diff --git a/projects/wobble_bobble/shaders/update_grid_forces.comp b/projects/wobble_bobble/shaders/update_grid_forces.comp
index b0de5190a3c441b19dd9e8f8c4abb58ae6a728b0..485a727c57d67910ae870b12d5029b1dea433e12 100644
--- a/projects/wobble_bobble/shaders/update_grid_forces.comp
+++ b/projects/wobble_bobble/shaders/update_grid_forces.comp
@@ -14,6 +14,8 @@ layout(set=0, binding=2, std430) buffer particleBuffer {
};
layout( push_constant ) uniform constants {
+ float K;
+ float E;
float t;
float dt;
};
@@ -23,8 +25,24 @@ layout( push_constant ) uniform constants {
shared Particle shared_particles [SHARED_PARTICLES_BATCH_SIZE];
void main() {
+ const float K9_E = (9.0f * K - E);
+
+ float lame1 = 3.0f * K * (3.0f * K - E);
+ float lame2 = 3.0f * K * E;
+ float poisson = (3.0f * K - E);
+ float M = 3.0f * K * (3.0f * K + E);
+
+ if (K9_E > 0.0f) {
+ lame1 /= K9_E;
+ lame2 /= K9_E;
+ M /= K9_E;
+ }
+
+ if (K > 0.0f) {
+ poisson /= (6.0f * K);
+ }
+
const vec3 position = (vec3(gl_GlobalInvocationID) + vec3(0.5f)) / imageSize(gridImage);
- const float elasticity_module = 12.5f * 1000000.0f; // 10..15 = Wood
memoryBarrierImage();
@@ -59,14 +77,17 @@ void main() {
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;
- mat3 deformation = mat3(shared_particles[gl_LocalInvocationIndex].deformation);
+ mat3 F = mat3(shared_particles[gl_LocalInvocationIndex].deformation);
+
+ float J = determinant(F);
+
+ if ((J > 0.0f) && (volume > 0.0f)) {
+ mat3 F_invT = inverse(transpose(F));
- float J = determinant(deformation);
+ vec3 v = shared_particles[gl_LocalInvocationIndex].minimal.velocity;
+ float m = shared_particles[gl_LocalInvocationIndex].minimal.mass;
- if ((abs(J) > 0.0f) && (volume > 0.0f)) {
- mat3 epsilon = deformation - mat3(1.0f);
- mat3 delta = elasticity_module * epsilon;
- mat3 delta_cauchy = J * delta * inverse(transpose(deformation));
+ mat3 delta = lame2 * (F - F_invT) + lame1 * log(J) * F_invT;
vec3 weight_gradient = voxel_particle_grad_weight(
position,
@@ -75,7 +96,7 @@ void main() {
force -= (
volume *
- delta_cauchy *
+ delta * transpose(F) *
weight_gradient
);
}
diff --git a/projects/wobble_bobble/shaders/update_particle_deformation.comp b/projects/wobble_bobble/shaders/update_particle_deformation.comp
index d6b585d771380e800727d57d3fed90f0fc19656e..8cd2aabe439764d4572502667d3f587d2f8726e5 100644
--- a/projects/wobble_bobble/shaders/update_particle_deformation.comp
+++ b/projects/wobble_bobble/shaders/update_particle_deformation.comp
@@ -36,11 +36,10 @@ void main() {
if (length(offset) < minimal.size * 2.0f) {
vec4 gridSample = texture(sampler3D(gridImage, gridSampler), voxel);
- // TODO: needs to be activated once everything else is stable!
