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# Visualization of particles with gravity
# Source: http://enja.org/2010/08/27/adventures-in-opencl-part-2-particles-with-opengl/
import pyopencl as cl # OpenCL - GPU computing interface
mf = cl.mem_flags
from pyopencl.tools import get_gl_sharing_context_properties
from OpenGL.GL import * # OpenGL - GPU rendering interface
from OpenGL.GLU import * # OpenGL tools (mipmaps, NURBS, perspective projection, shapes)
from OpenGL.GLUT import * # OpenGL tool to make a visualization window
from OpenGL.arrays import vbo
import numpy # Number tools
import sys # System tools (path, modules, maxint)
width = 800
height = 600
num_particles = 100000
time_step = .005
mouse_down = False
mouse_old = {'x': 0., 'y': 0.}
rotate = {'x': 0., 'y': 0., 'z': 0.}
translate = {'x': 0., 'y': 0., 'z': 0.}
initial_translate = {'x': 0., 'y': 0., 'z': -2.5}
def glut_window():
glutInit(sys.argv)
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(width, height)
glutInitWindowPosition(0, 0)
window = glutCreateWindow("Particle Simulation")
glutDisplayFunc(on_display) # Called by GLUT every frame
glutKeyboardFunc(on_key)
glutMouseFunc(on_click)
glutMotionFunc(on_mouse_move)
glutTimerFunc(10, on_timer, 10) # Call draw every 30 ms
glViewport(0, 0, width, height)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
gluPerspective(60., width / float(height), .1, 1000.)
return(window)
def initial_buffers(num_particles):
np_position = numpy.ndarray((num_particles, 4), dtype=numpy.float32)
np_color = numpy.ndarray((num_particles, 4), dtype=numpy.float32)
np_velocity = numpy.ndarray((num_particles, 4), dtype=numpy.float32)
np_position[:,0] = numpy.sin(numpy.arange(0., num_particles) * 2.001 * numpy.pi / num_particles)
np_position[:,0] *= numpy.random.random_sample((num_particles,)) / 3. + .2
np_position[:,1] = numpy.cos(numpy.arange(0., num_particles) * 2.001 * numpy.pi / num_particles)
np_position[:,1] *= numpy.random.random_sample((num_particles,)) / 3. + .2
np_position[:,2] = 0.
np_position[:,3] = 1.
np_color[:,:] = [1.,1.,1.,1.] # White particles
np_velocity[:,0] = np_position[:,0] * 2.
np_velocity[:,1] = np_position[:,1] * 2.
np_velocity[:,2] = 3.
np_velocity[:,3] = numpy.random.random_sample((num_particles, ))
gl_position = vbo.VBO(data=np_position, usage=GL_DYNAMIC_DRAW, target=GL_ARRAY_BUFFER)
gl_position.bind()
gl_color = vbo.VBO(data=np_color, usage=GL_DYNAMIC_DRAW, target=GL_ARRAY_BUFFER)
gl_color.bind()
return (np_position, np_velocity, gl_position, gl_color)
def on_timer(t):
glutTimerFunc(t, on_timer, t)
glutPostRedisplay()
def on_key(*args):
if args[0] == '\033' or args[0] == 'q':
sys.exit()
def on_click(button, state, x, y):
mouse_old['x'] = x
mouse_old['y'] = y
def on_mouse_move(x, y):
rotate['x'] += (y - mouse_old['y']) * .2
rotate['y'] += (x - mouse_old['x']) * .2
mouse_old['x'] = x
mouse_old['y'] = y
def on_display():
"""Render the particles"""
# Update or particle positions by calling the OpenCL kernel
cl.enqueue_acquire_gl_objects(queue, [cl_gl_position, cl_gl_color])
kernelargs = (cl_gl_position, cl_gl_color, cl_velocity, cl_start_position, cl_start_velocity, numpy.float32(time_step))
program.particle_fountain(queue, (num_particles,), None, *(kernelargs))
cl.enqueue_release_gl_objects(queue, [cl_gl_position, cl_gl_color])
queue.finish()
glFlush()
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
# Handle mouse transformations
glTranslatef(initial_translate['x'], initial_translate['y'], initial_translate['z'])
glRotatef(rotate['x'], 1, 0, 0)
glRotatef(rotate['y'], 0, 1, 0) #we switched around the axis so make this rotate_z
glTranslatef(translate['x'], translate['y'], translate['z'])
# Render the particles
glEnable(GL_POINT_SMOOTH)
glPointSize(2)
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
# Set up the VBOs
gl_color.bind()
glColorPointer(4, GL_FLOAT, 0, gl_color)
gl_position.bind()
glVertexPointer(4, GL_FLOAT, 0, gl_position)
glEnableClientState(GL_VERTEX_ARRAY)
glEnableClientState(GL_COLOR_ARRAY)
# Draw the VBOs
glDrawArrays(GL_POINTS, 0, num_particles)
glDisableClientState(GL_COLOR_ARRAY)
glDisableClientState(GL_VERTEX_ARRAY)
glDisable(GL_BLEND)
glutSwapBuffers()
window = glut_window()
(np_position, np_velocity, gl_position, gl_color) = initial_buffers(num_particles)
platform = cl.get_platforms()[0]
context = cl.Context(properties=[(cl.context_properties.PLATFORM, platform)] + get_gl_sharing_context_properties())
queue = cl.CommandQueue(context)
cl_velocity = cl.Buffer(context, mf.COPY_HOST_PTR, hostbuf=np_velocity)
cl_start_position = cl.Buffer(context, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=np_position)
cl_start_velocity = cl.Buffer(context, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=np_velocity)
cl_gl_position = cl.GLBuffer(context, mf.READ_WRITE, int(gl_position))
cl_gl_color = cl.GLBuffer(context, mf.READ_WRITE, int(gl_color))
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kernel = """__kernel void particle_fountain(__global float4* position,
__global float4* color,
__global float4* velocity,
__global float4* start_position,
__global float4* start_velocity,
float time_step)
{
unsigned int i = get_global_id(0);
float4 p = position[i];
float4 v = velocity[i];
float life = velocity[i].w;
life -= time_step;
if (life <= 0.f)
{
p = start_position[i];
v = start_velocity[i];
life = 1.0f;
}
v.z -= 9.8f*time_step;
p.x += v.x*time_step;
p.y += v.y*time_step;
p.z += v.z*time_step;
v.w = life;
position[i] = p;
velocity[i] = v;
color[i].w = life; /* Fade points as life decreases */
}"""
program = cl.Program(context, kernel).build()
glutMainLoop()