src/mesh.cpp - chromiumos/third_party/glmark2 - Git at Google

 /*
  * Copyright © 2008 Ben Smith
  * Copyright © 2010-2011 Linaro Limited
  *
  * This file is part of the glmark2 OpenGL (ES) 2.0 benchmark.
  *
  * glmark2 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 3 of the License, or (at your option) any later
  * version.
  *
  * glmark2 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
  * glmark2.  If not, see <http://www.gnu.org/licenses/>.
  *
  * Authors:
  *  Ben Smith (original glmark benchmark)
  *  Alexandros Frantzis (glmark2)
  */
 #include "mesh.h"
 #include "log.h"
 #include "gl-headers.h"


 Mesh::Mesh() :
     vertex_size_(0), interleave_(false), vbo_update_method_(VBOUpdateMethodMap),
     vbo_usage_(VBOUsageStatic)
 {
 }

 Mesh::~Mesh()
 {
     reset();
 }

 /*
  * Sets the vertex format for this mesh.
  *
  * The format consists of a vector of integers, each
  * specifying the size in floats of each vertex attribute.
  *
  * e.g. {4, 3, 2} => 3 attributes vec4, vec3, vec2
  */
 void
 Mesh::set_vertex_format(const std::vector<int> &format)
 {
     int pos = 0;
     vertex_format_.clear();

     for (std::vector<int>::const_iterator iter = format.begin();
          iter != format.end();
          iter++)
     {
         int n = *iter;
         vertex_format_.push_back(std::pair<int,int>(n, pos));

         pos += n;
     }

     vertex_size_ = pos;
 }

 /*
  * Sets the attribute locations.
  *
  * These are the locations used in glEnableVertexAttribArray()
  * and other related functions.
  */
 void
 Mesh::set_attrib_locations(const std::vector<int> &locations)
 {
     if (locations.size() != vertex_format_.size())
         Log::error("Trying to set attribute locations using wrong size\n");
     attrib_locations_ = locations;
 }


 /**
  * Checks that an attribute is of the correct dimensionality.
  *
  * @param pos the position/index of the attribute to check
  * @param dim the size of the attribute (in #floats)
  *
  * @return whether the check succeeded
  */
 bool
 Mesh::check_attrib(unsigned int pos, int dim)
 {
     if (pos > vertex_format_.size()) {
         Log::error("Trying to set non-existent attribute\n");
         return false;
     }

     if (vertex_format_[pos].first != dim) {
         Log::error("Trying to set attribute with value of invalid type\n");
         return false;
     }

     return true;
 }


 /**
  * Ensures that we have a vertex to process.
  *
  * @return the vertex to process
  */
 std::vector<float> &
 Mesh::ensure_vertex()
 {
     if (vertices_.empty())
         next_vertex();

     return vertices_.back();
 }

 /*
  * Sets the value of an attribute in the current vertex.
  *
  * The pos parameter refers to the position of the attribute
  * as specified indirectly when setting the format using
  * set_vertex_format(). e.g. 0 = first attribute, 1 = second
  * etc
  */
 void
 Mesh::set_attrib(unsigned int pos, const LibMatrix::vec2 &v, std::vector<float> *vertex)
 {
     if (!check_attrib(pos, 2))
         return;

     std::vector<float> &vtx = !vertex ? ensure_vertex() : *vertex;

     int offset = vertex_format_[pos].second;

     vtx[offset] = v.x();
     vtx[offset + 1] = v.y();
 }

 void
 Mesh::set_attrib(unsigned int pos, const LibMatrix::vec3 &v, std::vector<float> *vertex)
 {
     if (!check_attrib(pos, 3))
         return;

     std::vector<float> &vtx = !vertex ? ensure_vertex() : *vertex;

     int offset = vertex_format_[pos].second;

     vtx[offset] = v.x();
     vtx[offset + 1] = v.y();
     vtx[offset + 2] = v.z();
 }

 void
 Mesh::set_attrib(unsigned int pos, const LibMatrix::vec4 &v, std::vector<float> *vertex)
 {
     if (!check_attrib(pos, 4))
         return;

     std::vector<float> &vtx = !vertex ? ensure_vertex() : *vertex;

     int offset = vertex_format_[pos].second;

     vtx[offset] = v.x();
     vtx[offset + 1] = v.y();
     vtx[offset + 2] = v.z();
     vtx[offset + 3] = v.w();
 }

 /*
  * Adds a new vertex to the list and makes it current.
  */
 void
 Mesh::next_vertex()
 {
     vertices_.push_back(std::vector<float>(vertex_size_));
 }

