From fb65f0d82386d08ae07f43ab76b92c040936191a Mon Sep 17 00:00:00 2001
From: Tobias Frisch <tfrisch@uni-koblenz.de>
Date: Tue, 1 Feb 2022 15:26:27 +0100
Subject: [PATCH] Added several physical properties to match materials
Signed-off-by: Tobias Frisch <tfrisch@uni-koblenz.de>
---
projects/wobble_bobble/shaders/grid.vert | 7 +-
.../shaders/init_particle_volumes.comp | 35 ++++++++-
projects/wobble_bobble/shaders/particle.inc | 10 +++
.../shaders/update_grid_forces.comp | 9 +--
projects/wobble_bobble/src/main.cpp | 76 ++++++++++++++++---
5 files changed, 119 insertions(+), 18 deletions(-)
diff --git a/projects/wobble_bobble/shaders/grid.vert b/projects/wobble_bobble/shaders/grid.vert
index b504f81a..d0068e47 100644
--- a/projects/wobble_bobble/shaders/grid.vert
+++ b/projects/wobble_bobble/shaders/grid.vert
@@ -1,4 +1,7 @@
#version 450
+#extension GL_GOOGLE_include_directive : enable
+
+#include "particle.inc"
layout(set=0, binding=0) uniform texture3D gridImage;
layout(set=0, binding=1) uniform sampler gridSampler;
@@ -34,6 +37,8 @@ void main() {
vec4 gridData = texture(sampler3D(gridImage, gridSampler), position);
float mass = gridData.w;
+ float density = mass / sphere_volume(size);
+ float alpha = clamp(density / 100000000.0f, 0.0f, 1.0f);
passPos = vertexPos;
passVelocity = gridData.xyz;
@@ -41,5 +46,5 @@ void main() {
// align voxel to face camera
gl_Position = mvp * vec4(position, 1); // transform position into projected view space
- gl_Position.xy += vertexPos * (size * 2.0f) * (mass * 100.0f); // move position directly in view space
+ gl_Position.xy += vertexPos * mix(0.0f, size * 2.0f, alpha); // move position directly in view space
}
\ No newline at end of file
diff --git a/projects/wobble_bobble/shaders/init_particle_volumes.comp b/projects/wobble_bobble/shaders/init_particle_volumes.comp
index 5f30307f..9fde7700 100644
--- a/projects/wobble_bobble/shaders/init_particle_volumes.comp
+++ b/projects/wobble_bobble/shaders/init_particle_volumes.comp
@@ -9,11 +9,44 @@ layout(set=0, binding=0, std430) buffer particleBuffer {
Particle particles [];
};
+layout(set=0, binding=1) uniform texture3D gridImage;
+layout(set=0, binding=2) uniform sampler gridSampler;
+
void main() {
memoryBarrierBuffer();
+ memoryBarrierImage();
if (gl_GlobalInvocationID.x < particles.length()) {
- // nothing
+ ParticleMinimal minimal = particles[gl_GlobalInvocationID.x].minimal;
+
+ ivec3 gridResolution = textureSize(sampler3D(gridImage, gridSampler), 0);
+ ivec3 gridWindow = ivec3(minimal.size * 2.0f * gridResolution);
+
+ float volume = sphere_volume(minimal.size);
+
+ float mass = 0.0f;
+ int i, j, k;
+
+ for (i = -gridWindow.x; i <= gridWindow.x; i++) {
+ for (j = -gridWindow.y; j <= gridWindow.y; j++) {
+ for (k = -gridWindow.z; k <= gridWindow.z; k++) {
+ vec3 offset = vec3(i, j, k) / gridResolution;
+ vec3 voxel = minimal.position + offset;
+
+ if (length(offset) < minimal.size * 2.0f) {
+ vec4 gridSample = texture(sampler3D(gridImage, gridSampler), voxel);
+
+ mass += gridSample.w * voxel_particle_weight(voxel, minimal);
+ }
+ }
+ }
+ }
+
+ if (volume > 0.0f) {
+ //volume = minimal.mass / (mass / volume);
+ }
+
+ particles[gl_GlobalInvocationID.x].minimal.size = sphere_radius(volume);
}
memoryBarrierBuffer();
diff --git a/projects/wobble_bobble/shaders/particle.inc b/projects/wobble_bobble/shaders/particle.inc
index f5791e20..65580262 100644
--- a/projects/wobble_bobble/shaders/particle.inc
+++ b/projects/wobble_bobble/shaders/particle.inc
@@ -13,6 +13,16 @@ struct Particle {
mat4 deformation;
};
+const float PI = 3.1415926535897932384626433832795;
+
+float sphere_volume(float radius) {
+ return 4.0f * (radius * radius * radius) * PI / 3.0f;
+}
+
+float sphere_radius(float volume) {
+ return pow(volume * 3.0f / 4.0f / PI, 1.0f / 3.0f);
+}
+
float weight_A(float x) {
return max(1.0f - x, 0.0f);
}
