; All positions/velocities are signed 16.16; bounded pools and fixed ticks.
HFDistance PROC x0:DWORD,y0:DWORD,x1:DWORD,y1:DWORD
    mov eax,x0
    sub eax,x1
    cdq
    xor eax,edx
    sub eax,edx
    mov ecx,eax
    mov eax,y0
    sub eax,y1
    cdq
    xor eax,edx
    sub eax,edx
    cmp eax,ecx
    jae @F
    mov eax,ecx
@@:
    ret
HFDistance ENDP

HFPlayerCanWalk PROC uses esi edi px:DWORD,py:DWORD
    invoke CanWalk3D,px,py
    test eax,eax
    jz hf_player_walk_done
    mov esi,OFFSET hfEnemies
    mov edi,HF_ENEMIES
hf_player_body:
    cmp [esi].HFEnemy.hp,0
    jle hf_player_body_next
    invoke HFDistance,px,py,[esi].HFEnemy.x,[esi].HFEnemy.y
    cmp eax,FP_1*9/20
    jb hf_player_body_block
hf_player_body_next:
    add esi,SIZEOF HFEnemy
    dec edi
    jnz hf_player_body
    mov eax,1
    ret
hf_player_body_block:
    xor eax,eax
hf_player_walk_done:
    ret
HFPlayerCanWalk ENDP

HFLineClear PROC uses ebx esi edi x0:DWORD,y0:DWORD,x1:DWORD,y1:DWORD
    local stepX:DWORD,stepY:DWORD,rx:DWORD,ry:DWORD
    invoke HFDistance,x0,y0,x1,y1
    shr eax,12 ; quarter of a collision radius per sample, <= 1/16 tile
    inc eax
    mov ebx,eax
    mov eax,x1
    sub eax,x0
    cdq
    idiv ebx
    mov stepX,eax
    mov eax,y1
    sub eax,y0
    cdq
    idiv ebx
    mov stepY,eax
    mov esi,x0
    mov edi,y0
hf_los_step:
    add esi,stepX
    add edi,stepY
    mov eax,esi
    sar eax,16
    cmp eax,32
    jae hf_los_blocked
    mov ecx,edi
    sar ecx,16
    cmp ecx,32
    jae hf_los_blocked
    shl ecx,5
    add eax,ecx
    cmp hfMap[eax],0
    jne hf_los_blocked
    dec ebx
    jnz hf_los_step
    mov eax,1
    ret
hf_los_blocked:
    xor eax,eax
    ret
HFLineClear ENDP

HFDamagePlayer PROC uses ebx amount:DWORD
    cmp hfState,0
    jne hf_damage_done
    mov ebx,amount
    mov eax,ebx
    shr eax,1
    cmp eax,hfArmor
    jbe @F
    mov eax,hfArmor
@@:
    sub hfArmor,eax
    sub ebx,eax
    sub hfHealth,ebx
    mov hfHurt,10
    invoke HFPlaySound,2
    cmp hfHealth,0
    jg hf_damage_done
    mov hfHealth,0
    mov hfState,1
    mov hfFireHeld,0
hf_damage_done:
    ret
HFDamagePlayer ENDP

HFDamageEnemy PROC uses esi enemy:DWORD,amount:DWORD
    mov esi,enemy
    cmp [esi].HFEnemy.hp,0
    jle hf_enemy_damage_done
    mov eax,amount
    sub [esi].HFEnemy.hp,eax
    mov [esi].HFEnemy.awake,1
    mov [esi].HFEnemy.pose,6
    mov [esi].HFEnemy.timer,4
    cmp [esi].HFEnemy.hp,0
    jg hf_enemy_damage_done
    mov [esi].HFEnemy.hp,0
    mov [esi].HFEnemy.pose,7
    mov [esi].HFEnemy.timer,0
    inc hfKills
hf_enemy_damage_done:
    ret
HFDamageEnemy ENDP

