@cesium/engine
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CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.
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JavaScript
import Color from "../Core/Color.js";
import Frozen from "../Core/Frozen.js";
import defined from "../Core/defined.js";
import Event from "../Core/Event.js";
import GeographicTilingScheme from "../Core/GeographicTilingScheme.js";
const defaultColor = new Color(1.0, 1.0, 1.0, 0.4);
const defaultGlowColor = new Color(0.0, 1.0, 0.0, 0.05);
const defaultBackgroundColor = new Color(0.0, 0.5, 0.0, 0.2);
/**
* @typedef {object} GridImageryProvider.ConstructorOptions
*
* Initialization options for the GridImageryProvider constructor
*
* @property {TilingScheme} [tilingScheme=new GeographicTilingScheme()] The tiling scheme for which to draw tiles.
* @property {Ellipsoid} [ellipsoid=Ellipsoid.default] The ellipsoid. If the tilingScheme is specified,
* this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
* parameter is specified, the default ellipsoid is used.
* @property {number} [cells=8] The number of grids cells.
* @property {Color} [color=Color(1.0, 1.0, 1.0, 0.4)] The color to draw grid lines.
* @property {Color} [glowColor=Color(0.0, 1.0, 0.0, 0.05)] The color to draw glow for grid lines.
* @property {number} [glowWidth=6] The width of lines used for rendering the line glow effect.
* @property {Color} [backgroundColor=Color(0.0, 0.5, 0.0, 0.2)] Background fill color.
* @property {number} [tileWidth=256] The width of the tile for level-of-detail selection purposes.
* @property {number} [tileHeight=256] The height of the tile for level-of-detail selection purposes.
* @property {number} [canvasSize=256] The size of the canvas used for rendering.
*/
/**
* An {@link ImageryProvider} that draws a wireframe grid on every tile with controllable background and glow.
* May be useful for custom rendering effects or debugging terrain.
*
* @alias GridImageryProvider
* @constructor
* @param {GridImageryProvider.ConstructorOptions} options Object describing initialization options
*
*/
function GridImageryProvider(options) {
options = options ?? Frozen.EMPTY_OBJECT;
this._defaultAlpha = undefined;
this._defaultNightAlpha = undefined;
this._defaultDayAlpha = undefined;
this._defaultBrightness = undefined;
this._defaultContrast = undefined;
this._defaultHue = undefined;
this._defaultSaturation = undefined;
this._defaultGamma = undefined;
this._defaultMinificationFilter = undefined;
this._defaultMagnificationFilter = undefined;
this._tilingScheme = defined(options.tilingScheme)
? options.tilingScheme
: new GeographicTilingScheme({ ellipsoid: options.ellipsoid });
this._cells = options.cells ?? 8;
this._color = options.color ?? defaultColor;
this._glowColor = options.glowColor ?? defaultGlowColor;
this._glowWidth = options.glowWidth ?? 6;
this._backgroundColor = options.backgroundColor ?? defaultBackgroundColor;
this._errorEvent = new Event();
this._tileWidth = options.tileWidth ?? 256;
this._tileHeight = options.tileHeight ?? 256;
// A little larger than tile size so lines are sharper
// Note: can't be too much difference otherwise texture blowout
this._canvasSize = options.canvasSize ?? 256;
// We only need a single canvas since all tiles will be the same
this._canvas = this._createGridCanvas();
}
Object.defineProperties(GridImageryProvider.prototype, {
/**
* Gets the proxy used by this provider.
* @memberof GridImageryProvider.prototype
* @type {Proxy}
* @readonly
*/
proxy: {
get: function () {
return undefined;
},
},
/**
* Gets the width of each tile, in pixels.
* @memberof GridImageryProvider.prototype
* @type {number}
* @readonly
*/
tileWidth: {
get: function () {
return this._tileWidth;
},
},
/**
* Gets the height of each tile, in pixels.
* @memberof GridImageryProvider.prototype
* @type {number}
* @readonly
*/
tileHeight: {
get: function () {
return this._tileHeight;
},
},
/**
* Gets the maximum level-of-detail that can be requested.
* @memberof GridImageryProvider.prototype
* @type {number|undefined}
* @readonly
*/
maximumLevel: {
get: function () {
return undefined;
},
},
/**
* Gets the minimum level-of-detail that can be requested.
* @memberof GridImageryProvider.prototype
* @type {number}
* @readonly
*/
minimumLevel: {
get: function () {
return undefined;
},
},
/**
* Gets the tiling scheme used by this provider.
* @memberof GridImageryProvider.prototype
* @type {TilingScheme}
* @readonly
*/
tilingScheme: {
get: function () {
return this._tilingScheme;
},
},
/**
* Gets the rectangle, in radians, of the imagery provided by this instance.
