itowns
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A JS/WebGL framework for 3D geospatial data visualization
92 lines (77 loc) • 2.88 kB
JavaScript
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.computeMinMaxElevation = computeMinMaxElevation;
exports.checkNodeElevationTextureValidity = checkNodeElevationTextureValidity;
exports.insertSignificantValuesFromParent = insertSignificantValuesFromParent;
/**
* Calculates the minimum maximum elevation of xbil buffer
*
* @param {number} buffer The buffer to parse
* @param {number} width The buffer's width
* @param {number} height The buffer's height
* @param {THREE.Vector4} pitch The pitch, restrict zone to parse
* @return {Object} The minimum maximum elevation.
*/
function computeMinMaxElevation(buffer, width, height, pitch) {
var min = 1000000;
var max = -1000000;
if (!buffer) {
// Return null values means there's no elevation values.
// They can't be determined.
// Don't return 0 because the result will be wrong
return {
min: null,
max: null
};
}
var sizeX = pitch ? Math.floor(pitch.z * width) : buffer.length;
var sizeY = pitch ? Math.floor(pitch.z * height) : 1;
var xs = pitch ? Math.floor(pitch.x * width) : 0;
var ys = pitch ? Math.floor(pitch.y * height) : 0;
var inc = pitch ? Math.max(Math.floor(sizeX / 8), 2) : 16;
for (var y = ys; y < ys + sizeY; y += inc) {
var pit = y * (width || 0);
for (var x = xs; x < xs + sizeX; x += inc) {
var val = buffer[pit + x];
if (val > -10) {
max = Math.max(max, val);
min = Math.min(min, val);
}
}
}
if (max === -1000000 || min === 1000000) {
// Return null values means the elevation values are incoherent
// They can't be determined.
// Don't return 0, -1000000 or 1000000 because the result will be wrong
return {
min: null,
max: null
};
}
return {
min: min,
max: max
};
} // We check if the elevation texture has some significant values through corners
function checkNodeElevationTextureValidity(data, noDataValue) {
var l = data.length;
return data[0] > noDataValue && data[l - 1] > noDataValue && data[Math.sqrt(l) - 1] > noDataValue && data[l - Math.sqrt(l)] > noDataValue;
}
function getIndiceWithPitch(i, pitch, w) {
// Return corresponding indice in parent tile using pitch
// normalized
var currentY = Math.floor(i / w) / w; // normalized
var newX = pitch.x + i % w / w * pitch.z;
var newY = pitch.y + currentY * pitch.w;
var newIndice = Math.floor(newY * w) * w + Math.floor(newX * w);
return newIndice;
} // This function replaces noDataValue by significant values from parent texture
function insertSignificantValuesFromParent(data, dataParent, noDataValue, pitch) {
for (var i = 0, l = data.length; i < l; ++i) {
if (data[i] === noDataValue) {
data[i] = dataParent[getIndiceWithPitch(i, pitch, 256)];
}
}
}
;