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Add multiple enemy shots.

main
Colin McMillen 9 years ago
parent
commit
2bb1bc161d
  1. 4
      memory.asm
  2. 27
      pewpew.asm

4
memory.asm

@ -13,7 +13,7 @@
; 0030-003F: (x, y) velocities of each of the 8 possible shot states.
; 0040-009F: {sprite, x, y, x-velocity, y-velocity, unused} per player shot.
; If sprite is 0, the shot is disabled.
; 00A0-00FF: As above, for enemy shots.
; 00A0-015F: As above, for enemy shots.
; [gap]
; Sprite table buffers -- copied each frame to OAM during VBlank, using DMA.
; 1000-11FF: table 1 (4 bytes each: x/y coord, tile #, flip/priority/palette)
@ -34,7 +34,7 @@
.define playerShotArray $40
.define playerShotArrayLength 16
.define enemyShotArray $A0
.define enemyShotArrayLength 16
.define enemyShotArrayLength 32
.define shotSize 6
.define numSprites 128

27
pewpew.asm

@ -488,22 +488,35 @@ UpdateShotCooldown:
SpawnEnemyShots:
lda vBlankCounter
bit #%00111111
bit #%00001111
beq +
rts
+
ldy #0
-
lda enemyShotArray, Y
cmp #0
beq +
.rept 6
iny
.endr
cpy #(enemyShotArrayLength * shotSize)
bne -
rts ; Too many shots; bail.
+
lda #12 ; Sprite number.
sta enemyShotArray
sta enemyShotArray, Y
lda #254
sta enemyShotArray + 1 ; x.
sta enemyShotArray + 1, Y ; x.
lda #((224 - 32) / 2)
and #%01111111
sta enemyShotArray + 2 ; y.
sta enemyShotArray + 2, Y ; y.
lda #-6
sta enemyShotArray + 3 ; x-velocity.
lda #-4
sta enemyShotArray + 3, Y ; x-velocity.
GetRandomByte
and #%00000111 ; [0, 7]
@ -513,7 +526,7 @@ SpawnEnemyShots:
bne +
lda #0 ; [-3, 3] with 2x chance of zero.
+
sta enemyShotArray + 4 ; y-velocity.
sta enemyShotArray + 4, Y ; y-velocity.
rts

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