; when bird is hit it loses control for a few frames and is pushed back
; collision detection based on just a few sample pixels. edges and center of edges?
; and the current x and y position
+; each ball collection will reduce score by 1, when score is 0 -> go to next map and reduce lvl counter
+; load a new random map
+; TODO fix ball
+; make ball change positon after 10 seconds
PAL = 0
NTSC = 1
Temp ds 4 ; 4 bytes of temp storage
; object X positions in $89-8C
-ObjectX: ds 4 ; player0, player1, missile0, missile1
+ObjectX: ds 5 ; player0, player1, missile0, missile1, ball
; object Y positions in $8D-90
-ObjectY: ds 4 ; player0, player1, missile0, missile1
+ObjectY: ds 5 ; player0, player1, missile0, missile1, ball
; DoDraw storage in $91-92
TurtleDraw: ds 1 ; used for drawing player0
BirdDraw: ds 1 ; used for drawing player1
-BallDraw: ds 1
+M0Draw: ds 1
; DoDraw Graphic Pointer in $93-94
TurtlePtr: ds 2 ; used for drawing player0
BirdPtr: ds 2 ; used for drawing player1
-M0Ptr: ds 2
; used for Bird AI to keep track of movement
BirdAICounter ds 1
CurrentMap: ds 1 ; map counter - must increment by 6 for new map to fully load
Lives: ds 1 ; live counter
Level: ds 1 ; level counter
+MapsCleared: ds 1 ; amount of clreaded maps this level
AnimationTimer ds 4 ; animation timer for p0, p1, m0, m1
PreviousX ds 4
PreviousY ds 4
+M0RespawnTimer ds 1 ; ball will change location after x secnds (each time framecount rolls over this is dec)
+
; used by Random for an 8 bit random number
Rand8 ds 1
P0STARTY = $32
P1STARTX = 0
P1STARTY = 0
-BallHeight = 8
+M0HEIGHT = 8
+M0RESPAWNT = 255
;===============================================================================
; Define Start of Cartridge
ldx #5
stx Lives ; 5 lives
+ jsr NextMap
jsr NextLevel
jsr ResetPPositions
- jsr SetBallPosition
+ jsr SetM0Pos
jsr PlayIntroSong
StartOfFrame
; start of new frame
inc FRAMECOUNT
+ ; compare framecount to 0
+ ldx FRAMECOUNT
+ cpx #0
+ bne FramesNotRolledOver
+ dec M0RespawnTimer ; dec this if rolled over
+
+ ; compare to 0
+ ldx M0RespawnTimer
+ cpx #0
+ bne FramesNotRolledOver
+ ; reset ball
+ jsr SetM0Pos
+FramesNotRolledOver
jsr VerticalSync
jsr VerticalBlank
jsr Picture
VerticalBlank
; game logic call
jsr ProcessJoystick
+ jsr GameProgress
jsr PositionObjects
jsr SetObjectColours
jsr PrepScoreForDisplay
; ball stuff
ldx #1 ; d1=0 so ball will be off
- lda #BallHeight-1 ; height of ball gfx
- dcp BallDraw ; decrement and compare
- bcs DoEnableBall
+ lda #M0HEIGHT-1 ; height of m0 gfx
+ dcp M0Draw ; decrement and compare
+ bcs DoEnableM0
.byte $24
-DoEnableBall
+DoEnableM0
inx ; d1=1 so ball will be on
; precalculate date for next line
sta WSYNC
; start of line 2 of the 2LK
sta GRP1
- stx ENABL ; enable ball
+ stx ENAM0 ; enable m0
dey ; decrease the loop counter
bne pfLoop ; branch if more left to draw
leftRightBirdMoveDone
rts
+GameProgress
+ ; first we check if required maps for next level have been reached
+ ldx Level
+ inx ; maps for level are always Level+1
+ cpx MapsCleared ; if it is the same next level
+ beq NextLevelProg
+ ldx Score
+ cpx #0 ; if score is 0 advance to the next stage
+ beq NextMapProg
+
+ jmp ProgressDone
+NextMapProg
+ jsr NextMap
+ jmp ProgressDone
+NextLevelProg
+ jsr NextLevel
+ProgressDone
+ rts
+
;====================
; This sub checks for collision based on inputs stored
; Expected inputs:
; now we dio p0 m0 collision. m0 must be collected by turtle to advance
; each time collision happens m0 will get a new position
- bit CXP0FB
- bvc NoP0BallCollision
+ bit CXM0P
+ bvc NoP0M0Collision
- stx Score
- cpx Score
- beq NoP0BallCollision ; prevent underflow!
+ ldx Score
+ cpx #0
+ beq NoP0M0Collision ; prevent underflow!
