/*
===========================================================================
Doom 3 BFG Edition GPL Source Code
Copyright (C) 2014 Hawar Doghramachi
Copyright (C) 2022 Robert Beckebans (id Tech 4x integration)
This file is part of the Doom 3 BFG Edition GPL Source Code ("Doom 3 BFG Edition Source Code").
Doom 3 BFG Edition Source Code is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Doom 3 BFG Edition Source Code is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Doom 3 BFG Edition Source Code. If not, see .
In addition, the Doom 3 BFG Edition Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 BFG Edition Source Code. If not, please request a copy in writing from id Software at the address below.
If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.
===========================================================================
*/
#ifndef TILE_MAP_H
#define TILE_MAP_H
// Tile specifies the position and size within a texture atlas.
struct Tile
{
Tile():
size( 0.0f )
{
}
idVec2 position;
float size;
};
// TileNode of a quad-tree that efficiently packs all tiles in a limited area.
struct TileNode
{
TileNode():
level( 0 ),
minLevel( 0 )
{
for( unsigned int i = 0; i < 4; i++ )
{
childIndices[i] = -1;
}
}
idVec2 position;
int childIndices[4];
unsigned int level;
unsigned int minLevel;
};
// TileMap
//
// Quad-tree that manages tiles in a power of two/ squared texture atlas. At initialization the quad-tree is build so that
// all nodes already have the information of the position for the corresponding tile. All nodes are kept in a cache-friendly
// manner in one linear list, which makes clearing the quad-tree very fast. Therefore instead of pointer indirections, indices
// into the underlying list are used.
// At runtime each relevant light will request per frame a tile with a size that corresponds to the screen-space light-area of
// the light. Thereby the size is clamped between a min/ max resolution. To determine the level of the requested tile first the
// next power of two size is determined which is larger than the requested size. However, instead of using the power of two size
// of the determined tile, the actual incoming dynamically changing size is used. In this way unpleasant popping of shadows can
// be avoided, which would occur otherwise when discrete power of two steps would be used.
// Since this operation is working with a O(n) complexity, the quad-tree is held on software-side, which is faster than keeping
// the quad-tree on the GPU.
class TileMap
{
public:
TileMap():
mapSize( 0.0f ),
log2MapSize( 0 ),
minAbsTileSize( 0.0f ),
maxAbsTileSize( 0.0f ),
numLevels( 0 ),
numNodes( 0 ),
nodeIndex( 0 ),
foundNode( NULL )
{
}
~TileMap()
{
Release();
}
void Release();
bool Init( unsigned int mapSize, unsigned int maxAbsTileSize, unsigned int numLevels );
void Clear();
bool GetTile( float size, Tile& tile );
private:
void BuildTree( TileNode& parentNode, unsigned int level );
void FindNode( TileNode& parentNode, unsigned int level );
float mapSize;
unsigned int log2MapSize;
float minAbsTileSize;
float maxAbsTileSize;
unsigned int numLevels;
idList tileNodeList;
unsigned int numNodes;
unsigned int nodeIndex;
TileNode* foundNode;
};
#endif