2 // Copyright (c) 2002-2010 The ANGLE Project Authors. All rights reserved.
3 // Use of this source code is governed by a BSD-style license that can be
4 // found in the LICENSE file.
7 // geometry/vertexconversion.h: A library of vertex conversion classes that can be used to build
8 // the FormatConverter objects used by the buffer conversion system.
10 #ifndef LIBGLESV2_GEOMETRY_VERTEXCONVERSION_H_
11 #define LIBGLESV2_GEOMETRY_VERTEXCONVERSION_H_
16 #include "libGLESv2/Context.h" // Defines Index
22 // static const bool identity: true if this is an identity transform, false otherwise
23 // static U convert(T): convert a single element from the input type to the output type
24 // typedef ... OutputType: the type produced by this conversion
29 static const bool identity = true;
39 template <class FromT, class ToT>
42 static const bool identity = false;
44 typedef ToT OutputType;
46 static ToT convert(FromT x)
48 return static_cast<ToT>(x);
55 static const bool identity = true;
61 return static_cast<T>(x);
68 static const bool identity = false;
70 typedef float OutputType;
72 static float convert(T x)
74 typedef std::numeric_limits<T> NL;
75 float f = static_cast<float>(x);
79 // const float => VC2008 computes it at compile time
80 // static const float => VC2008 computes it the first time we get here, stores it to memory with static guard and all that.
81 const float divisor = 1.0f/(2*static_cast<float>(NL::max())+1);
82 return (2*f+1)*divisor;
91 template <class FromType, std::size_t ScaleBits>
94 static const bool identity = false;
96 typedef float OutputType;
98 static float convert(FromType x)
100 const float divisor = 1.0f / static_cast<float>(static_cast<FromType>(1) << ScaleBits);
101 return static_cast<float>(x) * divisor;
106 // static const unsigned int initialWidth: number of components before conversion
107 // static const unsigned int finalWidth: number of components after conversion
109 // Float is supported at any size.
110 template <std::size_t N>
113 static const std::size_t initialWidth = N;
114 static const std::size_t finalWidth = N;
117 // SHORT, norm-SHORT, norm-UNSIGNED_SHORT are supported but only with 2 or 4 components
118 template <std::size_t N>
121 static const std::size_t initialWidth = N;
122 static const std::size_t finalWidth = N+(N&1);
125 template <std::size_t N>
128 static const std::size_t initialWidth = N;
129 static const std::size_t finalWidth = 4;
132 // Most types have 0 and 1 that are just that.
134 struct SimpleDefaultValues
136 static T zero() { return static_cast<T>(0); }
137 static T one() { return static_cast<T>(1); }
140 // But normalised types only store [0,1] or [-1,1] so 1.0 is represented by the max value.
142 struct NormalizedDefaultValues
144 static T zero() { return static_cast<T>(0); }
145 static T one() { return std::numeric_limits<T>::max(); }
149 // static const bool identity: true if this is an identity transform (with no widening)
150 // static const std::size_t finalSize: number of bytes per output vertex
151 // static void convertArray(const void *in, std::size_t stride, std::size_t n, void *out): convert an array of vertices. Input may be strided, but output will be unstrided.
153 template <class InT, class WidenRule, class Converter, class DefaultValueRule = SimpleDefaultValues<InT> >
154 struct VertexDataConverter
156 typedef typename Converter::OutputType OutputType;
157 typedef InT InputType;
159 static const bool identity = (WidenRule::initialWidth == WidenRule::finalWidth) && Converter::identity;
160 static const std::size_t finalSize = WidenRule::finalWidth * sizeof(OutputType);
162 static void convertArray(const InputType *in, std::size_t stride, std::size_t n, OutputType *out)
164 for (std::size_t i = 0; i < n; i++)
166 const InputType *ein = pointerAddBytes(in, i * stride);
168 copyComponent(out, ein, 0, static_cast<OutputType>(DefaultValueRule::zero()));
169 copyComponent(out, ein, 1, static_cast<OutputType>(DefaultValueRule::zero()));
170 copyComponent(out, ein, 2, static_cast<OutputType>(DefaultValueRule::zero()));
171 copyComponent(out, ein, 3, static_cast<OutputType>(DefaultValueRule::one()));
173 out += WidenRule::finalWidth;
177 static void convertArray(const void *in, std::size_t stride, std::size_t n, void *out)
179 return convertArray(static_cast<const InputType*>(in), stride, n, static_cast<OutputType*>(out));
183 // Advance the given pointer by a number of bytes (not pointed-to elements).
185 static T *pointerAddBytes(T *basePtr, std::size_t numBytes)
187 return reinterpret_cast<T *>(reinterpret_cast<uintptr_t>(basePtr) + numBytes);
190 static void copyComponent(OutputType *out, const InputType *in, std::size_t elementindex, OutputType defaultvalue)
192 if (WidenRule::finalWidth > elementindex)
194 if (WidenRule::initialWidth > elementindex)
196 out[elementindex] = Converter::convert(in[elementindex]);
200 out[elementindex] = defaultvalue;
208 #endif // LIBGLESV2_GEOMETRY_VERTEXCONVERSION_H_