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"""
GPU version of https://github.com/salt-die/navier-stokes
Interact with the window using to add pressure and momentum.
* Left mouse button (including drag) pokes the surface
* Right mouse button places walls
"""
import random
from pathlib import Path
import glm
import moderngl_window
from moderngl_window import geometry
external_flow = 0.35
viscosity = 0.018 # Is it odd that negative viscosity still works?
rho = 1.06 # Density
damping = 0.999
class NavierStokes2D(moderngl_window.WindowConfig):
title = "Navier Stokes 2D"
resource_dir = (Path(__file__) / "../../resources").absolute()
# window_size = 3440, 1440
# window_size = 512, 512
aspect_ratio = None # Aspect ratio should change with window size
resizable = False
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
# various vars
self.m_proj = glm.ortho(
0,
self.wnd.buffer_width,
0,
self.wnd.buffer_height,
-1,
1,
)
size = self.wnd.buffer_size
# Geometry
self.quad_fs = geometry.quad_fs()
sprite_size = 9 * 4
self.drop_geometry = geometry.quad_2d(size=(sprite_size, sprite_size))
self.wall_geometry = geometry.quad_2d(size=(sprite_size, sprite_size))
# Framebuffers
self.momentum_texture_1 = self.ctx.texture(size, 1, dtype="f4")
self.momentum_texture_1.repeat_x = True
self.momentum_texture_1.repeat_y = True
self.momentum_texture_2 = self.ctx.texture(size, 1, dtype="f4")
self.momentum_texture_2.repeat_x = True
self.momentum_texture_2.repeat_y = True
self.pressure_texture_1 = self.ctx.texture(size, 1, dtype="f4")
self.pressure_texture_2 = self.ctx.texture(size, 1, dtype="f4")
self.walls_texture = self.ctx.texture(size, 1, dtype="f4")
self.difference_texture = self.ctx.texture(size, 1, dtype="f4")
self.momentum_fbo_1 = self.ctx.framebuffer(color_attachments=[self.momentum_texture_1])
self.momentum_fbo_2 = self.ctx.framebuffer(color_attachments=[self.momentum_texture_2])
self.pressure_fbo_1 = self.ctx.framebuffer(color_attachments=[self.pressure_texture_1])
self.pressure_fbo_2 = self.ctx.framebuffer(color_attachments=[self.pressure_texture_2])
self.walls_fbo = self.ctx.framebuffer(color_attachments=[self.walls_texture])
self.difference_fbo = self.ctx.framebuffer(color_attachments=[self.difference_texture])
# programs
self.texture_prog = self.load_program("programs/navier-stokes/texture.glsl")
self.drop_prog = self.load_program("programs/navier-stokes/drop.glsl")
self.drop_prog["m_proj"].write(self.m_proj)
self.combine_prog = self.load_program("programs/navier-stokes/combine.glsl")
self.combine_prog["pressure_texture"].value = 0
self.combine_prog["wall_texture"].value = 1
self.momentum_prog = self.load_program("programs/navier-stokes/momentum.glsl")
self.momentum_prog["rho"].value = rho
self.momentum_prog["damping"].value = damping
self.momentum_prog["external_flow"].value = external_flow
self.momentum_prog["momentum_texture"].value = 0
self.momentum_prog["pressure_texture"].value = 1
self.momentum_prog["walls_texture"].value = 3
self.flow_prog = self.load_program("programs/navier-stokes/flow.glsl")
self.flow_prog["external_flow"].value = external_flow
self.poisson_prog = self.load_program("programs/navier-stokes/poisson.glsl")
self.pressure_prog = self.load_program("programs/navier-stokes/pressure.glsl")
self.pressure_prog["rho"].value = rho
self.pressure_prog["damping"].value = damping
self.pressure_prog["pressure_texture"].value = 0
self.pressure_prog["difference_texture"].value = 1
self.pressure_prog["walls_texture"].value = 3
self.reset()
def reset(self):
self.momentum_fbo_2.clear()
self.pressure_fbo_2.clear()
self.walls_fbo.clear()
def drop(self, x, y):
rng = 40
for i in range(10):
pos = (
x + int((random.random() - 0.5) * rng),
self.wnd.buffer_size[1] - y + int((random.random() - 0.5) * rng),
)
# Render drop into pressure texture
self.pressure_fbo_2.use()
self.drop_prog["pos"].value = pos
self.drop_prog["force"].value = random.random() * 2.0
self.drop_prog["write_value"].value = 1.0
# self.drop.use()
self.drop_geometry.render(self.drop_prog)
self.momentum_fbo_2.use()
self.drop_prog["write_value"].value = 0.0
self.drop_geometry.render(self.drop_prog)
def wall(self, x, y):
pos = x, self.wnd.buffer_height - y
self.walls_fbo.use()
self.drop_prog["pos"].value = pos
self.drop_prog["force"].value = 1.0
self.drop_prog["write_value"].value = 1.0
self.drop_geometry.render(self.drop_prog)
def on_render(self, time: float, frame_time: float):
# calculate momentum
self.momentum_fbo_1.use()
self.momentum_texture_2.use(location=0)
self.pressure_texture_2.use(location=1)
self.walls_texture.use(location=3)
self.quad_fs.render(self.momentum_prog)
# External Flow
self.momentum_swap()
self.momentum_fbo_1.use()
self.momentum_texture_2.use()
self.quad_fs.render(self.flow_prog)
# change in momentum
# .. poisson momentum
self.difference_fbo.use()
self.momentum_texture_1.use()
self.quad_fs.render(self.poisson_prog)
# .. pressure
self.pressure_fbo_1.use()
self.pressure_texture_2.use(location=0)
self.difference_texture.use(location=1)
self.walls_texture.use(location=3)
self.quad_fs.render(self.pressure_prog)
# Render final result
self.wnd.fbo.use()
self.pressure_texture_1.use(location=0)
self.walls_texture.use(location=1)
self.quad_fs.render(self.combine_prog)
self.momentum_swap()
self.pressure_swap()
def momentum_swap(self):
self.momentum_texture_1, self.momentum_texture_2 = (
self.momentum_texture_2,
self.momentum_texture_1,
)
self.momentum_fbo_1, self.momentum_fbo_2 = (
self.momentum_fbo_2,
self.momentum_fbo_1,
)
def pressure_swap(self):
self.pressure_texture_1, self.pressure_texture_2 = (
self.pressure_texture_2,
self.pressure_texture_1,
)
self.pressure_fbo_1, self.pressure_fbo_2 = (
self.pressure_fbo_2,
self.pressure_fbo_1,
)
def on_mouse_press_event(self, x, y, button):
if button == self.wnd.mouse.left:
self.drop(x, y)
elif button == self.wnd.mouse.right:
self.wall(x, y)
def on_mouse_drag_event(self, x, y, dx, dy):
if self.wnd.mouse_states.left:
self.drop(x, y)
elif self.wnd.mouse_states.right:
self.wall(x, y)
def on_key_event(self, key, action, modifiers):
keys = self.wnd.keys
if action == keys.ACTION_PRESS:
if key == keys.R:
self.reset()
if __name__ == "__main__":
NavierStokes2D.run()
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