135 lines
3.7 KiB
WebGPU Shading Language
135 lines
3.7 KiB
WebGPU Shading Language
// Copyright 2020 The Tint Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// vertex shader
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[[stage(vertex)]]
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fn vert_main([[location(0)]] a_particlePos : vec2<f32>,
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[[location(1)]] a_particleVel : vec2<f32>,
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[[location(2)]] a_pos : vec2<f32>)
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-> [[builtin(position)]] vec4<f32> {
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var angle : f32 = -atan2(a_particleVel.x, a_particleVel.y);
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var pos : vec2<f32> = vec2<f32>(
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(a_pos.x * cos(angle)) - (a_pos.y * sin(angle)),
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(a_pos.x * sin(angle)) + (a_pos.y * cos(angle)));
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return vec4<f32>(pos + a_particlePos, 0.0, 1.0);
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}
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// fragment shader
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[[stage(fragment)]]
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fn frag_main() -> [[location(0)]] vec4<f32> {
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return vec4<f32>(1.0, 1.0, 1.0, 1.0);
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}
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// compute shader
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struct Particle {
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pos : vec2<f32>;
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vel : vec2<f32>;
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};
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[[block]] struct SimParams {
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deltaT : f32;
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rule1Distance : f32;
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rule2Distance : f32;
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rule3Distance : f32;
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rule1Scale : f32;
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rule2Scale : f32;
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rule3Scale : f32;
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};
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[[block]] struct Particles {
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particles : array<Particle, 5>;
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};
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[[binding(0), group(0)]] var<uniform> params : SimParams;
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[[binding(1), group(0)]] var<storage> particlesA : [[access(read_write)]] Particles;
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[[binding(2), group(0)]] var<storage> particlesB : [[access(read_write)]] Particles;
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// https://github.com/austinEng/Project6-Vulkan-Flocking/blob/master/data/shaders/computeparticles/particle.comp
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[[stage(compute)]]
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fn comp_main(
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[[builtin(global_invocation_id)]] gl_GlobalInvocationID : vec3<u32>) {
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var index : u32 = gl_GlobalInvocationID.x;
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if (index >= 5u) {
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return;
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}
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var vPos : vec2<f32> = particlesA.particles[index].pos;
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var vVel : vec2<f32> = particlesA.particles[index].vel;
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var cMass : vec2<f32> = vec2<f32>(0.0, 0.0);
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var cVel : vec2<f32> = vec2<f32>(0.0, 0.0);
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var colVel : vec2<f32> = vec2<f32>(0.0, 0.0);
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var cMassCount : i32 = 0;
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var cVelCount : i32 = 0;
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var pos : vec2<f32>;
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var vel : vec2<f32>;
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for(var i : u32 = 0u; i < 5u; i = i + 1u) {
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if (i == index) {
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continue;
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}
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pos = particlesA.particles[i].pos.xy;
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vel = particlesA.particles[i].vel.xy;
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if (distance(pos, vPos) < params.rule1Distance) {
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cMass = cMass + pos;
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cMassCount = cMassCount + 1;
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}
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if (distance(pos, vPos) < params.rule2Distance) {
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colVel = colVel - (pos - vPos);
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}
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if (distance(pos, vPos) < params.rule3Distance) {
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cVel = cVel + vel;
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cVelCount = cVelCount + 1;
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}
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}
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if (cMassCount > 0) {
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cMass =
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(cMass / vec2<f32>(f32(cMassCount), f32(cMassCount))) - vPos;
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}
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if (cVelCount > 0) {
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cVel = cVel / vec2<f32>(f32(cVelCount), f32(cVelCount));
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}
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vVel = vVel + (cMass * params.rule1Scale) + (colVel * params.rule2Scale) +
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(cVel * params.rule3Scale);
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// clamp velocity for a more pleasing simulation
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vVel = normalize(vVel) * clamp(length(vVel), 0.0, 0.1);
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// kinematic update
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vPos = vPos + (vVel * params.deltaT);
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// Wrap around boundary
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if (vPos.x < -1.0) {
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vPos.x = 1.0;
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}
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if (vPos.x > 1.0) {
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vPos.x = -1.0;
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}
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if (vPos.y < -1.0) {
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vPos.y = 1.0;
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}
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if (vPos.y > 1.0) {
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vPos.y = -1.0;
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}
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// Write back
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particlesB.particles[index].pos = vPos;
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particlesB.particles[index].vel = vVel;
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}
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