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class.RenderContext

API > RenderContext

Class: RenderContext

The view specific context for rendering and picking.

Remarks​

A render context describes a view into which a RenderState can be rendered. It is tightly bound to a HTML canvas and WebGL2RenderingContext. Consequently, it will be disposed if the gl context is lost and recreated when the gl context is restored.

The render context must be initialized with an array of render modules. Unused modules may be removed and custom ones inserted here. Ordering the modules correctly is important as they are rendered in order. The TonemapModule should be last, as it will copy the HDR render buffers into the output canvas to make things visible.

Features such as async picking and shader linking requires poll to be called at regular intervals, e.g. at the start of each frame. Otherwise the promises will never be resolved.

Properties​

buffers​

buffers: RenderBuffers

WebGL render and pick buffers

Remarks​

Note that these buffers will be recreated whenever the RenderState.output size changes.

Source​

@novorender/core3d/context.ts:128

cameraUniforms​

readonly cameraUniforms: WebGLBuffer

WebGL uniform buffer for camera related uniforms.

Source​

@novorender/core3d/context.ts:87

canvas​

readonly canvas: HTMLCanvasElement

The HTML canvas used for this context.

Source​

@novorender/core3d/context.ts:152

changed​

changed: boolean = true

Set to true to force a re-render when state not contained in RenderState has changed, e.g. download complete etc.

Source​

@novorender/core3d/context.ts:121

clippingUniforms​

readonly clippingUniforms: WebGLBuffer

WebGL uniform buffer for clipping related uniforms.

Source​

@novorender/core3d/context.ts:89

commonChunk​

readonly commonChunk: string

WebGL common GLSL code header used across shaders.

Source​

@novorender/core3d/context.ts:40

currentState​

currentState: undefined | DerivedRenderState

RenderState used to make the newest state available during render.

Source​

@novorender/core3d/context.ts:118

defaultIBLTextureParams​

readonly defaultIBLTextureParams: TextureParamsCubeUncompressed

WebGL basic fallback IBL textures to use while loading proper IBL textures.

Source​

@novorender/core3d/context.ts:42

deviceProfile​

readonly deviceProfile: DeviceProfile

The device profile use for this context.

Source​

@novorender/core3d/context.ts:150

gl​

readonly gl: WebGL2RenderingContext

WebGL2 render context associated with this object.

Source​

@novorender/core3d/context.ts:38

iblTextures​

iblTextures: object

WebGL textures used for image based lighting (IBL).

Remarks​

Note that these buffers will be changed by the background module when download of the specified RenderState.background.url IBL textures completes.

The process to create the textures are similar to that of https://github.com/KhronosGroup/glTF-IBL-Sampler/

Type declaration​

iblTextures.default​

readonly default: boolean

True if these are the default IBL textures.

iblTextures.diffuse​

readonly diffuse: WebGLTexture

WebGL cubemap texture containing the irradiance/diffuse values of current IBL environment.

iblTextures.numMipMaps​

readonly numMipMaps: number

mip maps in current specular texture.

iblTextures.specular​

readonly specular: WebGLTexture

WebGL cubemap texture containing the radiance/specular values of current IBL environment.

Source​

@novorender/core3d/context.ts:136

imports​

readonly imports: Core3DImports

Imported resources.

Source​

@novorender/core3d/context.ts:154

lut_ggx​

readonly lut_ggx: WebGLTexture

WebGL GGX/PBR shading lookup table texture.

Source​

@novorender/core3d/context.ts:93

outlineRenderers​

outlineRenderers: WeakMap\< ReadonlyVec4, OutlineRenderer >

Source​

@novorender/core3d/context.ts:108

outlineUniforms​

readonly outlineUniforms: WebGLBuffer

WebGL uniform buffer for outline related uniforms.

Source​

@novorender/core3d/context.ts:91

prevState​

prevState: undefined | DerivedRenderState

RenderState used to render the previous frame, if any.

Source​

@novorender/core3d/context.ts:114

samplerEnvMip​

readonly samplerEnvMip: WebGLSampler

WebGL Sampler used to sample mip mapped IBL texture trilinear.

Source​

@novorender/core3d/context.ts:95

samplerMip​

readonly samplerMip: WebGLSampler

WebGL Sampler used to sample mipmapped texture trilinear.

Source​

@novorender/core3d/context.ts:97

samplerMipRepeat​

readonly samplerMipRepeat: WebGLSampler

WebGL Sampler used to sample mipmapped texture trilinear repeating UV.

Source​

@novorender/core3d/context.ts:99

samplerSingle​

readonly samplerSingle: WebGLSampler

WebGL Sampler used to sample other, non-mipmapped IBL textures bilinear.

Source​

@novorender/core3d/context.ts:101

usePrepass​

readonly usePrepass: false = false

Source​

@novorender/core3d/context.ts:74

wasm​

readonly wasm: WasmInstance

Web assembly instance.

Source​

@novorender/core3d/context.ts:44

Accessors​

height​

get height(): number

Return the current pixel height of the drawing buffer.

Returns​

number

Source​

@novorender/core3d/context.ts:331

width​

get width(): number

Return the current pixel width of the drawing buffer.

Returns​

number

Source​

@novorender/core3d/context.ts:326

Methods​

clearPickBuffers​

clearPickBuffers(): void

Returns​

void

Source​

@novorender/core3d/context.ts:735

dispose​

dispose(): void

Dispose of the GPU resources used by this context, effectively destroying it and freeing up memory.

