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SkyAtmosphere.js
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SkyAtmosphere.js
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import Cartesian3 from "../Core/Cartesian3.js";
import defaultValue from "../Core/defaultValue.js";
import defined from "../Core/defined.js";
import destroyObject from "../Core/destroyObject.js";
import Ellipsoid from "../Core/Ellipsoid.js";
import EllipsoidGeometry from "../Core/EllipsoidGeometry.js";
import GeometryPipeline from "../Core/GeometryPipeline.js";
import CesiumMath from "../Core/Math.js";
import Matrix4 from "../Core/Matrix4.js";
import VertexFormat from "../Core/VertexFormat.js";
import BufferUsage from "../Renderer/BufferUsage.js";
import DrawCommand from "../Renderer/DrawCommand.js";
import RenderState from "../Renderer/RenderState.js";
import ShaderProgram from "../Renderer/ShaderProgram.js";
import ShaderSource from "../Renderer/ShaderSource.js";
import VertexArray from "../Renderer/VertexArray.js";
import SkyAtmosphereCommon from "../Shaders/SkyAtmosphereCommon.js";
import SkyAtmosphereFS from "../Shaders/SkyAtmosphereFS.js";
import SkyAtmosphereVS from "../Shaders/SkyAtmosphereVS.js";
import Axis from "./Axis.js";
import BlendingState from "./BlendingState.js";
import CullFace from "./CullFace.js";
import SceneMode from "./SceneMode.js";
/**
* An atmosphere drawn around the limb of the provided ellipsoid. Based on
* {@link https://developer.nvidia.com/gpugems/GPUGems2/gpugems2_chapter16.html|Accurate Atmospheric Scattering}
* in GPU Gems 2.
* <p>
* This is only supported in 3D. Atmosphere is faded out when morphing to 2D or Columbus view.
* </p>
*
* @alias SkyAtmosphere
* @constructor
*
* @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid that the atmosphere is drawn around.
*
* @example
* scene.skyAtmosphere = new Cesium.SkyAtmosphere();
*
* @demo {@link https://sandcastle.cesium.com/index.html?src=Sky%20Atmosphere.html|Sky atmosphere demo in Sandcastle}
*
* @see Scene.skyAtmosphere
*/
function SkyAtmosphere(ellipsoid) {
ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
/**
* Determines if the atmosphere is shown.
*
* @type {Boolean}
* @default true
*/
this.show = true;
/**
* Compute atmosphere per-fragment instead of per-vertex.
* This produces better looking atmosphere with a slight performance penalty.
*
* @type {Boolean}
* @default false
*/
this.perFragmentAtmosphere = false;
this._ellipsoid = ellipsoid;
const outerEllipsoidScale = 1.025;
const scaleVector = Cartesian3.multiplyByScalar(
ellipsoid.radii,
outerEllipsoidScale,
new Cartesian3()
);
this._scaleMatrix = Matrix4.fromScale(scaleVector);
this._modelMatrix = new Matrix4();
this._command = new DrawCommand({
owner: this,
modelMatrix: this._modelMatrix,
});
this._spSkyFromSpace = undefined;
this._spSkyFromAtmosphere = undefined;
this._flags = undefined;
/**
* The hue shift to apply to the atmosphere. Defaults to 0.0 (no shift).
* A hue shift of 1.0 indicates a complete rotation of the hues available.
* @type {Number}
* @default 0.0
*/
this.hueShift = 0.0;
/**
* The saturation shift to apply to the atmosphere. Defaults to 0.0 (no shift).
* A saturation shift of -1.0 is monochrome.
* @type {Number}
* @default 0.0
*/
this.saturationShift = 0.0;
/**
* The brightness shift to apply to the atmosphere. Defaults to 0.0 (no shift).
* A brightness shift of -1.0 is complete darkness, which will let space show through.
* @type {Number}
* @default 0.0
*/
this.brightnessShift = 0.0;
this._hueSaturationBrightness = new Cartesian3();
// outer radius, inner radius, dynamic atmosphere color flag
const radiiAndDynamicAtmosphereColor = new Cartesian3();
radiiAndDynamicAtmosphereColor.x =
ellipsoid.maximumRadius * outerEllipsoidScale;
radiiAndDynamicAtmosphereColor.y = ellipsoid.maximumRadius;
// Toggles whether the sun position is used. 0 treats the sun as always directly overhead.
radiiAndDynamicAtmosphereColor.z = 0;
this._radiiAndDynamicAtmosphereColor = radiiAndDynamicAtmosphereColor;
const that = this;
this._command.uniformMap = {
u_radiiAndDynamicAtmosphereColor: function () {
return that._radiiAndDynamicAtmosphereColor;
},
u_hsbShift: function () {
that._hueSaturationBrightness.x = that.hueShift;
that._hueSaturationBrightness.y = that.saturationShift;
that._hueSaturationBrightness.z = that.brightnessShift;
return that._hueSaturationBrightness;
},
};
}
Object.defineProperties(SkyAtmosphere.prototype, {
/**
* Gets the ellipsoid the atmosphere is drawn around.
