Module: JavaScript

Methods

(static) allocateMercatorUniforms(uniformsopt) → {object}

Allocate arrays to store projection uniform values. Will add uniforms to existing object, if provided.
Parameters:
Name Type Attributes Description
uniforms object <optional>
 Optional object containing existing uniforms.
Source:
Returns:
Object containing projection uniforms.
Type
object

(static) highPrecisionLngLat(lnglat, offset, stride) → {Float32Array}

Create a Float32Array containing the low-part of 64-bit floats. The low parts can be passed to GLSL projection functions to improve numerical stability.
Parameters:
Name Type Description
lnglat Float32Array Array containing longitude latitude data (assumed to be in adjacent elements).
offset number Offset of the first longitude value from the start of the array.
stride number Number of elements between each pair of longitude/latitude values.
Source:
Returns:
Array containing the low parts of input longitude/latitude data.
Type
Float32Array

(static) injectMercatorGLSL(vsSource) → {string}

Inject MercatorGL projection functions in to GLSL vertex shader source string.
Parameters:
Name Type Description
vsSource string Vertex shader source code. Can be GLSL 1 or 3.
Source:
Returns:
Source code with the projection functions injected.
Type
string

(static) lngLatToClip(out, lngLat, viewProjectionMatrix) → {array}

Transform a 2d longitude/latitude point to clip space to clip space.
Parameters:
Name Type Description
out array 4-element array into which the results will be written.
lngLat array Longitude/latitude coordinate.
viewProjectionMatrix array 4x4 matrix to transform from mercator space to clip space.
Source:
Returns:
The "out" array provided, containing the results.
Type
array

(static) lngLatToMercator(out, lngLat, zoom) → {array}

Transform a longitude/latitude point to a 4d homegeneous coordinate in Mercator space.
Parameters:
Name Type Description
out array 4-element array into which the results will be written.
lngLat array Longitude/latitude coordinate.
zoom number Current mercator zoom level.
Source:
Returns:
The "out" array provided, containing the results.
Type
array

(static) mercatorToClip(out, mercatorPosition, viewProjectionMatrix) → {array}

Transform a homegeneous 4d representation of a mercator point on the plane (x, y, 0, 1) to clip space.
Parameters:
Name Type Description
out array 4-element array into which the results will be written.
mercatorPosition array Homegeneous 4d coordinate on the mercator plane.
viewProjectionMatrix array 4x4 matrix to transform from mercator space to clip space.
Source:
Returns:
The "out" array provided, containing the results.
Type
array

(static) pixelsPerDegree(out, latitude, zoom) → {array}

Mercator pixels/degree of longitude and latitude at the current latitude and zoom level (using 512x512 tile size).
Parameters:
Name Type Description
out array Two-element array into which the results will be written.
latitude number Current latitude of the camera center.
zoom number Current mercator zoom level.
Source:
Returns:
The "out" array provided, containing the results.
Type
array

(static) pixelsPerMeter(latitude, zoom) → {number}

Mercator pixels/meter at the current latitude and zoom level (using 512x512 tile size).
Parameters:
Name Type Description
latitude number Current latitude of the camera center.
zoom number Current mercator zoom level.
Source:
Returns:
Number of pixels per meter.
Type
number

(static) updateMercatorUniforms(uniforms, lngLat, zoom, viewProjectionMatrix) → {object}

Update projection uniforms based on current mercator settings and provided view-projection matrix. The view projection matrix is expected to project from a 512x512x mercator space to clip space.
Parameters:
Name Type Description
uniforms object Object containing existing uniforms.
lngLat array Current camera center as a 2-element longitude/latitude array.
zoom number Current mercator zoom level.
viewProjectionMatrix array 4x4 matrix to transform from mercator space to clip space.
Source:
Returns:
Object containing updated uniforms.
Type
object