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Rearranged ambient occlusion code.

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This commit is contained in:
David Williams 2012-10-05 16:38:28 +02:00
parent bcea851f2c
commit 8c7e2671be
2 changed files with 96 additions and 93 deletions
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95
library/PolyVoxCore/include/PolyVoxCore/AmbientOcclusionCalculator.h
View File

@ -64,99 +64,10 @@ namespace PolyVox
IsVoxelTransparentCallback mIsVoxelTransparentCallback; IsVoxelTransparentCallback mIsVoxelTransparentCallback;
}; };
// NOTE: The callback needs to be a functor not a function. I haven't been
// able to work the required template magic to get functions working as well.
template<typename VolumeType, typename IsVoxelTransparentCallback> template<typename VolumeType, typename IsVoxelTransparentCallback>
void calculateAmbientOcclusion(VolumeType* volInput, Array<3, uint8_t>* arrayResult, Region region, float fRayLength, uint8_t uNoOfSamplesPerOutputElement, IsVoxelTransparentCallback isVoxelTransparentCallback) void calculateAmbientOcclusion(VolumeType* volInput, Array<3, uint8_t>* arrayResult, Region region, float fRayLength, uint8_t uNoOfSamplesPerOutputElement, IsVoxelTransparentCallback isVoxelTransparentCallback);
{
typename VolumeType::Sampler m_sampVolume(volInput);
uint16_t uRandomUnitVectorIndex = 0;
uint16_t uRandomVectorIndex = 0;
uint16_t uIndexIncreament;
//Make sure that the size of the volume is an exact multiple of the size of the array.
assert(volInput->getWidth() % arrayResult->getDimension(0) == 0);
assert(volInput->getHeight() % arrayResult->getDimension(1) == 0);
assert(volInput->getDepth() % arrayResult->getDimension(2) == 0);
//Our initial indices. It doesn't matter exactly what we set here, but the code below makes
//sure they are different for different regions which helps reduce tiling patterns in the results.
uRandomUnitVectorIndex += region.getLowerCorner().getX() + region.getLowerCorner().getY() + region.getLowerCorner().getZ();
uRandomVectorIndex += region.getLowerCorner().getX() + region.getLowerCorner().getY() + region.getLowerCorner().getZ();
//This value helps us jump around in the array a bit more, so the
//nth 'random' value isn't always followed by the n+1th 'random' value.
uIndexIncreament = 1;
const int iRatioX = volInput->getWidth() / arrayResult->getDimension(0);
const int iRatioY = volInput->getHeight() / arrayResult->getDimension(1);
const int iRatioZ = volInput->getDepth() / arrayResult->getDimension(2);
const float fRatioX = iRatioX;
const float fRatioY = iRatioY;
const float fRatioZ = iRatioZ;
const Vector3DFloat v3dRatio(fRatioX, fRatioY, fRatioZ);
const float fHalfRatioX = fRatioX * 0.5f;
const float fHalfRatioY = fRatioY * 0.5f;
const float fHalfRatioZ = fRatioZ * 0.5f;
const Vector3DFloat v3dHalfRatio(fHalfRatioX, fHalfRatioY, fHalfRatioZ);
const Vector3DFloat v3dOffset(0.5f,0.5f,0.5f);
//This loop iterates over the bottom-lower-left voxel in each of the cells in the output array
for(uint16_t z = region.getLowerCorner().getZ(); z <= region.getUpperCorner().getZ(); z += iRatioZ)
{
for(uint16_t y = region.getLowerCorner().getY(); y <= region.getUpperCorner().getY(); y += iRatioY)
{
for(uint16_t x = region.getLowerCorner().getX(); x <= region.getUpperCorner().getX(); x += iRatioX)
{
//Compute a start position corresponding to
//the centre of the cell in the output array.
Vector3DFloat v3dStart(x, y, z);
v3dStart -= v3dOffset;
v3dStart += v3dHalfRatio;
//Keep track of how many rays did not hit anything
uint8_t uVisibleDirections = 0;
for(int ct = 0; ct < uNoOfSamplesPerOutputElement; ct++)
{
//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
Vector3DFloat v3dJitter = randomVectors[(uRandomVectorIndex += (++uIndexIncreament)) % 1019]; //Prime number helps avoid repetition on sucessive loops.
v3dJitter *= v3dHalfRatio;
const Vector3DFloat v3dRayStart = v3dStart + v3dJitter;
Vector3DFloat v3dRayDirection = randomUnitVectors[(uRandomUnitVectorIndex += (++uIndexIncreament)) % 1021]; //Differenct prime number.
v3dRayDirection *= fRayLength;
AmbientOcclusionCalculatorRaycastCallback<IsVoxelTransparentCallback> ambientOcclusionCalculatorRaycastCallback(isVoxelTransparentCallback);
MyRaycastResult result = raycastWithDirection(volInput, v3dRayStart, v3dRayDirection, ambientOcclusionCalculatorRaycastCallback);
if(result == MyRaycastResults::Completed)
{
++uVisibleDirections;
}
}
float fVisibility;
if(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>(uNoOfSamplesPerOutputElement);
assert((fVisibility >= 0.0f) && (fVisibility <= 1.0f));
}
(*arrayResult)[z / iRatioZ][y / iRatioY][x / iRatioX] = static_cast<uint8_t>(255.0f * fVisibility);
}
}
}
}
} }
#include "PolyVoxCore/AmbientOcclusionCalculator.inl" #include "PolyVoxCore/AmbientOcclusionCalculator.inl"

