Class BlockDXT

common/dds.cpp:387–428

struct BlockDXT {
    Color565 col0;
    Color565 col1;
    uchar row[4];

    void GetColors( Color8888 color_array[4] ) {
        color_array[0].r = (col0.c.r << 3) | (col0.c.r >> 2);
        color_array[0].g = (col0.c.g << 2) | (col0.c.g >> 4);
        color_array[0].b = (col0.c.b << 3) | (col0.c.b >> 2);
        color_array[0].a = 0xFF;

        color_array[1].r = (col1.c.r << 3) | (col1.c.r >> 2);
        color_array[1].g = (col1.c.g << 2) | (col1.c.g >> 4);
        color_array[1].b = (col1.c.b << 3) | (col1.c.b >> 2);
        color_array[1].a = 0xFF;

        if( col0.u > col1.u ) {
            // Four-color block: derive the other two colors.
            color_array[2].r = (2 * color_array[0].r + color_array[1].r) / 3;
            color_array[2].g = (2 * color_array[0].g + color_array[1].g) / 3;
            color_array[2].b = (2 * color_array[0].b + color_array[1].b) / 3;
            color_array[2].a = 0xFF;

            color_array[3].r = (2 * color_array[1].r + color_array[0].r) / 3;
            color_array[3].g = (2 * color_array[1].g + color_array[0].g) / 3;
            color_array[3].b = (2 * color_array[1].b + color_array[0].b) / 3;
            color_array[3].a = 0xFF;
        } else {
            // Three-color block: derive the other color.
            color_array[2].r = (color_array[0].r + color_array[1].r) / 2;
            color_array[2].g = (color_array[0].g + color_array[1].g) / 2;
            color_array[2].b = (color_array[0].b + color_array[1].b) / 2;
            color_array[2].a = 0xFF;

            // Set all components to 0 to match DXT specs.
            color_array[3].r = 0x00; // color_array[2].r;
            color_array[3].g = 0x00; // color_array[2].g;
            color_array[3].b = 0x00; // color_array[2].b;
            color_array[3].a = 0x00;
        }
    }
};


static QDataStream & operator>> ( QDataStream & s, BlockDXT & c )