/*
* Copyright 2003-2006, 2009, 2017, United States Government, as represented by the Administrator of the
* National Aeronautics and Space Administration. All rights reserved.
*
* The NASAWorldWind/WebWorldWind platform is licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @exports AtmosphereLayer
*/
define([
'../error/ArgumentError',
'../shaders/GroundProgram',
'../layer/Layer',
'../util/Logger',
'../geom/Matrix',
'../geom/Matrix3',
'../geom/Sector',
'../shaders/SkyProgram',
'../util/SunPosition',
'../geom/Vec3',
'../util/WWUtil'
],
function (ArgumentError,
GroundProgram,
Layer,
Logger,
Matrix,
Matrix3,
Sector,
SkyProgram,
SunPosition,
Vec3,
WWUtil) {
"use strict";
/**
* Constructs a layer showing the Earth's atmosphere.
* @alias AtmosphereLayer
* @constructor
* @classdesc Provides a layer showing the Earth's atmosphere.
* @param {URL} nightImageSource optional url for the night texture.
* @augments Layer
*/
var AtmosphereLayer = function (nightImageSource) {
Layer.call(this, "Atmosphere");
// The atmosphere layer is not pickable.
this.pickEnabled = false;
//Documented in defineProperties below.
this._nightImageSource = nightImageSource ||
WorldWind.configuration.baseUrl + 'images/dnb_land_ocean_ice_2012.png';
//Internal use only.
//The light direction in cartesian space, computed from the layer time or defaults to the eyePoint.
this._activeLightDirection = new Vec3(0, 0, 0);
this._fullSphereSector = Sector.FULL_SPHERE;
//Internal use only. Intentionally not documented.
this._skyData = {};
//Internal use only. The number of longitudinal points in the grid for the sky geometry.
this._skyWidth = 128;
//Internal use only. The number of latitudinal points in the grid for the sky geometry.
this._skyHeight = 128;
//Internal use only. Number of indices for the sky geometry.
this._numIndices = 0;
//Internal use only. Texture coordinate matrix used for the night texture.
this._texMatrix = Matrix3.fromIdentity();
//Internal use only. The night texture.
this._activeTexture = null;
};
AtmosphereLayer.prototype = Object.create(Layer.prototype);
Object.defineProperties(AtmosphereLayer.prototype, {
/**
* Url for the night texture.
* @memberof AtmosphereLayer.prototype
* @type {URL}
*/
nightImageSource: {
get: function () {
return this._nightImageSource;
},
set: function (value) {
this._nightImageSource = value;
}
}
});
// Documented in superclass.
AtmosphereLayer.prototype.doRender = function (dc) {
if (dc.globe.is2D()) {
return;
}
this.determineLightDirection(dc);
this.drawSky(dc);
this.drawGround(dc);
};
// Internal. Intentionally not documented.
AtmosphereLayer.prototype.applySkyVertices = function (dc) {
var gl = dc.currentGlContext,
program = dc.currentProgram,
skyData = this._skyData,
skyPoints, vboId;
if (!skyData.verticesVboCacheKey) {
skyData.verticesVboCacheKey = dc.gpuResourceCache.generateCacheKey();
}
vboId = dc.gpuResourceCache.resourceForKey(skyData.verticesVboCacheKey);
if (!vboId) {
skyPoints = this.assembleVertexPoints(dc, this._skyHeight, this._skyWidth, program.getAltitude());
vboId = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vboId);
gl.bufferData(gl.ARRAY_BUFFER, skyPoints, gl.STATIC_DRAW);
gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);
dc.gpuResourceCache.putResource(skyData.verticesVboCacheKey, vboId,
skyPoints.length * 4);
dc.frameStatistics.incrementVboLoadCount(1);
}
else {
gl.bindBuffer(gl.ARRAY_BUFFER, vboId);
gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);
}
};
// Internal. Intentionally not documented.
AtmosphereLayer.prototype.applySkyIndices = function (dc) {
var gl = dc.currentGlContext,
skyData = this._skyData,
skyIndices, vboId;
if (!skyData.indicesVboCacheKey) {
skyData.indicesVboCacheKey = dc.gpuResourceCache.generateCacheKey();
}
vboId = dc.gpuResourceCache.resourceForKey(skyData.indicesVboCacheKey);
if (!vboId) {
skyIndices = this.assembleTriStripIndices(this._skyWidth, this._skyHeight);
vboId = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, vboId);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, skyIndices, gl.STATIC_DRAW);
dc.frameStatistics.incrementVboLoadCount(1);
dc.gpuResourceCache.putResource(skyData.indicesVboCacheKey, vboId, skyIndices.length * 2);
}
else {
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, vboId);
}
};
// Internal. Intentionally not documented.
