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Prevent liquid emitters from emitting if the neighbourhood is already…
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… heavily compressed. This prevents severe overpressure from developing in the sim.
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Chris Lewin committed Aug 20, 2024
1 parent 03c25d9 commit e0536f8
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Showing 4 changed files with 83 additions and 83 deletions.
138 changes: 63 additions & 75 deletions scenes/seedLogo.json
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Original file line number Diff line number Diff line change
@@ -1,213 +1,196 @@
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"settings": [
Expand All @@ -219,7 +202,7 @@
{
"name": "fixedPointMultiplierExponent",
"type": "range",
"value": "6"
"value": "8"
},
{
"name": "gravityStrength",
Expand All @@ -231,6 +214,11 @@
"type": "range",
"value": "0"
},
{
"name": "borderFriction",
"type": "range",
"value": "0"
},
{
"name": "renderMode",
"type": "combo",
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2 changes: 1 addition & 1 deletion shaders/g2p2g.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -362,7 +362,7 @@ fn csMain( @builtin(local_invocation_index) indexInGroup: u32, @builtin(workgrou
}


if(g_simConstants.iteration != g_simConstants.iterationCount-1)
//if(g_simConstants.iteration != g_simConstants.iterationCount-1)
{
// Particle update
if(particle.material == MaterialLiquid)
Expand Down
16 changes: 13 additions & 3 deletions shaders/particleEmit.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
@group(0) @binding(2) var<storage, read_write> g_particles : array<Particle>;
@group(0) @binding(3) var<storage> g_shapes : array<SimShape>;
@group(0) @binding(4) var<storage, read_write> g_freeIndices : array<atomic<i32>>;
@group(0) @binding(5) var<storage> g_grid : array<i32>;

fn createParticle(position: vec2f, material: f32, mass: f32, volume: f32, color: vec3f) -> Particle
{
Expand Down Expand Up @@ -93,7 +94,9 @@ fn csMain( @builtin(global_invocation_id) id: vec3u )
let gridSize = g_simConstants.gridSize;
let pos = vec2f(id.xy);


let weightInfo = quadraticWeightInit(pos);
let nearestCell = vec2i(weightInfo.cellIndex) + vec2i(1,1);
let nearestCellVolume = decodeFixedPoint(g_grid[gridVertexIndex(vec2u(nearestCell), g_simConstants.gridSize) + 3], g_simConstants.fixedPointMultiplier);

for(var shapeIndex = 0u; shapeIndex < g_simConstants.shapeCount; shapeIndex++)
{
Expand All @@ -107,6 +110,12 @@ fn csMain( @builtin(global_invocation_id) id: vec3u )
continue;
}

// Skip emission if we are spewing liquid into an already compressed space
if(isEmitter && shape.emitMaterial == MaterialLiquid && nearestCellVolume > 1.5)
{
continue;
}

let particleCountPerCellAxis = u32(g_simConstants.particlesPerCellAxis);
let volumePerParticle = 1.0f / f32(particleCountPerCellAxis*particleCountPerCellAxis);

Expand All @@ -115,7 +124,6 @@ fn csMain( @builtin(global_invocation_id) id: vec3u )
{
let emitEvery = u32(1.0 / (shape.emissionRate * g_simConstants.deltaTime));


for(var i = 0u; i < particleCountPerCellAxis; i++)
{
for(var j = 0u; j < particleCountPerCellAxis; j++)
Expand All @@ -127,9 +135,11 @@ fn csMain( @builtin(global_invocation_id) id: vec3u )
let emitDueToMyTurnHappening = isEmitter && 0 == ((hashCode + g_simConstants.simFrame) % emitEvery);
let emitDueToInitialEmission = isInitialEmitter && g_simConstants.simFrame == 0;

let emitPos = pos + vec2f(f32(i),f32(j))/f32(particleCountPerCellAxis);

if(emitDueToInitialEmission || emitDueToMyTurnHappening)
{
addParticle(pos + vec2f(f32(i),f32(j))/f32(particleCountPerCellAxis), shape.emitMaterial, volumePerParticle, 1.0, 1.0/f32(particleCountPerCellAxis));
addParticle(emitPos, shape.emitMaterial, volumePerParticle, 1.0, 1.0/f32(particleCountPerCellAxis));
}
}
}
Expand Down
10 changes: 6 additions & 4 deletions src/sim.js
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Original file line number Diff line number Diff line change
Expand Up @@ -125,13 +125,13 @@ export function init(insertHandlers)
g_shapeFactory = shapeFactory;
}

function doEmission(gpuContext, simUniformBuffer, inputs, shapeBuffer)
function doEmission(gpuContext, simUniformBuffer, inputs, shapeBuffer, gridBuffer)
{
const threadGroupCountX = gpu.divUp(inputs.gridSize[0], DispatchSizes.GridDispatchSize);
const threadGroupCountY = gpu.divUp(inputs.gridSize[1], DispatchSizes.GridDispatchSize);
const gridThreadGroupCounts = [threadGroupCountX, threadGroupCountY, 1];

gpu.computeDispatch(Shaders.particleEmit, [simUniformBuffer, gpuContext.particleCountBuffer, gpuContext.particleBuffer, shapeBuffer, gpuContext.particleFreeIndicesBuffer], gridThreadGroupCounts);
gpu.computeDispatch(Shaders.particleEmit, [simUniformBuffer, gpuContext.particleCountBuffer, gpuContext.particleBuffer, shapeBuffer, gpuContext.particleFreeIndicesBuffer, gridBuffer], gridThreadGroupCounts);
gpu.computeDispatch(Shaders.setIndirectArgs, [gpuContext.particleCountBuffer, gpuContext.particleSimDispatchBuffer, gpuContext.particleRenderDispatchBuffer], [1,1,1]);
}

Expand Down Expand Up @@ -183,8 +183,7 @@ export function update(gpuContext, inputs)
for(let substepIdx = 0; substepIdx < substepCount; ++substepIdx)
{
var simUniformBuffer = constructSimUniformBuffer(gpuContext, inputs, bukkitSystem, 0);
doEmission(gpuContext, simUniformBuffer, inputs, shapeBuffer);
bukkitizeParticles(gpuContext, simUniformBuffer, bukkitSystem);


for(let iterationIdx = 0; iterationIdx < inputs.iterationCount; ++iterationIdx)
{
Expand All @@ -198,6 +197,9 @@ export function update(gpuContext, inputs)
gpu.computeDispatch(Shaders.g2p2g, [simUniformBuffer, gpuContext.particleBuffer, currentGrid, nextGrid, nextNextGrid, bukkitSystem.threadData, bukkitSystem.particleData, shapeBuffer, gpuContext.particleFreeIndicesBuffer], bukkitSystem.dispatch)
}

doEmission(gpuContext, simUniformBuffer, inputs, shapeBuffer, gridBuffers[bufferIdx]);
bukkitizeParticles(gpuContext, simUniformBuffer, bukkitSystem);

g_substepIndex = (g_substepIndex + 1);
}
}
Expand Down

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