HFFire PROC uses esi edi ebx
    local pellet:DWORD,angle:DWORD,rx:DWORD,ry:DWORD,stepX:DWORD,stepY:DWORD,steps:DWORD
    cmp hfCooldown,0
    jne hf_fire_done
    cmp hfWeapon,1
    je hf_fire_shotgun
    cmp hfBullets,0
    je hf_fire_done
    dec hfBullets
    mov hfCooldown,9
    mov pellet,1
    invoke HFPlaySound,4
    jmp hf_fire_begin
hf_fire_shotgun:
    cmp hfShells,0
    je hf_fire_done
    dec hfShells
    mov hfCooldown,29
    mov pellet,HF_SHOT_PELLETS
    invoke HFPlaySound,0
hf_fire_begin:
    mov hfFlash,4
hf_fire_pellet:
    mov eax,playerAngle
    cmp hfWeapon,0
    je @F
    mov ecx,pellet
    add eax,hfPelletSpread[ecx*4-4]
@@:
    and eax,511
    mov angle,eax
    mov ecx,tableCos[eax*4]
    sar ecx,3
    mov stepX,ecx
    mov ecx,tableSin[eax*4]
    sar ecx,3
    mov stepY,ecx
    mov eax,playerX
    mov rx,eax
    mov eax,playerY
    mov ry,eax
    mov steps,192
hf_ray_step:
    mov eax,stepX
    add rx,eax
    mov eax,stepY
    add ry,eax
    mov eax,rx
    sar eax,16
    cmp eax,32
    jae hf_ray_end
    mov ecx,ry
    sar ecx,16
    cmp ecx,32
    jae hf_ray_end
    shl ecx,5
    add eax,ecx
    cmp hfMap[eax],0
    jne hf_ray_end
    mov esi,OFFSET hfEnemies
    mov ebx,HF_ENEMIES
hf_ray_enemy:
    cmp [esi].HFEnemy.hp,0
    jle hf_ray_next_enemy
    invoke HFDistance,rx,ry,[esi].HFEnemy.x,[esi].HFEnemy.y
    cmp eax,FP_1*7/20
    ja hf_ray_next_enemy
    invoke RandomRange3D,9
    add eax,8
    invoke HFDamageEnemy,esi,eax
    jmp hf_ray_end
hf_ray_next_enemy:
    add esi,SIZEOF HFEnemy
    dec ebx
    jnz hf_ray_enemy
    dec steps
    jnz hf_ray_step
hf_ray_end:
    ; Each pellet owns its own impact; stay just in front of a wall's depth.
    mov ecx,pellet
    dec ecx
    imul ecx,SIZEOF HFImpact
    mov eax,rx
    sub eax,stepX
    sub eax,stepX
    mov hfImpacts[ecx].x,eax
    mov eax,ry
    sub eax,stepY
    sub eax,stepY
    mov hfImpacts[ecx].y,eax
    mov hfImpacts[ecx].life,8
    dec pellet
    jnz hf_fire_pellet
hf_fire_done:
    ret
HFFire ENDP

HFSpawnBolt PROC uses esi ebx x:DWORD,y:DWORD,damage:DWORD
    local distance:DWORD
    mov esi,OFFSET hfBolts
    mov ebx,32
@@:
    cmp [esi].HFBolt.life,0
    je hf_bolt_slot
    add esi,SIZEOF HFBolt
    dec ebx
    jnz @B
    ret
hf_bolt_slot:
    invoke HFDistance,x,y,playerX,playerY
    cmp eax,FP_1/2
    jae @F
    mov eax,FP_1/2
@@:
    mov distance,eax
    mov eax,x
    mov [esi].HFBolt.x,eax
    mov eax,y
    mov [esi].HFBolt.y,eax
    mov eax,damage
    mov [esi].HFBolt.damage,eax
    mov [esi].HFBolt.life,210
    mov eax,playerX
    sub eax,x
    mov ecx,FP_1/7
    imul ecx
    idiv distance
    mov [esi].HFBolt.vx,eax
    mov eax,playerY
    sub eax,y
    mov ecx,FP_1/7
    imul ecx
    idiv distance
    mov [esi].HFBolt.vy,eax
    invoke HFPlaySound,1
    ret
HFSpawnBolt ENDP

