Merge pull request #86 from algosup/change-the-strategy-for-ghost-col…

…lision Changed the strategy for ghost collision
algosup · Dec 21, 2023 · 7f5224d · 7f5224d
2 parents 46fa3aa + 0d58584
commit 7f5224d
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Showing 2 changed files with 55 additions and 49 deletions.
diff --git a/src/collider.asm b/src/collider.asm
@@ -24,11 +24,14 @@ section .text
             ret
 
     PinkyContact:
-        mov bx, [strcPinky  + posX]
-        mov ax, [strcPinky  + posY]
-        mov dx, [strcPinky + isChased]
-        mov [afraid], dx
+
+        mov ax, [strcPinky + isChased]
+        mov [afraid], ax
+
+        mov cx, [strcPinky  + posX]
+        mov dx, [strcPinky  + posY]
         call isThereContact
+        
         cmp byte [ghostCollision], 1
         jne .noGhostCollision
             call ClearPinky
@@ -42,11 +45,13 @@ section .text
         ret
         
     BlinkyContact:
-        mov bx, [strcBlinky  + posX]
-        mov ax, [strcBlinky  + posY]
-        mov dx, [strcBlinky + isChased]
-        mov [afraid], dx
+        mov ax, [strcBlinky + isChased]
+        mov [afraid], ax
+
+        mov cx, [strcBlinky  + posX]
+        mov dx, [strcBlinky  + posY]
         call isThereContact
+
         cmp byte [ghostCollision], 1
         jne .noGhostCollision
             call ClearBlinky
@@ -60,11 +65,13 @@ section .text
         ret
 
     InkyContact:
-        mov bx, [strcInky  + posX]
-        mov ax, [strcInky  + posY]
-        mov dx, [strcInky + isChased]
-        mov [afraid], dx
+        mov ax, [strcInky + isChased]
+        mov [afraid], ax
+
+        mov cx, [strcInky  + posX]
+        mov dx, [strcInky  + posY]
         call isThereContact
+        
         cmp byte [ghostCollision], 1
         jne .noGhostCollision
             call ClearInky
@@ -78,11 +85,13 @@ section .text
         ret
     
     ClydeContact:
-        mov bx, [strcClyde  + posX]
-        mov ax, [strcClyde  + posY]
-        mov dx, [strcClyde + isChased]
-        mov [afraid], dx
+        mov ax, [strcClyde + isChased]
+        mov [afraid], ax
+
+        mov cx, [strcClyde  + posX]
+        mov dx, [strcClyde  + posY]
         call isThereContact
+        
         cmp byte [ghostCollision], 1
         jne .noGhostCollision
             call ClearClyde
@@ -95,47 +104,25 @@ section .text
         .noGhostCollision:
         ret
 
-
     isThereContact:
     ; read if a ghost touched pacman (or the reverse)
 
-        push ds ; pop at the end
+        mov ax, [strcPacMan + posX]
+        mov bx, [strcPacMan + posY]
 
-        ;calculates the linear position of the ghost (result in ax)
-        mov cx, SCREEN_WIDTH
-        mul cx
-        add ax, bx 
 
-        ;stores the color of pacman into 'ah'
-        mov di, palette
-        inc di, ;(add 1 to di) cause '1' is the color of pacman according to the palette of colors for the spritesheet
-        xor bx, bx
-        mov bl, [ds:di]
-
-        ;the destination is 'al'
+        call AbsoluteDifference
+        cmp ax, TILE_SIZE
+        jg .notTouched
         
-        ;set the source 'ds:si'
-        push word [ScreenBufferSegment]
-        pop ds
-        mov si, ax  
+        mov ax, bx
+        mov cx, dx
+        call AbsoluteDifference
+        cmp ax, TILE_SIZE
+        jg .notTouched
         
-        mov dx, SPRITE_SIZE
-        .eachLine:
-            mov cx, SPRITE_SIZE
-            .eachPixel:
-                lodsb
-                cmp al, bl
-                je .touched
-                dec cx
-                jnz .eachPixel
-            add si, SCREEN_WIDTH - SPRITE_SIZE
-            dec dx
-            jnz .eachLine
-        pop ds
-        jmp .notTouched
 
         .touched:
-            pop ds
             cmp byte [afraid], 0
             je .normalContact
             
@@ -184,7 +171,26 @@ section .text
         .notTouched:
         
         ret
+
+    AbsoluteDifference:
+    ; get the absolute difference between 2 numbers
+    ; parameters :
+    ; ax : number 1
+    ; cx : number 2
+    ; return : ax = absolute difference
+
+        sub ax, cx
+        ; get the absolute value of this difference
+        mov cx, ax
+        sar cx, 15
+        xor ax, cx
+        shr cx, 15
+        add ax, cx
+
+        ret
     
+
+
     isColliding:
 
         ; Set offset for the corner to check

diff --git a/src/constants.asm b/src/constants.asm
@@ -19,7 +19,7 @@ endstruc
 %define FRAMES_COUNTER_GHOSTS_ANIMATION 6
 %define FRAMES_COUNTER_POWER_PELLET_ANIMATION 6
 
-%define SPRITE_SPEED_PIXELS 2
+%define SPRITE_SPEED_PIXELS 1
 
 %define NUMBER_OF_PELLETS 260