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WIP combining indirect buffers
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@toji
toji committed Jan 9, 2024
1 parent f819f63 commit 8736472
Showing 1 changed file with 67 additions and 21 deletions.
88 changes: 67 additions & 21 deletions index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,8 @@
const MAX_INSTANCES_PER_DRAWABLE = QueryArgs.getInt("instancesPerDrawable", navigator.userAgentData?.mobile ? 500 : 1000);
const INSTANCE_ELEMENT_LENGTH = 16;

const SPLIT_INDIRECT_ARGS_BUFFER = QueryArgs.getBool("splitIndirectArgsBuffer", true);

const GEOMETRY_SHADER = (geometry, culled = false) => {
const layout = geometry.layout;

Expand All @@ -52,13 +54,18 @@
@group(1) @binding(0) var<uniform> material: Material;
@group(2) @binding(0) var<storage, read> instances: array<mat4x4f>;
@group(2) @binding(1) var<storage, read> culledInstances: array<u32>;
struct CulledInstances {
indirectIndex: u32,
instances: array<u32>,
}
@group(2) @binding(1) var<storage, read> culled: CulledInstances;
@vertex
fn vertexMain(in: VertexIn) -> VertexOut {
var out: VertexOut;
#if ${culled}
let instanceIndex = culledInstances[in.instanceIndex];
let instanceIndex = culled.instances[in.instanceIndex];
#else
let instanceIndex = in.instanceIndex;
#endif
Expand Down Expand Up @@ -100,13 +107,21 @@
@group(0) @binding(0) var<uniform> camera: CameraUniforms;
@group(1) @binding(0) var<storage, read> instances: array<mat4x4f>;
@group(1) @binding(1) var<storage, read_write> culledInstances: array<u32>;
struct CulledInstances {
indirectIndex: u32,
instances: array<u32>,
}
@group(1) @binding(1) var<storage, read_write> culled: CulledInstances;
struct IndirectArgs {
drawCount: u32,
instanceCount: atomic<u32>,
reserved0: u32,
reserved1: u32,
reserved2: u32,
}
@group(1) @binding(2) var<storage, read_write> indirect: IndirectArgs;
@group(1) @binding(2) var<storage, read_write> indirectArgs: array<IndirectArgs>;
fn isVisible(instanceIndex: u32) -> bool {
let model = instances[instanceIndex];
Expand All @@ -130,8 +145,8 @@
if (!isVisible(instanceIndex)) { return; }
let culledIndex = atomicAdd(&indirect.instanceCount, 1u);
culledInstances[culledIndex] = instanceIndex;
let culledIndex = atomicAdd(&indirectArgs[culled.indirectIndex].instanceCount, 1u);
culled.instances[culledIndex] = instanceIndex;
}
`;

Expand Down Expand Up @@ -398,6 +413,20 @@

this.instanceArray = new Float32Array(MAX_INSTANCES_PER_DRAWABLE * INSTANCE_ELEMENT_LENGTH);

let indirectBuffer;
let indirectBufferOffset = 0;
let indirectArgs;

if (!SPLIT_INDIRECT_ARGS_BUFFER) {
indirectBuffer = this.device.createBuffer({
label: 'Instance indirect',
size: 20 * this.materials.length * this.geometries.length,
usage: GPUBufferUsage.INDIRECT | GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_DST,
mappedAtCreation: true,
});
indirectArgs = new Uint32Array(indirectBuffer.getMappedRange());
}

for (const material of this.materials) {
for (const geometry of this.geometries) {
let instances = [];
Expand All @@ -416,22 +445,34 @@
usage: GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_DST
});

const indirectOffset = indirectBufferOffset;
if (SPLIT_INDIRECT_ARGS_BUFFER) {
indirectBuffer = this.device.createBuffer({
label: 'Instance indirect',
size: 20,
usage: GPUBufferUsage.INDIRECT | GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_DST,
mappedAtCreation: true,
});
const indirectArgs = new Uint32Array(indirectBuffer.getMappedRange());
indirectArgs[0] = geometry.drawCount;
indirectArgs[1] = MAX_INSTANCES_PER_DRAWABLE;
indirectBuffer.unmap();
} else {
const index = (indirectOffset / 20) * 5;
indirectArgs[index] = geometry.drawCount;
indirectArgs[index+1] = MAX_INSTANCES_PER_DRAWABLE;
indirectBufferOffset += 20;
}

const culledInstanceBuffer = this.device.createBuffer({
label: 'Culled Instance',
size: MAX_INSTANCES_PER_DRAWABLE * Uint32Array.BYTES_PER_ELEMENT,
usage: GPUBufferUsage.STORAGE
});

const indirectBuffer = this.device.createBuffer({
label: 'Instance indirect',
size: 20,
usage: GPUBufferUsage.INDIRECT | GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_DST,
size: (MAX_INSTANCES_PER_DRAWABLE * Uint32Array.BYTES_PER_ELEMENT) + 4,
usage: GPUBufferUsage.STORAGE,
mappedAtCreation: true,
});
const indirectArgs = new Uint32Array(indirectBuffer.getMappedRange());
indirectArgs[0] = geometry.drawCount;
indirectArgs[1] = MAX_INSTANCES_PER_DRAWABLE;
indirectBuffer.unmap();
const culledInstanceArray = new Uint32Array(culledInstanceBuffer.getMappedRange(0, 4));
culledInstanceArray[0] = indirectOffset / 20;
culledInstanceBuffer.unmap();

const instanceBindGroup = this.device.createBindGroup({
label: 'Instance',
Expand Down Expand Up @@ -467,12 +508,17 @@
instanceCount: MAX_INSTANCES_PER_DRAWABLE,
instanceBuffer,
indirectBuffer,
indirectOffset,
instanceBindGroup,
culledInstanceBindGroup,
});
}
}

if (!SPLIT_INDIRECT_ARGS_BUFFER) {
indirectBuffer.unmap();
}

this.updateInstanceBuffer(performance.now());

const updateInstanceCount = () => {
Expand Down Expand Up @@ -588,7 +634,7 @@
commandEncoder.pushDebugGroup('Reset indirect instance counts');
// Clear the instance count of the indirect buffer for each drawable
for (const drawable of this.drawables) {
commandEncoder.clearBuffer(drawable.indirectBuffer, 4, 4);
commandEncoder.clearBuffer(drawable.indirectBuffer, drawable.indirectOffset + 4, 4);
}
commandEncoder.popDebugGroup();

Expand Down Expand Up @@ -637,9 +683,9 @@

case RenderModes.culled:
if(drawable.geometry.indexBinding) {
renderEncoder.drawIndexedIndirect(drawable.indirectBuffer, 0);
renderEncoder.drawIndexedIndirect(drawable.indirectBuffer, drawable.indirectOffset);
} else {
renderEncoder.drawIndirect(drawable.indirectBuffer, 0);
renderEncoder.drawIndirect(drawable.indirectBuffer, drawable.indirectOffset);
}
break;
}
Expand Down

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