//----------------------------------------------------------------------------
void SEVertexBuffer::BuildCompatibleArray(const SEAttributes& rIAttributes,
bool bPackARGB, int& rChannels, float*& rCompatible) const
{
// 注意这里使用unsigned int来存储数据,
// 从而允许同时存储float和32位ARGB格式的unsigned int数据,
// 把float指针显示类型转换为unsigned int指针然后取*操作没有任何问题,
// 但反过来把unsigned int指针显示类型转换为float指针并取*操作,
// 则取出的数据可能为非法浮点数据,
// 因此如果使用std::vector<float>将可能存在数据非正常转换的问题
std::vector<unsigned int> tempCompatible;
const unsigned int* puiData;
float fOne = 1.0f;
unsigned int* puiOne = (unsigned int*)&fOne;
int iUnit, iIChannels, iVBChannels;
for( int i = 0, j; i < m_iVertexCount; i++ )
{
// 填充顶点
if( rIAttributes.HasPosition() )
{
iIChannels = rIAttributes.GetPositionChannels();
iVBChannels = m_Attributes.GetPositionChannels();
puiData = (unsigned int*)PositionTuple(i);
if( iVBChannels < iIChannels )
{
for( j = 0; j < iVBChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
for( j = iVBChannels; j < iIChannels; j++ )
{
// 将w分量填充为1.0,从而成为齐次空间顶点
tempCompatible.push_back(*puiOne);
}
}
else
{
for( j = 0; j < iIChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
}
}
// 填充法线
if( rIAttributes.HasNormal() )
{
iIChannels = rIAttributes.GetNormalChannels();
iVBChannels = m_Attributes.GetNormalChannels();
puiData = (unsigned int*)NormalTuple(i);
if( iVBChannels < iIChannels )
{
for( j = 0; j < iVBChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
for( j = iVBChannels; j < iIChannels; j++ )
{
// 将w分量填充为0.0,从而成为齐次空间向量
tempCompatible.push_back(0);
}
}
else
{
for( j = 0; j < iIChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
}
}
// 填充若干组颜色
for( iUnit = 0; iUnit < (int)rIAttributes.GetMaxColors(); iUnit++ )
{
if( rIAttributes.HasColor(iUnit) )
{
unsigned int auiColor[4], uiPackColor, uiValue;
float fValue;
iIChannels = rIAttributes.GetColorChannels(iUnit);
iVBChannels = m_Attributes.GetColorChannels(iUnit);
puiData = (unsigned int*)ColorTuple(iUnit, i);
if( iVBChannels < iIChannels )
{
for( j = 0; j < iVBChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
for( j = iVBChannels; j < iIChannels; j++ )
{
// 将a分量填充为1.0,成为不透明颜色
tempCompatible.push_back(*puiOne);
}
if( bPackARGB )
{
for( j = iIChannels; j < 4; j++ )
{
// 将a分量填充为1.0,成为不透明颜色
tempCompatible.push_back(*puiOne);
}
// 从[0.0f, 1.0f]映射到[0,255]
for( j = 3; j >= 0; j-- )
{
uiValue = tempCompatible.back();
fValue = *(float*)&uiValue;
auiColor[j] = (unsigned int)(255.0f * fValue);
tempCompatible.pop_back();
}
uiPackColor =
(auiColor[2] ) | // blue
(auiColor[1] << 8) | // green
(auiColor[0] << 16) | // red
(auiColor[3] << 24); // alpha
tempCompatible.push_back(uiPackColor);
}
}
else
{
for( j = 0; j < iIChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
if( bPackARGB )
{
for( j = iIChannels; j < 4; j++ )
{
// 将a分量填充为1.0,成为不透明颜色
tempCompatible.push_back(*puiOne);
}
// 从[0.0f, 1.0f]映射到[0,255]
for( j = 3; j >= 0; j-- )
{
uiValue = tempCompatible.back();
fValue = *(float*)&uiValue;
auiColor[j] = (unsigned int)(255.0f * fValue);
tempCompatible.pop_back();
}
uiPackColor =
(auiColor[2] ) | // blue
(auiColor[1] << 8) | // green
(auiColor[0] << 16) | // red
(auiColor[3] << 24); // alpha
tempCompatible.push_back(uiPackColor);
}
}
}
}
// 填充若干组纹理坐标
for( iUnit = 0; iUnit < (int)rIAttributes.GetMaxTCoords(); iUnit++ )
{
if( rIAttributes.HasTCoord(iUnit) )
{
iIChannels = rIAttributes.GetTCoordChannels(iUnit);
iVBChannels = m_Attributes.GetTCoordChannels(iUnit);
puiData = (unsigned int*)TCoordTuple(iUnit, i);
if( iVBChannels < iIChannels )
{
for( j = 0; j < iVBChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
for( j = iVBChannels; j < iIChannels; j++ )
{
// 填充为0,从而高维纹理坐标兼容低维纹理坐标
tempCompatible.push_back(0);
}
}
else
{
for( j = 0; j < iIChannels; j++ )
{
tempCompatible.push_back(*puiData++);
}
}
}
}
}
rChannels = (int)tempCompatible.size();
if( !rCompatible )
{
// 调用者有责任释放该内存
rCompatible = SE_NEW float[rChannels];
}
