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Return split values in a single interleaved Float32Array

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This commit is contained in:
Tom Payne
2013-05-30 20:05:02 +02:00
parent 42f15f000b
commit db2f805ed9
2 changed files with 25 additions and 35 deletions
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src/ol/structs/buffer.js
+13 -19
View File
@@ -22,12 +22,6 @@ ol.structs.BufferUsage = {
ol.BUFFER_REPLACE_UNUSED_ENTRIES_WITH_NANS = goog.DEBUG; ol.BUFFER_REPLACE_UNUSED_ENTRIES_WITH_NANS = goog.DEBUG;
/**
* @typedef {{high: Float32Array, low: Float32Array}}
*/
ol.structs.BufferSplit32;
/** /**
* @constructor * @constructor
@@ -70,7 +64,7 @@ ol.structs.Buffer = function(opt_arr, opt_used, opt_usage) {
/** /**
* @private * @private
* @type {?ol.structs.BufferSplit32} * @type {?Float32Array}
*/ */
this.split32_ = null; this.split32_ = null;
@@ -165,9 +159,12 @@ ol.structs.Buffer.prototype.getFreeSet = function() {
/** /**
* Splits this buffer into two Float32Arrays. * Returns a Float32Array twice the length of the buffer containing each value
* split into two 32-bit floating point values that, when added together,
* approximate the original value. Even indicies contain the high bits, odd
* indicies contain the low bits.
* @see http://blogs.agi.com/insight3d/index.php/2008/09/03/precisions-precisions/ * @see http://blogs.agi.com/insight3d/index.php/2008/09/03/precisions-precisions/
* @return {ol.structs.BufferSplit32} Split. * @return {Float32Array} Split.
*/ */
ol.structs.Buffer.prototype.getSplit32 = function() { ol.structs.Buffer.prototype.getSplit32 = function() {
var arr = this.arr_; var arr = this.arr_;
@@ -177,24 +174,21 @@ ol.structs.Buffer.prototype.getSplit32 = function() {
this.addDirtySet(this.split32DirtySet_); this.addDirtySet(this.split32DirtySet_);
} }
if (goog.isNull(this.split32_)) { if (goog.isNull(this.split32_)) {
this.split32_ = { this.split32_ = new Float32Array(2 * n);
high: new Float32Array(n),
low: new Float32Array(n)
};
} }
var split32 = this.split32_; var split32 = this.split32_;
this.split32DirtySet_.forEachRange(function(start, stop) { this.split32DirtySet_.forEachRange(function(start, stop) {
var doubleHigh, i, value; var doubleHigh, i, j, value;
for (i = start; i < stop; ++i) { for (i = start, j = 2 * start; i < stop; ++i, j += 2) {
value = arr[i]; value = arr[i];
if (value < 0) { if (value < 0) {
doubleHigh = 65536 * Math.floor(-value / 65536); doubleHigh = 65536 * Math.floor(-value / 65536);
split32.high[i] = -doubleHigh; split32[j] = -doubleHigh;
split32.low[i] = value + doubleHigh; split32[j + 1] = value + doubleHigh;
} else { } else {
doubleHigh = 65536 * Math.floor(value / 65536); doubleHigh = 65536 * Math.floor(value / 65536);
split32.high[i] = doubleHigh; split32[j] = doubleHigh;
split32.low[i] = value - doubleHigh; split32[j + 1] = value - doubleHigh;
} }
} }
}); });
test/spec/ol/structs/buffer.test.js
+12 -16
View File
@@ -231,14 +231,12 @@ describe('ol.structs.Buffer', function() {
it('returns the expected value', function() { it('returns the expected value', function() {
var split32 = b.getSplit32(); var split32 = b.getSplit32();
expect(split32.high).to.be.a(Float32Array); expect(split32).to.be.a(Float32Array);
expect(split32.low).to.be.a(Float32Array); expect(split32).to.have.length(4);
expect(split32.high).to.have.length(2); expect(split32[0]).to.roughlyEqual(1179648.0, 1e1);
expect(split32.low).to.have.length(2); expect(split32[1]).to.roughlyEqual(54919.12345670001, 1e-2);
expect(split32.high[0]).to.roughlyEqual(1179648.0, 1e1); expect(split32[2]).to.roughlyEqual(-7602176.0, 1e1);
expect(split32.low[0]).to.roughlyEqual(54919.12345670001, 1e-2); expect(split32[3]).to.roughlyEqual(-52145.76543209981, 1e-2);
expect(split32.high[1]).to.roughlyEqual(-7602176.0, 1e1);
expect(split32.low[1]).to.roughlyEqual(-52145.76543209981, 1e-2);
}); });
it('tracks updates', function() { it('tracks updates', function() {
@@ -246,14 +244,12 @@ describe('ol.structs.Buffer', function() {
b.getArray()[0] = 0; b.getArray()[0] = 0;
b.markDirty(1, 0); b.markDirty(1, 0);
var split32 = b.getSplit32(); var split32 = b.getSplit32();
expect(split32.high).to.be.a(Float32Array); expect(split32).to.be.a(Float32Array);
expect(split32.low).to.be.a(Float32Array); expect(split32).to.have.length(4);
expect(split32.high).to.have.length(2); expect(split32[0]).to.be(0);
expect(split32.low).to.have.length(2); expect(split32[1]).to.be(0);
expect(split32.high[0]).to.be(0); expect(split32[2]).to.roughlyEqual(-7602176.0, 1e1);
expect(split32.low[0]).to.be(0); expect(split32[3]).to.roughlyEqual(-52145.76543209981, 1e-2);
expect(split32.high[1]).to.roughlyEqual(-7602176.0, 1e1);
expect(split32.low[1]).to.roughlyEqual(-52145.76543209981, 1e-2);
}); });
}); });