vertexBufferObject.cpp

#include "common_header.h"

#include "vertexBufferObject.h"

CVertexBufferObject::CVertexBufferObject()
{
	bDataUploaded = false;
}

// Creates vertex buffer object.
// a_iSize - initial size of buffer
void CVertexBufferObject::CreateVBO(int a_iSize)
{
	glGenBuffers(1, &uiBuffer);
	data.reserve(a_iSize);
	iSize = a_iSize;
}

// Releases VBO and frees all memory.
void CVertexBufferObject::DeleteVBO()
{
	glDeleteBuffers(1, &uiBuffer);
	bDataUploaded = false;
	data.clear();
}

// Maps whole buffer data to memory and returns pointer to data.
// iUsageHint - GL_READ_ONLY, GL_WRITE_ONLY...
void* CVertexBufferObject::MapBufferToMemory(int iUsageHint)
{
	if(!bDataUploaded)return NULL;
	void* ptrRes = glMapBuffer(iBufferType, iUsageHint);
	return ptrRes;
}

// Maps specified part of buffer to memory.
// iUsageHint - GL_READ_ONLY, GL_WRITE_ONLY...
// uiOffset - data offset(from where should data be mapped).
// uiLength - length of data
void* CVertexBufferObject::MapSubBufferToMemory(int iUsageHint, uint uiOffset, uint uiLength)
{
	if(!bDataUploaded)return NULL;
	void* ptrRes = glMapBufferRange(iBufferType, uiOffset, uiLength, iUsageHint);
	return ptrRes;
}

// Unmaps previously mapped buffer.
void CVertexBufferObject::UnmapBuffer()
{
	glUnmapBuffer(iBufferType);
}

// Binds this VBO.
// a_iBufferType - buffer type (GL_ARRAY_BUFFER, ...)
void CVertexBufferObject::BindVBO(int a_iBufferType)
{
	iBufferType = a_iBufferType;
	glBindBuffer(iBufferType, uiBuffer);
}

// Sends data to GPU.
// iUsageHint - GL_STATIC_DRAW, GL_DYNAMIC_DRAW...
void CVertexBufferObject::UploadDataToGPU(int iDrawingHint)
{
	glBufferData(iBufferType, data.size(), &data[0], iDrawingHint);
	bDataUploaded = true;
	data.clear();
}

// Adds arbitrary data to VBO.
// ptrData - pointer to arbitrary data
// uiDataSize - data size in bytes
void CVertexBufferObject::AddData(void* ptrData, uint uiDataSize)
{
	data.insert(data.end(), (unsigned char*)ptrData, (unsigned char*)ptrData+uiDataSize);
}

// Returns data pointer (only before uploading).
void* CVertexBufferObject::GetDataPointer()
{
	if(bDataUploaded)return NULL;
	return (void*)&(data[0]);
}

// Returns VBO ID.
uint CVertexBufferObject::GetBufferID()
{
	return uiBuffer;
}