From c7d03d508a360d69cadc4052e860819ce01c5f39 Mon Sep 17 00:00:00 2001
From: Tobias Frisch <tfrisch@uni-koblenz.de>
Date: Sun, 30 Jan 2022 01:11:54 +0100
Subject: [PATCH] Added elastic force calculation (I think..)
Signed-off-by: Tobias Frisch <tfrisch@uni-koblenz.de>
---
.../shaders/transform_particles_to_grid.comp | 2 +
.../shaders/update_grid_forces.comp | 51 ++++++++++++++++++-
projects/wobble_bobble/src/main.cpp | 1 +
3 files changed, 53 insertions(+), 1 deletion(-)
diff --git a/projects/wobble_bobble/shaders/transform_particles_to_grid.comp b/projects/wobble_bobble/shaders/transform_particles_to_grid.comp
index defc9c3e..bfd902b5 100644
--- a/projects/wobble_bobble/shaders/transform_particles_to_grid.comp
+++ b/projects/wobble_bobble/shaders/transform_particles_to_grid.comp
@@ -29,6 +29,8 @@ void main() {
if (localOffset < particles.length()) {
shared_particles[gl_LocalInvocationIndex] = particles[localOffset].minimal;
} else {
+ shared_particles[gl_LocalInvocationIndex].position = vec3(0.0f);
+ shared_particles[gl_LocalInvocationIndex].size = 0.0f;
shared_particles[gl_LocalInvocationIndex].velocity = vec3(0.0f);
shared_particles[gl_LocalInvocationIndex].mass = 0.0f;
}
diff --git a/projects/wobble_bobble/shaders/update_grid_forces.comp b/projects/wobble_bobble/shaders/update_grid_forces.comp
index cfb8e201..4920e493 100644
--- a/projects/wobble_bobble/shaders/update_grid_forces.comp
+++ b/projects/wobble_bobble/shaders/update_grid_forces.comp
@@ -1,18 +1,30 @@
#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"
layout(set=0, binding=0, rgba32f) uniform image3D gridImage;
+layout(set=0, binding=1, std430) buffer particleBuffer {
+ Particle particles [];
+};
layout( push_constant ) uniform constants {
float t;
float dt;
};
+#define SHARED_PARTICLES_BATCH_SIZE 64
+
+shared Particle shared_particles [SHARED_PARTICLES_BATCH_SIZE];
+
void main() {
+ const vec3 position = (vec3(gl_GlobalInvocationID) + vec3(0.5f)) / imageSize(gridImage);
+ const float elasticity_module = 12.5f * 1000000.0f; // 10..15 = Wood
+
memoryBarrierImage();
vec4 gridSample = imageLoad(
@@ -23,7 +35,44 @@ void main() {
vec3 velocity = gridSample.xyz;
float mass = gridSample.w;
- velocity += vec3(0.0f, 0.0f, 0.0f) * dt;
+ vec3 force = vec3(0.0f);
+ uint offset = 0;
+
+ memoryBarrierBuffer();
+
+ for (offset = 0; offset < particles.length(); offset += SHARED_PARTICLES_BATCH_SIZE) {
+ uint localOffset = offset + gl_LocalInvocationIndex;
+
+ if (localOffset < particles.length()) {
+ shared_particles[gl_LocalInvocationIndex] = particles[localOffset];
+ } else {
+ shared_particles[gl_LocalInvocationIndex].minimal.position = vec3(0.0f);
+ shared_particles[gl_LocalInvocationIndex].minimal.size = 0.0f;
+ shared_particles[gl_LocalInvocationIndex].minimal.velocity = vec3(0.0f);
+ shared_particles[gl_LocalInvocationIndex].minimal.mass = 0.0f;
+ shared_particles[gl_LocalInvocationIndex].deformation = mat4(0.0f);
+ }
+
+ 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;
+ mat3 deformation = mat3(shared_particles[gl_LocalInvocationIndex].deformation);
+
+ mat3 epsilon = deformation - mat3(1.0f);
+ mat3 delta = elasticity_module * epsilon;
+ mat3 delta_cauchy = determinant(deformation) * delta * inverse(transpose(deformation));
+
+ force -= (
+ volume *
+ delta_cauchy *
+ vec3(voxel_particle_weight(position, shared_particles[gl_LocalInvocationIndex].minimal))
+ );
+ }
+ }
+
+ velocity += force * dt / mass;
bvec3 lowerID = lessThanEqual(gl_GlobalInvocationID, ivec3(0));
bvec3 negativeVelocity = lessThan(velocity, vec3(0.0f));
diff --git a/projects/wobble_bobble/src/main.cpp b/projects/wobble_bobble/src/main.cpp
index 674af9b1..f76a7d53 100644
--- a/projects/wobble_bobble/src/main.cpp
+++ b/projects/wobble_bobble/src/main.cpp
@@ -214,6 +214,7 @@ int main(int argc, const char **argv) {
{
vkcv::DescriptorWrites writes;
writes.storageImageWrites.push_back(vkcv::StorageImageDescriptorWrite(0, grid.getHandle()));
+ writes.storageBufferWrites.push_back(vkcv::BufferDescriptorWrite(1, particles.getHandle()));
core.writeDescriptorSet(updateGridForcesSets[0], writes);
}
--
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