20.2. The SharedRenderContext Object

Added SDK 0.28.0

The SharedRenderContext object provides a utility for handling the sharing of particle state textures, and mapping table textures between many particle systems.

The context can be used to allocate new regions of the double-buffered renderable textures required by a ParticleSystem and a ParticleView which is z-sorted.

This object does not expose any way of releasing previously allocated regions, as the underlying allocation algorithm (OnlineTexturePacker) does not support this. The intention is that these shared textures are used where systems are either permanent, or short-lived and recycled.

Note

This is a low-level particle system API.

20.2.1. Methods

20.2.1.1. create

Summary

Create a new SharedRenderContext object.

Syntax

var sharedRenderContext = SharedRenderContext.create({
    graphicsDevice: graphicsDevice
});

20.2.1.2. allocate

Summary

Allocate a new region of the shared textures. May return null in the case that an attempt is made to allocate a texture region larger than is supported by the GraphicsDevice.

Syntax

function setCallbackFn(newRegion)
{
    // The shared render context was resized by some later allocations
    // and the uvRectangle and renderTargets have been changed.
    // .. handle changes here.
}
var region = sharedRenderContext.allocate({
    width: 64,
    height: 64,
    set: setCallbackFn
});
var renderTargets = region.renderTargets;
var uvRectangle = region.uvRectangle;

width

The width of the region required.

height

The height of the region required.

set

A function to be called when resizing the shared textures from which the region was allocated, and the uv-rectangle of the region has changed.

The region object returned has the following fields:

renderTargets

The pair of RenderTargets representing the double buffer texture store region is allocated from.

uvRectangle

A Vector4 object representing the texture coordinate rectangle of the region in the shared textures. This is of the form [x0, y0, x1, y1] in normalize coordinates.

20.2.1.3. release

Summary

Release an allocated region for re-use.

Note

The intention is that these shared textures are used where systems are either permanent, or short-lived and recycled. The underlying algorithm responsible for allocating regions does not perform any defragmentation or merging of free regions, and as such releasing an allocated region should be done with care.

Syntax

sharedRenderContext.release(region);

region

The region returned by allocate, or passed to the set callback.

20.2.1.4. destroy

Summary

Destroy all render targets and textures owned by this shared context. The shared context, nor any of its previously allocated regions can be used following this call.

Syntax

sharedRenderContext.destroy();