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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vispy: gallery 30
"""
Demonstration of boids simulation. Boids is an artificial life
program, developed by Craig Reynolds in 1986, which simulates the
flocking behaviour of birds.
Based on code from glumpy by Nicolas Rougier.
"""
import time
import numpy as np
from scipy.spatial import cKDTree
from vispy import gloo
from vispy import app
VERT_SHADER = """
#version 120
attribute vec3 position;
attribute vec4 color;
attribute float size;
varying vec4 v_color;
void main (void) {
gl_Position = vec4(position, 1.0);
v_color = color;
gl_PointSize = size;
}
"""
FRAG_SHADER = """
#version 120
varying vec4 v_color;
void main()
{
float x = 2.0*gl_PointCoord.x - 1.0;
float y = 2.0*gl_PointCoord.y - 1.0;
float a = 1.0 - (x*x + y*y);
gl_FragColor = vec4(v_color.rgb, a*v_color.a);
}
"""
class Canvas(app.Canvas):
def __init__(self):
app.Canvas.__init__(self, keys='interactive')
ps = self.pixel_scale
# Create boids
n = 1000
size_type = ('size', 'f4', 1*ps) if ps > 1 else ('size', 'f4')
self.particles = np.zeros(2 + n, [('position', 'f4', 3),
('position_1', 'f4', 3),
('position_2', 'f4', 3),
('velocity', 'f4', 3),
('color', 'f4', 4),
size_type])
self.boids = self.particles[2:]
self.target = self.particles[0]
self.predator = self.particles[1]
self.boids['position'] = np.random.uniform(-0.25, +0.25, (n, 3))
self.boids['velocity'] = np.random.uniform(-0.00, +0.00, (n, 3))
self.boids['size'] = 4*ps
self.boids['color'] = 1, 1, 1, 1
self.target['size'] = 16*ps
self.target['color'][:] = 1, 1, 0, 1
self.predator['size'] = 16*ps
self.predator['color'][:] = 1, 0, 0, 1
self.target['position'][:] = 0.25, 0.0, 0
# Time
self._t = time.time()
self._pos = 0.0, 0.0
self._button = None
width, height = self.physical_size
gloo.set_viewport(0, 0, width, height)
# Create program
self.program = gloo.Program(VERT_SHADER, FRAG_SHADER)
# Create vertex buffers
self.vbo_position = gloo.VertexBuffer(self.particles['position']
.copy())
self.vbo_color = gloo.VertexBuffer(self.particles['color'].copy())
self.vbo_size = gloo.VertexBuffer(self.particles['size'].copy())
# Bind vertex buffers
self.program['color'] = self.vbo_color
self.program['size'] = self.vbo_size
self.program['position'] = self.vbo_position
gloo.set_state(clear_color=(0, 0, 0, 1), blend=True,
blend_func=('src_alpha', 'one'))
self._timer = app.Timer('auto', connect=self.update, start=True)
self.show()
def on_resize(self, event):
width, height = event.physical_size
gloo.set_viewport(0, 0, width, height)
def on_mouse_press(self, event):
self._button = event.button
self.on_mouse_move(event)
def on_mouse_release(self, event):
self._button = None
self.on_mouse_move(event)
def on_mouse_move(self, event):
if not self._button:
return
w, h = self.size
x, y = event.pos
sx = 2 * x / float(w) - 1.0
sy = - (2 * y / float(h) - 1.0)
if self._button == 1:
self.target['position'][:] = sx, sy, 0
elif self._button == 2:
self.predator['position'][:] = sx, sy, 0
def on_draw(self, event):
gloo.clear()
# Draw
self.program.draw('points')
# Next iteration
self._t = self.iteration(time.time() - self._t)
def iteration(self, dt):
t = self._t
t += 0.5 * dt
# self.target[...] = np.array([np.sin(t),np.sin(2*t),np.cos(3*t)])*.1
t += 0.5 * dt
# self.predator[...] = np.array([np.sin(t),np.sin(2*t),np.cos(3*t)])*.2
self.boids['position_2'] = self.boids['position_1']
self.boids['position_1'] = self.boids['position']
n = len(self.boids)
P = self.boids['position']
V = self.boids['velocity']
# Cohesion: steer to move toward the average position of local
# flockmates
C = -(P - P.sum(axis=0) / n)
# Alignment: steer towards the average heading of local flockmates
A = -(V - V.sum(axis=0) / n)
# Repulsion: steer to avoid crowding local flockmates
D, idxs = cKDTree(P).query(P, 5)
M = np.repeat(D < 0.05, 3, axis=1).reshape(n, 5, 3)
Z = np.repeat(P, 5, axis=0).reshape(n, 5, 3)
R = -((P[idxs] - Z) * M).sum(axis=1)
# Target : Follow target
T = self.target['position'] - P
# Predator : Move away from predator
dP = P - self.predator['position']
D = np.maximum(0, 0.3 -
np.sqrt(dP[:, 0] ** 2 +
dP[:, 1] ** 2 +
dP[:, 2] ** 2))
D = np.repeat(D, 3, axis=0).reshape(n, 3)
dP *= D
# self.boids['velocity'] += 0.0005*C + 0.01*A + 0.01*R +
# 0.0005*T + 0.0025*dP
self.boids['velocity'] += 0.0005 * C + 0.01 * \
A + 0.01 * R + 0.0005 * T + 0.025 * dP
self.boids['position'] += self.boids['velocity']
self.vbo_position.set_data(self.particles['position'].copy())
return t
if __name__ == '__main__':
c = Canvas()
app.run()
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