1/* 2The MIT License (MIT) 3 4Copyright (c) 2022 Sascha Willems 5 6Permission is hereby granted, free of charge, to any person obtaining a copy 7of this software and associated documentation files (the "Software"), to deal 8in the Software without restriction, including without limitation the rights 9to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10copies of the Software, and to permit persons to whom the Software is 11furnished to do so, subject to the following conditions: 12 13The above copyright notice and this permission notice shall be included in all 14copies or substantial portions of the Software. 15 16THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22SOFTWARE. 23*/ 24 25#version 450 26 27struct Particle { 28 vec4 pos; 29 vec4 vel; 30 vec4 uv; 31 vec4 normal; 32 float pinned; 33}; 34 35layout(std430, binding = 0) buffer ParticleIn { 36 Particle particleIn[ ]; 37}; 38 39layout(std430, binding = 1) buffer ParticleOut { 40 Particle particleOut[ ]; 41}; 42 43// todo: use shared memory to speed up calculation 44 45layout (local_size_x = 10, local_size_y = 10) in; 46 47layout (binding = 2) uniform UBO 48{ 49 float deltaT; 50 float particleMass; 51 float springStiffness; 52 float damping; 53 float restDistH; 54 float restDistV; 55 float restDistD; 56 float sphereRadius; 57 vec4 spherePos; 58 vec4 gravity; 59 ivec2 particleCount; 60} params; 61 62layout (push_constant) uniform PushConsts { 63 uint calculateNormals; 64} pushConsts; 65 66vec3 springForce(vec3 p0, vec3 p1, float restDist) 67{ 68 vec3 dist = p0 - p1; 69 return normalize(dist) * params.springStiffness * (length(dist) - restDist); 70} 71 72void main() 73{ 74 uvec3 id = gl_GlobalInvocationID; 75 76 uint index = id.y * params.particleCount.x + id.x; 77 if (index > params.particleCount.x * params.particleCount.y) 78 return; 79 80 // Pinned? 81 if (particleIn[index].pinned == 1.0) { 82 particleOut[index].pos = particleOut[index].pos; 83 particleOut[index].vel = vec4(0.0); 84 return; 85 } 86 87 // Initial force from gravity 88 vec3 force = params.gravity.xyz * params.particleMass; 89 90 vec3 pos = particleIn[index].pos.xyz; 91 vec3 vel = particleIn[index].vel.xyz; 92 93 // Spring forces from neighboring particles 94 // left 95 if (id.x > 0) { 96 force += springForce(particleIn[index-1].pos.xyz, pos, params.restDistH); 97 } 98 // right 99 if (id.x < params.particleCount.x - 1) { 100 force += springForce(particleIn[index + 1].pos.xyz, pos, params.restDistH); 101 } 102 // upper 103 if (id.y < params.particleCount.y - 1) { 104 force += springForce(particleIn[index + params.particleCount.x].pos.xyz, pos, params.restDistV); 105 } 106 // lower 107 if (id.y > 0) { 108 force += springForce(particleIn[index - params.particleCount.x].pos.xyz, pos, params.restDistV); 109 } 110 // upper-left 111 if ((id.x > 0) && (id.y < params.particleCount.y - 1)) { 112 force += springForce(particleIn[index + params.particleCount.x - 1].pos.xyz, pos, params.restDistD); 113 } 114 // lower-left 115 if ((id.x > 0) && (id.y > 0)) { 116 force += springForce(particleIn[index - params.particleCount.x - 1].pos.xyz, pos, params.restDistD); 117 } 118 // upper-right 119 if ((id.x < params.particleCount.x - 1) && (id.y < params.particleCount.y - 1)) { 120 force += springForce(particleIn[index + params.particleCount.x + 1].pos.xyz, pos, params.restDistD); 121 } 122 // lower-right 123 if ((id.x < params.particleCount.x - 1) && (id.y > 0)) { 124 force += springForce(particleIn[index - params.particleCount.x + 1].pos.xyz, pos, params.restDistD); 125 } 126 127 force += (-params.damping * vel); 128 129 // Integrate 130 vec3 f = force * (1.0 / params.particleMass); 131 particleOut[index].pos = vec4(pos + vel * params.deltaT + 0.5 * f * params.deltaT * params.deltaT, 1.0); 132 particleOut[index].vel = vec4(vel + f * params.deltaT, 0.0); 133 134 // Sphere collision 135 vec3 sphereDist = particleOut[index].pos.xyz - params.spherePos.xyz; 136 if (length(sphereDist) < params.sphereRadius + 0.01) { 137 // If the particle is inside the sphere, push it to the outer radius 138 particleOut[index].pos.xyz = params.spherePos.xyz + normalize(sphereDist) * (params.sphereRadius + 0.01); 139 // Cancel out velocity 140 particleOut[index].vel = vec4(0.0); 141 } 142 143 // Normals 144 if (pushConsts.calculateNormals == 1) { 145 vec3 normal = vec3(0.0); 146 vec3 a, b, c; 147 if (id.y > 0) { 148 if (id.x > 0) { 149 a = particleIn[index - 1].pos.xyz - pos; 150 b = particleIn[index - params.particleCount.x - 1].pos.xyz - pos; 151 c = particleIn[index - params.particleCount.x].pos.xyz - pos; 152 normal += cross(a,b) + cross(b,c); 153 } 154 if (id.x < params.particleCount.x - 1) { 155 a = particleIn[index - params.particleCount.x].pos.xyz - pos; 156 b = particleIn[index - params.particleCount.x + 1].pos.xyz - pos; 157 c = particleIn[index + 1].pos.xyz - pos; 158 normal += cross(a,b) + cross(b,c); 159 } 160 } 161 if (id.y < params.particleCount.y - 1) { 162 if (id.x > 0) { 163 a = particleIn[index + params.particleCount.x].pos.xyz - pos; 164 b = particleIn[index + params.particleCount.x - 1].pos.xyz - pos; 165 c = particleIn[index - 1].pos.xyz - pos; 166 normal += cross(a,b) + cross(b,c); 167 } 168 if (id.x < params.particleCount.x - 1) { 169 a = particleIn[index + 1].pos.xyz - pos; 170 b = particleIn[index + params.particleCount.x + 1].pos.xyz - pos; 171 c = particleIn[index + params.particleCount.x].pos.xyz - pos; 172 normal += cross(a,b) + cross(b,c); 173 } 174 } 175 particleOut[index].normal = vec4(normalize(normal), 0.0f); 176 } 177} 178