Difference between revisions of "Remove the Air Speed Cap"
From Sonic Retro
(Cleanup.) |
(Wrong branch instruction meant air cap is removed only if going to the left) |
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| Line 38: | Line 38: | ||
<asm> sub.w d5,d0 ; +++ remove this frame's acceleration change | <asm> sub.w d5,d0 ; +++ remove this frame's acceleration change | ||
cmp.w d1,d0 ; +++ compare speed with top speed | cmp.w d1,d0 ; +++ compare speed with top speed | ||
| − | + | bge.s + ; +++ if speed was already greater than the maximum, branch</asm> | |
The final result should look like this: | The final result should look like this: | ||
| Line 71: | Line 71: | ||
sub.w d5,d0 ; +++ remove this frame's acceleration change | sub.w d5,d0 ; +++ remove this frame's acceleration change | ||
cmp.w d1,d0 ; +++ compare speed with top speed | cmp.w d1,d0 ; +++ compare speed with top speed | ||
| − | + | bge.s + ; +++ if speed was already greater than the maximum, branch | |
move.w d6,d0 ; limit speed in air going right, even if Sonic was already going faster (speed limit/cap) | move.w d6,d0 ; limit speed in air going right, even if Sonic was already going faster (speed limit/cap) | ||
; Obj01_JumpMove: | ; Obj01_JumpMove: | ||
Revision as of 22:10, 11 October 2010
(Guide written by Selbi; code by Puto, taken from the Sonic 1 Speed Cap page)
In Sonic 1 is a function, that limits Sonic's top speed when you are keep pressing in the direction you are looking at (you can feel that best when running down a hill). In Sonic 2 this function doesn't apply; well, at least not completely. Running on the ground works just fine, but in the air you still have it. So let's fix that:
Go to Sonic_ChgJumpDir, which should look like this in Xenowhirl's 2007 Sonic 2 disassembly: <asm>Sonic_ChgJumpDir: move.w (Sonic_top_speed).w,d6 move.w (Sonic_acceleration).w,d5 asl.w #1,d5 btst #4,status(a0) ; did Sonic jump from rolling? bne.s Obj01_Jump_ResetScr ; if yes, branch to skip midair control move.w x_vel(a0),d0 btst #2,(Ctrl_1_Held_Logical).w beq.s + ; if not holding left, branch
bset #0,status(a0) sub.w d5,d0 ; add acceleration to the left move.w d6,d1 neg.w d1 cmp.w d1,d0 ; compare new speed with top speed bgt.s + ; if new speed is less than the maximum, branch move.w d1,d0 ; limit speed in air going left, even if Sonic was already going faster (speed limit/cap) + btst #3,(Ctrl_1_Held_Logical).w beq.s + ; if not holding right, branch bclr #0,status(a0) add.w d5,d0 ; accelerate right in the air cmp.w d6,d0 ; compare new speed with top speed blt.s + ; if new speed is less than the maximum, branch move.w d6,d0 ; limit speed in air going right, even if Sonic was already going faster (speed limit/cap)
- Obj01_JumpMove
+ move.w d0,x_vel(a0)</asm> If you look closely, you will notice that this code works excactly like in Sonic 1. This is good, because we can use the excact same methods to fix it. After the line bgt.s + ; if new speed is less than the maximum, branch add these lines: <asm> add.w d5,d0 ; +++ remove this frame's acceleration change cmp.w d1,d0 ; +++ compare speed with top speed ble.s + ; +++ if speed was already greater than the maximum, branch</asm> Do the same thing after blt.s + ; if new speed is less than the maximum, branch by using these lines: <asm> sub.w d5,d0 ; +++ remove this frame's acceleration change cmp.w d1,d0 ; +++ compare speed with top speed bge.s + ; +++ if speed was already greater than the maximum, branch</asm>
The final result should look like this: <asm>Sonic_ChgJumpDir: move.w (Sonic_top_speed).w,d6 move.w (Sonic_acceleration).w,d5 asl.w #1,d5 btst #4,status(a0) ; did Sonic jump from rolling? bne.s Obj01_Jump_ResetScr ; if yes, branch to skip midair control move.w x_vel(a0),d0 btst #2,(Ctrl_1_Held_Logical).w beq.s + ; if not holding left, branch
bset #0,status(a0) sub.w d5,d0 ; add acceleration to the left move.w d6,d1 neg.w d1 cmp.w d1,d0 ; compare new speed with top speed bgt.s + ; if new speed is less than the maximum, branch add.w d5,d0 ; +++ remove this frame's acceleration change cmp.w d1,d0 ; +++ compare speed with top speed ble.s + ; +++ if speed was already greater than the maximum, branch move.w d1,d0 ; limit speed in air going left, even if Sonic was already going faster (speed limit/cap) + btst #3,(Ctrl_1_Held_Logical).w beq.s + ; if not holding right, branch
bclr #0,status(a0) add.w d5,d0 ; accelerate right in the air cmp.w d6,d0 ; compare new speed with top speed blt.s + ; if new speed is less than the maximum, branch sub.w d5,d0 ; +++ remove this frame's acceleration change cmp.w d1,d0 ; +++ compare speed with top speed bge.s + ; +++ if speed was already greater than the maximum, branch move.w d6,d0 ; limit speed in air going right, even if Sonic was already going faster (speed limit/cap)
- Obj01_JumpMove
+ move.w d0,x_vel(a0)</asm>