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Thread: Transparent Texture Map question

  1. #1
    Junior Member Newbie
    Join Date
    Dec 2000
    Location
    Ann Arbor, MI, USA
    Posts
    3

    Transparent Texture Map question

    How do you set the Alpha value for specific colors to be transparent in the texture map?

  2. #2
    Junior Member Newbie
    Join Date
    Sep 2000
    Posts
    15

    Re: Transparent Texture Map question

    I'm also curious if there is an easy way to do this. As of now I just load the bitmap textures then convert them to 32-bit changing the alpha values based on the the pixel color. Then I create the RGBA texture.

    // convert 24-bit data to 32-bit
    pData = new unsigned char [m_width*m_height*4];
    unsigned int row,col;
    for (row=0;row<m_height;row++)
    {
    for (col=0;col<m_width;col++)
    {
    int index=row*m_width*4+col*4;
    int indexIn=row*m_width*3+col*3;
    pData[index]=m_pRGB[indexIn];
    pData[index+1]=m_pRGB[indexIn+1];
    pData[index+2]=m_pRGB[indexIn+2];
    pData[index+3]=255;
    }
    }
    if (m_pRGB)
    delete[] m_pRGB;
    m_pRGB=pData;

    // add alpha color mask
    int i;
    int count=m_width*m_height;
    unsigned int* pData=(unsigned int*)m_pRGB;
    for (i=0;i<count;i++)
    {
    if ((pData[i] & 0x00FFFFFF)==color)
    pData[i]= (((alpha << 24) & 0xFF000000)|color);
    }

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