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shadowAtlas.cxx
1/**
2 *
3 * RenderPipeline
4 *
5 * Copyright (c) 2014-2016 tobspr <tobias.springer1@gmail.com>
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 *
25 */
26
27
28#include "shadowAtlas.h"
29#include <string.h>
30
31NotifyCategoryDef(shadowatlas, "");
32
33/**
34 * @brief Constructs a new shadow atlas.
35 * @details This constructs a new shadow atlas with the given size and tile size.
36 *
37 * The size determines the total size of the atlas in pixels. It should be a
38 * power-of-two to favour the GPU.
39 *
40 * The tile_size determines the smallest unit of tiles the atlas can store.
41 * If, for example, a tile_size of 32 is used, then every entry stored must
42 * have a resolution of 32 or greater, and the resolution must be a multiple
43 * of 32. This is to optimize the search in the atlas, so the atlas does not
44 * have to check every pixel, and instead can just check whole tiles.
45 *
46 * If you want to disable the use of tiles, set the tile_size to 1, which
47 * will make the shadow atlas use pixels instead of tiles.
48 *
49 * @param size Atlas-size in pixels
50 * @param tile_size tile-size in pixels, or 1 to use no tiles.
51 */
52 ShadowAtlas::ShadowAtlas(size_t size, size_t tile_size) {
53 nassertv(size > 1 && tile_size >= 1);
54 nassertv(tile_size < size && size % tile_size == 0);
55 _size = size;
56 _tile_size = tile_size;
57 _num_used_tiles = 0;
58 init_tiles();
59}
60
61/**
62 * @brief Destructs the shadow atlas.
63 * @details This destructs the shadow atlas, freeing all used resources.
64 */
65 ShadowAtlas::~ShadowAtlas() {
66 delete [] _flags;
67}
68
69/**
70 * @brief Internal method to init the storage.
71 * @details This method setups the storage used for storing the tile flags.
72 */
73 void ShadowAtlas::init_tiles() {
74 _num_tiles = _size / _tile_size;
75 _flags = new bool[_num_tiles * _num_tiles];
76 memset(_flags, 0x0, sizeof(bool) * _num_tiles * _num_tiles);
77}
78
79/**
80 * @brief Internal method to reserve a region in the atlas.
81 * @details This reserves a given region in the shadow atlas. The region should
82 * be in tile space.This is called by the ShadowAtlas::find_and_reserve_region.
83 * It sets all flags in that region to true, indicating that those are used.
84 * When an invalid region is passed, an assertion is triggered. If assertions
85 * are optimized out, undefined behaviour occurs.
86 *
87 * @param x x- start positition of the region
88 * @param y y- start position of the region
89 * @param w width of the region
90 * @param h height of the region
91 */
92 void ShadowAtlas::reserve_region(size_t x, size_t y, size_t w, size_t h) {
93 // Check if we are out of bounds, this should be disabled for performance
94 // reasons at some point.
95 nassertv(x >= 0 && y >= 0 && x + w <= _num_tiles && y + h <= _num_tiles);
96
97 _num_used_tiles += w * h;
98
99 // Iterate over every tile in the region and mark it as used
100 for (size_t cx = 0; cx < w; ++cx) {
101 for (size_t cy = 0; cy < h; ++cy) {
102 set_tile(cx + x, cy + y, true);
103 }
104 }
105}
106
107/**
108 * @brief Finds space for a map of the given size in the atlas.
109 * @details This methods searches for a space to store a region of the given
110 * size in the atlas. tile_width and tile_height should be already in tile
111 * space. They can be converted using ShadowAtlas::get_required_tiles.
112 *
113 * If no region is found, or an invalid size is passed, an integer vector with
114 * all components set to -1 is returned.
115 *
116 * If a region is found, an integer vector with the given layout is returned:
117 * x: x- Start of the region
118 * y: y- Start of the region
119 * z: width of the region
120 * w: height of the region
121 *
122 * The layout is in tile space, and can get converted to uv space using
123 * ShadowAtlas::region_to_uv.
124 *
125 * @param tile_width Width of the region in tile space
126 * @param tile_height Height of the region in tile space
127 *
128 * @return Region, see description, or -1 when no region is found.
129 */
130LVecBase4i ShadowAtlas::find_and_reserve_region(size_t tile_width, size_t tile_height) {
131
132 // Check for empty region
133 if (tile_width < 1 || tile_height < 1) {
134 shadowatlas_cat.error() << "Called find_and_reserve_region with null-region!" << std::endl;
135 return LVecBase4i(-1);
136 }
137
138 // Check for region bigger than the shadow atlas
139 if (tile_width > _num_tiles || tile_height > _num_tiles) {
140 shadowatlas_cat.error() << "Requested region exceeds shadow atlas size!" << std::endl;
141 return LVecBase4i(-1);
142 }
143
144 // Iterate over every possible region and check if its still free
145 for (size_t x = 0; x <= _num_tiles - tile_width; ++x) {
146 for (size_t y = 0; y <= _num_tiles - tile_height; ++y) {
147 if (region_is_free(x, y, tile_width, tile_height)) {
148 // Found free region, now reserve it
149 reserve_region(x, y, tile_width, tile_height);
150 return LVecBase4i(x, y, tile_width, tile_height);
151 }
152 }
153 }
154
155 // When we reached this part, we couldn't find a free region, so the atlas
156 // seems to be full.
157 shadowatlas_cat.error() << "Failed to find a free region of size " << tile_width
158 << " x " << tile_height << "!" << std::endl;
159 return LVecBase4i(-1);
160}
161
162/**
163 * @brief Frees a given region
164 * @details This frees a given region, marking it as free so that other shadow
165 * maps can use the space again. The region should be the same as returned
166 * by ShadowAtlas::find_and_reserve_region.
167 *
168 * If an invalid region is passed, an assertion is triggered. If assertions
169 * are compiled out, undefined behaviour will occur.
170 *
171 * @param region Region to free
172 */
173 void ShadowAtlas::free_region(const LVecBase4i& region) {
174 // Out of bounds check, can't hurt
175 nassertv(region.get_x() >= 0 && region.get_y() >= 0);
176 nassertv(region.get_x() + region.get_z() <= (int)_num_tiles && region.get_y() + region.get_w() <= (int)_num_tiles);
177
178 _num_used_tiles -= region.get_z() * region.get_w();
179
180 for (int x = 0; x < region.get_z(); ++x) {
181 for (int y = 0; y < region.get_w(); ++y) {
182 // Could do an assert here, that the tile should have been used (=true) before
183 set_tile(region.get_x() + x, region.get_y() + y, false);
184 }
185 }
186}
ShadowAtlas::find_and_reserve_region
LVecBase4i find_and_reserve_region(size_t tile_width, size_t tile_height)
Finds space for a map of the given size in the atlas.
Definition shadowAtlas.cxx:130
ShadowAtlas::free_region
void free_region(const LVecBase4i &region)
Frees a given region.
Definition shadowAtlas.cxx:173
ShadowAtlas::ShadowAtlas
ShadowAtlas(size_t size, size_t tile_size=32)
Constructs a new shadow atlas.
Definition shadowAtlas.cxx:52
ShadowAtlas::~ShadowAtlas
~ShadowAtlas()
Destructs the shadow atlas.
Definition shadowAtlas.cxx:65