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Make a table of possible shot velocities.

Also fix bug caused by omission of "clc" before "adc".
main
Colin McMillen 9 years ago
parent
commit
0fa70c0889
  1. 84
      pewpew.asm

84
pewpew.asm

@ -16,7 +16,8 @@
; 0022: shot cooldown timer.
; 0023: next-shot state.
; [gap]
; 0030-008F: {sprite, x, y, x-velocity, y-velocity, unused} per shot.
; 0030-003F: (x, y) velocities of each of the 8 possible shot states.
; 0040-009F: {sprite, x, y, x-velocity, y-velocity, unused} per shot.
; If sprite is 0, the shot is disabled.
; [gap]
; Sprite table buffers -- copied each frame to OAM during VBlank, using DMA.
@ -34,7 +35,8 @@
.define playerY $21
.define shotCooldown $22
.define nextShotState $23
.define shotArray $30
.define shotVelocityTable $30
.define shotArray $40
.define shotArrayLength 16
.define shotSize 6
@ -101,6 +103,7 @@ Start:
SetA8Bit
jsr LoadPaletteAndTileData
; TODO(mcmillen): do we even need to init the sprite tables any more?
jsr InitializeSpriteTables
jsr InitializeWorld
@ -304,6 +307,47 @@ InitializeWorld:
lda #((224 - 32) / 2)
sta playerY
; (x-velocity, y-velocity) of 4 different player shot patterns.
lda #6
sta shotVelocityTable
lda #0
sta shotVelocityTable + 1
lda #3
sta shotVelocityTable + 2
lda #3
sta shotVelocityTable + 3
lda #0
sta shotVelocityTable + 4
lda #6
sta shotVelocityTable + 5
lda #-3
sta shotVelocityTable + 6
lda #3
sta shotVelocityTable + 7
lda #-6
sta shotVelocityTable + 8
lda #0
sta shotVelocityTable + 9
lda #-3
sta shotVelocityTable + 10
lda #-3
sta shotVelocityTable + 11
lda #0
sta shotVelocityTable + 12
lda #-6
sta shotVelocityTable + 13
lda #3
sta shotVelocityTable + 14
lda #-3
sta shotVelocityTable + 15
rts
@ -471,32 +515,37 @@ MaybeShoot:
sta 0, X
lda playerX
clc
adc #20
sta 1, X
lda playerY
sta 2, X
; x-velocity.
lda #6
sta 3, X
; y-velocity.
; Get x- and y-velocity out of shotVelocityTable.
lda nextShotState
cmp #1
and #%00000111 ; 8 possibilities.
ldy #0
-
cmp #0
beq +
lda #2
sta 4, X
inc nextShotState
jmp ++
.rept 2
iny
.endr
dec A
bra -
+
lda #-2
inc nextShotState
; x-velocity.
lda shotVelocityTable, Y
sta 3, X
; y-velocity.
lda shotVelocityTable + 1, Y
sta 4, X
dec nextShotState
++
; Set cooldown timer.
lda #10
lda #8
sta shotCooldown
MaybeShootDone:
rts
@ -549,6 +598,7 @@ UpdateShotY:
bne UpdateShotWithNegativeYVelocity
lda shotArray + 2, X
clc
adc $00
cmp #224
bcs DisableShot
@ -563,8 +613,8 @@ UpdateShotWithNegativeYVelocity:
sta shotArray + 2, X ; save the result,
jmp ShotDone ; and we know it shouldn't be reaped.
+
clc
adc $00
dec A ; Two's complement means that we need to -1 again in this case.
cmp #224
bcc DisableShot ; If it's now wrapped around, reap it.
sta shotArray + 2, X

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