- /*velocity_gradient += outerProduct(
+ velocity_gradient += outerProduct(
gridSample.xyz,
voxel_particle_grad_weight(voxel, minimal)
- );*/
+ );
}
}
}
diff --git a/projects/wobble_bobble/shaders/update_particle_positions.comp b/projects/wobble_bobble/shaders/update_particle_positions.comp
index 29d51dba2b4f235d12f668ee8e758880aae2d335..bd01b40286835cb50277c5100dbc9270377061e0 100644
--- a/projects/wobble_bobble/shaders/update_particle_positions.comp
+++ b/projects/wobble_bobble/shaders/update_particle_positions.comp
@@ -10,6 +10,8 @@ layout(set=0, binding=0, std430) buffer particleBuffer {
};
layout( push_constant ) uniform constants {
+ float K;
+ float E;
float t;
float dt;
};
diff --git a/projects/wobble_bobble/src/main.cpp b/projects/wobble_bobble/src/main.cpp
index 55280f7d6f4ce7d93fa22448f25381a48aa24dff..f58ad91ec5cd14a029b6f66373b4cd596444fef6 100644
--- a/projects/wobble_bobble/src/main.cpp
+++ b/projects/wobble_bobble/src/main.cpp
@@ -14,7 +14,9 @@ struct Particle {
glm::mat4 deformation;
};
-struct Time {
+struct Physics {
+ float K;
+ float E;
float t;
float dt;
};
@@ -537,6 +539,11 @@ int main(int argc, const char **argv) {
bool initializedParticleVolumes = false;
bool renderGrid = true;
+
+ // Glass is glass and glass breaks...
+ float compression_modulus = 65.0f;
+ float elasticity_modulus = 45.0f;
+
float alpha = 0.5f;
float beta = 0.75f;
@@ -572,12 +579,14 @@ int main(int argc, const char **argv) {
current = next;
- Time timeConstants;
- timeConstants.t = static_cast<float>(0.000001 * static_cast<double>(time.count()));
- timeConstants.dt = static_cast<float>(0.000001 * static_cast<double>(deltatime.count()));
+ 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.t = static_cast<float>(0.000001 * static_cast<double>(time.count()));
+ physics.dt = static_cast<float>(0.000001 * static_cast<double>(deltatime.count()));
- vkcv::PushConstants timePushConstants (sizeof(timeConstants));
- timePushConstants.appendDrawcall(timeConstants);
+ vkcv::PushConstants physicsPushConstants (sizeof(physics));
+ physicsPushConstants.appendDrawcall(physics);
Tweaks tweaks;
tweaks.alpha = alpha;
@@ -586,7 +595,7 @@ int main(int argc, const char **argv) {
vkcv::PushConstants tweakPushConstants (sizeof(tweaks));
tweakPushConstants.appendDrawcall(tweaks);
- cameraManager.update(timeConstants.dt);
+ cameraManager.update(physics.dt);
glm::mat4 mvp = cameraManager.getActiveCamera().getMVP();
vkcv::PushConstants cameraPushConstants (sizeof(glm::mat4));
@@ -640,7 +649,7 @@ int main(int argc, const char **argv) {
{ vkcv::DescriptorSetUsage(
0, core.getDescriptorSet(updateGridForcesSets[0]).vulkanHandle
) },
- timePushConstants
+ physicsPushConstants
);
core.recordImageMemoryBarrier(cmdStream, grid.getHandle());
@@ -686,7 +695,7 @@ int main(int argc, const char **argv) {
{ vkcv::DescriptorSetUsage(
0, core.getDescriptorSet(updateParticlePositionsSets[0]).vulkanHandle
) },
- timePushConstants
+ physicsPushConstants
);
core.recordBufferMemoryBarrier(cmdStream, particles.getHandle());
@@ -748,6 +757,9 @@ int main(int argc, const char **argv) {
ImGui::Begin("Settings");
+ ImGui::SliderFloat("Compression Modulus", &compression_modulus, 0.0f, 500.0f);
+ ImGui::SliderFloat("Elasticity Modulus", &elasticity_modulus, 0.0f, 1000.0f);
+
ImGui::Checkbox("Render Grid", &renderGrid);
ImGui::SliderFloat("Alpha (PIC -> FLIP)", &alpha, 0.0f, 1.0f);
ImGui::SameLine(0.0f, 10.0f);
@@ -760,7 +772,7 @@ int main(int argc, const char **argv) {
beta = 0.75f;
}
- ImGui::DragFloat3("Initial velocity", reinterpret_cast<float*>(&initialVelocity));
+ ImGui::DragFloat3("Initial Velocity", reinterpret_cast<float*>(&initialVelocity));
ImGui::SameLine(0.0f, 10.0f);
if (ImGui::Button("Reset##particle_velocity")) {
resetParticles(particles, initialVelocity);