 /**
  * Gets the mesh vertices.
  *
  * You should use the ::set_attrib() method to manipulate
  * the vertex data.
  *
  * You shouldn't resize the vector (change the number of vertices)
  * manually. Use ::next_vertex() instead.
  */
 std::vector<std::vector<float> >&
 Mesh::vertices()
 {
     return vertices_;
 }

 /**
  * Sets the VBO update method.
  *
  * The default value is VBOUpdateMethodMap.
  */
 void
 Mesh::vbo_update_method(Mesh::VBOUpdateMethod method)
 {
     vbo_update_method_ = method;
 }

 /**
  * Sets the VBO usage hint.
  *
  * The usage hint takes effect in the next call to ::build_vbo().
  *
  * The default value is VBOUsageStatic.
  */
 void
 Mesh::vbo_usage(Mesh::VBOUsage usage)
 {
     vbo_usage_ = usage;
 }

 /**
  * Sets the vertex attribute interleaving mode.
  *
  * If true the vertex attributes are going to be interleaved in a single
  * buffer. Otherwise they will be separated into different buffers (one
  * per attribute).
  *
  * Interleaving mode takes effect in the next call to ::build_array() or
  * ::build_vbo().
  *
  * @param interleave whether to interleave
  */
 void
 Mesh::interleave(bool interleave)
 {
     interleave_ = interleave;
 }

 /**
  * Resets a Mesh object to its initial, empty state.
  */
 void
 Mesh::reset()
 {
     delete_array();
     delete_vbo();

     vertices_.clear();
     vertex_format_.clear();
     attrib_locations_.clear();
     attrib_data_ptr_.clear();
     vertex_size_ = 0;
     vertex_stride_ = 0;
 }

 /**
  * Builds a vertex array containing the mesh vertex data.
  *
  * The way the vertex array is constructed is affected by the current
  * interleave value, which can set using ::interleave().
  */
 void
 Mesh::build_array()
 {
     int nvertices = vertices_.size();

     if (!interleave_) {
         /* Create an array for each attribute */
         for (std::vector<std::pair<int, int> >::const_iterator ai = vertex_format_.begin();
              ai != vertex_format_.end();
              ai++)
         {
             float *array = new float[nvertices * ai->first];
             float *cur = array;

             /* Fill in the array */
             for (std::vector<std::vector<float> >::const_iterator vi = vertices_.begin();
                     vi != vertices_.end();
                     vi++)
             {
                 for (int i = 0; i < ai->first; i++)
                     *cur++ = (*vi)[ai->second + i];
             }

             vertex_arrays_.push_back(array);
             attrib_data_ptr_.push_back(array);
         }
         vertex_stride_ = 0;
     }
     else {
         float *array = new float[nvertices * vertex_size_];
         float *cur = array;

         for (std::vector<std::vector<float> >::const_iterator vi = vertices_.begin();
              vi != vertices_.end();
              vi++)
         {
             /* Fill in the array */
             for (int i = 0; i < vertex_size_; i++)
                 *cur++ = (*vi)[i];
         }

         for (size_t i = 0; i < vertex_format_.size(); i++)
             attrib_data_ptr_.push_back(array + vertex_format_[i].second);

         vertex_arrays_.push_back(array);
         vertex_stride_ = vertex_size_ * sizeof(float);
     }
 }

 /**
  * Builds a vertex buffer object containing the mesh vertex data.
  *
  * The way the VBO is constructed is affected by the current interleave
  * value (::interleave()) and the vbo usage hint (::vbo_usage()).
  */
 void
 Mesh::build_vbo()
 {
     delete_array();
     build_array();

     int nvertices = vertices_.size();

     attrib_data_ptr_.clear();

     GLenum buffer_usage;
     if (vbo_usage_ == Mesh::VBOUsageStream)
         buffer_usage = GL_STREAM_DRAW;
     else if (vbo_usage_ == Mesh::VBOUsageDynamic)
         buffer_usage = GL_DYNAMIC_DRAW;
     else /* if (vbo_usage_ == Mesh::VBOUsageStatic) */
         buffer_usage = GL_STATIC_DRAW;

     if (!interleave_) {
         /* Create a vbo for each attribute */
         for (std::vector<std::pair<int, int> >::const_iterator ai = vertex_format_.begin();
              ai != vertex_format_.end();
              ai++)
         {
             float *data = vertex_arrays_[ai - vertex_format_.begin()];
             GLuint vbo;