92
library/PolyVoxCore/include/PolyVoxCore/AmbientOcclusionCalculator.inl
View File

@ -23,5 +23,97 @@ freely, subject to the following restrictions:
namespace PolyVox namespace PolyVox
{ {
template<typename VolumeType, typename IsVoxelTransparentCallback>
void calculateAmbientOcclusion(VolumeType* volInput, Array<3, uint8_t>* arrayResult, Region region, float fRayLength, uint8_t uNoOfSamplesPerOutputElement, IsVoxelTransparentCallback isVoxelTransparentCallback)
{
typename VolumeType::Sampler m_sampVolume(volInput);
uint16_t uRandomUnitVectorIndex = 0;
uint16_t uRandomVectorIndex = 0;
uint16_t uIndexIncreament;
//Make sure that the size of the volume is an exact multiple of the size of the array.
assert(volInput->getWidth() % arrayResult->getDimension(0) == 0);
assert(volInput->getHeight() % arrayResult->getDimension(1) == 0);
assert(volInput->getDepth() % arrayResult->getDimension(2) == 0);
//Our initial indices. It doesn't matter exactly what we set here, but the code below makes
//sure they are different for different regions which helps reduce tiling patterns in the results.
uRandomUnitVectorIndex += region.getLowerCorner().getX() + region.getLowerCorner().getY() + region.getLowerCorner().getZ();
uRandomVectorIndex += region.getLowerCorner().getX() + region.getLowerCorner().getY() + region.getLowerCorner().getZ();
//This value helps us jump around in the array a bit more, so the
//nth 'random' value isn't always followed by the n+1th 'random' value.
uIndexIncreament = 1;
const int iRatioX = volInput->getWidth() / arrayResult->getDimension(0);
const int iRatioY = volInput->getHeight() / arrayResult->getDimension(1);
const int iRatioZ = volInput->getDepth() / arrayResult->getDimension(2);
const float fRatioX = iRatioX;
const float fRatioY = iRatioY;
const float fRatioZ = iRatioZ;
const Vector3DFloat v3dRatio(fRatioX, fRatioY, fRatioZ);
const float fHalfRatioX = fRatioX * 0.5f;
const float fHalfRatioY = fRatioY * 0.5f;
const float fHalfRatioZ = fRatioZ * 0.5f;
const Vector3DFloat v3dHalfRatio(fHalfRatioX, fHalfRatioY, fHalfRatioZ);
const Vector3DFloat v3dOffset(0.5f,0.5f,0.5f);
//This loop iterates over the bottom-lower-left voxel in each of the cells in the output array
for(uint16_t z = region.getLowerCorner().getZ(); z <= region.getUpperCorner().getZ(); z += iRatioZ)
{
for(uint16_t y = region.getLowerCorner().getY(); y <= region.getUpperCorner().getY(); y += iRatioY)
{
for(uint16_t x = region.getLowerCorner().getX(); x <= region.getUpperCorner().getX(); x += iRatioX)
{
//Compute a start position corresponding to
//the centre of the cell in the output array.
Vector3DFloat v3dStart(x, y, z);
v3dStart -= v3dOffset;
v3dStart += v3dHalfRatio;
//Keep track of how many rays did not hit anything
uint8_t uVisibleDirections = 0;
for(int ct = 0; ct < uNoOfSamplesPerOutputElement; ct++)
{
//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
Vector3DFloat v3dJitter = randomVectors[(uRandomVectorIndex += (++uIndexIncreament)) % 1019]; //Prime number helps avoid repetition on sucessive loops.
v3dJitter *= v3dHalfRatio;
const Vector3DFloat v3dRayStart = v3dStart + v3dJitter;
Vector3DFloat v3dRayDirection = randomUnitVectors[(uRandomUnitVectorIndex += (++uIndexIncreament)) % 1021]; //Differenct prime number.
v3dRayDirection *= fRayLength;
AmbientOcclusionCalculatorRaycastCallback<IsVoxelTransparentCallback> ambientOcclusionCalculatorRaycastCallback(isVoxelTransparentCallback);
MyRaycastResult result = raycastWithDirection(volInput, v3dRayStart, v3dRayDirection, ambientOcclusionCalculatorRaycastCallback);
if(result == MyRaycastResults::Completed)
{
++uVisibleDirections;
}
}
float fVisibility;
if(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>(uNoOfSamplesPerOutputElement);
assert((fVisibility >= 0.0f) && (fVisibility <= 1.0f));
}
(*arrayResult)[z / iRatioZ][y / iRatioY][x / iRatioX] = static_cast<uint8_t>(255.0f * fVisibility);
}
}
}
}
} }