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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 | |
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22 | #include <Image_PixMapTypedData.hxx> |
23 | |
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24 | #include <vector> |
25 | |
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26 | class Graphic3d_RenderingParams; |
27 | |
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28 | //! Tool object used for sampling screen tiles according to estimated pixel variance (used in path tracing engine). |
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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. |
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35 | class OpenGl_TileSampler |
36 | { |
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37 | public: |
38 | |
39 | //! Creates new tile sampler. |
40 | Standard_EXPORT OpenGl_TileSampler(); |
41 | |
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42 | //! Size of individual tile in pixels. |
43 | Graphic3d_Vec2i TileSize() const { return Graphic3d_Vec2i (myTileSize, myTileSize); } |
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44 | |
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45 | //! Scale factor for quantization of visual error (float) into signed integer. |
46 | float VarianceScaleFactor() const { return myScaleFactor; } |
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47 | |
48 | //! Returns number of tiles in X dimension. |
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49 | int NbTilesX() const { return (int)myTiles.SizeX; } |
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50 | |
51 | //! Returns number of tiles in Y dimension. |
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52 | int NbTilesY() const { return (int)myTiles.SizeY; } |
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53 | |
54 | //! Returns total number of tiles in viewport. |
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55 | int NbTiles() const { return int(myTiles.SizeX * myTiles.SizeY); } |
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56 | |
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57 | //! Returns ray-tracing viewport. |
58 | const Graphic3d_Vec2i& ViewSize() const { return myViewSize; } |
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59 | |
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60 | //! Number of tiles within offsets texture. |
61 | Graphic3d_Vec2i NbOffsetTiles (bool theAdaptive) const |
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62 | { |
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63 | return theAdaptive |
64 | ? Graphic3d_Vec2i ((int )myOffsetsShrunk.SizeX, (int )myOffsetsShrunk.SizeY) |
65 | : Graphic3d_Vec2i ((int )myOffsets.SizeX, (int )myOffsets.SizeY); |
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66 | } |
67 | |
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68 | //! Maximum number of tiles within offsets texture. |
69 | Graphic3d_Vec2i NbOffsetTilesMax() const { return NbOffsetTiles (true).cwiseMax (NbOffsetTiles (false)); } |
70 | |
71 | //! Viewport for rendering using offsets texture. |
72 | Graphic3d_Vec2i OffsetTilesViewport (bool theAdaptive) const { return NbOffsetTiles (theAdaptive) * myTileSize; } |
73 | |
74 | //! Maximum viewport for rendering using offsets texture. |
75 | Graphic3d_Vec2i OffsetTilesViewportMax() const { return NbOffsetTilesMax() * myTileSize; } |
76 | |
77 | //! Specifies size of ray-tracing viewport and recomputes tile size. |
78 | Standard_EXPORT void SetSize (const Graphic3d_RenderingParams& theParams, |
79 | const Graphic3d_Vec2i& theSize); |
80 | |
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81 | //! Fetches current error estimation from the GPU and |
82 | //! builds 2D discrete distribution for tile sampling. |
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83 | Standard_EXPORT void GrabVarianceMap (const Handle(OpenGl_Context)& theContext, |
84 | const Handle(OpenGl_Texture)& theTexture); |
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85 | |
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86 | //! Resets (restart) tile sampler to initial state. |
87 | void Reset() { myLastSample = 0; } |
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88 | |
89 | //! Uploads offsets of sampled tiles to the given OpenGL texture. |
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90 | Standard_EXPORT bool UploadOffsets (const Handle(OpenGl_Context)& theContext, |
91 | const Handle(OpenGl_Texture)& theOffsetsTexture, |
92 | const bool theAdaptive); |
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93 | |
94 | protected: |
95 | |
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96 | //! Returns number of pixels in the given tile. |
97 | int tileArea (int theX, int theY) const |
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98 | { |
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99 | const int aSizeX = Min (myTileSize, myViewSize.x() - theX * myTileSize); |
100 | const int aSizeY = Min (myTileSize, myViewSize.y() - theY * myTileSize); |
101 | return aSizeX * aSizeY; |
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102 | } |
103 | |
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104 | //! Samples tile location according to estimated error. |
105 | Standard_EXPORT Graphic3d_Vec2i nextTileToSample(); |
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106 | |
107 | protected: |
108 | |
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109 | Image_PixMapTypedData<unsigned int> myTiles; //!< number of samples per tile (initially all 1) |
110 | Image_PixMapTypedData<float> myVarianceMap; //!< Estimation of visual error per tile |
111 | Image_PixMapTypedData<int> myVarianceRaw; //!< Estimation of visual error per tile (raw data) |
112 | Image_PixMapTypedData<Graphic3d_Vec2i> myOffsets; //!< 2D array of tiles redirecting to another tile |
113 | Image_PixMapTypedData<Graphic3d_Vec2i> myOffsetsShrunk; //!< 2D array of tiles redirecting to another tile (shrunk) |
114 | std::vector<float> myMarginalMap; //!< Marginal distribution of 2D error map |
115 | OpenGl_HaltonSampler mySampler; //!< Halton sequence generator |
116 | unsigned int myLastSample; //!< Index of generated sample |
117 | float myScaleFactor; //!< scale factor for quantization of visual error (float) into signed integer |
118 | int myTileSize; //!< tile size |
119 | Graphic3d_Vec2i myViewSize; //!< ray-tracing viewport |
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120 | |
121 | }; |
122 | |
123 | #endif // _OpenGl_TileSampler_H |