playcanvas
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Open-source WebGL/WebGPU 3D engine for the web
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JavaScript
/**
* @import { GraphicsDevice } from './graphics-device.js'
* @import { IndexBuffer } from './index-buffer.js'
* @import { ScopeId } from './scope-id.js'
* @import { Shader } from './shader.js'
* @import { StorageBuffer } from './storage-buffer.js'
* @import { Texture } from './texture.js'
* @import { TextureView } from './texture-view.js'
* @import { Vec2 } from '../../core/math/vec2.js'
* @import { VertexBuffer } from './vertex-buffer.js'
*/ /**
* A helper class storing a parameter value as well as its scope ID.
*
* @ignore
*/ class ComputeParameter {
constructor(){
/** @type {ScopeId} */ this.scopeId = null;
}
}
/**
* A representation of a compute shader with the associated resources, that can be executed on the
* GPU. Only supported on WebGPU platform.
*/ class Compute {
/**
* Sets a shader parameter on a compute instance.
*
* @param {string} name - The name of the parameter to set.
* @param {number|number[]|Float32Array|Texture|StorageBuffer|VertexBuffer|IndexBuffer|TextureView} value -
* The value for the specified parameter.
*/ setParameter(name, value) {
let param = this.parameters.get(name);
if (!param) {
param = new ComputeParameter();
param.scopeId = this.device.scope.resolve(name);
this.parameters.set(name, param);
}
param.value = value;
}
/**
* Returns the value of a shader parameter from the compute instance.
*
* @param {string} name - The name of the parameter to get.
* @returns {number|number[]|Float32Array|Texture|StorageBuffer|VertexBuffer|IndexBuffer|undefined}
* The value of the specified parameter.
*/ getParameter(name) {
return this.parameters.get(name)?.value;
}
/**
* Deletes a shader parameter from the compute instance.
*
* @param {string} name - The name of the parameter to delete.
*/ deleteParameter(name) {
this.parameters.delete(name);
}
/**
* Frees resources associated with this compute instance.
*/ destroy() {
this.impl?.destroy();
this.impl = null;
}
/**
* Apply the parameters to the scope.
*
* @ignore
*/ applyParameters() {
for (const [, param] of this.parameters){
param.scopeId.setValue(param.value);
}
}
/**
* Prepare the compute work dispatch.
*
* @param {number} x - X dimension of the grid of work-groups to dispatch.
* @param {number} [y] - Y dimension of the grid of work-groups to dispatch.
* @param {number} [z] - Z dimension of the grid of work-groups to dispatch.
*/ setupDispatch(x, y, z) {
this.countX = x;
this.countY = y;
this.countZ = z;
// reset indirect dispatch state
this.indirectSlotIndex = -1;
this.indirectBuffer = null;
}
/**
* Prepare the compute work dispatch to use indirect parameters from a buffer. The dispatch
* parameters (x, y, z workgroup counts) are read from the buffer at the specified slot index.
*
* When using the device's built-in buffer (buffer parameter is null), this method must be
* called each frame as slots are only valid for the current frame.
*
* @param {number} slotIndex - Slot index in the indirect dispatch buffer. When using the
* device's built-in buffer, obtain this by calling {@link GraphicsDevice#getIndirectDispatchSlot}.
* @param {StorageBuffer|null} [buffer] - Optional custom storage buffer containing dispatch
* parameters. If not provided, uses the device's built-in {@link GraphicsDevice#indirectDispatchBuffer}.
* When providing a custom buffer, the user is responsible for its lifetime and contents.
* @example
* // Reserve a slot in the indirect dispatch buffer
* const slot = device.getIndirectDispatchSlot();
*
* // First compute shader writes dispatch parameters to the buffer
* prepareCompute.setParameter('indirectBuffer', device.indirectDispatchBuffer);
* prepareCompute.setParameter('slot', slot);
* prepareCompute.setupDispatch(1, 1, 1);
* device.computeDispatch([prepareCompute]);
*
* // Second compute shader uses indirect dispatch
* processCompute.setupIndirectDispatch(slot);
* device.computeDispatch([processCompute]);
*/ setupIndirectDispatch(slotIndex, buffer = null) {
this.indirectSlotIndex = slotIndex;
this.indirectBuffer = buffer;
this.indirectFrameStamp = this.device.renderVersion;
}
/**
* Calculate near-square 2D dispatch dimensions for a given workgroup count,
* respecting the WebGPU per-dimension limit. When the count fits within a single
* dimension, Y is 1. Otherwise, dimensions are chosen to be roughly square to
* minimize wasted padding threads.
*
* @param {number} count - Total number of workgroups needed.
* @param {Vec2} result - Output vector to receive X (x) and Y (y) dimensions.
* @param {number} [maxDimension] - Maximum workgroups per dimension.
* @returns {Vec2} The result vector with dimensions set.
* @ignore
*/ static calcDispatchSize(count, result, maxDimension = 65535) {
if (count <= maxDimension) {
return result.set(count, 1);
}
const y = Math.ceil(count / maxDimension);
return result.set(Math.ceil(count / y), y);
}
/**
* Create a compute instance. Note that this is supported on WebGPU only and is a no-op on
* other platforms.
*
* @param {GraphicsDevice} graphicsDevice -
* The graphics device.
* @param {Shader} shader - The compute shader.
* @param {string} [name] - The name of the compute instance, used for debugging only.
*/ constructor(graphicsDevice, shader, name = 'Unnamed'){
/**
* A compute shader.
*
* @type {Shader|null}
* @ignore
*/ this.shader = null;
/**
* @type {Map<string, ComputeParameter>}
* @ignore
*/ this.parameters = new Map();
/**
* @type {number}
* @ignore
*/ this.countX = 1;
/**
* Slot index in the indirect dispatch buffer, or -1 for direct dispatch.
*
* @type {number}
* @ignore
*/ this.indirectSlotIndex = -1;
/**
* Custom buffer for indirect dispatch, or null to use device's built-in buffer.
*
* @type {StorageBuffer|null}
* @ignore
*/ this.indirectBuffer = null;
/**
* Frame stamp (device.renderVersion) when indirect slot was set. Used for validation
* when using the built-in buffer.
*
* @type {number}
* @ignore
*/ this.indirectFrameStamp = 0;
this.device = graphicsDevice;
this.shader = shader;
this.name = name;
if (graphicsDevice.supportsCompute) {
this.impl = graphicsDevice.createComputeImpl(this);
}
}
}
export { Compute };