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authorAdrian Kummerlaender2019-09-23 15:42:21 +0200
committerAdrian Kummerlaender2019-09-23 15:42:21 +0200
commitbeda0edf885608ffbb6498f97bf7e4fc08df1e27 (patch)
treeb5244d2543b0e1f0726265a45f2977581dd3c027
parentd883ebc4a57fd26c1dd860d2627c69d6a70107cd (diff)
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Implement basic diffusive lighting in volumetric raytracer
Approximated surface normals are encoded into the moments texture. These normals are restored when the ray marcher encounters an impermeable cell. Note that normals are shifted to be >= 0 as negative values are not representable using OpenGL textures. If this prototype works out it might be preferable to calculate better surface normals during preprocessing to be stored separately. Compare to 6123c8a.
-rw-r--r--channel_3d_volumetric_rendering_gl_interop.py92
-rw-r--r--template/opengl.mako31
2 files changed, 78 insertions, 45 deletions
diff --git a/channel_3d_volumetric_rendering_gl_interop.py b/channel_3d_volumetric_rendering_gl_interop.py
index a3d2da4..efef0a2 100644
--- a/channel_3d_volumetric_rendering_gl_interop.py
+++ b/channel_3d_volumetric_rendering_gl_interop.py
@@ -24,10 +24,10 @@ lattice_x = 256
lattice_y = 64
lattice_z = 64
-updates_per_frame = 8
+updates_per_frame = 5
-inflow = 0.05
-relaxation_time = 0.515
+inflow = 0.01
+relaxation_time = 0.51
lbm = LBM(D3Q27)
@@ -35,23 +35,26 @@ 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
+ 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
+ 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, 29), 5),
- (lambda x, y, z: x > 3*g.size_x//20-30 and
- x < 3*g.size_x//20+30 and
- (y-g.size_y//2)*(y-g.size_y//2) + (z-g.size_z//2)*(z-g.size_z//2) < 8*8, 1),
+ # wall with hole
+ (Box(2*g.size_x//20, 2.5*g.size_x//20, 0, g.size_y, 0, g.size_z), 5),
+ (Sphere(2.5*g.size_x//20, g.size_y//2, g.size_z//2, 10), 1),
- (Box(10*g.size_x//20, 11*g.size_x//20, 0, g.size_y, 1.5*g.size_z//3, g.size_z), 5),
+ # obstacle
+ (Cylinder(6*g.size_x//20, 0, 1*g.size_z//5, 4, l = g.size_y), 5),
+ (Cylinder(6*g.size_x//20, 0, 2*g.size_z//5, 4, l = g.size_y), 5),
+ (Cylinder(6*g.size_x//20, 0, 3*g.size_z//5, 4, l = g.size_y), 5),
+ (Cylinder(6*g.size_x//20, 0, 4*g.size_z//5, 4, l = g.size_y), 5),
(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
+ z == 0 or z == g.size_z-1, 0) # ghost cells
]
boundary = Template("""
@@ -129,7 +132,7 @@ raycast_fragment_shader = shaders.compileShader(Template("""
in vec3 frag_pos;
-uniform mat4 inverse_rotation;
+uniform vec4 camera_pos;
uniform sampler3D moments;
@@ -139,35 +142,32 @@ vec3 unit(vec3 v) {
return vec3(v[0] / $size_x, v[1] / $size_y, v[2] / $size_z);
}
-float norm(vec3 v) {
- return v[0]*v[0] + v[1]*v[1] + v[2]*v[2];
-}
-
-vec3 blueRedPalette(float x) {
+vec3 palette(float x) {
return mix(
- vec3(0.0, 0.0, 1.0),
+ vec3(0.0, 0.0, 0.0),
vec3(1.0, 0.0, 0.0),
x
);
}
-void main(){
- const vec4 camera_pos = inverse_rotation * vec4(0,-2*$size_x,0,1);
-
- const vec3 ray = normalize(frag_pos - camera_pos.xyz);
-
- vec4 color = vec4(0.0,0.0,0.0,1.0);
+vec3 trace(vec3 pos, vec3 ray) {
const float ray_length = $max_ray_length;
+ const float delta = 1./ray_length;
+
+ vec3 color = vec3(0.0);
+ float value = 0.0;
- for (float t = 0.0; t < 1.0; t += 1./ray_length) {
- const vec3 sample_pos = unit(frag_pos + t*ray_length*ray);
- if (norm(sample_pos) < 3.05) {
+ for (float t = 0.0; t < 1.0; t += delta) {
+ const vec3 sample_pos = unit(pos + t*ray_length*ray);
+ if (length(sample_pos) < sqrt(3.1)) {
const vec4 data = texture(moments, sample_pos);
if (data[3] != 1.0) {
- const float norm = sqrt(norm(data.yzw)) / $inflow;
- color.rgb += 0.01*blueRedPalette(norm);
+ const float norm = length(data.yzw) / $inflow;
+ value += delta * 0.5 * norm;
} else {
- color.rgb += 0.5;
+ const vec3 n = normalize(-0.5 + data.xyz); // recover surface normal
+ const float brightness = clamp(dot(n, ray), 0, 1);
+ color = vec3(max(0.3,brightness));
break;
}
} else {