* @memberof SkyAtmosphere.prototype
*
* @type {Ellipsoid}
* @readonly
*/
ellipsoid: {
get: function () {
return this._ellipsoid;
},
},
});
/**
* @private
*/
SkyAtmosphere.prototype.setDynamicAtmosphereColor = function (
enableLighting,
useSunDirection
) {
const lightEnum = enableLighting ? (useSunDirection ? 2.0 : 1.0) : 0.0;
this._radiiAndDynamicAtmosphereColor.z = lightEnum;
};
const scratchModelMatrix = new Matrix4();
/**
* @private
*/
SkyAtmosphere.prototype.update = function (frameState, globe) {
if (!this.show) {
return undefined;
}
const mode = frameState.mode;
if (mode !== SceneMode.SCENE3D && mode !== SceneMode.MORPHING) {
return undefined;
}
// The atmosphere is only rendered during the render pass; it is not pickable, it doesn't cast shadows, etc.
if (!frameState.passes.render) {
return undefined;
}
// Align the ellipsoid geometry so it always faces the same direction as the
// camera to reduce artifacts when rendering atmosphere per-vertex
const rotationMatrix = Matrix4.fromRotationTranslation(
frameState.context.uniformState.inverseViewRotation,
Cartesian3.ZERO,
scratchModelMatrix
);
const rotationOffsetMatrix = Matrix4.multiplyTransformation(
rotationMatrix,
Axis.Y_UP_TO_Z_UP,
scratchModelMatrix
);
const modelMatrix = Matrix4.multiply(
this._scaleMatrix,
rotationOffsetMatrix,
scratchModelMatrix
);
Matrix4.clone(modelMatrix, this._modelMatrix);
const context = frameState.context;
const colorCorrect = hasColorCorrection(this);
const translucent = frameState.globeTranslucencyState.translucent;
const perFragmentAtmosphere =
this.perFragmentAtmosphere || translucent || !defined(globe) || !globe.show;
const command = this._command;
if (!defined(command.vertexArray)) {
const geometry = EllipsoidGeometry.createGeometry(
new EllipsoidGeometry({
radii: new Cartesian3(1.0, 1.0, 1.0),
slicePartitions: 256,
stackPartitions: 256,
vertexFormat: VertexFormat.POSITION_ONLY,
})
);
command.vertexArray = VertexArray.fromGeometry({
context: context,
geometry: geometry,
attributeLocations: GeometryPipeline.createAttributeLocations(geometry),
bufferUsage: BufferUsage.STATIC_DRAW,
});
command.renderState = RenderState.fromCache({
cull: {
enabled: true,
face: CullFace.FRONT,
},
blending: BlendingState.ALPHA_BLEND,
depthMask: false,
});
}
const flags =
colorCorrect | (perFragmentAtmosphere << 2) | (translucent << 3);
if (flags !== this._flags) {
this._flags = flags;
const defines = [];
if (colorCorrect) {
defines.push("COLOR_CORRECT");
}
if (perFragmentAtmosphere) {
defines.push("PER_FRAGMENT_ATMOSPHERE");
}
if (translucent) {
defines.push("GLOBE_TRANSLUCENT");
}
let vs = new ShaderSource({
defines: defines.concat("SKY_FROM_SPACE"),
sources: [SkyAtmosphereCommon, SkyAtmosphereVS],
});
let fs = new ShaderSource({
defines: defines.concat("SKY_FROM_SPACE"),
sources: [SkyAtmosphereCommon, SkyAtmosphereFS],
});
this._spSkyFromSpace = ShaderProgram.fromCache({
context: context,
vertexShaderSource: vs,
fragmentShaderSource: fs,
});
vs = new ShaderSource({
defines: defines.concat("SKY_FROM_ATMOSPHERE"),
sources: [SkyAtmosphereCommon, SkyAtmosphereVS],
});
fs = new ShaderSource({
defines: defines.concat("SKY_FROM_ATMOSPHERE"),
sources: [SkyAtmosphereCommon, SkyAtmosphereFS],
});
this._spSkyFromAtmosphere = ShaderProgram.fromCache({
context: context,
vertexShaderSource: vs,
fragmentShaderSource: fs,
});
}
const cameraPosition = frameState.camera.positionWC;
const cameraHeight = Cartesian3.magnitude(cameraPosition);
if (cameraHeight > this._radiiAndDynamicAtmosphereColor.x) {
// Camera in space
command.shaderProgram = this._spSkyFromSpace;
} else {
// Camera in atmosphere
command.shaderProgram = this._spSkyFromAtmosphere;
}
return command;
};
function hasColorCorrection(skyAtmosphere) {
return !(
CesiumMath.equalsEpsilon(
skyAtmosphere.hueShift,
0.0,
CesiumMath.EPSILON7
) &&
CesiumMath.equalsEpsilon(
skyAtmosphere.saturationShift,
0.0,
CesiumMath.EPSILON7
) &&
CesiumMath.equalsEpsilon(
skyAtmosphere.brightnessShift,
0.0,
CesiumMath.EPSILON7
)
);
}
/**
* Returns true if this object was destroyed; otherwise, false.
* <br /><br />
* If this object was destroyed, it should not be used; calling any function other than
* <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
*
* @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
*
* @see SkyAtmosphere#destroy
*/
SkyAtmosphere.prototype.isDestroyed = function () {
return false;
};
/**
* Destroys the WebGL resources held by this object. Destroying an object allows for deterministic
* release of WebGL resources, instead of relying on the garbage collector to destroy this object.
* <br /><br />
* Once an object is destroyed, it should not be used; calling any function other than
* <code>isDestroyed</code> will result in a {@link DeveloperError} exception. Therefore,
* assign the return value (<code>undefined</code>) to the object as done in the example.
*
* @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
*
*
* @example
* skyAtmosphere = skyAtmosphere && skyAtmosphere.destroy();
*
* @see SkyAtmosphere#isDestroyed
*/
SkyAtmosphere.prototype.destroy = function () {
const command = this._command;
command.vertexArray = command.vertexArray && command.vertexArray.destroy();
this._spSkyFromSpace = this._spSkyFromSpace && this._spSkyFromSpace.destroy();
this._spSkyFromAtmosphere =
this._spSkyFromAtmosphere && this._spSkyFromAtmosphere.destroy();
return destroyObject(this);
};
export default SkyAtmosphere;