diff options
| -rw-r--r-- | .nasm/segments.txt | 2 | ||||
| -rw-r--r-- | src/enemies.s | 42 |
2 files changed, 26 insertions, 18 deletions
diff --git a/.nasm/segments.txt b/.nasm/segments.txt index a53110b..c1071d7 100644 --- a/.nasm/segments.txt +++ b/.nasm/segments.txt @@ -1,4 +1,4 @@ - HEADER: 16/16 (100%) -- ROM0: 5260/32762 (16.06%) +- ROM0: 5271/32762 (16.09%) - ROMV: 6/6 (100%) - ROM2: 8192/8192 (100%) diff --git a/src/enemies.s b/src/enemies.s index 9bda83d..b2b9ca6 100644 --- a/src/enemies.s +++ b/src/enemies.s @@ -512,25 +512,17 @@ ora Globals::zp_tmp0 sta Enemies::zp_enemies_pool_base + 3, x - ;; Check collisions with the background. + ;; Check collisions with the background. The check is pretty dumb and we + ;; just check all four corners, as trying to be smart about it became + ;; too complex for what I needed (and the dumb approach is actually not + ;; that slow). - ;; Remember that background checks are done in tile coordinates, not - ;; screen ones. So we have to do the translation to it (3 x - ;; 'lsr'). After that, for the X coordinate, depending if the enemy is - ;; facing left/right, we have to increment this coordinate (i.e. twice - ;; if facing right as an enemy of this type is always 2x2 sprites). + ;; Translate the X coordinate into tile ones. lda Enemies::zp_enemies_pool_base + 2, x lsr lsr lsr - tay - lda Enemies::zp_enemies_pool_base, x - and #$80 - beq @after_x - iny - iny - @after_x: - sty Globals::zp_arg1 + sta Globals::zp_arg1 ;; Translate the Y coordinate into tile ones. lda Enemies::zp_enemies_pool_base + 1, x @@ -539,14 +531,20 @@ lsr sta Globals::zp_arg0 - ;; Perform a collision check with the upper boundary. + ;; Perform a collision check with the upper left boundary. + jsr Background::collides + beq @check_up_right + JAL bite_the_dust + + @check_up_right: + ;; Increase the X tile coordinate to check for the upper right boundary. + inc Globals::zp_arg1 jsr Background::collides beq @check_down JAL bite_the_dust @check_down: - ;; If that failed, then increment the vertical tile coordinate to get - ;; the bottom boundary and check again. Note that the "bottom" is + ;; Now let's go for bottom boundaries. The notion of "bottom" is ;; different if it's the regular 'basic' enemy or it's the fighter jet ;; re-using this algorithm. That's why if the level kind is 3 the bottom ;; is increased by one and not twice. @@ -555,7 +553,17 @@ cpy #3 beq @skip_second_inc inc Globals::zp_arg0 + @skip_second_inc: + ;; And the actual check. + jsr Background::collides + beq @check_down_left + JAL bite_the_dust + + @check_down_left: + ;; So now the only corner left is the bottom left one. Adjust the X tile + ;; coordinate and try again. + dec Globals::zp_arg1 jsr Background::collides beq @end JAL bite_the_dust |