fireworks_glut.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Example demonstrating simulation of fireworks using point sprites.
(adapted from the "OpenGL ES 2.0 Programming Guide")

This example is equivalent to the fireworks examples, but does runs
on GLUT instead of vispy.

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 time
import numpy as np
import OpenGL.GLUT as glut
import ctypes

import OpenGL.GL as gl  # We only use the ES 2.0 subset
import vispy_io as io


# Create a texture
radius = 32
im1 = np.random.normal(0.8, 0.3, (radius*2+1, radius*2+1))

# Mask it with a disk
L = np.linspace(-radius, radius, 2 * radius + 1)
(X, Y) = np.meshgrid(L, L)
im1 *= np.array((X**2 + Y**2) <= radius * radius, dtype='float32')

# Set number of particles, you should be able to scale this to 100000
N = 10000

# Create vertex data container
vertex_data = np.zeros((N,), dtype=[('a_lifetime', np.float32, 1),
                                    ('a_startPosition', np.float32, 3),
                                    ('a_endPosition', np.float32, 3)])


VERT_CODE = """
// explosion vertex shader
#version 120

uniform float u_time;
uniform vec3 u_centerPosition;
attribute float a_lifetime;
attribute vec3 a_startPosition;
attribute vec3 a_endPosition;
varying float v_lifetime;

void main () {
    if (u_time <= a_lifetime)
    {
        gl_Position.xyz = a_startPosition + (u_time * a_endPosition);
        gl_Position.xyz += u_centerPosition;
        gl_Position.y -= 1.0 * u_time * u_time;
        gl_Position.w = 1.0;
    }
    else
        gl_Position = vec4(-1000, -1000, 0, 0);
    
    v_lifetime = 1.0 - (u_time / a_lifetime);
    v_lifetime = clamp(v_lifetime, 0.0, 1.0);
    gl_PointSize = (v_lifetime * v_lifetime) * 40.0;
}
"""

FRAG_CODE = """
// explostion fragment shader
#version 120

uniform sampler2D s_texture;
uniform vec4 u_color;
varying float v_lifetime;

void main()
{    
    vec4 texColor;
    texColor = texture2D(s_texture, gl_PointCoord);
    gl_FragColor = vec4(u_color) * texColor;
    gl_FragColor.a *= v_lifetime;
}
"""


class Canvas:
    def __init__(self):
        self._starttime = time.time()
        self._new_explosion()
    
    
    def on_initialize(self):
        gl.glClearColor(0,0,0,1);
        
        # Enable blending
        gl.glEnable(gl.GL_BLEND)
        gl.glBlendFunc(gl.GL_SRC_ALPHA, gl.GL_ONE)
        
        # Note: normal GL requires these lines, ES 2.0 does not
        from OpenGL import GL
        gl.glEnable(GL.GL_VERTEX_PROGRAM_POINT_SIZE)
        gl.glEnable(GL.GL_POINT_SPRITE)
        
        # Create shader program
        self._prog_handle = gl.glCreateProgram()

        # Create vertex shader
        shader = gl.glCreateShader(gl.GL_VERTEX_SHADER)
        gl.glShaderSource(shader, VERT_CODE)
        gl.glCompileShader(shader)
        status = gl.glGetShaderiv(shader, gl.GL_COMPILE_STATUS)
        if not status:
            # We could show more useful info here, but that takes a few lines
            raise RuntimeError('Vertex shader did not compile.')
        else:
            gl.glAttachShader(self._prog_handle, shader)
        
        # Create fragment shader
        shader = gl.glCreateShader(gl.GL_FRAGMENT_SHADER)
        gl.glShaderSource(shader, FRAG_CODE)
        gl.glCompileShader(shader)
        status = gl.glGetShaderiv(shader, gl.GL_COMPILE_STATUS)
        if not status:
            # We could show more useful info here, but that takes a few lines
            raise RuntimeError('Fragment shader did not compile.')
        else:
            gl.glAttachShader(self._prog_handle, shader)
        
        # Link
        gl.glLinkProgram(self._prog_handle)
        status = gl.glGetProgramiv(self._prog_handle, gl.GL_LINK_STATUS)
        if not status:
            # We could show more useful info here, but that takes a few lines
            raise RuntimeError('Program did not link.')
        
