Play around with volumetric rendering using ray marching

1 files changed, 302 insertions, 0 deletions

diff --git a/channel_3d_volumetric_rendering_gl_interop.py b/channel_3d_volumetric_rendering_gl_interop.py
new file mode 100644
index 0000000..b3be853
--- /dev/null
+++ b/channel_3d_volumetric_rendering_gl_interop.py
@@ -0,0 +1,302 @@
+import numpy
+from string import Template
+
+from simulation         import Lattice, Geometry
+from utility.particles  import Particles
+from symbolic.generator import LBM
+
+import symbolic.D3Q27 as D3Q27
+
+from OpenGL.GL   import *
+from OpenGL.GLUT import *
+
+from OpenGL.GL import shaders
+
+from pyrr import matrix44, quaternion
+
+from geometry.sphere   import Sphere
+from geometry.box      import Box
+from geometry.cylinder import Cylinder
+
+from utility.opengl import MomentsTexture
+
+lattice_x = 256
+lattice_y = 64
+lattice_z = 64
+
+updates_per_frame = 10
+
+lid_speed = 0.05
+relaxation_time = 0.51
+
+def get_cavity_material_map(g):
+    return [
+        (lambda x, y, z: x > 0 and x < g.size_x-1 and
+                         y > 0 and y < g.size_y-1 and
+                         z > 0 and z < g.size_z-1,            1), # bulk fluid
+        (lambda x, y, z: x == 1 or x == g.size_x-2 or
+                         y == 1 or y == g.size_y-2 or
+                         z == 1 or z == g.size_z-2,           2), # walls
+        (lambda x, y, z: x == 1,                                     3), # inflow
+        (lambda x, y, z: x == g.size_x-2,                     4), # outflow
+
+        (Sphere(3*g.size_x//20, g.size_y//2, g.size_z//2, 28), 5),
+        (Sphere(1*g.size_x//20, g.size_y//2, g.size_z//2, 12), 1),
+        (Sphere(3*g.size_x//20, g.size_y//2, g.size_z//2, 16), 1),
+        (Sphere(5*g.size_x//20, g.size_y//2, g.size_z//2, 16), 1),
+
+        (lambda x, y, z: x == 0 or x == g.size_x-1 or
+                         y == 0 or y == g.size_y-1 or
+                         z == 0 or z == g.size_z-1,           0)  # ghost cells
+    ]
+
+boundary = Template("""
+    if ( m == 2 || m == 5 ) {
+        u_0 = 0.0;
+        u_1 = 0.0;
+        u_2 = 0.0;
+    }
+    if ( m == 3 ) {
+        u_0 = min(time/5000.0 * $inflow, $inflow);
+        u_1 = 0.0;
+        u_2 = 0.0;
+    }
+    if ( m == 4 ) {
+        rho = 1.0;
+    }
+""").substitute({
+    "inflow": lid_speed
+})
+
+def get_projection(width, height):
+    world_width = lattice_x
+    world_height = world_width / width * height
+
+    projection = matrix44.create_perspective_projection(20.0, width/height, 0.1, 1000.0)
+    look = matrix44.create_look_at(
+        eye    = [0, -2*lattice_x, 0],
+        target = [0, 0, 0],
+        up     = [0, 0, -1])
+
+    point_size = 1
+
+    return numpy.matmul(look, projection), point_size
+
+class Rotation:
+    def __init__(self, shift, x = numpy.pi, z = numpy.pi):
+        self.shift = shift
+        self.rotation_x = x
+        self.rotation_z = z
+
+    def update(self, x, z):
+        self.rotation_x += x
+        self.rotation_z += z
+
+    def get(self):
+        qx = quaternion.Quaternion(quaternion.create_from_eulers([self.rotation_x,0,0]))
+        qz = quaternion.Quaternion(quaternion.create_from_eulers([0,0,self.rotation_z]))
+        rotation = qz.cross(qx)
+        return numpy.matmul(
+            matrix44.create_from_translation(self.shift),
+            matrix44.create_from_quaternion(rotation)
+        )
+
+def glut_window(fullscreen = False):
+    glutInit(sys.argv)
+    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
+
+    if fullscreen:
+        window = glutEnterGameMode()
+    else:
+        glutInitWindowSize(800, 500)
+        glutInitWindowPosition(0, 0)
+        window = glutCreateWindow("LBM")
+
+    return window
+
+lbm = LBM(D3Q27)
+
+window = glut_window(fullscreen = False)
+
+vertex_shader = shaders.compileShader(Template("""
+#version 430
+
+layout (location=0) in vec4 vertex;
+                   out vec3 color;
+
+uniform mat4 projection;
+uniform mat4 rotation;
+
+void main() {
+    gl_Position = projection * rotation * vertex;
+    color = vec3(1.0,1.0,1.0);
+}""").substitute({}), GL_VERTEX_SHADER)
+
+fragment_shader = shaders.compileShader("""
+#version 430
+
+in vec3 color;
+
+void main(){
+    gl_FragColor = vec4(color.xyz, 0.0);
+}""", GL_FRAGMENT_SHADER)
+
+lighting_vertex_shader = shaders.compileShader("""
+#version 430
+
+layout (location=0) in vec4 vertex;
+                   out vec3 frag_pos;
