A decoder includes circuitry configured to receive a bitstream, including a current picture having a current block with a first boundary partitioning the block into first and second non-rectangular regions and a second boundary further partitioning the second non-rectangular region. The decoder determines a first predictor for use within the first non-rectangular region using a first motion vector selected from a first list of motion vector candidates, determines a second predictor for use within the second non-rectangular region using a second motion vector selected from a second list of motion vector candidates, smooths the predictors across the partition boundary and decodes the current block using the first and second predictors.