1/*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1.  Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 * 2.  Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
18 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
21 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef LoopBlinnTextureCoords_h
27#define LoopBlinnTextureCoords_h
28
29#include "FloatPoint3D.h"
30#include "LoopBlinnClassifier.h"
31#include "LoopBlinnConstants.h"
32
33#include <wtf/Noncopyable.h>
34
35namespace WebCore {
36
37// Computes three-dimensional texture coordinates for the control
38// points of a cubic curve for rendering via the shader in "Rendering
39// Vector Art on the GPU" by Loop and Blinn, GPU Gems 3, Chapter 25.
40class LoopBlinnTextureCoords {
41public:
42    // Container for the cubic texture coordinates and other associated
43    // information.
44    struct Result {
45        Result()
46            : isLineOrPoint(false)
47            , hasRenderingArtifact(false)
48            , subdivisionParameterValue(0.0f) { }
49
50        // The (k, l, m) texture coordinates that are to be associated
51        // with the four control points of the cubic curve.
52        FloatPoint3D klmCoordinates[4];
53
54        // Indicates whether the curve is a line or a point, in which case
55        // we do not need to add its triangles to the mesh.
56        bool isLineOrPoint;
57
58        // For the loop case, indicates whether a rendering artifact was
59        // detected, in which case the curve needs to be further
60        // subdivided.
61        bool hasRenderingArtifact;
62
63        // If a rendering artifact will occur for the given loop curve,
64        // this is the parameter value (0 <= value <= 1) at which the
65        // curve needs to be subdivided to fix the artifact.
66        float subdivisionParameterValue;
67    };
68
69    // Computes the texture coordinates for a cubic curve segment's
70    // control points, given the classification of the curve as well as
71    // an indication of which side is to be filled.
72    static Result compute(const LoopBlinnClassifier::Result& classification,
73                          LoopBlinnConstants::FillSide sideToFill);
74
75private:
76    // This class does not need to be instantiated.
77    LoopBlinnTextureCoords() { }
78};
79
80} // namespace WebCore
81
82#endif // LoopBlinnTextureCoords_h
83