; dec score. if screen is left and score is 0 continue
- dec Score
- jsr SetBallPosition ; new position for m0
-NoP0BallCollision
+ dex
+ stx Score
+ jsr SetM0Pos ; new position for m0
+NoP0M0Collision
; now we check if m0 is in a wall
- bit CXBLPF
- beq NoBallPFCollision ; if it is reloacte
- jsr SetBallPosition
-NoBallPFCollision
- ; now we check if ball is oob
- ldx ObjectX+2
- cpx #160
- bpl BallNotOOB ; if smaller do nothing
- ldx ObjectY+2
- cpx 255
- bpl BallNotOOB
- jsr SetBallPosition
-BallNotOOB
+ bit CXM0FB
+ bvc NoM0PFCollision ; if it is reloacte
+ jsr SetM0Pos
+NoM0PFCollision
CollisionDone
lda #1
sta CXCLR ; clear collision
sta AUDV0
rts
-SetBallPosition
- jsr Random
- ;ldx Rand8
- ldx #10
- stx ObjectX+2
- jsr Random
- ;ldx Rand8
- ldx #10
- stx ObjectY+2
+SetM0Pos
+ ldx 2
+ jsr RandomLocation
+ lda #M0RESPAWNT ; load ball respawn time
+ ; dec level from that
+ clc
+ sbc Level
+ sta M0RespawnTimer
+ rts
+
+ ;===============================================================================
+ ; RandomLocation
+ ; --------------
+ ; call with X to set to the object to randomly position:
+ ; 1 - player1
+ ; 2 - missile0
+ ; 3 - missile1
+ ; 4 - ball
+ ;
+ ; X position
+ ; ----------
+ ; There are 160 pixels across the screen. There's also a border that takes up
+ ; 4 pixels on each side, plus the player objects span 8 pixels. That gives us
+ ; a range of 160 - 4*2 - 8 = 144 possible positions to place an object. Due to
+ ; due to the Arena border we need to shift that 4 to the right so the X position
+ ; can be anything from 4-148.
+ ;
+ ; Y position
+ ; ----------
+ ; Y position needs to be between 25-169
+ ;===============================================================================
+RandomLocation:
+ jsr Random ; get a random value between 0-255
+ and #127 ; limit range to 0-127
+ sta Temp ; save it
+ jsr Random ; get a random value between 0-255
+ and #15 ; limit range to 0-15
+ clc ; must clear carry for add
+ adc Temp ; add in random # from 0-127 for range of 0-142
+ adc #5 ; add 5 for range of 5-147
+ sta ObjectX,x ; save the random X position
+
+ jsr Random ; get a random value between 0-255
+ and #127 ; limit range to 0-127
+ sta Temp ; save it
+ jsr Random ; get a random value between 0-255
+ and #15 ; limit range to 0-15
+ clc ; must clear carry for add
+ adc Temp ; add in random # from 0-127 for range of 0-142
+ adc #26 ; add 26 for range of 26-168
+ sta ObjectY,x ; save the random Y position
rts
ResetPPositions
adc Level
; score is 3 + level
sta Score
+ ldx #0
+ stx MapsCleared
+ rts
+
+NextMap
+ inc MapsCleared
+ lda #3
+ adc Level
+ ; score is 3 + level
+ sta Score
rts
SetObjectColours
rts
PositionObjects
- ldx #3 ; position objects 0-1: player0 and player1 and m0
+ ldx #2 ; position objects 0-1: player0 and player1 and m0
POloop
lda ObjectX,x ; get the object's X position
jsr PosObject ; set coarse X position and fine-tune amount
lda #>(BirdSprite + BIRDHEIGHT - 1)
sbc #0
sta BirdPtr+1
- jmp RenderDone
+ jmp BallRender
BirdFrame2
; BirdDraw = PFHEIGHT + BIRDHEIGHT - Y position
lda #(PFHEIGHT + BIRDHEIGHT2)
ldx AnimationTimer+1
cpx #20 ; compare to 10 if 10 reset to 0
- bne RenderDone
+ bne BallRender
lda #0
sta AnimationTimer+1
- ; prep balls y position
- ldx #1 ; preload X for setting VDELBL
- lda ObjectY+2 ; get the balls's Y position
- clc
- adc #1 ; add 1 to compensate for priming of ball
- lsr ; divide by 2 for the 2LK position
- sta Temp ; save for position calculations
- bcs NoDelayBL ; if carry is set we don't need Vertical Delay
- stx VDELBL ; carry was clear, so set Vertical Delay
-
+BallRender
+ ldx #1
+ lda ObjectY+2
+ lsr
+ sta Temp
+ bcs NoDelayBL
+ stx VDELBL
NoDelayBL
- lda #(PFHEIGHT + BallHeight + 1)
+ ; prep m0 y position
+ lda #(PFHEIGHT + M0HEIGHT)
sec
sbc Temp
- sta BallDraw
+ sta M0Draw
RenderDone
; use Difficulty Switches to test how Vertical Delay works
;ldx #0
projects / turtlebay / .git / commitdiff