webgl | API Reference | ArcGIS Maps SDK for JavaScript 4.31

See also

RenderNode

Method Overview

Return Type	Summary	Object
Number []\|Float32Array\|Float64Array	Transforms positions from the internal rendering coordinate system to the output spatial reference.	webgl
Number []\|Float32Array	Computes a 4x4 affine transformation matrix that constitutes a linear coordinate transformation from a local Cartesian coordinate system to the virtual world coordinate system.	webgl
Number []\|Float32Array\|Float64Array	Transforms positions from the given spatial reference to the internal rendering coordinate system.	webgl

Method Details

fromRenderCoordinates Method fromRenderCoordinates(view, srcCoordinates, srcStart, destCoordinates, destStart, destSpatialReference, count){Number[] |Float32Array |Float64Array}

Transforms positions from the internal rendering coordinate system to the output spatial reference. The allowable output spatial reference is limited and depends on the viewingMode:

In global mode, it can either be Web Mercator or WGS84.
In local mode, it has to match view.spatialReference, and the call to this function simply copies the coordinates from srcCoordinates to destCoordinates.

If these conditions are not met, nothing is written to destCoordinates and the function returns null.

Parameters

view SceneView

The view related to the input coordinates.

srcCoordinates Number []|Float32Array|Float64Array

A linear array of one or more vectors that are interpreted as XYZ coordinates. For example, two position vectors would be represented as [x1, y1, z1, x2, y2, z2]. This must contain at least srcStart + 3 * count elements.

srcStart Number

An index in srcCoordinates from which the coordinates will start being read.

destCoordinates Number []|Float32Array|Float64Array

A reference to an array in which the results will be written.

destStart Number

An index in destCoordinates in which the coordinates will start to be written.

destSpatialReference SpatialReference

The spatial reference of the output coordinates. When null, view.spatialReference is used instead.

count Number

The number of vertices to be transformed.

Returns

Type	Description
Number [] \| Float32Array \| Float64Array	Returns a reference to `destCoordinates` if the operation succeeded, otherwise returns `null`.

Example

let cameraPositionGeographic = new Array(3);
webgl.fromRenderCoordinates(view,
  context.camera.eye, 0,
  cameraPositionGeographic, 0, SpatialReference.WGS84,
1);

renderCoordinateTransformAt Method renderCoordinateTransformAt(view, origin, srcSpatialReference, dest){Number[] |Float32Array}

Computes a 4x4 affine transformation matrix that constitutes a linear coordinate transformation from a local Cartesian coordinate system to the virtual world coordinate system. For example, this matrix can be used to transform the vertices of a 3D model to the rendering coordinate system.

The local Cartesian system is defined by its origin and the following axis definition:

X: Easting
Y: Northing
Z: Elevation

externalRenderers-renderCoordinateTransformAt

When view.viewingMode is global, a linear transformation does not take the curvature of the globe or other non-linear projection aspects into account. Thus, the resulting coordinates will only appear correct within a small region around the origin of the local Cartesian system.

The allowable spatial reference of origin depends on the viewingMode:

In global mode, it can either be Web Mercator or WGS84.
In local mode, it has to match view.spatialReference.

If these conditions are not met, nothing will be written to dest and the function will return null.

Parameters

view SceneView

The view for which the transformation will be used.

origin Number []|Float32Array|Float64Array

The global coordinates of the origin in the local Cartesian coordinate system.

srcSpatialReference SpatialReference

optional

The spatial reference of the origin coordinates. If undefined, view.spatialReference is used instead.

dest Number []|Float32Array

optional

A reference to an array where the 16 matrix elements will be stored. The resulting matrix follows WebGL conventions where the translation components occupy the 13th, 14th and 15th elements. If undefined, a newly created matrix returned.

Returns

Type	Description
Number [] \| Float32Array	Returns a reference to `dest` if the operation succeeds, otherwise returns `null`.