             glGenBuffers(1, &vbo);
             glBindBuffer(GL_ARRAY_BUFFER, vbo);
             glBufferData(GL_ARRAY_BUFFER, nvertices * ai->first * sizeof(float),
                          data, buffer_usage);

             vbos_.push_back(vbo);
             attrib_data_ptr_.push_back(0);
         }

         vertex_stride_ = 0;
     }
     else {
         GLuint vbo;
         /* Create a single vbo to store all attribute data */
         glGenBuffers(1, &vbo);
         glBindBuffer(GL_ARRAY_BUFFER, vbo);

         glBufferData(GL_ARRAY_BUFFER, nvertices * vertex_size_ * sizeof(float),
                      vertex_arrays_[0], GL_STATIC_DRAW);

         glBindBuffer(GL_ARRAY_BUFFER, 0);

         for (size_t i = 0; i < vertex_format_.size(); i++) {
             attrib_data_ptr_.push_back(reinterpret_cast<float *>(sizeof(float) * vertex_format_[i].second));
             vbos_.push_back(vbo);
         }
         vertex_stride_ = vertex_size_ * sizeof(float);
     }

     delete_array();
 }

 /**
  * Updates ranges of a single vertex array.
  *
  * @param ranges the ranges of vertices to update
  * @param n the index of the vertex array to update
  * @param nfloats how many floats to update for each vertex
  * @param offset the offset (in floats) in the vertex data to start reading from
  */
 void
 Mesh::update_single_array(const std::vector<std::pair<size_t, size_t> >& ranges,
                           size_t n, size_t nfloats, size_t offset)
 {
     float *array(vertex_arrays_[n]);

     /* Update supplied ranges */
     for (std::vector<std::pair<size_t, size_t> >::const_iterator ri = ranges.begin();
          ri != ranges.end();
          ri++)
     {
         /* Update the current range from the vertex data */
         float *dest(array + nfloats * ri->first);
         for (size_t n = ri->first; n <= ri->second; n++) {
             for (size_t i = 0; i < nfloats; i++)
                 *dest++ = vertices_[n][offset + i];
         }

     }
 }

 /**
  * Updates ranges of the vertex arrays.
  *
  * @param ranges the ranges of vertices to update
  */
 void
 Mesh::update_array(const std::vector<std::pair<size_t, size_t> >& ranges)
 {
     /* If we don't have arrays to update, create them */
     if (vertex_arrays_.empty()) {
         build_array();
         return;
     }

     if (!interleave_) {
         for (size_t i = 0; i < vertex_arrays_.size(); i++) {
             update_single_array(ranges, i, vertex_format_[i].first,
                                 vertex_format_[i].second);
         }
     }
     else {
         update_single_array(ranges, 0, vertex_size_, 0);
     }

 }


 /**
  * Updates ranges of a single VBO.
  *
  * This method use either glMapBuffer or glBufferSubData to perform
  * the update. The used method can be set with ::vbo_update_method().
  *
  * @param ranges the ranges of vertices to update
  * @param n the index of the vbo to update
  * @param nfloats how many floats to update for each vertex
  */
 void
 Mesh::update_single_vbo(const std::vector<std::pair<size_t, size_t> >& ranges,
                         size_t n, size_t nfloats)
 {
     float *src_start(vertex_arrays_[n]);
     float *dest_start(0);

     glBindBuffer(GL_ARRAY_BUFFER, vbos_[n]);

     if (vbo_update_method_ == VBOUpdateMethodMap) {
         dest_start = reinterpret_cast<float *>(
                 GLExtensions::MapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY)
                 );
     }

     /* Update supplied ranges */
     for (std::vector<std::pair<size_t, size_t> >::const_iterator iter = ranges.begin();
          iter != ranges.end();
          iter++)
     {
         float *src(src_start + nfloats * iter->first);
         float *src_end(src_start + nfloats * (iter->second + 1));

         if (vbo_update_method_ == VBOUpdateMethodMap) {
             float *dest(dest_start + nfloats * iter->first);
             std::copy(src, src_end, dest);
         }
         else if (vbo_update_method_ == VBOUpdateMethodSubData) {
             glBufferSubData(GL_ARRAY_BUFFER, nfloats * iter->first * sizeof(float),
                             (src_end - src) * sizeof(float), src);
         }
     }

     if (vbo_update_method_ == VBOUpdateMethodMap)
         GLExtensions::UnmapBuffer(GL_ARRAY_BUFFER);
 }

