0.82904, 0.83867, 0.84805, 0.85717, 0.86603, 0.87462, 0.88295, 0.89101,
    0.89879, 0.90631, 0.91355, 0.92050, 0.92718, 0.93358, 0.93969, 0.94552,
    0.95106, 0.95630, 0.96126, 0.96593, 0.97030, 0.97437, 0.97815, 0.98163,
    0.98481, 0.98769, 0.99027, 0.99255, 0.99452, 0.99619, 0.99756, 0.99863,
    0.99939, 0.99985, 1.00000
]
 
level = [] # Map.
fov = []
 
for x in range(W + 1): 
    fov.append([])     # Reset FOV
    level.append([])
 
    for y in range(H + 1):
        fov[x].append(False)
        level[x].append(False) # Every tile is floor
 
 
level[5][5] = 1  # Add some walls
level[11][11] = 1
level[10][16] = 1
level[11][17] = 1
 
px = 10  # Player coordinates
py = 10
 
# The FOV algo itself.
 
# It works like this:
# It starts at player coordinates and cast 360 rays
# (if step is 1, less is step is more than 1) in every direction,
# until it hits a wall.
# When ray hits floor, it is set as visible.
 
# Ray is casted by adding to x (initialy it is player's x coord)
# value of sin(i degrees) and to y (player's y) value of cos(i degrees),
# RAD times, and checking for collision with wall every step.
 
for i in range(0, RAYS + 1, STEP): 
    ax = sintable[i] # Get precalculated value sin(x / (180 / pi))
    ay = costable[i] # cos(x / (180 / pi))
 
    x = px # Player's x
    y = py # Player's y
 
    for z in range(RAD): # Cast the ray
        x += ax
        y += ay
 
        if x < 0 or y < 0 or x > W or y > H: # If ray is out of range
            break
 
        fov[int(round(x))][int(round(y))] = 1  # Make tile visible
 
        if level[int(round(x))][int(round(y))] == 1:  # Stop ray if it hit
            break                                     # a wall.
 
 
# Let's draw it in console to show how pretty is that FOV!
for x in range(W + 1):
    for y in range(H + 1):
        if (x, y) == (px, py):
            sys.stdout.write("@") # Player
        elif fov[x][y] == 1:
            if level[x][y] == 0: # Seen
                sys.stdout.write(".")
            else:
                sys.stdout.write("#")
        else:
            sys.stdout.write("?") # Unseen
    print
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