|
Routines |
| Prev: DCDC | Up: Map | Next: DD01 |
|
Used by the routines at UpdateCreature, UpdateFragment, UpdateShot, UpdateThrownItem, UpdateMonster and SpeedPlayerUp.
Sets the velocity of an object along the X and Y axes from its speed and the direction that it faces. Only one axis is used, and the velocity is negative for the directions that face down the screen and to the left.
|
||||||||||
|
Put the speed on the X axis.
|
||||||||||
| SetVelocityFromSpeed | DCE0 | LD H,$00 | Make the speed the X velocity, with no Y velocity. | |||||||
| DCE2 | LD L,A | |||||||||
| DCE3 | BIT 6,(IX+$06) | Jump to SetVelocityFromSpeed_Sign if the direction is along x. | ||||||||
| DCE7 | JR NZ,SetVelocityFromSpeed_Sign | |||||||||
|
Put the speed on the Y axis.
|
||||||||||
| DCE9 | LD H,A | Make the speed the Y velocity, with no X velocity. | ||||||||
| DCEA | LD L,$00 | |||||||||
|
Make the speed negative for down and left.
|
||||||||||
| SetVelocityFromSpeed_Sign | DCEC | BIT 7,(IX+$06) | Jump to SetVelocityFromSpeed_Set unless the direction faces down the screen or to the left. | |||||||
| DCF0 | JR Z,SetVelocityFromSpeed_Set | |||||||||
|
Negate the velocity along both axes.
|
||||||||||
| DCF2 | LD A,L | Make the X velocity negative. | ||||||||
| DCF3 | NEG | |||||||||
| DCF5 | LD L,A | |||||||||
| DCF6 | LD A,H | Make the Y velocity negative. | ||||||||
| DCF7 | NEG | |||||||||
| DCF9 | LD H,A | |||||||||
|
Store the velocities.
|
||||||||||
| SetVelocityFromSpeed_Set | DCFA | LD (IX+$0A),L | Set the X velocity of the object. | |||||||
| DCFD | LD (IX+$0B),H | Set the Y velocity and return. | ||||||||
| DD00 | RET | |||||||||
|
View the equivalent code in;
|
||||||||||
| Prev: DCDC | Up: Map | Next: DD01 |