AtmosphereLayer.prototype.drawSky = function (dc) {
var gl = dc.currentGlContext,
program = dc.findAndBindProgram(SkyProgram);
program.loadGlobeRadius(gl, dc.globe.equatorialRadius);
program.loadEyePoint(gl, dc.eyePoint);
program.loadVertexOrigin(gl, Vec3.ZERO);
program.loadModelviewProjection(gl, dc.modelviewProjection);
program.loadLightDirection(gl, this._activeLightDirection);
program.setScale(gl);
this.applySkyVertices(dc);
this.applySkyIndices(dc);
gl.depthMask(false);
gl.frontFace(gl.CW);
gl.enableVertexAttribArray(0);
gl.drawElements(gl.TRIANGLE_STRIP, this._numIndices, gl.UNSIGNED_SHORT, 0);
gl.depthMask(true);
gl.frontFace(gl.CCW);
gl.disableVertexAttribArray(0);
};
// Internal. Intentionally not documented.
AtmosphereLayer.prototype.drawGround = function (dc) {
if (!dc.terrain) {
return;
}
var gl = dc.currentGlContext,
program = dc.findAndBindProgram(GroundProgram),
terrain = dc.terrain,
textureBound;
program.loadGlobeRadius(gl, dc.globe.equatorialRadius);
program.loadEyePoint(gl, dc.eyePoint);
program.loadLightDirection(gl, this._activeLightDirection);
program.setScale(gl);
// Use this layer's night image when the layer has time value defined
if (this.nightImageSource && (this.time !== null)) {
this._activeTexture = dc.gpuResourceCache.resourceForKey(this.nightImageSource);
if (!this._activeTexture) {
this._activeTexture = dc.gpuResourceCache.retrieveTexture(gl, this.nightImageSource);
}
textureBound = this._activeTexture && this._activeTexture.bind(dc);
}
terrain.beginRendering(dc);
for (var idx = 0, len = terrain.surfaceGeometry.length; idx < len; idx++) {
var currentTile = terrain.surfaceGeometry[idx];
// Use the vertex origin for the terrain tile.
var terrainOrigin = currentTile.referencePoint;
program.loadVertexOrigin(gl, terrainOrigin);
// Use a tex coord matrix that registers the night texture correctly on each terrain.
if (textureBound) {
this._texMatrix.setToUnitYFlip();
this._texMatrix.multiplyByTileTransform(currentTile.sector, this._fullSphereSector);
program.loadTexMatrix(gl, this._texMatrix);
}
terrain.beginRenderingTile(dc, currentTile);
// Draw the tile, multiplying the current fragment color by the program's secondary color.
program.loadFragMode(gl, program.FRAGMODE_GROUND_SECONDARY);
gl.blendFunc(gl.DST_COLOR, gl.ZERO);
terrain.renderTile(dc, currentTile);
// Draw the terrain as triangles, adding the current fragment color to the program's primary color.
var fragMode = textureBound ?
program.FRAGMODE_GROUND_PRIMARY_TEX_BLEND : program.FRAGMODE_GROUND_PRIMARY;
program.loadFragMode(gl, fragMode);
gl.blendFunc(gl.ONE, gl.ONE);
terrain.renderTile(dc, currentTile);
terrain.endRenderingTile(dc, currentTile);
}
// Restore the default WorldWind OpenGL state.
terrain.endRendering(dc);
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
// Clear references to Gpu resources.
this._activeTexture = null;
};
// Internal. Intentionally not documented.
AtmosphereLayer.prototype.assembleVertexPoints = function (dc, numLat, numLon, altitude) {
var count = numLat * numLon;
var altitudes = new Array(count);
WWUtil.fillArray(altitudes, altitude);
var result = new Float32Array(count * 3);
return dc.globe.computePointsForGrid(this._fullSphereSector, numLat, numLon, altitudes, Vec3.ZERO, result);
};
// Internal. Intentionally not documented.
AtmosphereLayer.prototype.assembleTriStripIndices = function (numLat, numLon) {
var result = [];
var vertex = 0;
for (var latIndex = 0; latIndex < numLat - 1; latIndex++) {
// Create a triangle strip joining each adjacent column of vertices, starting in the bottom left corner and
// proceeding to the right. The first vertex starts with the left row of vertices and moves right to create
// a counterclockwise winding order.
for (var lonIndex = 0; lonIndex < numLon; lonIndex++) {
vertex = lonIndex + latIndex * numLon;
result.push(vertex + numLon);
result.push(vertex);
}
// Insert indices to create 2 degenerate triangles:
// - one for the end of the current row, and
// - one for the beginning of the next row
if (latIndex < numLat - 2) {
result.push(vertex);
result.push((latIndex + 2) * numLon);
}
}
this._numIndices = result.length;
return new Uint16Array(result);
};
// Internal. Intentionally not documented.
AtmosphereLayer.prototype.determineLightDirection = function (dc) {
if (this.time !== null) {
var sunLocation = SunPosition.getAsGeographicLocation(this.time);
dc.globe.computePointFromLocation(sunLocation.latitude, sunLocation.longitude,
this._activeLightDirection);
} else {
this._activeLightDirection.copy(dc.eyePoint);
}
this._activeLightDirection.normalize();
};
return AtmosphereLayer;
});