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/*
* Copyright (c) 2008-2016, NVIDIA CORPORATION. All rights reserved.
*
* NVIDIA CORPORATION and its licensors retain all intellectual property
* and proprietary rights in and to this software, related documentation
* and any modifications thereto. Any use, reproduction, disclosure or
* distribution of this software and related documentation without an express
* license agreement from NVIDIA CORPORATION is strictly prohibited.
*/
#include "ProjectionMatrixInfo.h"
#include "MatrixView.h"
//--------------------------------------------------------------------------------
GFSDK_SSAO_Status GFSDK::SSAO::ProjectionMatrixInfo::Init(const GFSDK_SSAO_Matrix& ProjectionMatrix, APIConventions API)
{
if (!IsValid(ProjectionMatrix))
{
return GFSDK_SSAO_INVALID_PROJECTION_MATRIX;
}
MatrixView m(ProjectionMatrix);
// In matrices generated with D3DXMatrixPerspectiveFovRH
// A = zf/(zn-zf)
// B = zn*zf/(zn-zf)
// C = -1
float A = m(2,2);
float B = m(3,2);
float C = m(2,3);
// In matrices generated with D3DXMatrixPerspectiveFovLH
// A = -zf/(zn-zf)
// B = zn*zf/(zn-zf)
// C = 1
if (C == 1.f)
{
A = -A;
}
// Rely on INFs to be generated in case of any divisions by zero
m_ZNear = (API == API_GL) ? (B / (A - 1.f)) : (B / A);
m_ZFar = B / (A + 1.f);
// Some matrices may use negative m00 or m11 terms to flip X/Y axises
m_TanHalfFovX = 1.f / fabs(m(0,0));
m_TanHalfFovY = 1.f / fabs(m(1,1));
return GFSDK_SSAO_OK;
}
//--------------------------------------------------------------------------------
bool GFSDK::SSAO::ProjectionMatrixInfo::IsValid(const GFSDK_SSAO_Matrix& ProjectionMatrix)
{
MatrixView m(ProjectionMatrix);
// Do not check m(2,0) and m(2,1) to allow off-centered projections
// Do not check m(2,2) to allow reverse infinite projections
return (m(0,0) != 0.0f && m(0,1) == 0.0f && m(0,2) == 0.0f && m(0,3) == 0.0f &&
m(1,0) == 0.0f && m(1,1) != 0.0f && m(1,2) == 0.0f && m(1,3) == 0.0f &&
fabs(m(2,3)) == 1.0f &&
m(3,0) == 0.0f && m(3,1) == 0.0f && m(3,2) != 0.0f && m(3,3) == 0.0f);
}
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