; Breadth-first distance field permits monsters to navigate around room pillars.
HFBuildFlow PROC uses esi edi ebx
    local head:DWORD,tail:DWORD,current:DWORD,neighbor:DWORD
    cld
    mov edi,OFFSET hfFlow
    mov eax,0FFFFFFFFh
    mov ecx,512
    rep stosd
    mov eax,playerY
    sar eax,16
    shl eax,5
    mov ecx,playerX
    sar ecx,16
    add eax,ecx
    mov hfFlow[eax*2],0
    mov hfQueue,eax
    mov head,0
    mov tail,1
hf_flow_pop:
    mov eax,head
    cmp eax,tail
    jae hf_flow_done
    mov eax,hfQueue[eax*4]
    mov current,eax
    movzx ebx,hfFlow[eax*2]
    inc ebx
    xor esi,esi
hf_flow_neighbor:
    mov eax,current
    cmp esi,0
    jne @F
    dec eax
@@:
    cmp esi,1
    jne @F
    inc eax
@@:
    cmp esi,2
    jne @F
    sub eax,32
@@:
    cmp esi,3
    jne @F
    add eax,32
@@:
    cmp eax,1024
    jae hf_flow_next
    cmp hfMap[eax],0
    jne hf_flow_next
    cmp hfFlow[eax*2],0FFFFh
    jne hf_flow_next
    mov hfFlow[eax*2],bx
    mov ecx,tail
    mov hfQueue[ecx*4],eax
    inc tail
hf_flow_next:
    inc esi
    cmp esi,4
    jb hf_flow_neighbor
    inc head
    jmp hf_flow_pop
hf_flow_done:
    ret
HFBuildFlow ENDP

HFMoveEnemy PROC uses esi edi ebx enemy:DWORD
    local tx:DWORD,ty:DWORD,distance:DWORD,speed:DWORD,best:DWORD,cell:DWORD,nx:DWORD,ny:DWORD
    mov esi,enemy
    mov eax,playerX
    mov tx,eax
    mov eax,playerY
    mov ty,eax
    invoke HFLineClear,[esi].HFEnemy.x,[esi].HFEnemy.y,playerX,playerY
    test eax,eax
    jnz hf_move_target
    mov eax,[esi].HFEnemy.y
    sar eax,16
    shl eax,5
    mov ecx,[esi].HFEnemy.x
    sar ecx,16
    add eax,ecx
    mov cell,eax
    movzx eax,hfFlow[eax*2]
    mov best,eax
    mov edi,-1
    xor ebx,ebx
hf_move_flow:
    mov eax,cell
    cmp ebx,0
    jne @F
    dec eax
@@:
    cmp ebx,1
    jne @F
    inc eax
@@:
    cmp ebx,2
    jne @F
    sub eax,32
@@:
    cmp ebx,3
    jne @F
    add eax,32
@@:
    cmp eax,1024
    jae hf_move_flow_next
    movzx ecx,hfFlow[eax*2]
    cmp ecx,best
    jae hf_move_flow_next
    mov best,ecx
    mov edi,eax
hf_move_flow_next:
    inc ebx
    cmp ebx,4
    jb hf_move_flow
    cmp edi,-1
    je hf_move_done
    mov eax,edi
    and eax,31
    shl eax,16
    add eax,FP_HALF
    mov tx,eax
    shr edi,5
    shl edi,16
    add edi,FP_HALF
    mov ty,edi
hf_move_target:
    invoke HFDistance,[esi].HFEnemy.x,[esi].HFEnemy.y,tx,ty
    cmp eax,FP_1/8
    jb hf_move_done
    mov distance,eax
    mov eax,[esi].HFEnemy.kind
    mov eax,hfMonsterSpeed[eax*4]
    mov speed,eax
    mov eax,tx
    sub eax,[esi].HFEnemy.x
    imul speed
    idiv distance
    add eax,[esi].HFEnemy.x
    mov nx,eax
    invoke CanWalk3D,eax,[esi].HFEnemy.y
    test eax,eax
    jz @F
    mov eax,nx
    mov [esi].HFEnemy.x,eax
@@:
    mov eax,ty
    sub eax,[esi].HFEnemy.y
    imul speed
    idiv distance
    add eax,[esi].HFEnemy.y
    mov ny,eax
    invoke CanWalk3D,[esi].HFEnemy.x,eax
    test eax,eax
    jz hf_move_done
    mov eax,ny
    mov [esi].HFEnemy.y,eax
hf_move_done:
    ret
HFMoveEnemy ENDP