 /**
  * Updates ranges of the VBOs.
  *
  * @param ranges the ranges of vertices to update
  */
 void
 Mesh::update_vbo(const std::vector<std::pair<size_t, size_t> >& ranges)
 {
     /* If we don't have VBOs to update, create them */
     if (vbos_.empty()) {
         build_vbo();
         return;
     }

     update_array(ranges);

     if (!interleave_) {
         for (size_t i = 0; i < vbos_.size(); i++)
             update_single_vbo(ranges, i, vertex_format_[i].first);
     }
     else {
         update_single_vbo(ranges, 0, vertex_size_);
     }

     glBindBuffer(GL_ARRAY_BUFFER, 0);
 }


 /**
  * Deletes all resources associated with built vertex arrays.
  */
 void
 Mesh::delete_array()
 {
     for (size_t i = 0; i < vertex_arrays_.size(); i++) {
         delete [] vertex_arrays_[i];
     }

     vertex_arrays_.clear();
 }

 /**
  * Deletes all resources associated with built VBOs.
  */
 void
 Mesh::delete_vbo()
 {
     for (size_t i = 0; i < vbos_.size(); i++) {
         GLuint vbo = vbos_[i];
         glDeleteBuffers(1, &vbo);
     }

     vbos_.clear();
 }


 /**
  * Renders a mesh using vertex arrays.
  *
  * The vertex arrays must have been previously initialized using
  * ::build_array().
  */
 void
 Mesh::render_array()
 {
     for (size_t i = 0; i < vertex_format_.size(); i++) {
         glEnableVertexAttribArray(attrib_locations_[i]);
         glVertexAttribPointer(attrib_locations_[i], vertex_format_[i].first,
                               GL_FLOAT, GL_FALSE, vertex_stride_,
                               attrib_data_ptr_[i]);
     }

     glDrawArrays(GL_TRIANGLES, 0, vertices_.size());

     for (size_t i = 0; i < vertex_format_.size(); i++) {
         glDisableVertexAttribArray(attrib_locations_[i]);
     }
 }

 /**
  * Renders a mesh using vertex buffer objects.
  *
  * The vertex buffer objects must have been previously initialized using
  * ::build_vbo().
  */
 void
 Mesh::render_vbo()
 {
     for (size_t i = 0; i < vertex_format_.size(); i++) {
         glEnableVertexAttribArray(attrib_locations_[i]);
         glBindBuffer(GL_ARRAY_BUFFER, vbos_[i]);
         glVertexAttribPointer(attrib_locations_[i], vertex_format_[i].first,
                               GL_FLOAT, GL_FALSE, vertex_stride_,
                               attrib_data_ptr_[i]);
     }

     glDrawArrays(GL_TRIANGLES, 0, vertices_.size());

     for (size_t i = 0; i < vertex_format_.size(); i++) {
         glDisableVertexAttribArray(attrib_locations_[i]);
     }
 }

 /**
  * Creates a grid mesh.
  *
  * @param n_x the number of grid cells on the X axis
  * @param n_y the number of grid cells on the Y axis
  * @param width the width X of the grid (normalized)
  * @param height the height Y of the grid (normalized)
  * @param spacing the spacing between cells (normalized)
  * @param conf_func a function to call to configure the grid (or NULL)
  */
 void
 Mesh::make_grid(int n_x, int n_y, double width, double height,
                 double spacing, grid_configuration_func conf_func)
 {
     double side_width = (width - (n_x - 1) * spacing) / n_x;
     double side_height = (height - (n_y - 1) * spacing) / n_y;

     for (int i = 0; i < n_x; i++) {
         for (int j = 0; j < n_y; j++) {
             LibMatrix::vec3 a(-width / 2 + i * (side_width + spacing),
                               height / 2 - j * (side_height + spacing), 0);
             LibMatrix::vec3 b(a.x(), a.y() - side_height, 0);
             LibMatrix::vec3 c(a.x() + side_width, a.y(), 0);
             LibMatrix::vec3 d(a.x() + side_width, a.y() - side_height, 0);

             if (!conf_func) {
                 std::vector<float> ul(vertex_size_);
                 std::vector<float> ur(vertex_size_);
                 std::vector<float> ll(vertex_size_);
                 std::vector<float> lr(vertex_size_);

                 set_attrib(0, a, &ul);
                 set_attrib(0, c, &ur);
                 set_attrib(0, b, &ll);
                 set_attrib(0, d, &lr);

