SciNEStist
Well-known member
While working on a new "Beat-Em-Up" game module to share with everyone,
THREAD HERE
VIDEO DEV BLOG HERE
...I have implemented a jump feature that people might enjoy using with other modules. So here is a detailed tutorial on implementing a sort of "Z axis" in the adventure module, that will allow players to jump over other objects. This tutorial doesn't cover having higher up tiles to walk on, as that can get really messy and complicated without dramatic rewrites of the tile collision code, but I might eventually add that later if there is enough demand.
If you have any trouble with tutorial, or it doesn't work for you, please post immediately. There's a good chance it's my fault.
on the other had, if you successfully implement jumping, please share your game here and let us all know!
Section 1: adding the jump
Step 1: add these to object variables in project settings default value can be left at 0
Object_floor
Object_z_lo
Object_z_hi
Object_z_speed_lo
Object_z_speed_hi
Step 2: reduce the object count down to below 10 (we need Total Bytes Used: down to below 250)
Step 3: add these to Overflow ram:
zHold_lo
zHold_hi
self_head
self_feet
other_head
other_feet
Step 4: add jumping input script:
For whatever button you want to make your character jump, add this input script on press:
(you may have to remove any existing inputs for the same button)
Step 5: add jumping/gravity into physics:
open up the "Handle Physics" script under subroutines. Right under this part around lines 32-36:
we add this:
Step 6: Drawing the jump
In order to visualize the jump, we need the higher the object is on this new "z" axis, the higher the object is drawn. So we edit "handle drawing sprites" in this section around: lines 40-48:
we add just one single line:
Step 7: adding a shadow
this step is optional, but I recommend it. adding a shadow to the object allows us to see where the ground is for an object when its in the air.
at the very bottom of the "Handle Drawing Sprites" script, add this code:
here Is how I drew a shadow in for this example (next to the key)
Step 8: Adjust player settings:
Set your player jump height using the jump speed slider in the object details. I recommend starting around 48, and adjust from there. You also might want to bump up the speeed to faster than the default tutorial.
DONE! you have added jumping!!! test it out and see how cool it is!!!!
except.....jumping doesnt really have an effect on anything yet. Sure it looks cool, but its not effecting anything like collisions yet.
so let's add in a way to check if the player is at the same height as other objects before we trigger the collision.
Section 2: Changing object collision detection to account for height differences
Step 1: setting up self object head and feet positions
in "Handle object collisions" near the top around line 47, you will see:
right under "sta bounds_bottom" and above "TYA" wedge in this bit of code:
Step 2: setting up the "other" head and feet positions
in the "compare bounding boxes" we are looking near the bottom of the script in the "getOtherColBox" section. At the bottom of that section, around line 65, below " STA other_center_y ;; self center in the vertical direction." and above the "PLA" line we add this code:
Step 3: we add the z axis checks to the comparing of object boxes
up higher in the same compare bounding boxes script, you will see a section around lines 17-26 that looks like this:
we are going to add our checks here, so erase all that section, and add this instead:
DONE!!! NOW YOU CAN jump over objects without touching them!!!
If you test again, you will see that you can now jump over monsters and other objects without touching them.
But wait again!!!! What about Tiles? what if we want to jump over hazards and trap tiles?
Section 3: Jumping over tiles
If you want to make sure you dont touch a tile while jumping, you just need to add this to the beginning of the tile code:
now, it will skip over any tile code i9f you are in the air, and only trigger it if you are on ground level.
Please post any questions you have, or even just post your game if you use this script!
THREAD HERE
VIDEO DEV BLOG HERE
...I have implemented a jump feature that people might enjoy using with other modules. So here is a detailed tutorial on implementing a sort of "Z axis" in the adventure module, that will allow players to jump over other objects. This tutorial doesn't cover having higher up tiles to walk on, as that can get really messy and complicated without dramatic rewrites of the tile collision code, but I might eventually add that later if there is enough demand.
If you have any trouble with tutorial, or it doesn't work for you, please post immediately. There's a good chance it's my fault.
on the other had, if you successfully implement jumping, please share your game here and let us all know!
Section 1: adding the jump
Step 1: add these to object variables in project settings default value can be left at 0
Object_floor
Object_z_lo
Object_z_hi
Object_z_speed_lo
Object_z_speed_hi
Step 2: reduce the object count down to below 10 (we need Total Bytes Used: down to below 250)
Step 3: add these to Overflow ram:
zHold_lo
zHold_hi
self_head
self_feet
other_head
other_feet
Step 4: add jumping input script:
For whatever button you want to make your character jump, add this input script on press:
(you may have to remove any existing inputs for the same button)
Code:
SwitchBank #$1C
TXA
STA temp
LDA Object_floor,x
CMP Object_z_hi,x
BEQ +
ReturnBank
RTS
+
ChangeActionStep temp, #$03
LDY Object_type,x
LDA ObjectJumpSpeedLo,y
STA Object_z_speed_lo,x
LDA ObjectJumpSpeedHi,y
STA Object_z_speed_hi,x
ReturnBank
RTSStep 5: add jumping/gravity into physics:
open up the "Handle Physics" script under subroutines. Right under this part around lines 32-36:
Code:
;;;;;;;;;;;; CUSTOMIZATION: IGNORE PHYSICS IF NOT ON MAIN GAME MODE
LDA gameState
BEQ +doHandlePhysics
JMP skipPhysics
+doHandlePhysicswe add this:
Code:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;GRAVITY THAT EFFECTS Z POSIITON;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
LDA Object_vulnerability,x
AND #%00000100
BEQ +doGravity
JMP +nograv
+doGravity
LDA Object_z_hi,x
ADC Object_z_speed_hi,x
STA zHold_hi
CMP Object_floor,x
BPL +
LDA Object_floor,x
STA Object_z_hi,x
LDA #$00
STA Object_z_speed_hi,x
STA Object_z_speed_lo,x
TXA
STA temp
GetActionStep temp
CMP #$03
BEQ +isjumping
CMP #$04
BEQ +isjumping
JMP +notjumping
+isjumping
LDA gamepad
AND #%11110000
BNE +walk
ChangeActionStep temp, #$00 ;not moving
+walk
ChangeActionStep temp, #$01 ;walking
+notjumping
JMP +decell
+
LDA zHold_hi
STA Object_z_hi,x
LDA zHold_lo
STA Object_z_lo,x
+decell
LDA Object_z_speed_lo,x
CLC
SBC #$40
STA Object_z_speed_lo,x
LDA Object_z_speed_hi,x
SBC #$00
STA Object_z_speed_hi,x
CMP #$04
BNE notOverFallSpeed;; is at least max fall speed.