HFEnemiesTick PROC uses esi edi ebx
    local distance:DWORD,visible:DWORD
    mov esi,OFFSET hfEnemies
    mov edi,HF_ENEMIES
hf_ai_enemy:
    cmp [esi].HFEnemy.hp,0
    jg hf_ai_alive
    cmp [esi].HFEnemy.pose,11
    jae hf_ai_next
    inc [esi].HFEnemy.timer
    cmp [esi].HFEnemy.timer,6
    jb hf_ai_next
    mov [esi].HFEnemy.timer,0
    inc [esi].HFEnemy.pose
    jmp hf_ai_next
hf_ai_alive:
    cmp [esi].HFEnemy.cooldown,0
    je @F
    dec [esi].HFEnemy.cooldown
@@:
    cmp [esi].HFEnemy.timer,0
    je hf_ai_perceive
    dec [esi].HFEnemy.timer
    jnz hf_ai_next
    cmp [esi].HFEnemy.pose,4
    jne hf_ai_next
    invoke HFLineClear,[esi].HFEnemy.x,[esi].HFEnemy.y,playerX,playerY
    test eax,eax
    jz hf_ai_next
    invoke HFDistance,[esi].HFEnemy.x,[esi].HFEnemy.y,playerX,playerY
    mov distance,eax
    mov ebx,[esi].HFEnemy.kind
    cmp eax,FP_1*7/10
    jbe hf_ai_melee
    cmp ebx,1
    je hf_ai_next
    cmp ebx,0
    jne hf_ai_projectile
    invoke RandomRange3D,4
    test eax,eax
    jz hf_ai_attack_pose
    invoke HFDamagePlayer,6
    jmp hf_ai_attack_pose
hf_ai_perceive:
    invoke HFDistance,[esi].HFEnemy.x,[esi].HFEnemy.y,playerX,playerY
    mov distance,eax
    mov visible,0
    cmp eax,16*FP_1
    ja hf_ai_awake
    invoke HFLineClear,[esi].HFEnemy.x,[esi].HFEnemy.y,playerX,playerY
    mov visible,eax
    test eax,eax
    jz hf_ai_awake
    mov [esi].HFEnemy.awake,1
hf_ai_awake:
    cmp [esi].HFEnemy.awake,0
    je hf_ai_next
    mov eax,hfTicks
    shr eax,3
    and eax,3
    mov [esi].HFEnemy.pose,eax
    cmp visible,0
    je hf_ai_move
    mov ebx,[esi].HFEnemy.kind
    cmp [esi].HFEnemy.cooldown,0
    jne hf_ai_spacing
    cmp distance,FP_1*7/10
    jbe hf_ai_windup
    cmp ebx,1
    je hf_ai_move
hf_ai_windup:
    mov [esi].HFEnemy.pose,4
    mov [esi].HFEnemy.timer,12
    jmp hf_ai_next
hf_ai_projectile:
    invoke HFSpawnBolt,[esi].HFEnemy.x,[esi].HFEnemy.y,hfMonsterDamage[ebx*4]
    jmp hf_ai_attack_pose
hf_ai_melee:
    invoke HFDamagePlayer,hfMonsterDamage[ebx*4]
hf_ai_attack_pose:
    mov [esi].HFEnemy.pose,5
    mov [esi].HFEnemy.timer,10
    mov [esi].HFEnemy.cooldown,55
    cmp ebx,3
    jne hf_ai_next
    mov [esi].HFEnemy.cooldown,18
    jmp hf_ai_next
hf_ai_spacing:
    cmp distance,FP_1*7/10
    jb hf_ai_next
    cmp ebx,1
    je hf_ai_move
    cmp distance,4*FP_1
    jb hf_ai_next
hf_ai_move:
    invoke HFMoveEnemy,esi
hf_ai_next:
    add esi,SIZEOF HFEnemy
    dec edi
    jnz hf_ai_enemy
    ret
HFEnemiesTick ENDP

