diff options
Diffstat (limited to 'src/enemies.s')
| -rw-r--r-- | src/enemies.s | 108 |
1 files changed, 105 insertions, 3 deletions
diff --git a/src/enemies.s b/src/enemies.s index 5acadc5..0279958 100644 --- a/src/enemies.s +++ b/src/enemies.s @@ -86,6 +86,15 @@ CURRENT_TILES_BYTES = ENEMIES_POOL_CAPACITY * 4 zp_current_tiles = $F0 ; asan:reserve CURRENT_TILES_BYTES + ;; Cached values for the tile coordinates from the player. This is set + ;; before enemy update, and it's then used during collision check for each + ;; enemy. + zp_player_tile_left = $FC + zp_player_tile_right = $FD + zp_player_tile_top = $FE + zp_player_tile_waist = $FF + zp_player_tile_bottom = $CF + ;; Values for the counter of enemies that fall. ;; ;; NOTE: values for this have to fit into a nibble. @@ -234,6 +243,45 @@ .proc update ldx #0 + ;; Save the player's tile coordinates now as it will be useful/faster + ;; for collision checking with each enemy. + lda Player::zp_screen_y + tay + lsr + lsr + lsr + sta Enemies::zp_player_tile_top + tya + clc + adc #Player::PLAYER_WAIST + lsr + lsr + lsr + sta Enemies::zp_player_tile_waist + tya + clc + adc #Player::PLAYER_HEIGHT + lsr + lsr + lsr + sta Enemies::zp_player_tile_bottom + + lda Player::zp_screen_x + tay + clc + adc #Player::LEFT_OFFSET + lsr + lsr + lsr + sta Enemies::zp_player_tile_left + tya + clc + adc #(Player::PLAYER_WIDTH / 2) + lsr + lsr + lsr + sta Enemies::zp_player_tile_right + ;; The loop index will be moved out of the 'y' register since movement ;; handlers might need to use it. Note that we loop over all the pool ;; instead of just deciding on active ones. This is just to give dead @@ -330,7 +378,14 @@ lsr sta Enemies::zp_current_tiles + 1, x - ;; TODO: collision with player + ;; Does this enemy collide with the player? + jsr Enemies::collides_with_player + beq @increase_index_next + + ;; Ooops, the player just kicked the bucket! Call the handlers for the + ;; enemy and the player and return early. + jsr Enemies::bite_the_dust + JAL Player::die_bart_die @increase_index_next: ;; Move the 'x' register to the current enemy for this iteration. @@ -486,12 +541,59 @@ rts .endproc + ;; Sets 'a' to 1 if the current enemy collides with the player, 0 otherwise. + .proc collides_with_player + ;; Top left/right are done only once because the top of the player is + ;; just the head, which in anchored to one side. Hence, depending on + ;; where the player is heading, we will check for top left or right. + bit Player::zp_state + bvs @set_left + lda Enemies::zp_player_tile_right + bne @store_top + @set_left: + lda Enemies::zp_player_tile_left + @store_top: + sta Globals::zp_arg1 + lda Enemies::zp_player_tile_top + sta Globals::zp_arg0 + jsr collides + bne @end + + ;; Waist left + lda Enemies::zp_player_tile_left + sta Globals::zp_arg1 + lda Enemies::zp_player_tile_waist + sta Globals::zp_arg0 + jsr collides + bne @end + + ;; Bottom left + lda Enemies::zp_player_tile_bottom + sta Globals::zp_arg0 + jsr collides + bne @end + + ;; Waist right + lda Enemies::zp_player_tile_right + sta Globals::zp_arg1 + lda Enemies::zp_player_tile_waist + sta Globals::zp_arg0 + jsr collides + bne @end + + ;; Bottom right + lda Enemies::zp_player_tile_bottom + sta Globals::zp_arg0 + jsr collides + + @end: + rts + .endproc + ;; The enemy has been set to dust, remove it. .proc bite_the_dust dec Enemies::zp_enemies_pool_size - ;; TODO: this assumes we are coming from within Enemies always. What - ;; about impacting bullets? ldx Enemies::zp_pool_index ;; Invalidate this enemy. |