                 next_vertex(); vertices_.back() = ul;
                 next_vertex(); vertices_.back() = ll;
                 next_vertex(); vertices_.back() = ur;
                 next_vertex(); vertices_.back() = ll;
                 next_vertex(); vertices_.back() = lr;
                 next_vertex(); vertices_.back() = ur;
             }
             else {
                 conf_func(*this, i, j, n_x, n_y, a, b, c, d);
             }
         }
     }
 }
	/*
	* Copyright © 2008 Ben Smith
	* Copyright © 2010-2011 Linaro Limited
	*
	* This file is part of the glmark2 OpenGL (ES) 2.0 benchmark.
	*
	* glmark2 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 3 of the License, or (at your option) any later
	* version.
	*
	* glmark2 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
	* glmark2. If not, see <http://www.gnu.org/licenses/>.
	*
	* Authors:
	* Ben Smith (original glmark benchmark)
	* Alexandros Frantzis (glmark2)
	*/
	#include "mesh.h"
	#include "log.h"
	#include "gl-headers.h"


	Mesh::Mesh() :
	vertex_size_(0), interleave_(false), vbo_update_method_(VBOUpdateMethodMap),
	vbo_usage_(VBOUsageStatic)
	{
	}

	Mesh::~Mesh()
	{
	reset();
	}

	/*
	* Sets the vertex format for this mesh.
	*
	* The format consists of a vector of integers, each
	* specifying the size in floats of each vertex attribute.
	*
	* e.g. {4, 3, 2} => 3 attributes vec4, vec3, vec2
	*/
	void
	Mesh::set_vertex_format(const std::vector<int> &format)
	{
	int pos = 0;
	vertex_format_.clear();

	for (std::vector<int>::const_iterator iter = format.begin();
	iter != format.end();
	iter++)
	{
	int n = *iter;
	vertex_format_.push_back(std::pair<int,int>(n, pos));

	pos += n;
	}

	vertex_size_ = pos;
	}

	/*
	* Sets the attribute locations.
	*
	* These are the locations used in glEnableVertexAttribArray()
	* and other related functions.
	*/
	void
	Mesh::set_attrib_locations(const std::vector<int> &locations)
	{
	if (locations.size() != vertex_format_.size())
	Log::error("Trying to set attribute locations using wrong size\n");
	attrib_locations_ = locations;
	}


	/**
	* Checks that an attribute is of the correct dimensionality.
	*
	* @param pos the position/index of the attribute to check
	* @param dim the size of the attribute (in #floats)
	*
	* @return whether the check succeeded
	*/
	bool
	Mesh::check_attrib(unsigned int pos, int dim)
	{
	if (pos > vertex_format_.size()) {
	Log::error("Trying to set non-existent attribute\n");
	return false;
	}

	if (vertex_format_[pos].first != dim) {
	Log::error("Trying to set attribute with value of invalid type\n");
	return false;
	}

	return true;
	}


	/**
	* Ensures that we have a vertex to process.
	*
	* @return the vertex to process
	*/
	std::vector<float> &
	Mesh::ensure_vertex()
	{
	if (vertices_.empty())
	next_vertex();

	return vertices_.back();
	}

	/*
	* Sets the value of an attribute in the current vertex.
	*
	* The pos parameter refers to the position of the attribute
	* as specified indirectly when setting the format using
	* set_vertex_format(). e.g. 0 = first attribute, 1 = second
	* etc
	*/
	void
	Mesh::set_attrib(unsigned int pos, const LibMatrix::vec2 &v, std::vector<float> *vertex)
	{
	if (!check_attrib(pos, 2))
	return;

	std::vector<float> &vtx = !vertex ? ensure_vertex() : *vertex;

	int offset = vertex_format_[pos].second;

	vtx[offset] = v.x();
	vtx[offset + 1] = v.y();
	}

	void
	Mesh::set_attrib(unsigned int pos, const LibMatrix::vec3 &v, std::vector<float> *vertex)
	{
	if (!check_attrib(pos, 3))
	return;

	std::vector<float> &vtx = !vertex ? ensure_vertex() : *vertex;

	int offset = vertex_format_[pos].second;

	vtx[offset] = v.x();
	vtx[offset + 1] = v.y();
	vtx[offset + 2] = v.z();
	}

	void
	Mesh::set_attrib(unsigned int pos, const LibMatrix::vec4 &v, std::vector<float> *vertex)
	{
	if (!check_attrib(pos, 4))
	return;

	std::vector<float> &vtx = !vertex ? ensure_vertex() : *vertex;

	int offset = vertex_format_[pos].second;

	vtx[offset] = v.x();
	vtx[offset + 1] = v.y();
	vtx[offset + 2] = v.z();
	vtx[offset + 3] = v.w();
	}

