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/* Copyright (C) 2012 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_VERTEXARRAY
#define INCLUDED_VERTEXARRAY
#include "renderer/VertexBuffer.h"
// Iterator
template<typename T>
class VertexArrayIterator
{
public:
typedef T Type;
public:
VertexArrayIterator() :
m_Data(0), m_Stride(0)
{
}
VertexArrayIterator(char* data, size_t stride) :
m_Data(data), m_Stride(stride)
{
}
VertexArrayIterator(const VertexArrayIterator& rhs) :
m_Data(rhs.m_Data), m_Stride(rhs.m_Stride)
{
}
VertexArrayIterator& operator=(const VertexArrayIterator& rhs)
{
m_Data = rhs.m_Data;
m_Stride = rhs.m_Stride;
return *this;
}
// Accessors
T& operator*() const { return *(T*)m_Data; }
T* operator->() const { return (T*)m_Data; }
T& operator[](size_t idx) const { return *(T*)(m_Data + idx*m_Stride); }
// Walking
VertexArrayIterator& operator++()
{
m_Data += m_Stride;
return *this;
}
VertexArrayIterator operator++(int)
{
VertexArrayIterator tmp = *this;
m_Data += m_Stride;
return tmp;
}
VertexArrayIterator& operator--()
{
m_Data -= m_Stride;
return *this;
}
VertexArrayIterator operator--(int)
{
VertexArrayIterator tmp = *this;
m_Data -= m_Stride;
return tmp;
}
VertexArrayIterator& operator+=(ssize_t rhs)
{
m_Data += rhs*m_Stride;
return *this;
}
VertexArrayIterator& operator-=(ssize_t rhs)
{
m_Data -= rhs*m_Stride;
return *this;
}
VertexArrayIterator operator+(ssize_t rhs) const
{
VertexArrayIterator tmp = *this;
tmp.m_Data += rhs*m_Stride;
return tmp;
}
VertexArrayIterator operator-(ssize_t rhs) const
{
VertexArrayIterator tmp = *this;
tmp.m_Data -= rhs*m_Stride;
return tmp;
}
// Accessors for raw buffer data, for performance-critical code
char* GetData() const
{
return m_Data;
}
size_t GetStride() const
{
return m_Stride;
}
private:
char* m_Data;
size_t m_Stride;
};
// Manage a vertex array with a runtime-determined set of attributes.
//
// Purpose: Different rendering paths sometimes require different sets of
// attributes (e.g. normal vector vs. color data), which is difficult to
// support with hardcoded vertex structures.
// This class chooses the vertex layout at runtime, based on the attributes
// that are actually needed.
//
// Note that this class will not allocate any OpenGL resources until one
// of the Upload functions is called.
class VertexArray
{
public:
struct Attribute
{
// Data type. Currently supported: GL_FLOAT, GL_SHORT, GL_UNSIGNED_SHORT, GL_UNSIGNED_BYTE.
GLenum type;
// How many elements per vertex (e.g. 3 for RGB, 2 for UV)
GLuint elems;
// Offset (in bytes) into a vertex structure (filled in by Layout())
size_t offset;
VertexArray* vertexArray;
Attribute() : type(0), elems(0), offset(0), vertexArray(0) { }
// Get an iterator over the backing store for the given attribute that
// initially points at the first vertex.
// Supported types T: CVector3D, CVector4D, float[2], SColor3ub, SColor4ub,
// u16, u16[2], u8, u8[4], short, short[2].
// This function verifies at runtime that the requested type T matches
// the attribute definition passed to AddAttribute().
template<typename T>
VertexArrayIterator<T> GetIterator() const;
};
public:
VertexArray(GLenum usage, GLenum target = GL_ARRAY_BUFFER);
~VertexArray();
// Set the number of vertices stored in the array
void SetNumVertices(size_t num);
// Add vertex attributes
void AddAttribute(Attribute* attr);
size_t GetNumVertices() const { return m_NumVertices; }
size_t GetStride() const { return m_Stride; }
// Layout the vertex array format and create backing buffer in RAM.
// You must call Layout() after changing the number of vertices or
// attributes.
// All vertex data is lost when a vertex array is re-layouted.
void Layout();
// (Re-)Upload the attributes of the vertex array from the backing store to
// the underlying VBO object.
void Upload();
// Make this vertex array's data available for the next series of calls to Bind
void PrepareForRendering();
// Bind this array, returns the base address for calls to glVertexPointer etc.
u8* Bind();
// If you know for certain that you'll never have to change the data again,
// call this to free some memory.
void FreeBackingStore();
private:
void Free();
template<typename T>
VertexArrayIterator<T> MakeIterator(const Attribute* attr)
{
ENSURE(attr->type && attr->elems);
return VertexArrayIterator<T>(m_BackingStore + attr->offset, m_Stride);
}
GLenum m_Usage;
GLenum m_Target;
size_t m_NumVertices;
std::vector<Attribute*> m_Attributes;
CVertexBuffer::VBChunk* m_VB;
size_t m_Stride;
char* m_BackingStore; // 16-byte aligned, to allow fast SSE access
};
/**
* A VertexArray that is specialised to handle 16-bit array indices.
* Call Bind() and pass the return value to the indices parameter of
* glDrawElements/glDrawRangeElements/glMultiDrawElements.
* Use CVertexBuffer::Unbind() to unbind the array when done.
*/
class VertexIndexArray : public VertexArray
{
public:
VertexIndexArray(GLenum usage);
/// Gets the iterator over the (only) attribute in this array, i.e. a u16.
VertexArrayIterator<u16> GetIterator() const;
private:
Attribute m_Attr;
};
#endif // INCLUDED_VERTEXARRAY
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