HFBoltsTick PROC uses esi edi
    mov esi,OFFSET hfBolts
    mov edi,32
hf_projectile:
    cmp [esi].HFBolt.life,0
    je hf_projectile_next
    dec [esi].HFBolt.life
    mov eax,[esi].HFBolt.vx
    add [esi].HFBolt.x,eax
    mov eax,[esi].HFBolt.vy
    add [esi].HFBolt.y,eax
    invoke CanWalk3D,[esi].HFBolt.x,[esi].HFBolt.y
    test eax,eax
    jz hf_projectile_destroy
    invoke HFDistance,[esi].HFBolt.x,[esi].HFBolt.y,playerX,playerY
    cmp eax,FP_1*3/10
    ja hf_projectile_next
    invoke HFDamagePlayer,[esi].HFBolt.damage
hf_projectile_destroy:
    mov [esi].HFBolt.life,0
hf_projectile_next:
    add esi,SIZEOF HFBolt
    dec edi
    jnz hf_projectile
    ret
HFBoltsTick ENDP

HFPickups PROC uses esi edi ebx
    xor ebx,ebx
    mov esi,OFFSET hfItemSeeds
hf_pickup:
    cmp hfItemTaken[ebx*4],0
    jne hf_pickup_next
    invoke HFDistance,playerX,playerY,[esi],[esi+4]
    cmp eax,FP_1*3/5
    ja hf_pickup_next
    mov edi,[esi+8]
    cmp edi,0
    jne hf_pick_armor
    cmp hfHealth,100
    jae hf_pickup_next
    add hfHealth,25
    cmp hfHealth,100
    jbe hf_pick_commit
    mov hfHealth,100
    jmp hf_pick_commit
hf_pick_armor:
    cmp edi,1
    jne hf_pick_bullets
    cmp hfArmor,100
    jae hf_pickup_next
    mov hfArmor,100
    jmp hf_pick_commit
hf_pick_bullets:
    cmp edi,2
    jne hf_pick_shells
    add hfBullets,40
    jmp hf_pick_commit
hf_pick_shells:
    cmp edi,3
    jne hf_pick_shotgun
    add hfShells,12
    jmp hf_pick_commit
hf_pick_shotgun:
    cmp edi,4
    jne hf_pick_key
    mov hfHasShotgun,1
    mov hfWeapon,1
    add hfShells,16
    jmp hf_pick_commit
hf_pick_key:
    mov hfKey,1
hf_pick_commit:
    mov hfItemTaken[ebx*4],1
    mov hfMessage,OFFSET hfPickupText
    cmp edi,5
    jne @F
    mov hfMessage,OFFSET hfKeyFoundText
@@:
    mov hfMessageTime,105
    invoke HFPlaySound,3
hf_pickup_next:
    add esi,12
    inc ebx
    cmp ebx,HF_ITEMS
    jb hf_pickup
    ret
HFPickups ENDP

