effects.py 文件源码

def blend_layers(control, shape, feather=1.0, *layers):
    layer_count = len(layers)

    control = normalize(control)

    control *= layer_count
    control_floor = tf.cast(control, tf.int32)

    x_index = row_index(shape)
    y_index = column_index(shape)

    layers = tf.stack(list(layers) + [layers[-1]])
    layer_count += 1

    floor_values = control_floor[:, :, 0]

    # I'm not sure why the mod operation is needed, but tensorflow-cpu explodes without it.
    combined_layer_0 = tf.gather_nd(layers, tf.stack([floor_values % layer_count, y_index, x_index], 2))
    combined_layer_1 = tf.gather_nd(layers, tf.stack([(floor_values + 1) % layer_count, y_index, x_index], 2))

    control_floor_fract = control - tf.floor(control)
    control_floor_fract = tf.minimum(tf.maximum(control_floor_fract - (1.0 - feather), 0.0) / feather, 1.0)

    return blend(combined_layer_0, combined_layer_1, control_floor_fract)