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Added control over the number of samples taken in the ambient occlusion calculator.

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This commit is contained in:
David Williams 2011-04-16 14:10:34 +01:00
parent f302e3612a
commit 55cbff1186
2 changed files with 22 additions and 5 deletions
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4
library/PolyVoxCore/include/AmbientOcclusionCalculator.h
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@ -32,7 +32,7 @@ namespace PolyVox
class AmbientOcclusionCalculator class AmbientOcclusionCalculator
{ {
public: public:
AmbientOcclusionCalculator(Volume<VoxelType>* volInput, Array<3, uint8_t>* arrayResult, Region region, float fRayLength); AmbientOcclusionCalculator(Volume<VoxelType>* volInput, Array<3, uint8_t>* arrayResult, Region region, float fRayLength, uint8_t uNoOfSamplesPerOutputElement);
~AmbientOcclusionCalculator(); ~AmbientOcclusionCalculator();
void execute(void); void execute(void);
@ -44,6 +44,8 @@ namespace PolyVox
Array<3, uint8_t>* m_arrayResult; Array<3, uint8_t>* m_arrayResult;
float m_fRayLength; float m_fRayLength;
uint8_t m_uNoOfSamplesPerOutputElement;
uint16_t mRandomUnitVectorIndex; uint16_t mRandomUnitVectorIndex;
uint16_t mRandomVectorIndex; uint16_t mRandomVectorIndex;
uint16_t mIndexIncreament; uint16_t mIndexIncreament;

23
library/PolyVoxCore/include/AmbientOcclusionCalculator.inl
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@ -32,12 +32,13 @@ freely, subject to the following restrictions:
namespace PolyVox namespace PolyVox
{ {
template <typename VoxelType> template <typename VoxelType>
AmbientOcclusionCalculator<VoxelType>::AmbientOcclusionCalculator(Volume<VoxelType>* volInput, Array<3, uint8_t>* arrayResult, Region region, float fRayLength) AmbientOcclusionCalculator<VoxelType>::AmbientOcclusionCalculator(Volume<VoxelType>* volInput, Array<3, uint8_t>* arrayResult, Region region, float fRayLength, uint8_t uNoOfSamplesPerOutputElement)
:m_region(region) :m_region(region)
,m_sampVolume(volInput) ,m_sampVolume(volInput)
,m_volInput(volInput) ,m_volInput(volInput)
,m_arrayResult(arrayResult) ,m_arrayResult(arrayResult)
,m_fRayLength(fRayLength) ,m_fRayLength(fRayLength)
,m_uNoOfSamplesPerOutputElement(uNoOfSamplesPerOutputElement)
{ {
//Make sure that the size of the volume is an exact multiple of the size of the array. //Make sure that the size of the volume is an exact multiple of the size of the array.
assert(m_volInput->getWidth() % arrayResult->getDimension(0) == 0); assert(m_volInput->getWidth() % arrayResult->getDimension(0) == 0);
@ -100,9 +101,9 @@ namespace PolyVox
//Keep track of how many rays did not hit anything //Keep track of how many rays did not hit anything
uint8_t uVisibleDirections = 0; uint8_t uVisibleDirections = 0;
for(int ct = 0; ct < 255; ct++) for(int ct = 0; ct < m_uNoOfSamplesPerOutputElement; ct++)
{ {
//We take a random vector with components going from -1 to 1 and scale it to go from -haflRatio to +halfRatio. //We take a random vector with components going from -1 to 1 and scale it to go from -halfRatio to +halfRatio.
//This jitter value moves our sample point from the center of the array cell to somewhere else in the array cell //This jitter value moves our sample point from the center of the array cell to somewhere else in the array cell
Vector3DFloat v3dJitter = randomVectors[(mRandomVectorIndex += (++mIndexIncreament)) % 1019]; //Prime number helps avoid repetition on sucessive loops. Vector3DFloat v3dJitter = randomVectors[(mRandomVectorIndex += (++mIndexIncreament)) % 1019]; //Prime number helps avoid repetition on sucessive loops.
v3dJitter *= v3dHalfRatio; v3dJitter *= v3dHalfRatio;
@ -120,7 +121,21 @@ namespace PolyVox
++uVisibleDirections; ++uVisibleDirections;
} }
} }
(*m_arrayResult)[z / iRatioZ][y / iRatioY][x / iRatioX] = uVisibleDirections;
float fVisibility;
if(m_uNoOfSamplesPerOutputElement == 0)
{
//The user might request zero samples (I've done this in the past while debugging - I don't want to
//wait for ambient occlusion but I do want as valid result for rendering). Avoid the divide by zero.
fVisibility = 1.0f;
}
else
{
fVisibility = static_cast<float>(uVisibleDirections) / static_cast<float>(m_uNoOfSamplesPerOutputElement);
assert((fVisibility >= 0.0f) && (fVisibility <= 1.0f));
}
(*m_arrayResult)[z / iRatioZ][y / iRatioY][x / iRatioX] = static_cast<uint8_t>(255.0f * fVisibility);
} }
} }
} }