	/*
	* Adds a new vertex to the list and makes it current.
	*/
	void
	Mesh::next_vertex()
	{
	vertices_.push_back(std::vector<float>(vertex_size_));
	}

	/**
	* Gets the mesh vertices.
	*
	* You should use the ::set_attrib() method to manipulate
	* the vertex data.
	*
	* You shouldn't resize the vector (change the number of vertices)
	* manually. Use ::next_vertex() instead.
	*/
	std::vector<std::vector<float> >&
	Mesh::vertices()
	{
	return vertices_;
	}

	/**
	* Sets the VBO update method.
	*
	* The default value is VBOUpdateMethodMap.
	*/
	void
	Mesh::vbo_update_method(Mesh::VBOUpdateMethod method)
	{
	vbo_update_method_ = method;
	}

	/**
	* Sets the VBO usage hint.
	*
	* The usage hint takes effect in the next call to ::build_vbo().
	*
	* The default value is VBOUsageStatic.
	*/
	void
	Mesh::vbo_usage(Mesh::VBOUsage usage)
	{
	vbo_usage_ = usage;
	}

	/**
	* Sets the vertex attribute interleaving mode.
	*
	* If true the vertex attributes are going to be interleaved in a single
	* buffer. Otherwise they will be separated into different buffers (one
	* per attribute).
	*
	* Interleaving mode takes effect in the next call to ::build_array() or
	* ::build_vbo().
	*
	* @param interleave whether to interleave
	*/
	void
	Mesh::interleave(bool interleave)
	{
	interleave_ = interleave;
	}

	/**
	* Resets a Mesh object to its initial, empty state.
	*/
	void
	Mesh::reset()
	{
	delete_array();
	delete_vbo();

	vertices_.clear();
	vertex_format_.clear();
	attrib_locations_.clear();
	attrib_data_ptr_.clear();
	vertex_size_ = 0;
	vertex_stride_ = 0;
	}

	/**
	* Builds a vertex array containing the mesh vertex data.
	*
	* The way the vertex array is constructed is affected by the current
	* interleave value, which can set using ::interleave().
	*/
	void
	Mesh::build_array()
	{
	int nvertices = vertices_.size();

	if (!interleave_) {
	/* Create an array for each attribute */
	for (std::vector<std::pair<int, int> >::const_iterator ai = vertex_format_.begin();
	ai != vertex_format_.end();
	ai++)
	{
	float array = new float[nvertices ai->first];
	float *cur = array;

	/* Fill in the array */
	for (std::vector<std::vector<float> >::const_iterator vi = vertices_.begin();
	vi != vertices_.end();
	vi++)
	{
	for (int i = 0; i < ai->first; i++)
	cur++ = (vi)[ai->second + i];
	}

	vertex_arrays_.push_back(array);
	attrib_data_ptr_.push_back(array);
	}
	vertex_stride_ = 0;
	}
	else {
	float array = new float[nvertices vertex_size_];
	float *cur = array;

	for (std::vector<std::vector<float> >::const_iterator vi = vertices_.begin();
	vi != vertices_.end();
	vi++)
	{
	/* Fill in the array */
	for (int i = 0; i < vertex_size_; i++)
	cur++ = (vi)[i];
	}

	for (size_t i = 0; i < vertex_format_.size(); i++)
	attrib_data_ptr_.push_back(array + vertex_format_[i].second);

	vertex_arrays_.push_back(array);
	vertex_stride_ = vertex_size_ * sizeof(float);
	}
	}

	/**
	* Builds a vertex buffer object containing the mesh vertex data.
	*
	* The way the VBO is constructed is affected by the current interleave
	* value (::interleave()) and the vbo usage hint (::vbo_usage()).
	*/
	void
	Mesh::build_vbo()
	{
	delete_array();
	build_array();

	int nvertices = vertices_.size();

	attrib_data_ptr_.clear();

	GLenum buffer_usage;
	if (vbo_usage_ == Mesh::VBOUsageStream)
	buffer_usage = GL_STREAM_DRAW;
	else if (vbo_usage_ == Mesh::VBOUsageDynamic)
	buffer_usage = GL_DYNAMIC_DRAW;
	else /* if (vbo_usage_ == Mesh::VBOUsageStatic) */
	buffer_usage = GL_STATIC_DRAW;

	if (!interleave_) {
	/* Create a vbo for each attribute */
	for (std::vector<std::pair<int, int> >::const_iterator ai = vertex_format_.begin();
	ai != vertex_format_.end();
	ai++)
	{
	float *data = vertex_arrays_[ai - vertex_format_.begin()];
	GLuint vbo;

