/*global define*/
define([
'./Cartesian2',
'./Cartesian3',
'./defaultValue',
'./defined',
'./DeveloperError',
'./Math'
], function(
Cartesian2,
Cartesian3,
defaultValue,
defined,
DeveloperError,
CesiumMath) {
'use strict';
/**
* Attribute compression and decompression functions.
*
* @exports AttributeCompression
*
* @private
*/
var AttributeCompression = {};
/**
* Encodes a normalized vector into 2 SNORM values in the range of [0-rangeMax] following the 'oct' encoding.
*
* Oct encoding is a compact representation of unit length vectors.
* The 'oct' encoding is described in "A Survey of Efficient Representations of Independent Unit Vectors",
* Cigolle et al 2014: {@link http://jcgt.org/published/0003/02/01/}
*
* @param {Cartesian3} vector The normalized vector to be compressed into 2 component 'oct' encoding.
* @param {Cartesian2} result The 2 component oct-encoded unit length vector.
* @param {Number} rangeMax The maximum value of the SNORM range. The encoded vector is stored in log2(rangeMax+1) bits.
* @returns {Cartesian2} The 2 component oct-encoded unit length vector.
*
* @exception {DeveloperError} vector must be normalized.
*
* @see AttributeCompression.octDecodeInRange
*/
AttributeCompression.octEncodeInRange = function(vector, rangeMax, result) {
//>>includeStart('debug', pragmas.debug);
if (!defined(vector)) {
throw new DeveloperError('vector is required.');
}
if (!defined(result)) {
throw new DeveloperError('result is required.');
}
var magSquared = Cartesian3.magnitudeSquared(vector);
if (Math.abs(magSquared - 1.0) > CesiumMath.EPSILON6) {
throw new DeveloperError('vector must be normalized.');
}
//>>includeEnd('debug');
result.x = vector.x / (Math.abs(vector.x) + Math.abs(vector.y) + Math.abs(vector.z));
result.y = vector.y / (Math.abs(vector.x) + Math.abs(vector.y) + Math.abs(vector.z));
if (vector.z < 0) {
var x = result.x;
var y = result.y;
result.x = (1.0 - Math.abs(y)) * CesiumMath.signNotZero(x);
result.y = (1.0 - Math.abs(x)) * CesiumMath.signNotZero(y);
}
result.x = CesiumMath.toSNorm(result.x, rangeMax);
result.y = CesiumMath.toSNorm(result.y, rangeMax);
return result;
};
/**
* Encodes a normalized vector into 2 SNORM values in the range of [0-255] following the 'oct' encoding.
*
* @param {Cartesian3} vector The normalized vector to be compressed into 2 byte 'oct' encoding.
* @param {Cartesian2} result The 2 byte oct-encoded unit length vector.
* @returns {Cartesian2} The 2 byte oct-encoded unit length vector.
*
* @exception {DeveloperError} vector must be normalized.
*
* @see AttributeCompression.octEncodeInRange
* @see AttributeCompression.octDecode
*/
AttributeCompression.octEncode = function(vector, result) {
return AttributeCompression.octEncodeInRange(vector, 255, result);
};
/**
* Decodes a unit-length vector in 'oct' encoding to a normalized 3-component vector.
*
* @param {Number} x The x component of the oct-encoded unit length vector.
* @param {Number} y The y component of the oct-encoded unit length vector.
* @param {Number} rangeMax The maximum value of the SNORM range. The encoded vector is stored in log2(rangeMax+1) bits.
* @param {Cartesian3} result The decoded and normalized vector
* @returns {Cartesian3} The decoded and normalized vector.
*
* @exception {DeveloperError} x and y must be an unsigned normalized integer between 0 and rangeMax.
*
* @see AttributeCompression.octEncodeInRange
*/
AttributeCompression.octDecodeInRange = function(x, y, rangeMax, result) {
//>>includeStart('debug', pragmas.debug);
if (!defined(result)) {
throw new DeveloperError('result is required.');
}
if (x < 0 || x > rangeMax || y < 0 || y > rangeMax) {
throw new DeveloperError('x and y must be a signed normalized integer between 0 and ' + rangeMax);
}
//>>includeEnd('debug');
result.x = CesiumMath.fromSNorm(x, rangeMax);
result.y = CesiumMath.fromSNorm(y, rangeMax);
result.z = 1.0 - (Math.abs(result.x) + Math.abs(result.y));
if (result.z < 0.0)
{
var oldVX = result.x;
result.x = (1.0 - Math.abs(result.y)) * CesiumMath.signNotZero(oldVX);
result.y = (1.0 - Math.abs(oldVX)) * CesiumMath.signNotZero(result.y);
}
return Cartesian3.normalize(result, result);
};
/**
* Decodes a unit-length vector in 2 byte 'oct' encoding to a normalized 3-component vector.
*
* @param {Number} x The x component of the oct-encoded unit length vector.
* @param {Number} y The y component of the oct-encoded unit length vector.
* @param {Cartesian3} result The decoded and normalized vector.
* @returns {Cartesian3} The decoded and normalized vector.
*
* @exception {DeveloperError} x and y must be an unsigned normalized integer between 0 and 255.
*
* @see AttributeCompression.octDecodeInRange
*/
AttributeCompression.octDecode = function(x, y, result) {
return AttributeCompression.octDecodeInRange(x, y, 255, result);
};
/**
* Packs an oct encoded vector into a single floating-point number.
*
* @param {Cartesian2} encoded The oct encoded vector.
* @returns {Number} The oct encoded vector packed into a single float.
