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# -*- coding: utf-8 -*-
# vispy: gallery 30
# -----------------------------------------------------------------------------
# 2014, Almar Klein
# Distributed under the terms of the new BSD License.
# -----------------------------------------------------------------------------
""" Visualization of traveling through space.
"""
import time
import numpy as np
from vispy import gloo
from vispy import app
from vispy.util.transforms import perspective
vertex = """
#version 120
uniform mat4 u_model;
uniform mat4 u_view;
uniform mat4 u_projection;
uniform float u_time_offset;
uniform float u_pixel_scale;
attribute vec3 a_position;
attribute float a_offset;
varying float v_pointsize;
void main (void) {
vec3 pos = a_position;
pos.z = pos.z - a_offset - u_time_offset;
vec4 v_eye_position = u_view * u_model * vec4(pos, 1.0);
gl_Position = u_projection * v_eye_position;
// stackoverflow.com/questions/8608844/...
// ... resizing-point-sprites-based-on-distance-from-the-camera
float radius = 1;
vec4 corner = vec4(radius, radius, v_eye_position.z, v_eye_position.w);
vec4 proj_corner = u_projection * corner;
gl_PointSize = 100.0 * u_pixel_scale * proj_corner.x / proj_corner.w;
v_pointsize = gl_PointSize;
}
"""
fragment = """
#version 120
varying float v_pointsize;
void main()
{
float x = 2.0*gl_PointCoord.x - 1.0;
float y = 2.0*gl_PointCoord.y - 1.0;
float a = 0.9 - (x*x + y*y);
a = a * min(1.0, v_pointsize/1.5);
gl_FragColor = vec4(1.0, 1.0, 1.0, a);
}
"""
N = 100000 # Number of stars
SIZE = 100
SPEED = 4.0 # time in seconds to go through one block
NBLOCKS = 10
class Canvas(app.Canvas):
def __init__(self):
app.Canvas.__init__(self, title='Spacy', keys='interactive',
size=(800, 600))
self.program = gloo.Program(vertex, fragment)
self.view = np.eye(4, dtype=np.float32)
self.model = np.eye(4, dtype=np.float32)
self.activate_zoom()
self.timer = app.Timer('auto', connect=self.update, start=True)
# Set uniforms (some are set later)
self.program['u_model'] = self.model
self.program['u_view'] = self.view
self.program['u_pixel_scale'] = self.pixel_scale
# Set attributes
self.program['a_position'] = np.zeros((N, 3), np.float32)
self.program['a_offset'] = np.zeros((N, 1), np.float32)
# Init
self._timeout = 0
self._active_block = 0
for i in range(NBLOCKS):
self._generate_stars()
self._timeout = time.time() + SPEED
gloo.set_state(clear_color='black', depth_test=False,
blend=True, blend_equation='func_add',
blend_func=('src_alpha', 'one_minus_src_alpha'))
self.show()
def on_key_press(self, event):
if event.text == ' ':
if self.timer.running:
self.timer.stop()
else:
self.timer.start()
def on_resize(self, event):
self.activate_zoom()
def activate_zoom(self):
width, height = self.size
gloo.set_viewport(0, 0, *self.physical_size)
far = SIZE*(NBLOCKS-2)
self.projection = perspective(25.0, width / float(height), 1.0, far)
self.program['u_projection'] = self.projection
def on_draw(self, event):
# Set time offset. Factor runs from 1 to 0
# the time offset goes from 0 to size
factor = (self._timeout - time.time()) / SPEED
self.program['u_time_offset'] = -(1-factor) * SIZE
# Draw
gloo.clear()
self.program.draw('points')
# Build new starts if the first block is fully behind us
if factor < 0:
self._generate_stars()
def on_close(self, event):
self.timer.stop()
def _generate_stars(self):
# Get number of stars in each block
blocksize = N // NBLOCKS
# Update active block
self._active_block += 1
if self._active_block >= NBLOCKS:
self._active_block = 0
# Create new position data for the active block
pos = np.zeros((blocksize, 3), 'float32')
pos[:, :2] = np.random.normal(0.0, SIZE/2., (blocksize, 2)) # x-y
pos[:, 2] = np.random.uniform(0, SIZE, (blocksize,)) # z
start_index = self._active_block * blocksize
self.program['a_position'].set_subdata(pos, offset=start_index)
#print(start_index)
# Set offsets - active block gets offset 0
for i in range(NBLOCKS):
val = i - self._active_block
if val < 0:
val += NBLOCKS
values = np.ones((blocksize, 1), 'float32') * val * SIZE
start_index = i*blocksize
self.program['a_offset'].set_subdata(values, offset=start_index)
# Reset timer
self._timeout += SPEED
if __name__ == '__main__':
c = Canvas()
app.run()
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