diff --git a/projects/wobble_bobble/shaders/update_grid_forces.comp b/projects/wobble_bobble/shaders/update_grid_forces.comp
index 485a727c..3e0259cc 100644
--- a/projects/wobble_bobble/shaders/update_grid_forces.comp
+++ b/projects/wobble_bobble/shaders/update_grid_forces.comp
@@ -1,8 +1,6 @@
#version 450
#extension GL_GOOGLE_include_directive : enable
-const float PI = 3.1415926535897932384626433832795;
-
layout(local_size_x = 4, local_size_y = 4, local_size_z = 4) in;
#include "particle.inc"
@@ -42,7 +40,9 @@ void main() {
poisson /= (6.0f * K);
}
- const vec3 position = (vec3(gl_GlobalInvocationID) + vec3(0.5f)) / imageSize(gridImage);
+ const vec3 gridResolution = vec3(imageSize(gridImage));
+ const vec3 position = (vec3(gl_GlobalInvocationID) + vec3(0.5f)) / gridResolution;
+ const float h3 = 1.0f / gridResolution.x / gridResolution.y / gridResolution.z;
memoryBarrierImage();
@@ -75,8 +75,7 @@ void main() {
memoryBarrierShared();
for (uint i = 0; i < SHARED_PARTICLES_BATCH_SIZE; i++) {
- float size = shared_particles[gl_LocalInvocationIndex].minimal.size;
- float volume = 4.0f / 3.0f * PI * size * size * size;
+ float volume = sphere_volume(shared_particles[gl_LocalInvocationIndex].minimal.size);
mat3 F = mat3(shared_particles[gl_LocalInvocationIndex].deformation);
float J = determinant(F);
diff --git a/projects/wobble_bobble/src/main.cpp b/projects/wobble_bobble/src/main.cpp
index f58ad91e..56074f61 100644
--- a/projects/wobble_bobble/src/main.cpp
+++ b/projects/wobble_bobble/src/main.cpp
@@ -26,6 +26,14 @@ struct Tweaks {
float beta;
};
+float sphere_volume(float radius) {
+ return 4.0f * (radius * radius * radius) * M_PI / 3.0f;
+}
+
+float sphere_radius(float volume) {
+ return pow(volume * 3.0f / 4.0f / M_PI, 1.0f / 3.0f);
+}
+
std::random_device random_dev;
std::uniform_int_distribution<int> dist(0, RAND_MAX);
@@ -55,11 +63,14 @@ void distributeParticles(Particle *particles, size_t count, const glm::vec3& cen
particles[i].size = size;
particles[i].velocity = velocity;
- volume += size;
+ volume += sphere_volume(size);
}
+ // Keep the same densitiy as planned!
+ mass *= (volume / sphere_volume(radius));
+
for (size_t i = 0; i < count; i++) {
- particles[i].mass = (mass * particles[i].size / volume);
+ particles[i].mass = (mass * sphere_volume(particles[i].size) / volume);
particles[i].deformation = glm::mat4(1.0f);
}
}
@@ -105,15 +116,16 @@ vkcv::ComputePipelineHandle createComputePipeline(vkcv::Core& core, vkcv::shader
return core.createComputePipeline(config);
}
-void resetParticles(vkcv::Buffer<Particle>& particles, const glm::vec3& velocity) {
+void resetParticles(vkcv::Buffer<Particle>& particles, const glm::vec3& velocity,
+ float density, float size) {
std::vector<Particle> particles_vec (particles.getCount());
distributeParticles(
particles_vec.data(),
particles_vec.size(),
glm::vec3(0.5f),
- 0.05f,
- 0.27f,
+ size,
+ density * sphere_volume(size),
velocity
);
@@ -154,13 +166,15 @@ int main(int argc, const char **argv) {
).getHandle();
glm::vec3 initialVelocity (0.0f, 0.0f, 0.0f);
+ float density = 2500.0f;
+ float radius = 0.1f;
vkcv::Buffer<Particle> particles = core.createBuffer<Particle>(
vkcv::BufferType::STORAGE,
1024
);
- resetParticles(particles, initialVelocity);
+ resetParticles(particles, initialVelocity, density, radius);
vkcv::Image grid = core.createImage(
vk::Format::eR32G32B32A32Sfloat,
@@ -230,6 +244,8 @@ int main(int argc, const char **argv) {
{
vkcv::DescriptorWrites writes;
writes.storageBufferWrites.push_back(vkcv::BufferDescriptorWrite(0, particles.getHandle()));
+ writes.sampledImageWrites.push_back(vkcv::SampledImageDescriptorWrite(1, grid.getHandle()));
+ writes.samplerWrites.push_back(vkcv::SamplerDescriptorWrite(2, gridSampler));
core.writeDescriptorSet(initParticleVolumesSets[0], writes);
}
@@ -542,7 +558,10 @@ int main(int argc, const char **argv) {
// Glass is glass and glass breaks...