Example

// places a tetrahedron in New York
let verticesLocal = [[10, 10, 10], [10, −10, −10], [−10, 10, −10], [−10, −10, 10]],
  transformation = new Array(16),
  geographicCoordinates = [
  //  lon     lat   elevation
      -74,   40.71,    10]

webgl.renderCoordinateTransformAt(view, geographicCoordinates, SpatialReference.WGS84, transformation);

let verticesGlobal = verticesLocal.map(function(vertexLocal) {
  // transform the coordinates with the computed transformation (using the syntax of glMatrix, see http://glmatrix.net)
  return vec3.transformMat4(new Array(3), vertexLocal, transformation);
});

toRenderCoordinates Method toRenderCoordinates(view, srcCoordinates, srcStart, srcSpatialReference, destCoordinates, destStart, count){Number[] |Float32Array |Float64Array}

Transforms positions from the given spatial reference to the internal rendering coordinate system. The allowable input spatial reference is limited and depends on the viewingMode:

In global mode, it can either be Web Mercator or WGS84.
In local mode, it has to match view.spatialReference; the call to this function simply copies the coordinates from srcCoordinates to destCoordinates.

If these conditions are not met, nothing is written to destCoordinates and the function returns null.

Parameters

view SceneView

The view in which the coordinates will be used.

srcCoordinates Number []|Float32Array|Float64Array

A linear array of one or more vectors which are interpreted as XYZ coordinates. For example, two position vectors would be represented as [x1, y1, z1, x2, y2, z2]. This must contain at least srcStart + 3 * count elements.

srcStart Number

An index in srcCoordinates from which the coordinates start to be read.

srcSpatialReference SpatialReference

The spatial reference of the input coordinates. When null, view.spatialReference is used instead.

destCoordinates Number []|Float32Array|Float64Array

A reference to an array where the results will be written.

destStart Number

An index in destCoordinates to which the coordinates will start to be written.

count Number

The number of vertices to be transformed.

Returns

Type	Description
Number [] \| Float32Array \| Float64Array	Returns a reference to `destCoordinates` if the operation succeeds, otherwise returns `null`.

Example

// A linear list of coordinate triples
let geographicCoordinates = [
  //  lon     lat   elevation
    -117.19, 34.05,   414,
     47.39,   8.51,   408];

// Allocate storage for the result
let renderCoordinates = new Array(6);

webgl.toRenderCoordinates(view,
  geographicCoordinates, 0, SpatialReference.WGS84,
  renderCoordinates, 0,
2);

Type Definitions

ConsumedNodes Type Definition ConsumedNodes Object

Describes the input framebuffer objects of a custom RenderNode.

Properties: required RenderNodeInput []

One or more required inputs. If a required input is not available, the render function will not be called.

optional RenderNodeInput []

optional
One or more optional inputs. You can use an optional input if you want the render function to be called even if this input is not available.

RenderNodeInput Type Definition RenderNodeInput String

Describes a specific RenderNodeInput.

RenderNodeInput	Description	FBO attachments
normals	Contains the normals in camera space for the front-most visible content in the SceneView per pixel stored in RGB.	color0
highlights	Contains the currently selected highlights in the SceneView. Only available when the scene has highlights.	color0

Furthermore all RenderNodeOutput framebuffers may also be used as an input.

Normals encoding

The normals color0 attachment is an rgba texture, where the rgb components encode the normal. To get the normal in camera space, the following glsl code can be used:

vec3 normal = 2.0 * texture(normalsTexture, uv).xyz - vec3(1.0);

Using the normals for a custom RenderNode can have measurable performance impact in some settings due to the additional render tasks necessary to provide the normal information.

Highlight encoding

The highlights color0 attachment uses only the red channel to encode a bit field as follows:

Fragments with bit 0 of the red channel set are highlighted
Fragments with bit 1 of the red channel set are highlighted but hidden behind other (not highlighted) geometry

The other bits and channels should not be set. Fragments always contain the front-most highlight only.

Usage example:

uint bits = uint(texelFetch(highlightTexture, uv, 0).r * 255.0);
bool isHighlit  = (bits & 1u) == 1u;
bool isOccluded = (bits & 3u) == 3u;

RenderNodeOutput Type Definition RenderNodeOutput String

Describes a specific RenderNodeOutput.

RenderNodeOutput	Description	Available RenderNodeInput FBOs	FBO attachments
opaque-color	Contains the rendered image after all opaque geometries have been drawn.	opaque-color, normals	color0, depth
transparent-color	Contains the rendered image after all opaque and transparent geometries have been drawn.	transparent-color, normals	color0, depth
composite-color	Contains the rendered image without any post processes applied.	composite-color, normals, highlights (if scene has highlights)	color0, depth
final-color	Contains the rendered image including post processes.	final-color, normals, highlights (if scene has highlights)	color0, depth

Possible Values:"composite-color" |"opaque-color" |"transparent-color" |"final-color"