LDA #$00
STA Object_z_speed_lo,x
notOverFallSpeed:
JMP +donegrav
+nograv
+donegrav
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;GRAVITY SECTION DONE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;Step 6: Drawing the jump
In order to visualize the jump, we need the higher the object is on this new "z" axis, the higher the object is drawn. So we edit "handle drawing sprites" in this section around: lines 40-48:
Code:
LDA Object_x_hi,x
SEC
SBC camX ;; is using scrolling
STA tempA
LDA Object_y_hi,x
sec
SBC camY
STA tempB
LDY Object_type,xwe add just one single line:
Code:
LDA Object_x_hi,x
SEC
SBC camX ;; is using scrolling
STA tempA
LDA Object_y_hi,x
sec
SBC camY
SBC Object_z_hi,x ;;;;;;;;;;;;;;;;;;;<WE ADDED THIS PART FOR JUMPING
STA tempB
LDY Object_type,xStep 7: adding a shadow
this step is optional, but I recommend it. adding a shadow to the object allows us to see where the ground is for an object when its in the air.
at the very bottom of the "Handle Drawing Sprites" script, add this code:
Code:
LDA Object_z_hi,x
CMP Object_floor,x
BNE +
JMP +doneshadow
+
LDY Object_type,x
LDA ObjectBboxLeft,y
STA self_left
LDA ObjectBboxTop,y
CLC
ADC ObjectHeight,y
STA self_bottom
LDA Object_y_hi,x
SBC Object_floor,x
ADC self_bottom
SBC #$04 ; adjust this line to center it vertically
STA tempy
LDA Object_x_hi,x
ADC self_left
ADC #$00 ; adjust this line to center horizontally
STA tempx
DrawSprite tempx, tempy, #$3C, #%00000000 ; edit this to point at the sprite you want your shadow to be.
+doneshadowStep 8: Adjust player settings:
Set your player jump height using the jump speed slider in the object details. I recommend starting around 48, and adjust from there. You also might want to bump up the speeed to faster than the default tutorial.
DONE! you have added jumping!!! test it out and see how cool it is!!!!
except.....jumping doesnt really have an effect on anything yet. Sure it looks cool, but its not effecting anything like collisions yet.
so let's add in a way to check if the player is at the same height as other objects before we trigger the collision.
Section 2: Changing object collision detection to account for height differences
Step 1: setting up self object head and feet positions
in "Handle object collisions" near the top around line 47, you will see:
Code:
STA bounds_bottom
TYA
PHA
Code:
LDA Object_z_hi,x
STA self_feet
LDA ObjectSize,y
AND #%00000111
ASL
ASL
ASL
ADC Object_z_hi,x
STA self_headStep 2: setting up the "other" head and feet positions
in the "compare bounding boxes" we are looking near the bottom of the script in the "getOtherColBox" section. At the bottom of that section, around line 65, below " STA other_center_y ;; self center in the vertical direction." and above the "PLA" line we add this code:
Code:
LDA Object_z_hi,x
STA other_feet
LDA ObjectSize,y
AND #%00000111
ASL
ASL
ASL
ADC Object_z_hi,x
STA other_headStep 3: we add the z axis checks to the comparing of object boxes
up higher in the same compare bounding boxes script, you will see a section around lines 17-26 that looks like this:
Code:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
LDA other_bottom
CMP bounds_top
BCC noBboxCollision
LDA bounds_bottom
CMP other_top
BCC noBboxCollision
LDA #$01 ;; read that YES, there was a collision here. (could make this the object ID)
RTS
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;we are going to add our checks here, so erase all that section, and add this instead:
Code:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
LDA other_bottom
CMP bounds_top
BCC noBboxCollision
LDA bounds_bottom
CMP other_top
BCC noBboxCollision
LDA self_head
CMP other_feet
BCC noBboxCollision
LDA other_head
CMP self_feet
BCC noBboxCollision
LDA #$01 ;; read that YES, there was a collision here. (could make this the object ID)
RTS
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;DONE!!! NOW YOU CAN jump over objects without touching them!!!
If you test again, you will see that you can now jump over monsters and other objects without touching them.
But wait again!!!! What about Tiles? what if we want to jump over hazards and trap tiles?
Section 3: Jumping over tiles
If you want to make sure you dont touch a tile while jumping, you just need to add this to the beginning of the tile code:
Code:
LDA Object_z_hi,x
BEQ +
RTS
+now, it will skip over any tile code i9f you are in the air, and only trigger it if you are on ground level.
Please post any questions you have, or even just post your game if you use this script!
Last edited:
