/**
* @exports StarFieldProgram
*/
import WorldWind from 'webworldwind-esa';
const {
ArgumentError,
GpuProgram,
Logger,
Matrix,
Color
} = WorldWind;
/**
* Constructs a new program.
* Initializes, compiles and links this GLSL program with the source code for its vertex and fragment shaders.
* <p>
* This method creates WebGL shaders for the program's shader sources and attaches them to a new GLSL program.
* This method then compiles the shaders and then links the program if compilation is successful.
* Use the bind method to make the program current during rendering.
*
* @alias StarFieldProgram
* @constructor
* @augments GpuProgram
* @classdesc StarFieldProgram is a GLSL program that draws points representing stars.
* @param {WebGLRenderingContext} gl The current WebGL context.
* @throws {ArgumentError} If the shaders cannot be compiled, or linking of the compiled shaders into a program
* fails.
*/
class StarFieldProgram extends GpuProgram {
constructor(gl) {
super(gl, 'attribute vec4 vertexPoint;\n' +
'uniform mat4 mvpMatrix;\n' +
//number of days (positive or negative) since Greenwich noon, Terrestrial Time,
// on 1 January 2000 (J2000.0)
'uniform float numDays;\n' +
'uniform vec2 magnitudeRange;\n' +
'varying float magnitudeWeight;\n' +
//normalizes an angle between 0.0 and 359.0
'float normalizeAngle(float angle) {\n' +
' float angleDivisions = angle / 360.0;\n' +
' return 360.0 * (angleDivisions - floor(angleDivisions));\n' +
'}\n' +
//transforms declination and right ascension in cartesian coordinates
'vec3 computePosition(float dec, float ra) {\n' +
' float GMST = normalizeAngle(280.46061837 + 360.98564736629 * numDays);\n' +
' float GHA = normalizeAngle(GMST - ra);\n' +
' float lon = -GHA + 360.0 * step(180.0, GHA);\n' +
' float latRad = radians(dec);\n' +
' float lonRad = radians(lon);\n' +
' float radCosLat = cos(latRad);\n' +
' return vec3(radCosLat * sin(lonRad), sin(latRad), radCosLat * cos(lonRad));\n' +
'}\n' +
//normalizes a value between 0.0 and 1.0
'float normalizeScalar(float value, float minValue, float maxValue){\n' +
' return (value - minValue) / (maxValue - minValue);\n' +
'}\n' +
'void main() {\n' +
' vec3 vertexPosition = computePosition(vertexPoint.x, vertexPoint.y);\n' +
' gl_Position = mvpMatrix * vec4(vertexPosition.xyz, 1.0);\n' +
' gl_Position.z = gl_Position.w - 0.00001;\n' +
' gl_PointSize = vertexPoint.z;\n' +
' magnitudeWeight = normalizeScalar(vertexPoint.w, magnitudeRange.x, magnitudeRange.y);\n' +
'}', 'precision mediump float;\n' +
'uniform sampler2D textureSampler;\n' +
'uniform int fragMode;\n' +
'uniform vec4 color;\n' +
'varying float magnitudeWeight;\n' +
'const vec4 white = vec4(1.0, 1.0, 1.0, 1.0);\n' +
'const vec4 grey = vec4(0.5, 0.5, 0.5, 1.0);\n' +
'void main() {\n' +
' if (fragMode == 1) {\n' +
' gl_FragColor = texture2D(textureSampler, gl_PointCoord);\n' +
' }\n' +
' else if (fragMode == 0) {\n' +
//paint the starts in shades of grey, where the brightest star is white and the dimmest star is grey
' gl_FragColor = mix(white, grey, magnitudeWeight);\n' +
' }\n' +
' else if (fragMode == 2) {\n' +
' gl_FragColor = color;\n' +
' }\n' +
'}', ["vertexPoint"]);
this.FRAG_MODE_MIX_COLOR = 0;
this.FRAG_MODE_TEXTURE = 1;
this.FRAG_MODE_COLOR = 2;
/**
* The WebGL location for this program's 'vertexPoint' attribute.
* @type {Number}
* @readonly
*/
this.vertexPointLocation = this.attributeLocation(gl, "vertexPoint");
/**
* The WebGL location for this program's 'mvpMatrix' uniform.
* @type {WebGLUniformLocation}
* @readonly
*/
this.mvpMatrixLocation = this.uniformLocation(gl, "mvpMatrix");
/**
* The WebGL location for this program's 'numDays' uniform.
* @type {WebGLUniformLocation}
* @readonly
*/
this.numDaysLocation = this.uniformLocation(gl, "numDays");
/**
* The WebGL location for this program's 'magnitudeRangeLocation' uniform.
