1 // Created on: 2016-06-16 2 // Created by: Denis BOGOLEPOV & Danila ULYANOV 3 // Copyright (c) 2016 OPEN CASCADE SAS 4 // 5 // This file is part of Open CASCADE Technology software library. 6 // 7 // This library is free software; you can redistribute it and/or modify it under 8 // the terms of the GNU Lesser General Public License version 2.1 as published 9 // by the Free Software Foundation, with special exception defined in the file 10 // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT 11 // distribution for complete text of the license and disclaimer of any warranty. 12 // 13 // Alternatively, this file may be used under the terms of Open CASCADE 14 // commercial license or contractual agreement. 15 16 #ifndef _OpenGl_TileSampler_H 17 #define _OpenGl_TileSampler_H 18 19 #include <OpenGl_Texture.hxx> 20 #include <OpenGl_HaltonSampler.hxx> 21 22 #include <Image_PixMapTypedData.hxx> 23 24 #include <vector> 25 26 class Graphic3d_RenderingParams; 27 28 //! Tool object used for sampling screen tiles according to estimated pixel variance (used in path tracing engine). 29 //! To improve GPU thread coherency, rendering window is split into pixel blocks or tiles. The important feature of 30 //! this approach is that it is possible to keep the same number of tiles for any screen resolution (e.g. 256 tiles 31 //! can be used for both 512 x 512 window and 1920 x 1080 window). So, a smaller number of tiles allows to increase 32 //! interactivity (FPS), but at the cost of higher per-frame variance ('noise'). On the contrary a larger number of 33 //! tiles decrease interactivity, but leads to lower per-frame variance. Note that the total time needed to produce 34 //! final final image is the same for both cases. 35 class OpenGl_TileSampler 36 { 37 public: 38 39 //! Creates new tile sampler. 40 Standard_EXPORT OpenGl_TileSampler(); 41 42 //! Size of individual tile in pixels. TileSize() const43 Graphic3d_Vec2i TileSize() const { return Graphic3d_Vec2i (myTileSize, myTileSize); } 44 45 //! Scale factor for quantization of visual error (float) into signed integer. VarianceScaleFactor() const46 float VarianceScaleFactor() const { return myScaleFactor; } 47 48 //! Returns number of tiles in X dimension. NbTilesX() const49 int NbTilesX() const { return (int)myTiles.SizeX; } 50 51 //! Returns number of tiles in Y dimension. NbTilesY() const52 int NbTilesY() const { return (int)myTiles.SizeY; } 53 54 //! Returns total number of tiles in viewport. NbTiles() const55 int NbTiles() const { return int(myTiles.SizeX * myTiles.SizeY); } 56 57 //! Returns ray-tracing viewport. ViewSize() const58 const Graphic3d_Vec2i& ViewSize() const { return myViewSize; } 59 60 //! Number of tiles within offsets texture. NbOffsetTiles(bool theAdaptive) const61 Graphic3d_Vec2i NbOffsetTiles (bool theAdaptive) const 62 { 63 return theAdaptive 64 ? Graphic3d_Vec2i ((int )myOffsetsShrunk.SizeX, (int )myOffsetsShrunk.SizeY) 65 : Graphic3d_Vec2i ((int )myOffsets.SizeX, (int )myOffsets.SizeY); 66 } 67 68 //! Maximum number of tiles within offsets texture. NbOffsetTilesMax() const69 Graphic3d_Vec2i NbOffsetTilesMax() const { return NbOffsetTiles (true).cwiseMax (NbOffsetTiles (false)); } 70 71 //! Viewport for rendering using offsets texture. OffsetTilesViewport(bool theAdaptive) const72 Graphic3d_Vec2i OffsetTilesViewport (bool theAdaptive) const { return NbOffsetTiles (theAdaptive) * myTileSize; } 73 74 //! Maximum viewport for rendering using offsets texture. OffsetTilesViewportMax() const75 Graphic3d_Vec2i OffsetTilesViewportMax() const { return NbOffsetTilesMax() * myTileSize; } 76 77 //! Return maximum number of samples per tile. MaxTileSamples() const78 int MaxTileSamples() const 79 { 80 int aNbSamples = 0; 81 for (Standard_Size aRowIter = 0; aRowIter < myTiles.SizeY; ++aRowIter) 82 { 83 for (Standard_Size aColIter = 0; aColIter < myTiles.SizeX; ++aColIter) 84 { 85 aNbSamples = Max (aNbSamples, myTiles.Value (aRowIter, aColIter)); 86 } 87 } 88 return aNbSamples; 89 } 90 91 //! Specifies size of ray-tracing viewport and recomputes tile size. 92 Standard_EXPORT void SetSize (const Graphic3d_RenderingParams& theParams, 93 const Graphic3d_Vec2i& theSize); 94 95 //! Fetches current error estimation from the GPU and 96 //! builds 2D discrete distribution for tile sampling. 