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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 | |
22 | #include <vector> |
23 | |
24 | //! Tool object used for sampling screen tiles according to estimated pixel variance (used in path tracing engine). |
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25 | //! To improve GPU thread coherency, rendering window is split into pixel blocks or tiles. The important feature of |
26 | //! this approach is that it is possible to keep the same number of tiles for any screen resolution (e.g. 256 tiles |
27 | //! can be used for both 512 x 512 window and 1920 x 1080 window). So, a smaller number of tiles allows to increase |
28 | //! interactivity (FPS), but at the cost of higher per-frame variance ('noise'). On the contrary a larger number of |
29 | //! tiles decrease interactivity, but leads to lower per-frame variance. Note that the total time needed to produce |
30 | //! final final image is the same for both cases. |
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31 | class OpenGl_TileSampler |
32 | { |
33 | public: |
34 | |
35 | //! Size of individual tile in pixels. |
36 | static int TileSize() { return 32; } |
37 | |
38 | public: |
39 | |
40 | //! Creates new tile sampler. |
41 | Standard_EXPORT OpenGl_TileSampler(); |
42 | |
43 | //! Returns width of ray-tracing viewport. |
44 | int SizeX() const { return mySizeX; } |
45 | |
46 | //! Returns height of ray-tracing viewport. |
47 | int SizeY() const { return mySizeY; } |
48 | |
49 | //! Returns number of tiles in X dimension. |
50 | int NbTilesX() const { return myTilesX; } |
51 | |
52 | //! Returns number of tiles in Y dimension. |
53 | int NbTilesY() const { return myTilesY; } |
54 | |
55 | //! Returns total number of tiles in viewport. |
56 | int NbTiles() const { return myTilesX * myTilesY; } |
57 | |
58 | //! Specifies size of ray-tracing viewport. |
59 | Standard_EXPORT void SetSize (const int theSizeX, |
60 | const int theSizeY); |
61 | |
62 | //! Returns number of pixels in the given tile. |
63 | int TileArea (const int theX, |
64 | const int theY) const |
65 | { |
66 | return Min (TileSize(), mySizeX - theX * TileSize()) |
67 | * Min (TileSize(), mySizeY - theY * TileSize()); |
68 | } |
69 | |
70 | //! Fetches current error estimation from the GPU and |
71 | //! builds 2D discrete distribution for tile sampling. |
72 | Standard_EXPORT void GrabVarianceMap (const Handle(OpenGl_Context)& theContext); |
73 | |
74 | //! Samples tile location according to estimated error. |
75 | Standard_EXPORT void Sample (int& theOffsetX, |
76 | int& theOffsetY); |
77 | |
78 | //! Resets tile sampler to initial state. |
79 | void Reset() { mySample = 0; } |
80 | |
81 | //! Uploads offsets of sampled tiles to the given OpenGL texture. |
82 | Standard_EXPORT void Upload (const Handle(OpenGl_Context)& theContext, |
83 | const Handle(OpenGl_Texture)& theTexture, |
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84 | const int theNbTilesX, |
85 | const int theNbTilesY, |
86 | const bool theAdaptive); |
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87 | |
88 | protected: |
89 | |
90 | //! Returns tile value (estimated error). |
91 | float Tile (const int theX, |
92 | const int theY) const |
93 | { |
94 | return myVarianceMap[theY * myTilesX + theX]; |
95 | } |
96 | |
97 | //! Returns tile value (estimated error). |
98 | float& ChangeTile (const int theX, |
99 | const int theY) |
100 | { |
101 | return myVarianceMap[theY * myTilesX + theX]; |
102 | } |
103 | |
104 | protected: |
105 | |
106 | std::vector<float> myVarianceMap; //!< Estimation of visual error per tile |
107 | std::vector<float> myMarginalMap; //!< Marginal distribution of 2D error map |
108 | OpenGl_HaltonSampler mySampler; //!< Halton sequence generator |
109 | int mySample; //!< Index of generated sample |
110 | int mySizeX; //!< Width of ray-tracing viewport |
111 | int mySizeY; //!< Height of ray-tracing viewport |
112 | int myTilesX; //!< Number of tiles in X dimension |
113 | int myTilesY; //!< Number of tiles in Y dimension |
114 | |
115 | }; |
116 | |
117 | #endif // _OpenGl_TileSampler_H |