@@ -175,7 +175,15 @@ void main(){
}
}
- result = color;
+ color += palette(value);
+
+ return color;
+}
+
+void main(){
+ const vec3 ray = normalize(frag_pos - camera_pos.xyz);
+
+ result = vec4(trace(frag_pos, ray), 1.0);
}
""").substitute({
"size_x": lattice_x,
@@ -192,7 +200,7 @@ domain_rotation_id = shaders.glGetUniformLocation(domain_program, 'rotation')
raycast_program = shaders.compileProgram(raycast_vertex_shader, raycast_fragment_shader)
raycast_projection_id = shaders.glGetUniformLocation(raycast_program, 'projection')
raycast_rotation_id = shaders.glGetUniformLocation(raycast_program, 'rotation')
-raycast_inverse_rotation_id = shaders.glGetUniformLocation(raycast_program, 'inverse_rotation')
+raycast_camera_pos_id = shaders.glGetUniformLocation(raycast_program, 'camera_pos')
lattice = Lattice(
descriptor = D3Q27,
@@ -226,23 +234,25 @@ def on_display():
glEnable(GL_DEPTH_TEST)
glDepthFunc(GL_LESS)
- shaders.glUseProgram(raycast_program)
- glUniformMatrix4fv(raycast_projection_id, 1, False, numpy.ascontiguousarray(projection.get()))
- glUniformMatrix4fv(raycast_rotation_id, 1, False, numpy.ascontiguousarray(rotation.get()))
- glUniformMatrix4fv(raycast_inverse_rotation_id, 1, False, numpy.ascontiguousarray(rotation.get_inverse()))
- moments_texture.bind()
- Box(0,lattice.geometry.size_x,0,lattice.geometry.size_y,0,lattice.geometry.size_z).draw()
+ camera_pos = numpy.matmul([0,-projection.distance,0,1], rotation.get_inverse())
shaders.glUseProgram(domain_program)
glUniformMatrix4fv(domain_projection_id, 1, False, numpy.ascontiguousarray(projection.get()))
glUniformMatrix4fv(domain_rotation_id, 1, False, numpy.ascontiguousarray(rotation.get()))
- glLineWidth(4)
+ glLineWidth(2)
glBegin(GL_LINES)
for i, j in cube_edges:
glVertex(cube_vertices[i])
glVertex(cube_vertices[j])
glEnd()
+ shaders.glUseProgram(raycast_program)
+ glUniformMatrix4fv(raycast_projection_id, 1, False, numpy.ascontiguousarray(projection.get()))
+ glUniformMatrix4fv(raycast_rotation_id, 1, False, numpy.ascontiguousarray(rotation.get()))
+ glUniform4fv(raycast_camera_pos_id, 1, camera_pos)
+ moments_texture.bind()
+ Box(0,lattice.geometry.size_x,0,lattice.geometry.size_y,0,lattice.geometry.size_z).draw()
+
glutSwapBuffers()
mouse_monitor = MouseDragMonitor(
diff --git a/template/opengl.mako b/template/opengl.mako
index 6b09f69..50cdbbc 100644
--- a/template/opengl.mako
+++ b/template/opengl.mako
@@ -55,6 +55,15 @@ __kernel void collect_gl_moments(__global __read_only ${float_type}* f,
moments[gid] = data;
}
+<%
+def neighbor_offset(c_i):
+ return {
+ 2: lambda: c_i[1]*memory.size_x + c_i[0],
+ 3: lambda: c_i[2]*memory.size_x*memory.size_y + c_i[1]*memory.size_x + c_i[0]
+ }.get(descriptor.d)()
+
+%>
+
__kernel void collect_gl_moments_to_texture(__global __read_only ${float_type}* f,
__global __read_only int* material,
% if descriptor.d == 2:
@@ -90,10 +99,24 @@ __kernel void collect_gl_moments_to_texture(__global __read_only ${float_type}*
data.w = ${ccode(moments_assignment[3].rhs)};
% endif
} else {
- data.x = 0.0;
- data.y = 0.0;
- data.z = 0.0;
- data.w = 1.0;
+ const int material_west = material[gid + ${neighbor_offset((-1,0,0))}];
+ const int material_east = material[gid + ${neighbor_offset((1,0,0))}];
+ const int material_north = material[gid + ${neighbor_offset((0,1,0))}];
+ const int material_south = material[gid + ${neighbor_offset((0,-1,0))}];
+ const int material_up = material[gid + ${neighbor_offset((0,0, 1))}];
+ const int material_down = material[gid + ${neighbor_offset((0,0,-1))}];
+
+ // recover surface normal approximation using surrounding materials
+ float3 n;
+ if (material_west != 5) { n.x = 1; }
+ if (material_east != 5) { n.x = -1; }
+ if (material_north != 5) { n.y = -1; }
+ if (material_south != 5) { n.y = 1; }
+ if (material_up != 5) { n.z = -1; }
+ if (material_down != 5) { n.z = 1; }
+
+ data.xyz = 0.5 + 0.5*n; // pack surface normal into texture
+ data.w = 1.0; // signal impermeable material to raytracer
}
write_imagef(moments, ${moments_cell()}, data);