HFUse PROC uses ebx esi
    invoke HFDistance,playerX,playerY,FP_1*11/2,FP_1*25/2
    cmp eax,FP_1*8/5
    ja hf_use_secret_two
    test hfDoorMask,1
    jnz hf_use_secret_two
    or hfDoorMask,1
    mov hfMap[12*32+5],0
    mov hfMap[12*32+6],0
    jmp hf_use_secret
hf_use_secret_two:
    invoke HFDistance,playerX,playerY,FP_1*45/2,27*FP_1
    cmp eax,FP_1*8/5
    ja hf_use_gate
    test hfDoorMask,2
    jnz hf_use_gate
    or hfDoorMask,2
    mov hfMap[26*32+22],0
    mov hfMap[27*32+22],0
hf_use_secret:
    inc hfSecrets
    mov hfMessage,OFFSET hfSecretText
    mov hfMessageTime,105
    invoke HFPlaySound,5
    ret
hf_use_gate:
    invoke HFDistance,playerX,playerY,FP_1*45/2,7*FP_1
    cmp eax,2*FP_1
    ja hf_use_exit
    cmp hfKey,0
    jne hf_use_unlock
    mov hfMessage,OFFSET hfNeedKeyText
    mov hfMessageTime,105
    ret
hf_use_unlock:
    mov hfMap[6*32+22],0
    mov hfMap[7*32+22],0
    or hfDoorMask,4
    mov hfMessage,OFFSET hfDoorText
    mov hfMessageTime,105
    invoke HFPlaySound,5
    ret
hf_use_exit:
    invoke HFDistance,playerX,playerY,28*FP_1,29*FP_1
    cmp eax,2*FP_1
    ja hf_use_done
    mov esi,OFFSET hfEnemies
    mov ebx,HF_ENEMIES
@@:
    cmp [esi].HFEnemy.kind,3
    jne hf_exit_next
    cmp [esi].HFEnemy.hp,0
    jg hf_exit_locked
hf_exit_next:
    add esi,SIZEOF HFEnemy
    dec ebx
    jnz @B
    mov hfState,2
    mov hfFireHeld,0
    mov hfMessageTime,0
    cmp hfCompleted,0
    jne hf_use_done
    mov hfCompleted,1
    mov hfAwarded,1
    invoke ArtifactCredit3D,6660
    call SaveProgress3D
    ret
hf_exit_locked:
    mov hfMessage,OFFSET hfExitText
    mov hfMessageTime,105
hf_use_done:
    ret
HFUse ENDP

HFTick PROC uses esi ecx
    mov esi,OFFSET hfImpacts
    mov ecx,HF_SHOT_PELLETS
hf_impact_tick:
    cmp [esi].HFImpact.life,0
    je @F
    dec [esi].HFImpact.life
@@:
    add esi,SIZEOF HFImpact
    loop hf_impact_tick
    inc hfTicks
    cmp hfCooldown,0
    je @F
    dec hfCooldown
@@:
    cmp hfFlash,0
    je @F
    dec hfFlash
@@:
    cmp hfHurt,0
    je @F
    dec hfHurt
@@:
    cmp hfMessageTime,0
    je @F
    dec hfMessageTime
@@:
    mov eax,hfFireHeld
    or eax,hfFirePending
    or al,keys3D[20h]
    jz @F
    call HFFire
@@:
    mov hfFirePending,0
    cmp hfUsePending,0
    je @F
    mov hfUsePending,0
    call HFUse
@@:
    cmp hfState,0
    jne hf_tick_done
    mov eax,hfTicks
    and eax,7
    jnz @F
    call HFBuildFlow
@@:
    call HFEnemiesTick
    call HFBoltsTick
    cmp hfState,0
    jne hf_tick_done
    call HFPickups
    ; Central lava channel: visible floor patch exactly matches damage bounds.
    mov eax,hfTicks
    xor edx,edx
    mov ecx,18
    div ecx
    test edx,edx
    jnz hf_tick_done
    cmp playerX,16*FP_1
    jb hf_tick_done
    cmp playerX,18*FP_1
    jae hf_tick_done
    cmp playerY,17*FP_1
    jb hf_tick_done
    cmp playerY,20*FP_1
    jae hf_tick_done
    invoke HFDamagePlayer,8
hf_tick_done:
    ret
HFTick ENDP