1 files changed, 63 insertions, 0 deletions
diff --git a/src/ProjectionMatrixInfo.cpp b/src/ProjectionMatrixInfo.cpp
new file mode 100644
index 0000000..2a19892
--- /dev/null
+++ b/src/ProjectionMatrixInfo.cpp
@@ -0,0 +1,63 @@
+/* 
+* 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);
+}