import clone from '../Core/clone.js';
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import defined from '../Core/defined.js';
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import Expression from './Expression.js';
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/**
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* An expression for a style applied to a {@link Cesium3DTileset}.
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* <p>
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* Evaluates a conditions expression defined using the
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* {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}.
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* </p>
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* <p>
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* Implements the {@link StyleExpression} interface.
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* </p>
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*
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* @alias ConditionsExpression
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* @constructor
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*
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* @param {Object} [conditionsExpression] The conditions expression defined using the 3D Tiles Styling language.
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* @param {Object} [defines] Defines in the style.
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*
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* @example
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* var expression = new Cesium.ConditionsExpression({
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* conditions : [
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* ['${Area} > 10, 'color("#FF0000")'],
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* ['${id} !== "1"', 'color("#00FF00")'],
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* ['true', 'color("#FFFFFF")']
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* ]
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* });
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* expression.evaluateColor(feature, result); // returns a Cesium.Color object
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*/
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function ConditionsExpression(conditionsExpression, defines) {
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this._conditionsExpression = clone(conditionsExpression, true);
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this._conditions = conditionsExpression.conditions;
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this._runtimeConditions = undefined;
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setRuntime(this, defines);
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}
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Object.defineProperties(ConditionsExpression.prototype, {
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/**
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* Gets the conditions expression defined in the 3D Tiles Styling language.
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*
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* @memberof ConditionsExpression.prototype
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*
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* @type {Object}
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* @readonly
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*
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* @default undefined
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*/
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conditionsExpression : {
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get : function() {
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return this._conditionsExpression;
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}
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}
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});
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function Statement(condition, expression) {
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this.condition = condition;
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this.expression = expression;
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}
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function setRuntime(expression, defines) {
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var runtimeConditions = [];
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var conditions = expression._conditions;
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if (!defined(conditions)) {
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return;
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}
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var length = conditions.length;
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for (var i = 0; i < length; ++i) {
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var statement = conditions[i];
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var cond = String(statement[0]);
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var condExpression = String(statement[1]);
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runtimeConditions.push(new Statement(
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new Expression(cond, defines),
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new Expression(condExpression, defines)
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));
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}
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expression._runtimeConditions = runtimeConditions;
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}
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/**
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* Evaluates the result of an expression, optionally using the provided feature's properties. If the result of
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* the expression in the
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* {@link https://github.com/CesiumGS/3d-tiles/tree/master/specification/Styling|3D Tiles Styling language}
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* is of type <code>Boolean</code>, <code>Number</code>, or <code>String</code>, the corresponding JavaScript
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* primitive type will be returned. If the result is a <code>RegExp</code>, a Javascript <code>RegExp</code>
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* object will be returned. If the result is a <code>Cartesian2</code>, <code>Cartesian3</code>, or <code>Cartesian4</code>,
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* a {@link Cartesian2}, {@link Cartesian3}, or {@link Cartesian4} object will be returned. If the <code>result</code> argument is
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* a {@link Color}, the {@link Cartesian4} value is converted to a {@link Color} and then returned.
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*
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* @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
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* @param {Object} [result] The object onto which to store the result.
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* @returns {Boolean|Number|String|RegExp|Cartesian2|Cartesian3|Cartesian4|Color} The result of evaluating the expression.
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*/
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ConditionsExpression.prototype.evaluate = function(feature, result) {
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var conditions = this._runtimeConditions;
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if (!defined(conditions)) {
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return undefined;
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}
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var length = conditions.length;
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for (var i = 0; i < length; ++i) {
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var statement = conditions[i];
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if (statement.condition.evaluate(feature)) {
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return statement.expression.evaluate(feature, result);
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}
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}
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};
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/**
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* Evaluates the result of a Color expression, using the values defined by a feature.
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* <p>
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* This is equivalent to {@link ConditionsExpression#evaluate} but always returns a {@link Color} object.
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* </p>
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* @param {Cesium3DTileFeature} feature The feature whose properties may be used as variables in the expression.
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* @param {Color} [result] The object in which to store the result
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* @returns {Color} The modified result parameter or a new Color instance if one was not provided.
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*/
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ConditionsExpression.prototype.evaluateColor = function(feature, result) {
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var conditions = this._runtimeConditions;
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if (!defined(conditions)) {
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return undefined;
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}
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var length = conditions.length;
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for (var i = 0; i < length; ++i) {
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var statement = conditions[i];
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if (statement.condition.evaluate(feature)) {
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return statement.expression.evaluateColor(feature, result);
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}
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}
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};
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/**
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* Gets the shader function for this expression.
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* Returns undefined if the shader function can't be generated from this expression.
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*
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* @param {String} functionName Name to give to the generated function.
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* @param {String} attributePrefix Prefix that is added to any variable names to access vertex attributes.
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* @param {Object} shaderState Stores information about the generated shader function, including whether it is translucent.
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* @param {String} returnType The return type of the generated function.
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*
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* @returns {String} The shader function.
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*
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* @private
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*/
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ConditionsExpression.prototype.getShaderFunction = function(functionName, attributePrefix, shaderState, returnType) {
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var conditions = this._runtimeConditions;
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if (!defined(conditions) || conditions.length === 0) {
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return undefined;
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}
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var shaderFunction = '';
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var length = conditions.length;
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for (var i = 0; i < length; ++i) {
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var statement = conditions[i];
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var condition = statement.condition.getShaderExpression(attributePrefix, shaderState);
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var expression = statement.expression.getShaderExpression(attributePrefix, shaderState);
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// Build the if/else chain from the list of conditions
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shaderFunction +=
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' ' + ((i === 0) ? 'if' : 'else if') + ' (' + condition + ') \n' +
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' { \n' +
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' return ' + expression + '; \n' +
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' } \n';
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}
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shaderFunction = returnType + ' ' + functionName + '() \n' +
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'{ \n' +
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shaderFunction +
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' return ' + returnType + '(1.0); \n' + // Return a default value if no conditions are met
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'} \n';
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return shaderFunction;
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};
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export default ConditionsExpression;
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