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1 /*
2  * Copyright (C) 2008 Alex Mathews <possessedpenguinbob@gmail.com>
3  * Copyright (C) 2004, 2005, 2006, 2007 Nikolas Zimmermann <zimmermann@kde.org>
4  * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
5  * Copyright (C) 2005 Eric Seidel <eric@webkit.org>
6  * Copyright (C) 2010 Zoltan Herczeg <zherczeg@webkit.org>
7  * Copyright (C) 2011 University of Szeged
8  * Copyright (C) 2011 Renata Hodovan <reni@webkit.org>
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY
20  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL UNIVERSITY OF SZEGED OR
23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
27  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include "config.h"
33 #include "platform/graphics/filters/SpotLightSource.h"
34 
35 #include "platform/text/TextStream.h"
36 
37 namespace blink {
38 
39 // spot-light edge darkening depends on an absolute treshold
40 // according to the SVG 1.1 SE light regression tests
41 static const float antiAliasTreshold = 0.016f;
42 
initPaintingData(PaintingData & paintingData) const43 void SpotLightSource::initPaintingData(PaintingData& paintingData) const
44 {
45     paintingData.privateColorVector = paintingData.colorVector;
46     paintingData.directionVector.setX(m_direction.x() - m_position.x());
47     paintingData.directionVector.setY(m_direction.y() - m_position.y());
48     paintingData.directionVector.setZ(m_direction.z() - m_position.z());
49     paintingData.directionVector.normalize();
50 
51     if (!m_limitingConeAngle) {
52         paintingData.coneCutOffLimit = 0.0f;
53         paintingData.coneFullLight = -antiAliasTreshold;
54     } else {
55         float limitingConeAngle = m_limitingConeAngle;
56         if (limitingConeAngle < 0.0f)
57             limitingConeAngle = -limitingConeAngle;
58         if (limitingConeAngle > 90.0f)
59             limitingConeAngle = 90.0f;
60         paintingData.coneCutOffLimit = cosf(deg2rad(180.0f - limitingConeAngle));
61         paintingData.coneFullLight = paintingData.coneCutOffLimit - antiAliasTreshold;
62     }
63 }
64 
updatePaintingData(PaintingData & paintingData,int x,int y,float z) const65 void SpotLightSource::updatePaintingData(PaintingData& paintingData, int x, int y, float z) const
66 {
67     paintingData.lightVector.setX(m_position.x() - x);
68     paintingData.lightVector.setY(m_position.y() - y);
69     paintingData.lightVector.setZ(m_position.z() - z);
70     paintingData.lightVectorLength = paintingData.lightVector.length();
71 
72     float cosineOfAngle = (paintingData.lightVector * paintingData.directionVector) / paintingData.lightVectorLength;
73     if (cosineOfAngle > paintingData.coneCutOffLimit) {
74         // No light is produced, scanlines are not updated
75         paintingData.colorVector.setX(0.0f);
76         paintingData.colorVector.setY(0.0f);
77         paintingData.colorVector.setZ(0.0f);
78         return;
79     }
80 
81     // Set the color of the pixel
82     float lightStrength;
83     if (1.0f == m_specularExponent) {
84         lightStrength = -cosineOfAngle; // -cosineOfAngle ^ 1 == -cosineOfAngle
85     } else {
86         lightStrength = powf(-cosineOfAngle, m_specularExponent);
87     }
88 
89     if (cosineOfAngle > paintingData.coneFullLight)
90         lightStrength *= (paintingData.coneCutOffLimit - cosineOfAngle) / (paintingData.coneCutOffLimit - paintingData.coneFullLight);
91 
92     if (lightStrength > 1.0f)
93         lightStrength = 1.0f;
94 
95     paintingData.colorVector.setX(paintingData.privateColorVector.x() * lightStrength);
96     paintingData.colorVector.setY(paintingData.privateColorVector.y() * lightStrength);
97     paintingData.colorVector.setZ(paintingData.privateColorVector.z() * lightStrength);
98 }
99 
setPosition(const FloatPoint3D & position)100 bool SpotLightSource::setPosition(const FloatPoint3D& position)
101 {
102     if (m_position == position)
103         return false;
104     m_position = position;
105     return true;
106 }
107 
setPointsAt(const FloatPoint3D & direction)108 bool SpotLightSource::setPointsAt(const FloatPoint3D& direction)
109 {
110     if (m_direction == direction)
111         return false;
112     m_direction = direction;
113     return true;
114 }
115 
setSpecularExponent(float specularExponent)116 bool SpotLightSource::setSpecularExponent(float specularExponent)
117 {
118     specularExponent = std::min(std::max(specularExponent, 1.0f), 128.0f);
119     if (m_specularExponent == specularExponent)
120         return false;
121     m_specularExponent = specularExponent;
122     return true;
123 }
124 
setLimitingConeAngle(float limitingConeAngle)125 bool SpotLightSource::setLimitingConeAngle(float limitingConeAngle)
126 {
127     if (m_limitingConeAngle == limitingConeAngle)
128         return false;
129     m_limitingConeAngle = limitingConeAngle;
130     return true;
131 }
132 
operator <<(TextStream & ts,const FloatPoint3D & p)133 static TextStream& operator<<(TextStream& ts, const FloatPoint3D& p)
134 {
135     ts << "x=" << p.x() << " y=" << p.y() << " z=" << p.z();
136     return ts;
137 }
138 
externalRepresentation(TextStream & ts) const139 TextStream& SpotLightSource::externalRepresentation(TextStream& ts) const
140 {
141     ts << "[type=SPOT-LIGHT] ";
142     ts << "[position=\"" << position() << "\"]";
143     ts << "[direction=\"" << direction() << "\"]";
144     ts << "[specularExponent=\"" << specularExponent() << "\"]";
145     ts << "[limitingConeAngle=\"" << limitingConeAngle() << "\"]";
146     return ts;
147 }
148 
149 }; // namespace blink
150