Cesium流动线纹理
1.扩展类PolylineTrailMaterialProperty
import Cesium from "cesium/Cesium";
export class PolylineTrailMaterialProperty {
constructor(options) {
options = Cesium.defaultValue(options, Cesium.defaultValue.EMPTY_OBJECT);
this._definitionChanged = new Cesium.Event();
this._color = undefined;
this._colorSubscription = undefined;
this.color = options.color;
this.duration = options.duration;
this.trailImage = options.trailImage;
this._time = performance.now();
}
}
Cesium.defineProperties(PolylineTrailMaterialProperty.prototype, {
isConstant: {
get: function() {
return false;
}
},
definitionChanged: {
get: function() {
return this._definitionChanged;
}
},
color: Cesium.createPropertyDescriptor('color')
});
PolylineTrailMaterialProperty.prototype.getType = function(time) {
return 'PolylineTrail';
}
PolylineTrailMaterialProperty.prototype.getValue = function(time, result) {
if (!Cesium.defined(result)) {
result = {};
}
result.color = Cesium.Property.getValueOrClonedDefault(this._color, time, Cesium.Color.WHITE, result.color);
//result.image = Cesium.Material.PolylineTrailImage;
result.image = this.trailImage;
result.time = ((performance.now() - this._time) % this.duration) / this.duration;
return result;
}
PolylineTrailMaterialProperty.prototype.equals = function(other) {
return this === other ||
(other instanceof PolylineTrailMaterialProperty &&
Cesium.Property.equals(this._color, other._color))
}
Cesium.Material.PolylineTrailType = 'PolylineTrail';
Cesium.Material.PolylineTrailImage = "images/colors.png";
Cesium.Material.PolylineTrailSource = "czm_material czm_getMaterial(czm_materialInput materialInput)\n\
{\n\
czm_material material = czm_getDefaultMaterial(materialInput);\n\
vec2 st = materialInput.st;\n\
vec4 colorImage = texture2D(image, vec2(fract(st.s - time), st.t));\n\
material.alpha = colorImage.a * color.a;\n\
material.diffuse = (colorImage.rgb+color.rgb)/2.0;\n\
return material;\n\
}";
Cesium.Material._materialCache.addMaterial(Cesium.Material.PolylineTrailType, {
fabric: {
type: Cesium.Material.PolylineTrailType,
uniforms: {
color: new Cesium.Color(1.0, 0.0, 0.0, 0.5),
image: Cesium.Material.PolylineTrailImage,
time: 0
},
source: Cesium.Material.PolylineTrailSource
},
translucent: function(material) {
return true;
}
});
Cesium.PolylineTrailMaterialProperty = PolylineTrailMaterialProperty;
2.使用