97 Standard_EXPORT void GrabVarianceMap (const Handle(OpenGl_Context)& theContext, 98 const Handle(OpenGl_Texture)& theTexture); 99 100 //! Resets (restart) tile sampler to initial state. Reset()101 void Reset() { myLastSample = 0; } 102 103 //! Uploads tile samples to the given OpenGL texture. UploadSamples(const Handle (OpenGl_Context)& theContext,const Handle (OpenGl_Texture)& theSamplesTexture,const bool theAdaptive)104 bool UploadSamples (const Handle(OpenGl_Context)& theContext, 105 const Handle(OpenGl_Texture)& theSamplesTexture, 106 const bool theAdaptive) 107 { 108 return upload (theContext, theSamplesTexture, Handle(OpenGl_Texture)(), theAdaptive); 109 } 110 111 //! Uploads offsets of sampled tiles to the given OpenGL texture. UploadOffsets(const Handle (OpenGl_Context)& theContext,const Handle (OpenGl_Texture)& theOffsetsTexture,const bool theAdaptive)112 bool UploadOffsets (const Handle(OpenGl_Context)& theContext, 113 const Handle(OpenGl_Texture)& theOffsetsTexture, 114 const bool theAdaptive) 115 { 116 return upload (theContext, Handle(OpenGl_Texture)(), theOffsetsTexture, theAdaptive); 117 } 118 119 protected: 120 121 //! Returns number of pixels in the given tile. tileArea(int theX,int theY) const122 int tileArea (int theX, int theY) const 123 { 124 const int aSizeX = Min (myTileSize, myViewSize.x() - theX * myTileSize); 125 const int aSizeY = Min (myTileSize, myViewSize.y() - theY * myTileSize); 126 return aSizeX * aSizeY; 127 } 128 129 //! Samples tile location according to estimated error. 130 Standard_EXPORT Graphic3d_Vec2i nextTileToSample(); 131 132 //! Uploads offsets of sampled tiles to the given OpenGL texture. 133 Standard_EXPORT bool upload (const Handle(OpenGl_Context)& theContext, 134 const Handle(OpenGl_Texture)& theSamplesTexture, 135 const Handle(OpenGl_Texture)& theOffsetsTexture, 136 const bool theAdaptive); 137 138 //! Auxiliary method for dumping 2D image map into stream (e.g. for debugging). 139 Standard_EXPORT void dumpMap (std::ostream& theStream, 140 const Image_PixMapTypedData<int>& theMap, 141 const char* theTitle) const; 142 143 protected: 144 145 Image_PixMapTypedData<unsigned int> myTiles; //!< number of samples per tile (initially all 1) 146 Image_PixMapTypedData<unsigned int> myTileSamples; //!< number of samples for all pixels within the tile (initially equals to Tile area) 147 Image_PixMapTypedData<float> myVarianceMap; //!< Estimation of visual error per tile 148 Image_PixMapTypedData<int> myVarianceRaw; //!< Estimation of visual error per tile (raw data) 149 Image_PixMapTypedData<Graphic3d_Vec2i> myOffsets; //!< 2D array of tiles redirecting to another tile 150 Image_PixMapTypedData<Graphic3d_Vec2i> myOffsetsShrunk; //!< 2D array of tiles redirecting to another tile (shrunk) 151 std::vector<float> myMarginalMap; //!< Marginal distribution of 2D error map 152 OpenGl_HaltonSampler mySampler; //!< Halton sequence generator 153 unsigned int myLastSample; //!< Index of generated sample 154 float myScaleFactor; //!< scale factor for quantization of visual error (float) into signed integer 155 int myTileSize; //!< tile size 156 Graphic3d_Vec2i myViewSize; //!< ray-tracing viewport 157 158 }; 159 160 #endif // _OpenGl_TileSampler_H 161