	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glBufferData(GL_ARRAY_BUFFER, nvertices * ai->first * sizeof(float),
	data, buffer_usage);

	vbos_.push_back(vbo);
	attrib_data_ptr_.push_back(0);
	}

	vertex_stride_ = 0;
	}
	else {
	GLuint vbo;
	/* Create a single vbo to store all attribute data */
	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);

	glBufferData(GL_ARRAY_BUFFER, nvertices * vertex_size_ * sizeof(float),
	vertex_arrays_[0], GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, 0);

	for (size_t i = 0; i < vertex_format_.size(); i++) {
	attrib_data_ptr_.push_back(reinterpret_cast<float >(sizeof(float) vertex_format_[i].second));
	vbos_.push_back(vbo);
	}
	vertex_stride_ = vertex_size_ * sizeof(float);
	}

	delete_array();
	}

	/**
	* Updates ranges of a single vertex array.
	*
	* @param ranges the ranges of vertices to update
	* @param n the index of the vertex array to update
	* @param nfloats how many floats to update for each vertex
	* @param offset the offset (in floats) in the vertex data to start reading from
	*/
	void
	Mesh::update_single_array(const std::vector<std::pair<size_t, size_t> >& ranges,
	size_t n, size_t nfloats, size_t offset)
	{
	float *array(vertex_arrays_[n]);

	/* Update supplied ranges */
	for (std::vector<std::pair<size_t, size_t> >::const_iterator ri = ranges.begin();
	ri != ranges.end();
	ri++)
	{
	/* Update the current range from the vertex data */
	float dest(array + nfloats ri->first);
	for (size_t n = ri->first; n <= ri->second; n++) {
	for (size_t i = 0; i < nfloats; i++)
	*dest++ = vertices_[n][offset + i];
	}

	}
	}

	/**
	* Updates ranges of the vertex arrays.
	*
	* @param ranges the ranges of vertices to update
	*/
	void
	Mesh::update_array(const std::vector<std::pair<size_t, size_t> >& ranges)
	{
	/* If we don't have arrays to update, create them */
	if (vertex_arrays_.empty()) {
	build_array();
	return;
	}

	if (!interleave_) {
	for (size_t i = 0; i < vertex_arrays_.size(); i++) {
	update_single_array(ranges, i, vertex_format_[i].first,
	vertex_format_[i].second);
	}
	}
	else {
	update_single_array(ranges, 0, vertex_size_, 0);
	}

	}


	/**
	* Updates ranges of a single VBO.
	*
	* This method use either glMapBuffer or glBufferSubData to perform
	* the update. The used method can be set with ::vbo_update_method().
	*
	* @param ranges the ranges of vertices to update
	* @param n the index of the vbo to update
	* @param nfloats how many floats to update for each vertex
	*/
	void
	Mesh::update_single_vbo(const std::vector<std::pair<size_t, size_t> >& ranges,
	size_t n, size_t nfloats)
	{
	float *src_start(vertex_arrays_[n]);
	float *dest_start(0);

	glBindBuffer(GL_ARRAY_BUFFER, vbos_[n]);

	if (vbo_update_method_ == VBOUpdateMethodMap) {
	dest_start = reinterpret_cast<float *>(
	GLExtensions::MapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY)
	);
	}

	/* Update supplied ranges */
	for (std::vector<std::pair<size_t, size_t> >::const_iterator iter = ranges.begin();
	iter != ranges.end();
	iter++)
	{
	float src(src_start + nfloats iter->first);
	float src_end(src_start + nfloats (iter->second + 1));

	if (vbo_update_method_ == VBOUpdateMethodMap) {
	float dest(dest_start + nfloats iter->first);
	std::copy(src, src_end, dest);
	}
	else if (vbo_update_method_ == VBOUpdateMethodSubData) {
	glBufferSubData(GL_ARRAY_BUFFER, nfloats * iter->first * sizeof(float),
	(src_end - src) * sizeof(float), src);
	}
	}

	if (vbo_update_method_ == VBOUpdateMethodMap)
	GLExtensions::UnmapBuffer(GL_ARRAY_BUFFER);
	}