        # Create texture
        self._tex_handle = gl.glGenTextures(1)
        gl.glPixelStorei(gl.GL_UNPACK_ALIGNMENT, 1)
        gl.glBindTexture(gl.GL_TEXTURE_2D, self._tex_handle)
        gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_LUMINANCE, 
            im1.shape[1], im1.shape[0], 0, gl.GL_LUMINANCE, gl.GL_FLOAT,
             im1.astype(np.float32))
        gl.glTexParameter(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR)
        gl.glTexParameter(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR)
        
        # Create vertex buffer
        self._vbo_handle = gl.glGenBuffers(1)
    
    
    def on_paint(self):
        
        # Technically, we would only need to set u_time on every draw,
        # because the program is enabled at the beginning and never disabled.
        # In vispy, the program is re-enabled at each draw though and we
        # want to keep the code similar.
        
        gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
        
        # Activate program  and texture
        gl.glUseProgram(self._prog_handle)
        gl.glBindTexture(gl.GL_TEXTURE_2D, self._tex_handle)
        
        # Update VBO
        gl.glBindBuffer(gl.GL_ARRAY_BUFFER, self._vbo_handle)
        gl.glBufferData(gl.GL_ARRAY_BUFFER, vertex_data.nbytes, vertex_data, gl.GL_DYNAMIC_DRAW)
        
        # Set attributes (again, the loc can be cached)
        loc = gl.glGetAttribLocation(self._prog_handle, 'a_lifetime')
        gl.glEnableVertexAttribArray(loc)
        gl.glVertexAttribPointer(loc, 1, gl.GL_FLOAT, False, 7*4, ctypes.c_voidp(0))
        #
        loc = gl.glGetAttribLocation(self._prog_handle, 'a_startPosition')
        gl.glEnableVertexAttribArray(loc)
        gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, 7*4, ctypes.c_voidp(1*4))
        #
        loc = gl.glGetAttribLocation(self._prog_handle, 'a_endPosition')
        gl.glEnableVertexAttribArray(loc)
        gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, 7*4, ctypes.c_voidp(4*4))
        #
        loc = gl.glGetUniformLocation(self._prog_handle, 'u_color')
        gl.glUniform4f(loc, *self._color)
        
        # Set unforms
        loc = gl.glGetUniformLocation(self._prog_handle, 'u_time')
        gl.glUniform1f(loc, time.time()-self._starttime)
        #
        loc = gl.glGetUniformLocation(self._prog_handle, 'u_centerPosition')
        gl.glUniform3f(loc, *self._centerpos)
        
        # Draw
        gl.glDrawArrays(gl.GL_POINTS, 0, N)
        
        # Swap buffers
        glut.glutSwapBuffers()
        
        # New explosion?
        if time.time() - self._starttime > 1.5:
            self._new_explosion()
            
        # Redraw 
        glut.glutPostRedisplay()
    
    
    def _new_explosion(self):
        # New centerpos
        self._centerpos = np.random.uniform(-0.5, 0.5, (3,))
        
        # New color, scale alpha with N
        alpha = 1.0 / N**0.08
        color = np.random.uniform(0.1, 0.9, (3,))
        self._color = tuple(color)+ (alpha,)
        
        # Create new vertex data
        vertex_data['a_lifetime'] = np.random.normal(2.0, 0.5, (N,))
        vertex_data['a_startPosition'] = np.random.normal(0.0, 0.2, (N,3))
        vertex_data['a_endPosition'] = np.random.normal(0.0, 1.2, (N,3))
        
        # Set time to zero
        self._starttime = time.time()
        
        
if __name__ == '__main__':
    c = Canvas()
    fps = 60
    use_buffers = False
    
    glut.glutInit([])
    glut.glutInitDisplayMode(glut.GLUT_DOUBLE | glut.GLUT_RGBA | glut.GLUT_DEPTH)
    glut.glutCreateWindow('glut-fireworks')
    glut.glutReshapeWindow(400, 400)
    glut.glutDisplayFunc(c.on_paint)
    
    # Go!
    c.on_initialize()
    glut.glutMainLoop()
    