Marble

ScanlineTextureMapperContext.h
1// SPDX-License-Identifier: LGPL-2.1-or-later
2//
3// SPDX-FileCopyrightText: 2007 Andrew Manson <g.real.ate@gmail.com>
4// SPDX-FileCopyrightText: 2011 Bernhard Beschow <bbeschow@cs.tu-berlin.de>
5//
6
7#ifndef MARBLE_SCANLINETEXTUREMAPPERCONTEXT_H
8#define MARBLE_SCANLINETEXTUREMAPPERCONTEXT_H
9
10#include <QSize>
11#include <QImage>
12
13#include "GeoSceneTileDataset.h"
14#include "MarbleMath.h"
15#include "MathHelper.h"
16
17namespace Marble
18{
19
20class StackedTile;
21class StackedTileLoader;
22class ViewportParams;
23
24
25class ScanlineTextureMapperContext
26{
27public:
28 ScanlineTextureMapperContext( StackedTileLoader * const tileLoader, int tileLevel );
29
30 void pixelValueF( const qreal lon, const qreal lat,
31 QRgb* const scanLine );
32 void pixelValue( const qreal lon, const qreal lat,
33 QRgb* const scanLine );
34
35 void pixelValueApproxF( const qreal lon, const qreal lat,
36 QRgb *scanLine, const int n );
37 void pixelValueApprox( const qreal lon, const qreal lat,
38 QRgb *scanLine, const int n );
39
40 static int interpolationStep( const ViewportParams *viewport, MapQuality mapQuality );
41
42 static QImage::Format optimalCanvasImageFormat( const ViewportParams *viewport );
43
44 int globalWidth() const;
45 int globalHeight() const;
46
47private:
48 // method for fast integer calculation
49 void nextTile( int& posx, int& posy );
50
51 // method for precise interpolation
52 void nextTile( qreal& posx, qreal& posy );
53
54 // Converts Radian to global texture coordinates
55 // ( with origin in center, measured in pixel)
56 qreal rad2PixelX( const qreal lon ) const;
57 qreal rad2PixelY( const qreal lat ) const;
58
59 // Checks whether the pixelValueApprox method will make use of more than
60 // one tile
61 bool isOutOfTileRange( const int itLon, const int itLat,
62 const int itStepLon, const int itStepLat,
63 const int n ) const;
64
65 bool isOutOfTileRangeF( const qreal itLon, const qreal itLat,
66 const qreal itStepLon, const qreal itStepLat,
67 const int n ) const;
68
69private:
70 StackedTileLoader *const m_tileLoader;
71 GeoSceneAbstractTileProjection::Type const m_textureProjection;
72 /// size of the tiles of the current texture layer
73 QSize const m_tileSize;
74
75 int const m_tileLevel;
76 int const m_globalWidth;
77 int const m_globalHeight;
78 qreal const m_normGlobalWidth;
79 qreal const m_normGlobalHeight;
80
81 const StackedTile *m_tile;
82
83 // Coordinate transformations:
84
85 // Position of the tile in global Texture Coordinates
86 // ( with origin in upper left corner, measured in pixel)
87 int m_tilePosX;
88 int m_tilePosY;
89
90 // Converts global texture coordinates
91 // ( with origin in center, measured in pixel)
92 // to tile coordinates ( measured in pixel )
93 qreal m_toTileCoordinatesLon;
94 qreal m_toTileCoordinatesLat;
95
96 // Previous coordinates
97 qreal m_prevLat;
98 qreal m_prevLon;
99 qreal m_prevPixelX;
100 qreal m_prevPixelY;
101};
102
103inline int ScanlineTextureMapperContext::globalWidth() const
104{
105 return m_globalWidth;
106}
107
108inline int ScanlineTextureMapperContext::globalHeight() const
109{
110 return m_globalHeight;
111}
112
113inline qreal ScanlineTextureMapperContext::rad2PixelX( const qreal lon ) const
114{
115 return lon * m_normGlobalWidth;
116}
117
118inline qreal ScanlineTextureMapperContext::rad2PixelY( const qreal lat ) const
119{
120 switch ( m_textureProjection ) {
121 case GeoSceneAbstractTileProjection::Equirectangular:
122 return -lat * m_normGlobalHeight;
123 case GeoSceneAbstractTileProjection::Mercator:
124 if ( fabs( lat ) < 1.4835 ) {
125 // We develop the inverse Gudermannian into a MacLaurin Series:
126 // In spite of the many elements needed to get decent
127 // accuracy this is still faster by far than calculating the
128 // trigonometric expression:
129 // return - asinh( tan( lat ) ) * 0.5 * m_normGlobalHeight;
130
131 // We are using the Horner Scheme as a polynom representation
132
133 return - gdInv( lat ) * 0.5 * m_normGlobalHeight;
134 }
135 if ( lat >= +1.4835 )
136 // asinh( tan (1.4835)) => 3.1309587
137 return - 3.1309587 * 0.5 * m_normGlobalHeight;
138 if ( lat <= -1.4835 )
139 // asinh( tan( -1.4835 )) => −3.1309587
140 return 3.1309587 * 0.5 * m_normGlobalHeight;
141 }
142
143 // Dummy value to avoid a warning.
144 return 0.0;
145}
146
147}
148
149#endif
Binds a QML item to a specific geodetic location in screen coordinates.
qreal gdInv(qreal x)
This method is a fast Mac Laurin power series approximation of the.
Definition MarbleMath.h:73
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