* @type {WebGLUniformLocation}
* @readonly
*/
this.magnitudeRangeLocation = this.uniformLocation(gl, "magnitudeRange");
/**
* The WebGL location for this program's 'textureSampler' uniform.
* @type {WebGLUniformLocation}
* @readonly
*/
this.textureUnitLocation = this.uniformLocation(gl, "textureSampler");
/**
* The WebGL location for this program's 'textureEnabled' uniform.
* @type {WebGLUniformLocation}
* @readonly
*/
this.fragModeLocation = this.uniformLocation(gl, "fragMode");
this.colorLocation = this.uniformLocation(gl, "color");
this.localState = {
mvpMatrix: null,
numDays: null,
magnitudeRange: null,
textureUnit: null,
fragMode: null,
color: null,
};
}
/**
* Loads the specified matrix as the value of this program's 'mvpMatrix' uniform variable.
*
* @param {WebGLRenderingContext} gl The current WebGL context.
* @param {Matrix} matrix The matrix to load.
* @throws {ArgumentError} If the specified matrix is null or undefined.
*/
loadModelviewProjection(gl, matrix) {
if (!matrix) {
throw new ArgumentError(
Logger.logMessage(Logger.LEVEL_SEVERE, "StarFieldProgram", "loadModelviewProjection", "missingMatrix"));
}
let forceLoad = false;
if (this.localState.mvpMatrix === null) {
forceLoad = true;
this.localState.mvpMatrix = Matrix.fromIdentity();
}
if (forceLoad || !this.localState.mvpMatrix.equals(matrix)) {
this.loadUniformMatrix(gl, matrix, this.mvpMatrixLocation);
this.localState.mvpMatrix.copy(matrix);
}
}
/**
* Loads the specified number as the value of this program's 'numDays' uniform variable.
*
* @param {WebGLRenderingContext} gl The current WebGL context.
* @param {Number} numDays The number of days (positive or negative) since Greenwich noon, Terrestrial Time,
* on 1 January 2000 (J2000.0)
* @throws {ArgumentError} If the specified number is null or undefined.
*/
loadNumDays(gl, numDays) {
if (numDays == null) {
throw new ArgumentError(
Logger.logMessage(Logger.LEVEL_SEVERE, "StarFieldProgram", "loadNumDays", "missingNumDays"));
}
if (this.localState.numDays !== numDays) {
gl.uniform1f(this.numDaysLocation, numDays);
this.localState.numDays = numDays;
}
}
/**
* Loads the specified numbers as the value of this program's 'magnitudeRange' uniform variable.
*
* @param {WebGLRenderingContext} gl The current WebGL context.
* @param {Number} minMag
* @param {Number} maxMag
* @throws {ArgumentError} If the specified numbers are null or undefined.
*/
loadMagnitudeRange(gl, minMag, maxMag) {
if (minMag == null) {
throw new ArgumentError(
Logger.logMessage(Logger.LEVEL_SEVERE, "StarFieldProgram", "loadMagRange", "missingMinMag"));
}
if (maxMag == null) {
throw new ArgumentError(
Logger.logMessage(Logger.LEVEL_SEVERE, "StarFieldProgram", "loadMagRange", "missingMaxMag"));
}
let forceLoad = false;
if (this.localState.magnitudeRange === null) {
forceLoad = true;
this.localState.magnitudeRange = [minMag, maxMag];
}
if (forceLoad || this.localState.magnitudeRange[0] !== minMag || this.localState.magnitudeRange[1] !== maxMag) {
gl.uniform2f(this.magnitudeRangeLocation, minMag, maxMag);
this.localState.magnitudeRange[0] = minMag;
this.localState.magnitudeRange[1] = maxMag;
}
}
/**
* Loads the specified number as the value of this program's 'textureSampler' uniform variable.
* @param {WebGLRenderingContext} gl The current WebGL context.
* @param {Number} unit The texture unit.
*/
loadTextureUnit(gl, unit) {
if (this.localState.textureUnit !== unit) {
gl.uniform1i(this.textureUnitLocation, unit - gl.TEXTURE0);
this.localState.textureUnit = unit;
}
}
loadFragMode(gl, mode) {
if (this.localState.fragMode !== mode) {
gl.uniform1i(this.fragModeLocation, mode);
this.localState.fragMode = mode;
}
}
loadColor(gl, color) {
let forceLoad = false;
if (this.localState.color === null) {
forceLoad = true;
this.localState.color = new Color(0, 0, 0, 0);
}
if (forceLoad || !this.localState.color.equals(color)) {
this.loadUniformColor(gl, color, this.colorLocation);
this.localState.color.copy(color);
}
}
}
/**
* A string that uniquely identifies this program.
* @type {string}
* @readonly
*/
StarFieldProgram.key = "WorldWindGpuStarFieldFullProgram";
export default StarFieldProgram;