VfxGpuSimulation

Remarks

What this owns and what it does not. It owns the buffers a VfxShaderEmitter-emitted shader binds, the descriptor set that names them, and the pipeline layout the two kernels share. It does not own the pipelines: turning Raven source into a module is the shader compiler's job, and a runtime that linked against one would be a runtime that shipped a compiler. The caller compiles and hands the PipelineHandle to Initialize and Update.

Why it lives here rather than in Vixen.Vfx. The particle runtime is device-free by design — it is testable, jobifiable and shippable without a graphics API, and its README says so. This is the module that already owns an IGraphicsDevice. What crosses the line is the layout, and that stayed behind: this file asks VfxShaderPacking what the bytes look like rather than knowing.

Upload and download are stalls, and are meant to be rare. A GPU effect exists so that particle state never leaves the device; the two transfer paths are here for the two cases where it must — seeding a system from a CPU spawn, and reading the result back to compare it against the CPU backend, which is the only way to ask whether the two agree. Neither belongs in a frame. The dispatches do, and they touch neither.

The push constants are the whole per-dispatch state. Twenty bytes written into the command buffer, so an initialize and an update can be recorded into one list with different values — which a uniform buffer could not do without being two buffers. See VfxShaderUniforms, whose field order is the shader's declaration order.

Fields and properties (9)

• public const int DrawArgumentsSize

  How many bytes a DrawIndexedIndirect command occupies.

• public int Capacity

  The most particles that can be alive at once.

• public long Bytes

  How much one set of the attributes occupies, in bytes.

• public bool HasReap

  Whether the shader has a reap kernel, and so whether this has the storage for one.

• public IReadOnlyList<VfxShaderBinding> Bindings

  The buffers, in the order the shader declares them.

• public PipelineLayoutHandle Layout

  The layout every kernel is created against.

• public DescriptorSetHandle Descriptors

  The set naming the live buffers as the source and the spare as the destination.

• public BufferHandle DrawArguments

  The indirect draw command WriteDrawArguments keeps up to date.

• public int IndicesPerParticle

  How many indices one particle's geometry uses.

Methods (13)

• public VfxGpuSimulation(IGraphicsDevice device, VfxShader shader, int capacity)

  Allocates the storage one emitted shader expects, and the descriptors naming it.

• public BufferHandle Storage(VfxAttribute attribute)

  The buffer holding one attribute, for a renderer that wants to draw from it.

• public BufferHandle Custom(int slot)

  The buffer holding one custom attribute.

• public static int Groups(int count)

  How many workgroups cover a run of particles.

• public void Upload(ICommandList list, ParticleBuffer particles, int count)

  Records the copies that put a CPU buffer's particles on the device.

• public void Initialize(ICommandList list, PipelineHandle pipeline, int first, int count, uint seed, float time, Vector3 origin = default(Vector3))

  Records the initializer dispatch over one run of newly spawned particles.

• public void Update(ICommandList list, PipelineHandle pipeline, int count, float deltaTime, uint seed, float time)

  Records the update dispatch over every live particle.

• public void Download(ICommandList list, int count)

  Records the copies that bring the device's particles back.

• public void Read(ParticleBuffer particles, int count)

  Puts a completed Download into a CPU buffer.

• public void Reap(ICommandList list, PipelineHandle pipeline, int count)

  Records the compaction: every survivor claims a slot, and the dead leave no hole.

• public int ReadSurvivors()

  How many particles the last Reap kept.

• public void WriteDrawArguments(ICommandList list)

  Records the copies that put the survivor count into the indirect draw command.

• public void Dispose()

  Frees every device object it made.

Used by (4)

• VfxAgreementTestsVixen.Vfx.Gpu.Tests
• VfxGpuSortVixen.Rendering
• VfxReapTestsVixen.Vfx.Gpu.Tests
• VfxSortTestsVixen.Vfx.Gpu.Tests