float compression_modulus = 65.0f;
+ int compression_exponent = 9;
+
float elasticity_modulus = 45.0f;
+ int elasticity_exponent = 9;
float alpha = 0.5f;
float beta = 0.75f;
@@ -580,8 +599,8 @@ int main(int argc, const char **argv) {
current = next;
Physics physics;
- physics.K = static_cast<float>(compression_modulus * std::pow(10.0, 9.0));
- physics.E = static_cast<float>(elasticity_modulus * std::pow(10.0, 9.0));
+ physics.K = static_cast<float>(compression_modulus * std::pow(10.0, compression_exponent));
+ physics.E = static_cast<float>(elasticity_modulus * std::pow(10.0, elasticity_exponent));
physics.t = static_cast<float>(0.000001 * static_cast<double>(time.count()));
physics.dt = static_cast<float>(0.000001 * static_cast<double>(deltatime.count()));
@@ -626,6 +645,8 @@ int main(int argc, const char **argv) {
if (!initializedParticleVolumes) {
core.recordBeginDebugLabel(cmdStream, "INIT PARTICLE VOLUMES", { 0.78f, 0.89f, 0.94f, 1.0f });
+ core.prepareImageForSampling(cmdStream, grid.getHandle());
+
core.recordComputeDispatchToCmdStream(
cmdStream,
initParticleVolumesPipeline,
@@ -642,6 +663,8 @@ int main(int argc, const char **argv) {
}
core.recordBeginDebugLabel(cmdStream, "UPDATE GRID FORCES", { 0.47f, 0.77f, 0.85f, 1.0f });
+ core.prepareImageForStorage(cmdStream, grid.getHandle());
+
core.recordComputeDispatchToCmdStream(
cmdStream,
updateGridForcesPipeline,
@@ -754,18 +777,49 @@ int main(int argc, const char **argv) {
core.submitCommandStream(cmdStream);
gui.beginGUI();
-
ImGui::Begin("Settings");
+ ImGui::SliderFloat("Density", &density, std::numeric_limits<float>::epsilon(), 5000.0f);
+ ImGui::SameLine(0.0f, 10.0f);
+ if (ImGui::SmallButton("Reset##density")) {
+ density = 2500.0f;
+ }
+
+ ImGui::SliderFloat("Radius", &radius, 0.0f, 0.5f);
+ ImGui::SameLine(0.0f, 10.0f);
+ if (ImGui::SmallButton("Reset##radius")) {
+ radius = 0.1f;
+ }
+
+ ImGui::BeginGroup();
ImGui::SliderFloat("Compression Modulus", &compression_modulus, 0.0f, 500.0f);
+ ImGui::SliderInt("##compression_exponent", &compression_exponent, 1, 9);
+ ImGui::SameLine(0.0f, 10.0f);
+ if (ImGui::SmallButton("Reset##compression")) {
+ compression_modulus = 65.0f;
+ compression_exponent = 9;
+ }
+ ImGui::EndGroup();
+
+ ImGui::BeginGroup();
ImGui::SliderFloat("Elasticity Modulus", &elasticity_modulus, 0.0f, 1000.0f);
+ ImGui::SliderInt("##elasticity_exponent", &elasticity_exponent, 1, 9);
+ ImGui::SameLine(0.0f, 10.0f);
+ if (ImGui::SmallButton("Reset##elasticity")) {
+ elasticity_modulus = 45.0f;
+ elasticity_exponent = 9;
+ }
+ ImGui::EndGroup();
+ ImGui::Spacing();
ImGui::Checkbox("Render Grid", &renderGrid);
+
ImGui::SliderFloat("Alpha (PIC -> FLIP)", &alpha, 0.0f, 1.0f);
ImGui::SameLine(0.0f, 10.0f);
if (ImGui::SmallButton("Reset##alpha")) {
alpha = 0.5f;
}
+
ImGui::SliderFloat("Beta (Alpha -> APIC)", &beta, 0.0f, 1.0f);
ImGui::SameLine(0.0f, 10.0f);
if (ImGui::SmallButton("Reset##beta")) {
@@ -775,11 +829,11 @@ int main(int argc, const char **argv) {
ImGui::DragFloat3("Initial Velocity", reinterpret_cast<float*>(&initialVelocity));
ImGui::SameLine(0.0f, 10.0f);
if (ImGui::Button("Reset##particle_velocity")) {
- resetParticles(particles, initialVelocity);
+ resetParticles(particles, initialVelocity, density, radius);
+ initializedParticleVolumes = false;
}
ImGui::End();
-
gui.endGUI();
core.endFrame(windowHandle);
--
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