	/**
	* Updates ranges of the VBOs.
	*
	* @param ranges the ranges of vertices to update
	*/
	void
	Mesh::update_vbo(const std::vector<std::pair<size_t, size_t> >& ranges)
	{
	/* If we don't have VBOs to update, create them */
	if (vbos_.empty()) {
	build_vbo();
	return;
	}

	update_array(ranges);

	if (!interleave_) {
	for (size_t i = 0; i < vbos_.size(); i++)
	update_single_vbo(ranges, i, vertex_format_[i].first);
	}
	else {
	update_single_vbo(ranges, 0, vertex_size_);
	}

	glBindBuffer(GL_ARRAY_BUFFER, 0);
	}


	/**
	* Deletes all resources associated with built vertex arrays.
	*/
	void
	Mesh::delete_array()
	{
	for (size_t i = 0; i < vertex_arrays_.size(); i++) {
	delete [] vertex_arrays_[i];
	}

	vertex_arrays_.clear();
	}

	/**
	* Deletes all resources associated with built VBOs.
	*/
	void
	Mesh::delete_vbo()
	{
	for (size_t i = 0; i < vbos_.size(); i++) {
	GLuint vbo = vbos_[i];
	glDeleteBuffers(1, &vbo);
	}

	vbos_.clear();
	}


	/**
	* Renders a mesh using vertex arrays.
	*
	* The vertex arrays must have been previously initialized using
	* ::build_array().
	*/
	void
	Mesh::render_array()
	{
	for (size_t i = 0; i < vertex_format_.size(); i++) {
	glEnableVertexAttribArray(attrib_locations_[i]);
	glVertexAttribPointer(attrib_locations_[i], vertex_format_[i].first,
	GL_FLOAT, GL_FALSE, vertex_stride_,
	attrib_data_ptr_[i]);
	}

	glDrawArrays(GL_TRIANGLES, 0, vertices_.size());

	for (size_t i = 0; i < vertex_format_.size(); i++) {
	glDisableVertexAttribArray(attrib_locations_[i]);
	}
	}

	/**
	* Renders a mesh using vertex buffer objects.
	*
	* The vertex buffer objects must have been previously initialized using
	* ::build_vbo().
	*/
	void
	Mesh::render_vbo()
	{
	for (size_t i = 0; i < vertex_format_.size(); i++) {
	glEnableVertexAttribArray(attrib_locations_[i]);
	glBindBuffer(GL_ARRAY_BUFFER, vbos_[i]);
	glVertexAttribPointer(attrib_locations_[i], vertex_format_[i].first,
	GL_FLOAT, GL_FALSE, vertex_stride_,
	attrib_data_ptr_[i]);
	}

	glDrawArrays(GL_TRIANGLES, 0, vertices_.size());

	for (size_t i = 0; i < vertex_format_.size(); i++) {
	glDisableVertexAttribArray(attrib_locations_[i]);
	}
	}

	/**
	* Creates a grid mesh.
	*
	* @param n_x the number of grid cells on the X axis
	* @param n_y the number of grid cells on the Y axis
	* @param width the width X of the grid (normalized)
	* @param height the height Y of the grid (normalized)
	* @param spacing the spacing between cells (normalized)
	* @param conf_func a function to call to configure the grid (or NULL)
	*/
	void
	Mesh::make_grid(int n_x, int n_y, double width, double height,
	double spacing, grid_configuration_func conf_func)
	{
	double side_width = (width - (n_x - 1) * spacing) / n_x;
	double side_height = (height - (n_y - 1) * spacing) / n_y;

	for (int i = 0; i < n_x; i++) {
	for (int j = 0; j < n_y; j++) {
	LibMatrix::vec3 a(-width / 2 + i * (side_width + spacing),
	height / 2 - j * (side_height + spacing), 0);
	LibMatrix::vec3 b(a.x(), a.y() - side_height, 0);
	LibMatrix::vec3 c(a.x() + side_width, a.y(), 0);
	LibMatrix::vec3 d(a.x() + side_width, a.y() - side_height, 0);

	if (!conf_func) {
	std::vector<float> ul(vertex_size_);
	std::vector<float> ur(vertex_size_);
	std::vector<float> ll(vertex_size_);
	std::vector<float> lr(vertex_size_);

	set_attrib(0, a, &ul);
	set_attrib(0, c, &ur);
	set_attrib(0, b, &ll);
	set_attrib(0, d, &lr);

	next_vertex(); vertices_.back() = ul;
	next_vertex(); vertices_.back() = ll;
	next_vertex(); vertices_.back() = ur;
	next_vertex(); vertices_.back() = ll;
	next_vertex(); vertices_.back() = lr;
	next_vertex(); vertices_.back() = ur;
	}
	else {
	conf_func(*this, i, j, n_x, n_y, a, b, c, d);
	}
	}
	}
	}