Collision detection: intermediate point

The intermediate point is the collision point.

ball position x = previous ball position x – x1
ball position y = previous ball position y + y1

ball position x = ball position x + (1-t)* velx //end ball position in x equals whole distance to be travelled minus distance travelled before intermediate point, multiplied by velocity in x
ball position y = ball position y + (1-t)* vely //end ball position in y equals whole distance to be travelled minus distance travelled before intermediate point, multiplied by velocity in y