*
*/
AttributeCompression.octPackFloat = function(encoded) {
//>>includeStart('debug', pragmas.debug);
if (!defined(encoded)) {
throw new DeveloperError('encoded is required.');
}
//>>includeEnd('debug');
return 256.0 * encoded.x + encoded.y;
};
var scratchEncodeCart2 = new Cartesian2();
/**
* Encodes a normalized vector into 2 SNORM values in the range of [0-255] following the 'oct' encoding and
* stores those values in a single float-point number.
*
* @param {Cartesian3} vector The normalized vector to be compressed into 2 byte 'oct' encoding.
* @returns {Number} The 2 byte oct-encoded unit length vector.
*
* @exception {DeveloperError} vector must be normalized.
*/
AttributeCompression.octEncodeFloat = function(vector) {
AttributeCompression.octEncode(vector, scratchEncodeCart2);
return AttributeCompression.octPackFloat(scratchEncodeCart2);
};
/**
* Decodes a unit-length vector in 'oct' encoding packed in a floating-point number to a normalized 3-component vector.
*
* @param {Number} value The oct-encoded unit length vector stored as a single floating-point number.
* @param {Cartesian3} result The decoded and normalized vector
* @returns {Cartesian3} The decoded and normalized vector.
*
*/
AttributeCompression.octDecodeFloat = function(value, result) {
//>>includeStart('debug', pragmas.debug);
if (!defined(value)) {
throw new DeveloperError('value is required.');
}
//>>includeEnd('debug');
var temp = value / 256.0;
var x = Math.floor(temp);
var y = (temp - x) * 256.0;
return AttributeCompression.octDecode(x, y, result);
};
/**
* Encodes three normalized vectors into 6 SNORM values in the range of [0-255] following the 'oct' encoding and
* packs those into two floating-point numbers.
*
* @param {Cartesian3} v1 A normalized vector to be compressed.
* @param {Cartesian3} v2 A normalized vector to be compressed.
* @param {Cartesian3} v3 A normalized vector to be compressed.
* @param {Cartesian2} result The 'oct' encoded vectors packed into two floating-point numbers.
* @returns {Cartesian2} The 'oct' encoded vectors packed into two floating-point numbers.
*
*/
AttributeCompression.octPack = function(v1, v2, v3, result) {
//>>includeStart('debug', pragmas.debug);
if (!defined(v1)) {
throw new DeveloperError('v1 is required.');
}
if (!defined(v2)) {
throw new DeveloperError('v2 is required.');
}
if (!defined(v3)) {
throw new DeveloperError('v3 is required.');
}
if (!defined(result)) {
throw new DeveloperError('result is required.');
}
//>>includeEnd('debug');
var encoded1 = AttributeCompression.octEncodeFloat(v1);
var encoded2 = AttributeCompression.octEncodeFloat(v2);
var encoded3 = AttributeCompression.octEncode(v3, scratchEncodeCart2);
result.x = 65536.0 * encoded3.x + encoded1;
result.y = 65536.0 * encoded3.y + encoded2;
return result;
};
/**
* Decodes three unit-length vectors in 'oct' encoding packed into a floating-point number to a normalized 3-component vector.
*
* @param {Cartesian2} packed The three oct-encoded unit length vectors stored as two floating-point number.
* @param {Cartesian3} v1 One decoded and normalized vector.
* @param {Cartesian3} v2 One decoded and normalized vector.
* @param {Cartesian3} v3 One decoded and normalized vector.
*/
AttributeCompression.octUnpack = function(packed, v1, v2, v3) {
//>>includeStart('debug', pragmas.debug);
if (!defined(packed)) {
throw new DeveloperError('packed is required.');
}
if (!defined(v1)) {
throw new DeveloperError('v1 is required.');
}
if (!defined(v2)) {
throw new DeveloperError('v2 is required.');
}
if (!defined(v3)) {
throw new DeveloperError('v3 is required.');
}
//>>includeEnd('debug');
var temp = packed.x / 65536.0;
var x = Math.floor(temp);
var encodedFloat1 = (temp - x) * 65536.0;
temp = packed.y / 65536.0;
var y = Math.floor(temp);
var encodedFloat2 = (temp - y) * 65536.0;
AttributeCompression.octDecodeFloat(encodedFloat1, v1);
AttributeCompression.octDecodeFloat(encodedFloat2, v2);
AttributeCompression.octDecode(x, y, v3);
};
/**
* Pack texture coordinates into a single float. The texture coordinates will only preserve 12 bits of precision.
*
* @param {Cartesian2} textureCoordinates The texture coordinates to compress. Both coordinates must be in the range 0.0-1.0.
* @returns {Number} The packed texture coordinates.
*
*/
AttributeCompression.compressTextureCoordinates = function(textureCoordinates) {
//>>includeStart('debug', pragmas.debug);
if (!defined(textureCoordinates)) {
throw new DeveloperError('textureCoordinates is required.');
}
//>>includeEnd('debug');
// Move x and y to the range 0-4095;
var x = (textureCoordinates.x * 4095.0) | 0;
var y = (textureCoordinates.y * 4095.0) | 0;
return 4096.0 * x + y;
};
/**
* Decompresses texture coordinates that were packed into a single float.
*
* @param {Number} compressed The compressed texture coordinates.
* @param {Cartesian2} result The decompressed texture coordinates.
* @returns {Cartesian2} The modified result parameter.
*
*/
AttributeCompression.decompressTextureCoordinates = function(compressed, result) {
//>>includeStart('debug', pragmas.debug);
if (!defined(compressed)) {
throw new DeveloperError('compressed is required.');
}
if (!defined(result)) {
throw new DeveloperError('result is required.');
}
//>>includeEnd('debug');
var temp = compressed / 4096.0;
var xZeroTo4095 = Math.floor(temp);
result.x = xZeroTo4095 / 4095.0;
result.y = (compressed - xZeroTo4095 * 4096) / 4095;
return result;
};
return AttributeCompression;
});