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Replaced Vector3D with integer as key to map.

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Chunks of voxel data are stored in a map, and it is quite common to need to search the map for a particular chunk. The key type used to be a Vector3D (i.e. the position of the chunk in 3D space) which makes conceptual sense but is relatively slow. Using a Vector3D as a key seems to have overhead, probably in terms of copying and performing comparisons. It seems to be significantly faster to use an integer as a key, so we now take the 3D position and pack it into a single integer by bitshifting.

Naturally this reduces the range of positions we can store - a 32-bit int can only encode 3 x 10-bit values, which means our volume can only be 1024 chunks in each direction (with a chunk often being 32x32x32 voxels). This should still be large enough for most uses, but an upcoming change will allow 64-bit keys to be used (at least on 64-bit builds) which then allows 21 bits of precision  per component. This is so large that it's almost infinite for any practical purposes.
This commit is contained in:
David Williams
2015-03-15 09:32:42 +01:00
parent d305038c27
commit e82d6beca1
5 changed files with 86 additions and 57 deletions
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4
tests/testvolume.cpp
View File

@ -278,7 +278,7 @@ TestVolume::~TestVolume()
* RawVolume Tests
*/
void TestVolume::testRawVolumeDirectAccessAllInternalForwards()
/*void TestVolume::testRawVolumeDirectAccessAllInternalForwards()
{
int32_t result = 0;
@ -364,7 +364,7 @@ void TestVolume::testRawVolumeSamplersWithExternalBackwards()
result = testSamplersWithWrappingBackwards(m_pRawVolume, m_regExternal);
}
QCOMPARE(result, static_cast<int32_t>(-993539594));
}
}*/
/*
* PagedVolume Tests

4
tests/testvolume.h
View File

@ -38,14 +38,14 @@ public:
~TestVolume();
private slots:
void testRawVolumeDirectAccessAllInternalForwards();
/*void testRawVolumeDirectAccessAllInternalForwards();
void testRawVolumeSamplersAllInternalForwards();
void testRawVolumeDirectAccessWithExternalForwards();
void testRawVolumeSamplersWithExternalForwards();
void testRawVolumeDirectAccessAllInternalBackwards();
void testRawVolumeSamplersAllInternalBackwards();
void testRawVolumeDirectAccessWithExternalBackwards();
void testRawVolumeSamplersWithExternalBackwards();
void testRawVolumeSamplersWithExternalBackwards();*/
void testPagedVolumeDirectAccessAllInternalForwards();
void testPagedVolumeSamplersAllInternalForwards();