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# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
# -----------------------------------------------------------------------------
# Author: Almar Klein & Nicolas P .Rougier
# Date: 04/03/2014
# Topic: Fireworks !
# Keywords: oarticles, gl, sprites
# -----------------------------------------------------------------------------
"""
Example demonstrating simulation of fireworks using point sprites
=================================================================
(adapted from the "OpenGL ES 2.0 Programming Guide")
This example demonstrates a series of explosions that last one second. The
visualization during the explosion is highly optimized using a Vertex Buffer
Object (VBO). After each explosion, vertex data for the next explosion are
calculated, such that each explostion is unique.
"""
import numpy as np
from vispy import app
from vispy.gloo import gl
vertex_code = """
#version 120
uniform float time;
uniform vec3 center;
attribute float lifetime;
attribute vec3 start;
attribute vec3 end;
varying float v_lifetime;
void main () {
if (time < lifetime) {
gl_Position.xyz = start + (time * end) + center;
gl_Position.w = 1.0;
gl_Position.y -= 1.5 * time * time;
} else {
gl_Position = vec4(-1000, -1000, 0, 0);
}
v_lifetime = clamp(1.0 - (time / lifetime), 0.0, 1.0);
gl_PointSize = (v_lifetime * v_lifetime) * 40.0;
}
"""
fragment_code = """
#version 120
uniform vec4 color;
varying float v_lifetime;
void main()
{
float d = 1 - length(gl_PointCoord - vec2(.5,.5)) / (sqrt(2)/2);
gl_FragColor = d*color;
gl_FragColor.a = d;
gl_FragColor.a *= v_lifetime;
}
"""
class Canvas(app.Canvas):
def __init__(self):
app.Canvas.__init__(self, size=(800, 600), title='GL Fireworks',
keys='interactive')
def on_initialize(self, event):
# Build & activate program
self.program = gl.glCreateProgram()
vertex = gl.glCreateShader(gl.GL_VERTEX_SHADER)
fragment = gl.glCreateShader(gl.GL_FRAGMENT_SHADER)
gl.glShaderSource(vertex, vertex_code)
gl.glShaderSource(fragment, fragment_code)
gl.glCompileShader(vertex)
gl.glCompileShader(fragment)
gl.glAttachShader(self.program, vertex)
gl.glAttachShader(self.program, fragment)
gl.glLinkProgram(self.program)
gl.glDetachShader(self.program, vertex)
gl.glDetachShader(self.program, fragment)
gl.glUseProgram(self.program)
# Build vertex buffer
n = 10000
self.data = np.zeros(n, dtype=[('lifetime', np.float32),
('start', np.float32, 3),
('end', np.float32, 3)])
vbuffer = gl.glCreateBuffer()
gl.glBindBuffer(gl.GL_ARRAY_BUFFER, vbuffer)
gl.glBufferData(gl.GL_ARRAY_BUFFER, self.data, gl.GL_DYNAMIC_DRAW)
# Bind buffer attributes
stride = self.data.strides[0]
offset = 0
loc = gl.glGetAttribLocation(self.program, "lifetime")
gl.glEnableVertexAttribArray(loc)
gl.glVertexAttribPointer(loc, 1, gl.GL_FLOAT, False, stride, offset)
offset = self.data.dtype["lifetime"].itemsize
loc = gl.glGetAttribLocation(self.program, "start")
gl.glEnableVertexAttribArray(loc)
gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)
offset = self.data.dtype["start"].itemsize
loc = gl.glGetAttribLocation(self.program, "end")
gl.glEnableVertexAttribArray(loc)
gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)
# OpenGL initalization
self.elapsed_time = 0
gl.glClearColor(0, 0, 0, 1)
gl.glDisable(gl.GL_DEPTH_TEST)
gl.glEnable(gl.GL_BLEND)
gl.glBlendFunc(gl.GL_SRC_ALPHA, gl.GL_ONE)
gl.glEnable(34370) # gl.GL_VERTEX_PROGRAM_POINT_SIZE
gl.glEnable(34913) # gl.GL_POINT_SPRITE
gl.glViewport(0, 0, *self.physical_size)
self.new_explosion()
self.timer = app.Timer('auto', self.on_timer, start=True)
def on_draw(self, event):
gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
gl.glDrawArrays(gl.GL_POINTS, 0, len(self.data))
def on_resize(self, event):
gl.glViewport(0, 0, *event.physical_size)
def on_timer(self, event):
self.elapsed_time += 1. / 60.
if self.elapsed_time > 1.5:
self.new_explosion()
self.elapsed_time = 0.0
loc = gl.glGetUniformLocation(self.program, "time")
gl.glUniform1f(loc, self.elapsed_time)
self.update()
def new_explosion(self):
n = len(self.data)
color = np.random.uniform(0.1, 0.9, 4).astype(np.float32)
color[3] = 1.0 / n ** 0.08
loc = gl.glGetUniformLocation(self.program, "color")
gl.glUniform4f(loc, *color)
center = np.random.uniform(-0.5, 0.5, 3)
loc = gl.glGetUniformLocation(self.program, "center")
gl.glUniform3f(loc, *center)
self.data['lifetime'] = np.random.normal(2.0, 0.5, (n,))
self.data['start'] = np.random.normal(0.0, 0.2, (n, 3))
self.data['end'] = np.random.normal(0.0, 1.2, (n, 3))
gl.glBufferData(gl.GL_ARRAY_BUFFER, self.data, gl.GL_DYNAMIC_DRAW)
if __name__ == '__main__':
c = Canvas()
c.show()
app.run()
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