+
+uniform mat4 projection;
+uniform mat4 rotation;
+
+void main() {
+    gl_Position = projection * rotation * vertex;
+    frag_pos    = vertex.xyz;
+}""", GL_VERTEX_SHADER)
+
+lighting_fragment_shader = shaders.compileShader(Template("""
+#version 430
+
+in vec3 frag_pos;
+
+uniform mat4 rotation;
+
+uniform sampler3D moments;
+
+out vec4 result;
+
+vec3 unit(vec3 v) {
+    return vec3(v[0] / $size_x, v[1] / $size_y, v[2] / $size_z);
+}
+
+float norm(vec3 v) {
+    return v[0]*v[0] + v[1]*v[1] + v[2]*v[2];
+}
+
+vec3 blueRedPalette(float x) {
+    return mix(
+        vec3(0.0, 0.0, 1.0),
+        vec3(1.0, 0.0, 0.0),
+        x
+    );
+}
+
+void main(){
+    const vec4 light_pos = rotation * vec4(0,-2*$size_x,0,1);
+
+    const vec3 ray = normalize(frag_pos - light_pos.xyz);
+
+    vec4 color = vec4(0.0,0.0,0.0,1.0);
+    const float ray_length = 128.0;
+
+    for (float t = 1.0; t < ray_length; t += ray_length/80.0) {
+        const vec3 sample_pos = unit(frag_pos + t*ray);
+        if (norm(sample_pos) < 3.05) {
+            const vec4 data = texture(moments, sample_pos);
+            if (data[3] != 1.0) {
+                const float norm = sqrt(data[1]*data[1]+data[2]*data[2]+data[3]*data[3]) / ($lid_speed);
+                color.rgb += 0.05 * (1.0 - t/ray_length) * blueRedPalette(0.5*norm);
+            } else {
+                color.rgb += 0.03;
+            }
+        } else {
+            break;
+        }
+    }
+
+    result = color;
+}
+""").substitute({
+    "size_x": lattice_x,
+    "size_y": lattice_y,
+    "size_z": lattice_z,
+    "lid_speed": lid_speed
+}), GL_FRAGMENT_SHADER)
+
+domain_program   = shaders.compileProgram(vertex_shader, fragment_shader)
+projection_id = shaders.glGetUniformLocation(domain_program, 'projection')
+rotation_id   = shaders.glGetUniformLocation(domain_program, 'rotation')
+
+obstacle_program = shaders.compileProgram(lighting_vertex_shader, lighting_fragment_shader)
+projection_id2 = shaders.glGetUniformLocation(obstacle_program, 'projection')
+rotation_id2   = shaders.glGetUniformLocation(obstacle_program, 'rotation')
+
+lattice = Lattice(
+    descriptor   = D3Q27,
+    geometry     = Geometry(lattice_x, lattice_y, lattice_z),
+    moments      = lbm.moments(optimize = True),
+    collide      = lbm.bgk(f_eq = lbm.equilibrium(), tau = relaxation_time),
+    boundary_src = boundary,
+    opengl       = True
+)
+
+moments_texture = MomentsTexture(lattice)
+
+material_map = get_cavity_material_map(lattice.geometry)
+primitives   = list(map(lambda material: material[0], filter(lambda material: not callable(material[0]), material_map)))
+lattice.apply_material_map(material_map)
+lattice.sync_material()
+
+rotation = Rotation([-lattice_x//2, -lattice_y//2, -lattice_z//2])
+
+cube_vertices, cube_edges = lattice.geometry.wireframe()
+
+def on_display():
+    for i in range(0,updates_per_frame):
+        lattice.evolve()
+
+    moments_texture.collect()
+
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
+
+    glEnable(GL_DEPTH_TEST)
+    glDepthFunc(GL_LESS)
+
+    shaders.glUseProgram(obstacle_program)
+    glUniformMatrix4fv(projection_id2, 1, False, numpy.ascontiguousarray(projection))
+    glUniformMatrix4fv(rotation_id2, 1, False, numpy.ascontiguousarray(rotation.get()))
+    moments_texture.bind()
+    Box(0,lattice.geometry.size_x,0,lattice.geometry.size_y,0,lattice.geometry.size_z).draw()
+
+    shaders.glUseProgram(domain_program)
+    glUniformMatrix4fv(projection_id, 1, False, numpy.ascontiguousarray(projection))
+    glUniformMatrix4fv(rotation_id, 1, False, numpy.ascontiguousarray(rotation.get()))
+    glLineWidth(4)
+    glBegin(GL_LINES)
+    for i, j in cube_edges:
+        glVertex(cube_vertices[i])
+        glVertex(cube_vertices[j])
+    glEnd()
+
+    glutSwapBuffers()
+
+def on_reshape(width, height):
+    global projection, point_size
+    glViewport(0,0,width,height)
+    projection, point_size = get_projection(width, height)
+
+def on_keyboard(key, x, y):
+    global rotation
+
+    x = {
+        b'w': -numpy.pi/20,
+        b's':  numpy.pi/20
+    }.get(key, 0.0)
+    z = {
+        b'a':  numpy.pi/20,
+        b'd': -numpy.pi/20
+    }.get(key, 0.0)
+
+    rotation.update(x,z)
+
+def on_timer(t):
+    glutTimerFunc(t, on_timer, t)
+    glutPostRedisplay()
+
+glutDisplayFunc(on_display)
+glutReshapeFunc(on_reshape)
+glutKeyboardFunc(on_keyboard)
+glutTimerFunc(10, on_timer, 10)
+
+glutMainLoop()