* @memberof GridImageryProvider.prototype
* @type {Rectangle}
* @readonly
*/
rectangle: {
get: function () {
return this._tilingScheme.rectangle;
},
},
/**
* Gets the tile discard policy. If not undefined, the discard policy is responsible
* for filtering out "missing" tiles via its shouldDiscardImage function. If this function
* returns undefined, no tiles are filtered.
* @memberof GridImageryProvider.prototype
* @type {TileDiscardPolicy}
* @readonly
*/
tileDiscardPolicy: {
get: function () {
return undefined;
},
},
/**
* Gets an event that is raised when the imagery provider encounters an asynchronous error. By subscribing
* to the event, you will be notified of the error and can potentially recover from it. Event listeners
* are passed an instance of {@link TileProviderError}.
* @memberof GridImageryProvider.prototype
* @type {Event}
* @readonly
*/
errorEvent: {
get: function () {
return this._errorEvent;
},
},
/**
* Gets the credit to display when this imagery provider is active. Typically this is used to credit
* the source of the imagery.
* @memberof GridImageryProvider.prototype
* @type {Credit}
* @readonly
*/
credit: {
get: function () {
return undefined;
},
},
/**
* Gets a value indicating whether or not the images provided by this imagery provider
* include an alpha channel. If this property is false, an alpha channel, if present, will
* be ignored. If this property is true, any images without an alpha channel will be treated
* as if their alpha is 1.0 everywhere. When this property is false, memory usage
* and texture upload time are reduced.
* @memberof GridImageryProvider.prototype
* @type {boolean}
* @readonly
*/
hasAlphaChannel: {
get: function () {
return true;
},
},
});
/**
* Draws a grid of lines into a canvas.
*/
GridImageryProvider.prototype._drawGrid = function (context) {
const minPixel = 0;
const maxPixel = this._canvasSize;
for (let x = 0; x <= this._cells; ++x) {
const nx = x / this._cells;
const val = 1 + nx * (maxPixel - 1);
context.moveTo(val, minPixel);
context.lineTo(val, maxPixel);
context.moveTo(minPixel, val);
context.lineTo(maxPixel, val);
}
context.stroke();
};
/**
* Render a grid into a canvas with background and glow
*/
GridImageryProvider.prototype._createGridCanvas = function () {
const canvas = document.createElement("canvas");
canvas.width = this._canvasSize;
canvas.height = this._canvasSize;
const minPixel = 0;
const maxPixel = this._canvasSize;
const context = canvas.getContext("2d");
// Fill the background
const cssBackgroundColor = this._backgroundColor.toCssColorString();
context.fillStyle = cssBackgroundColor;
context.fillRect(minPixel, minPixel, maxPixel, maxPixel);
// Glow for grid lines
const cssGlowColor = this._glowColor.toCssColorString();
context.strokeStyle = cssGlowColor;
// Wide
context.lineWidth = this._glowWidth;
context.strokeRect(minPixel, minPixel, maxPixel, maxPixel);
this._drawGrid(context);
// Narrow
context.lineWidth = this._glowWidth * 0.5;
context.strokeRect(minPixel, minPixel, maxPixel, maxPixel);
this._drawGrid(context);
// Grid lines
const cssColor = this._color.toCssColorString();
// Border
context.strokeStyle = cssColor;
context.lineWidth = 2;
context.strokeRect(minPixel, minPixel, maxPixel, maxPixel);
// Inner
context.lineWidth = 1;
this._drawGrid(context);
return canvas;
};
/**
* Gets the credits to be displayed when a given tile is displayed.
*
* @param {number} x The tile X coordinate.
* @param {number} y The tile Y coordinate.
* @param {number} level The tile level;
* @returns {Credit[]} The credits to be displayed when the tile is displayed.
*/
GridImageryProvider.prototype.getTileCredits = function (x, y, level) {
return undefined;
};
/**
* Requests the image for a given tile.
*
* @param {number} x The tile X coordinate.
* @param {number} y The tile Y coordinate.
* @param {number} level The tile level.
* @param {Request} [request] The request object. Intended for internal use only.
* @returns {Promise<HTMLCanvasElement>} The resolved image as a Canvas DOM object.
*/
GridImageryProvider.prototype.requestImage = function (x, y, level, request) {
return Promise.resolve(this._canvas);
};
/**
* Picking features is not currently supported by this imagery provider, so this function simply returns
* undefined.
*
* @param {number} x The tile X coordinate.
* @param {number} y The tile Y coordinate.
* @param {number} level The tile level.
* @param {number} longitude The longitude at which to pick features.
* @param {number} latitude The latitude at which to pick features.
* @return {undefined} Undefined since picking is not supported.
*/
GridImageryProvider.prototype.pickFeatures = function (
x,
y,
level,
longitude,
latitude,
) {
return undefined;
};
export default GridImageryProvider;