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
37namespace WebCore {
38
39// spot-light edge darkening depends on an absolute treshold
40// according to the SVG 1.1 SE light regression tests
41static const float antiAliasTreshold = 0.016f;
42
43void 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
65void 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
100bool SpotLightSource::setX(float x)
101{
102    if (m_position.x() == x)
103        return false;
104    m_position.setX(x);
105    return true;
106}
107
108bool SpotLightSource::setY(float y)
109{
110    if (m_position.y() == y)
111        return false;
112    m_position.setY(y);
113    return true;
114}
115
116bool SpotLightSource::setZ(float z)
117{
118    if (m_position.z() == z)
119        return false;
120    m_position.setZ(z);
121    return true;
122}
123
124bool SpotLightSource::setPointsAtX(float pointsAtX)
125{
126    if (m_direction.x() == pointsAtX)
127        return false;
128    m_direction.setX(pointsAtX);
129    return true;
130}
131
132bool SpotLightSource::setPointsAtY(float pointsAtY)
133{
134    if (m_direction.y() == pointsAtY)
135        return false;
136    m_direction.setY(pointsAtY);
137    return true;
138}
139
140bool SpotLightSource::setPointsAtZ(float pointsAtZ)
141{
142    if (m_direction.z() == pointsAtZ)
143        return false;
144    m_direction.setZ(pointsAtZ);
145    return true;
146}
147
148bool SpotLightSource::setSpecularExponent(float specularExponent)
149{
150    specularExponent = std::min(std::max(specularExponent, 1.0f), 128.0f);
151    if (m_specularExponent == specularExponent)
152        return false;
153    m_specularExponent = specularExponent;
154    return true;
155}
156
157bool SpotLightSource::setLimitingConeAngle(float limitingConeAngle)
158{
159    if (m_limitingConeAngle == limitingConeAngle)
160        return false;
161    m_limitingConeAngle = limitingConeAngle;
162    return true;
163}
164
165static TextStream& operator<<(TextStream& ts, const FloatPoint3D& p)
166{
167    ts << "x=" << p.x() << " y=" << p.y() << " z=" << p.z();
168    return ts;
169}
170
171TextStream& SpotLightSource::externalRepresentation(TextStream& ts) const
172{
173    ts << "[type=SPOT-LIGHT] ";
174    ts << "[position=\"" << position() << "\"]";
175    ts << "[direction=\"" << direction() << "\"]";
176    ts << "[specularExponent=\"" << specularExponent() << "\"]";
177    ts << "[limitingConeAngle=\"" << limitingConeAngle() << "\"]";
178    return ts;
179}
180
181}; // namespace WebCore
182