Core/ShadowCamera.cpp

   1 //
   2 // Copyright (c) Microsoft. All rights reserved.
   3 // This code is licensed under the MIT License (MIT).
   4 // THIS CODE IS PROVIDED *AS IS* WITHOUT WARRANTY OF
   5 // ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY
   6 // IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
   7 // PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.
   8 //
   9 // Developed by Minigraph
  10 //
  11 // Author:  James Stanard
  12 //
  13
  14 #include "pch.h"
  15 #include "ShadowCamera.h"
  16
  17 using namespace Math;
  18
  19 void GameCore::ShadowCamera::UpdateMatrix(
  20     Vector3 LightDirection, Vector3 ShadowCenter, Vector3 ShadowBounds,
  21     uint32_t BufferWidth, uint32_t BufferHeight, uint32_t BufferPrecision )
  22 {
  23     SetLookDirection( LightDirection, Vector3(kZUnitVector) );
  24
  25     // Converts world units to texel units so we can quantize the camera position to whole texel units
  26     Vector3 RcpDimensions = Recip(ShadowBounds);
  27     Vector3 QuantizeScale = Vector3((float)BufferWidth, (float)BufferHeight, (float)((1 << BufferPrecision) - 1)) * RcpDimensions;
  28
  29     //
  30     // Recenter the camera at the quantized position
  31     //
  32
  33     // Transform to view space
  34     ShadowCenter = ~GetRotation() * ShadowCenter;
  35     // Scale to texel units, truncate fractional part, and scale back to world units
  36     ShadowCenter = Floor( ShadowCenter * QuantizeScale ) / QuantizeScale;
  37     // Transform back into world space
  38     ShadowCenter = GetRotation() * ShadowCenter;
  39
  40     SetPosition( ShadowCenter );
  41
  42     SetProjMatrix( Matrix4::MakeScale(Vector3(2.0f, 2.0f, 1.0f) * RcpDimensions) );
  43
  44     Update();
  45
  46     // Transform from clip space to texture space
  47     m_ShadowMatrix =  Matrix4( AffineTransform( Matrix3::MakeScale( 0.5f, -0.5f, 1.0f ), Vector3(0.5f, 0.5f, 0.0f) ) ) * m_ViewProjMatrix;
  48 }