From bebb4481a03607a6306eeaa6ec16842685163586 Mon Sep 17 00:00:00 2001
From: Tobias Frisch <tfrisch@uni-koblenz.de>
Date: Sat, 26 Jun 2021 21:11:43 +0200
Subject: [PATCH] [#69] Added physically plausible gravity shader with
simulation pre-factors
Signed-off-by: Tobias Frisch <tfrisch@uni-koblenz.de>
---
.../shaders/shader_gravity.comp | 80 +++++++++++++++++++
projects/particle_simulation/src/Particle.hpp | 2 +-
2 files changed, 81 insertions(+), 1 deletion(-)
create mode 100644 projects/particle_simulation/shaders/shader_gravity.comp
diff --git a/projects/particle_simulation/shaders/shader_gravity.comp b/projects/particle_simulation/shaders/shader_gravity.comp
new file mode 100644
index 00000000..77954958
--- /dev/null
+++ b/projects/particle_simulation/shaders/shader_gravity.comp
@@ -0,0 +1,80 @@
+#version 450 core
+#extension GL_ARB_separate_shader_objects : enable
+
+layout(local_size_x = 256) in;
+
+struct Particle
+{
+ vec3 position;
+ float lifeTime;
+ vec3 velocity;
+ float mass;
+ vec3 reset_velocity;
+ float _padding;
+};
+
+layout(std430, binding = 0) coherent buffer buffer_inParticle
+{
+ Particle inParticle[];
+};
+
+layout( push_constant ) uniform constants{
+ float deltaTime;
+ float rand;
+};
+
+const int n = 4;
+vec4 gravityPoint[n] = vec4[n](
+ vec4(-0.8, -0.5, 0.0, 3),
+ vec4(-0.4, 0.5, 0.8, 2),
+ vec4( 0.8, 0.8, -0.3, 4),
+ vec4( 0.5, -0.7, -0.5, 1)
+);
+
+const float G = 6.6743015e-11;
+const float sim_d_factor = 10e11;
+const float sim_g_factor = 10e30;
+const float sim_t_factor = 5;
+const float c = 299792458;
+
+void main() {
+ uint id = gl_GlobalInvocationID.x;
+ inParticle[id].lifeTime -= deltaTime;
+ vec3 pos = inParticle[id].position;
+ vec3 vel = inParticle[id].velocity;
+ float mass = inParticle[id].mass;
+
+ if(inParticle[id].lifeTime < 0.f)
+ {
+ inParticle[id].lifeTime = 5.f * rand;
+ inParticle[id].mass *= rand;
+
+ pos = vec3(0);
+ vel *= rand;
+ }
+
+ for(int i = 0; i < n; i++)
+ {
+ vec3 d = (gravityPoint[i].xyz - pos) * sim_d_factor;
+ float r = length(d);
+ float g = G * (gravityPoint[i].w * sim_g_factor) / (r * r);
+
+ if (r > 0) {
+ vec3 dvel = (deltaTime * sim_t_factor) * g * (d / r);
+
+ vel = (vel + dvel) / (1.0 + dot(vel, dvel) / (c*c));
+ }
+ }
+
+ pos += vel * (deltaTime * sim_t_factor);
+
+ vec3 a_pos = abs(pos);
+
+ if ((a_pos.x > 2.0) || (a_pos.y > 2.0) || (a_pos.z > 2.0))
+ {
+ inParticle[id].lifeTime *= 0.9;
+ }
+
+ inParticle[id].position = pos;
+ inParticle[id].velocity = vel;
+}
diff --git a/projects/particle_simulation/src/Particle.hpp b/projects/particle_simulation/src/Particle.hpp
index 268e4bcf..f374218f 100644
--- a/projects/particle_simulation/src/Particle.hpp
+++ b/projects/particle_simulation/src/Particle.hpp
@@ -28,7 +28,7 @@ private:
glm::vec3 m_position;
float m_lifeTime;
glm::vec3 m_velocity;
- float padding_2 = 0.f;
+ float mass = 1.f;
glm::vec3 m_reset_velocity;
float padding_3 = 0.f;
};
--
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