Returns​

void

Source​

@novorender/core3d/context.ts:306

Remarks​

Calling this method is optional as the garbage collection of the underlying WebGL render context will do the same thing. This may take some time, however, so calling this function is recommended if you plan to create a new context shortly thereafter.

getDeviations​

getDeviations(): Promise\< DeviationSample[] >

scan the pick buffer for deviation values

Returns​

Promise\< DeviationSample[] >

Return pixel coordinates and deviation values for any deviation on screen

Source​

@novorender/core3d/context.ts:799

getLinearDepths​

getLinearDepths(pick): IterableIterator\< number >

Parameters​

ParameterType
pickUint32Array

Returns​

IterableIterator\< number >

Source​

@novorender/core3d/context.ts:788

getOutlines​

getOutlines(): Promise\< OutlineSample[] >

scan the pick buffer for pixels from clipping outline

Returns​

Promise\< OutlineSample[] >

Return pixel coordinates and world position for any clipping outline on screen

Source​

@novorender/core3d/context.ts:845

hasStateChanged​

hasStateChanged(state): boolean

Helper function to check for changes in render state.

Parameters​

ParameterTypeDescription
statePartial\< DerivedRenderState >The parts of the render state to check for changes.

Returns​

boolean

True if any of the specified parts has changed since last frame.

Source​

@novorender/core3d/context.ts:407

Remarks​

Since the render state is immutable, any changes will automatically trickle up to the container object as well. Thus, this function does a shallow strict equality of the parts of the renderstate specified in the state parameter.

Example​

Example of how to check for changes in either camera or output render state.

const {camera, output} = renderState;
if(renderContext.hasStateChanged({camera, output})) {
  // update related GPU state here...
}

init​

init(modules?): Promise\< void >

Initialize render context with specified render modules.

Parameters​

ParameterType
modules?readonly RenderModule[]

Returns​

Promise\< void >

Source​

@novorender/core3d/context.ts:253

Remarks​

The default/built-in render modules can be retrieved using createDefaultModules. These will be used if no modules are specified. Developers may introduce their own render modules here. Note that the order of the modules matters, as this is the order by which they will be rendered.

isContextLost​

isContextLost(): boolean

Query whether the underlying WebGL render context is currently lost.

Returns​

boolean

Source​

@novorender/core3d/context.ts:347

Remarks​

This could occur when too many resources are allocated or when browser window is dragged across screens. Loss and restoration of WebGL contexts is supported by this API automatically.

isPickBuffersValid​

isPickBuffersValid(): boolean

Query if pick buffers are valid.

Returns​

boolean

Source​

@novorender/core3d/context.ts:338

Remarks​

This could be useful for optimistic/non-async picking.

makeProgramAsync​

makeProgramAsync(resourceBin, params): Promise\< WebGLProgram >

Compile WebGL/GLSL shader program asynchronously.

Parameters​

ParameterType
resourceBinResourceBin
paramsAsyncProgramParams

Returns​

Promise\< WebGLProgram >

Source​

@novorender/core3d/context.ts:427

pick​

pick( x, y, options?): Promise\< PickSample[] >

Pick information about underlying object and geometry.

Parameters​

ParameterTypeDescription
xnumberCenter x coordinate in CSS pixels.
ynumberCenter y coordinate in CSS pixels.
options?PickOptionsMore details of pick operation.

Returns​

Promise\< PickSample[] >

A set of pick samples of the specified sample disc.

Source​

@novorender/core3d/context.ts:1034

poll​

poll(): void

Poll the status of WebGL pick fences and timers and resolve associated promises when possible.

Returns​

void

Source​

@novorender/core3d/context.ts:533

render​

render(state): Promise\< RenderStatistics >

Render a new frame using the specified render state.

Parameters​

ParameterTypeDescription
stateRenderStateAn object describing what the frame should look like.

Returns​

Promise\< RenderStatistics >

A promise to the performance related statistics involved in rendering this frame.

Source​

@novorender/core3d/context.ts:582

renderPickBuffers​

renderPickBuffers(): void

Returns​

void

Source​

@novorender/core3d/context.ts:740

resourceBin​

resourceBin(name): ResourceBin

Create a new named resource bin.

Parameters​

ParameterType
namestring

Returns​

ResourceBin

Source​

@novorender/core3d/context.ts:422

setPolygonFillMode​

setPolygonFillMode(mode): void

Parameters​

ParameterType
mode"FILL" | "LINE"

Returns​

void

Source​

@novorender/core3d/context.ts:1070

updateIBLTextures​

updateIBLTextures(params): void

Explicitly update WebGL IBL textures from specified parameters.

Parameters​

ParameterType
paramsnull | {
diffuse: TextureParamsCubeUncompressed;
specular: TextureParamsCubeUncompressedMipMapped;
}

Returns​

void

Source​

@novorender/core3d/context.ts:370

updateUniformBuffer​

updateUniformBuffer(uniformBuffer, proxy): void

Helper function to update WebGL uniform buffer from proxies.

Parameters​

ParameterType
uniformBufferWebGLBuffer
proxyUniformsProxy

Returns​

void

Source​

@novorender/core3d/context.ts:361

nextFrame​

static nextFrame(context): Promise\< number >

Wait for the next frame to be ready for rendering.

Parameters​

ParameterTypeDescription
contextundefined | RenderContextrender context to wait for, if any.

Returns​

Promise\< number >

Source​

@novorender/core3d/context.ts:561

Remarks​

Use this function instead of requestAnimationFrame()!