Better collision code

diff --git a/main.asm b/main.asm
index 6cb3c6184d90b89c7aaeda0f94dc8b63f8cf6b35..7e4f96568745b53110a65977c8caced2b4cc47b4 100644 (file)
--- a/main.asm
+++ b/main.asm
@@ -296,24 +296,15 @@ Overscan
        lda #32 ; set time for 27 scanlines 32 = ((27 * 76) / 64)
        sta TIM64T ; timer will go off after 27 scanlines
 
-       ldy #0 ; collision detection
-       ;sty Temp
-CollisionLoop
-       sty Temp
        jsr CollisionDetection
-       iny
-       cpy #3
-       bne CollisionLoop
 
        lda #1
-       sta CXCLR ; clear collision
 overscanLoop
        sta WSYNC
        lda INTIM ; check timer
        bpl overscanLoop
        rts
 
-
 ProcessJoystick
        ; now we store old x and y
        ldx ObjectX
@@ -469,35 +460,57 @@ MoveDone
        ;====================
        ; This sub checks for collision based on inputs stored
        ; Expected inputs:
-       ; y - object's address offset, p0, p1, m0, m1
-       ; set Temp memory address to 1 to ignore collision.
-       ; every other value will NOT ignore collision
-       ; Retruns: 0, 1 or 2 in x
-       ; 0 = no collision
-       ; 1 = wall collision
-       ; 2 = bird collision
-       ; 3 = missile collision
+       ; y = object's address offset
+       ; Retruns: nothing
        ;====================
-CollisionDetection
-       ldx Temp ; check if collision is enabled
-       cpx #1 ; if it is 1 just return no
-       beq CollisionDone
-       ; otherwise check collision
-       ldx CXP0FB,y ; load into x for bit operation
-       stx Temp+1 ; sotre for bit operation
-       bit Temp+1 ; N = player0/playfield, V=player0/ball
-       bpl NoPFCollision ; if N is off, then player did not collide with playfield
-       ; if collision restore position.
+RestorePos
        lda PreviousX,y
        sta ObjectX,y
        lda PreviousY,y
        sta ObjectY,y
+       rts
 
-       ldx #1 ; this means wall collision
-       jmp CollisionDone
-NoPFCollision
-       ldx #0
+       ;====================
+       ; This sub checks for collision based on inputs stored
+       ; Expected inputs:
+       ; y - object's address offset, p0, p1, m0, m1
+       ; set Temp memory address to 1 to ignore collision.
+       ; set Temp to 2 to not restore position
+       ; every other value will NOT ignore collision
+       ; Retruns: 0 or 1 in Temp and Temp+1
+       ; 0 = no collision
+       ; 1 = collision
+       ; returns Temp for lower bit and Temp+1 for higher bit
+       ; those mean different things depending on the check performed
+       ;====================
+CollisionDetection
+       ; First we check collision for p0 and pf
+       bit CXP0FB ; N = player0/playfield, V=player0/ball
+       bpl NoP0PFCollision ; if N is off, then player did not collide with playfield
+       ldy #0 ; 0th object is player0
+       jsr RestorePos
+NoP0PFCollision
+       ; now we check collision between p0 and p1
+       bit CXPPMM
+       bpl NoP0P1Collision
+       dec Lives ; kill p0
+NoP0P1Collision ; p0 and p1 did not collide!
 CollisionDone
+       lda #1
+       sta CXCLR ; clear collision
+       rts
+
+PlayerCollision
+       ; now we do special case collision
+       ; first collision between p1 and p0
+       ldx Temp ; x must be 1 if p1 and p0 collided
+       cpx #1
+       bne NoPlayerCollision
+
+       ; if player is hit by bird remove a life
+       dec Lives
+
+NoPlayerCollision
        rts
 
 ; Plays the Intro noise
@@ -593,7 +606,7 @@ TurtleFrame1
        lda #>(TurtleSprite + TURTLEHEIGHT - 1)
        sbc #0
        sta TurtlePtr+1
-       jmp BirdFrame1
+       jmp BirdRender
 
 TurtleFrame2
        ; TurtleDraw = PFHEIGHT + TURTLEHEIGHT - Y position
@@ -613,10 +626,18 @@ TurtleFrame2
 
        ldx AnimationTimer
        cpx #20 ; compare to 10 if 10 reset to 0
-       bne BirdFrame1
+       bne BirdRender
        lda #0
        sta AnimationTimer
 
+BirdRender
+       ; every other frame load different animation
+       ldx AnimationTimer+1
+       inc AnimationTimer+1
+       cpx #10 ; every 5th or more frame draw 2nd frame
+       bmi BirdFrame1
+       jmp BirdFrame2 ; TODO this can be made much better
+
 BirdFrame1
        ; BirdDraw = PFHEIGHT + BIRDHEIGHT - Y position
        lda #(PFHEIGHT + BIRDHEIGHT)
@@ -632,7 +653,30 @@ BirdFrame1
        lda #>(BirdSprite + BIRDHEIGHT - 1)
        sbc #0
        sta BirdPtr+1
+       jmp RenderDone
+BirdFrame2
+       ; BirdDraw = PFHEIGHT + BIRDHEIGHT - Y position
+       lda #(PFHEIGHT + BIRDHEIGHT2)
+       sec
+       sbc ObjectY+1
+       sta BirdDraw
 
+       ; BirdPtr = TurtleSprite + TURTLEHEIGHT - 1 - Y position
+       lda #<(BirdSprite2 + BIRDHEIGHT2 - 1)
+       sec
+       sbc ObjectY+1
+       sta BirdPtr
+       lda #>(BirdSprite2 + BIRDHEIGHT2 - 1)
+       sbc #0
+       sta BirdPtr+1
+
+       ldx AnimationTimer+1
+       cpx #20 ; compare to 10 if 10 reset to 0
+       bne RenderDone
+       lda #0
+       sta AnimationTimer+1
+
+RenderDone
        ; use Difficulty Switches to test how Vertical Delay works
        ldx #0
        stx VDELP0      ; turn off VDEL for player0
@@ -712,15 +756,15 @@ TurtleSprite2:
 TURTLEHEIGHT2 = * - TurtleSprite2
 
 TurtleDeadSprite:
+       .byte %10000001
        .byte %01000010
-       .byte %11000011
-       .byte %00111100
-       .byte %00111100
-       .byte %00111100
-       .byte %01111110
-       .byte %01011010
+       .byte %00100100
+       .byte %00011000
+       .byte %00011000
+       .byte %00100100
        .byte %01000010
-TURTLEHDEADEIGHT2 = * - TurtleDeadSprite
+       .byte %10000001
+TURTLEHDEADEIGHT = * - TurtleDeadSprite
 
 BirdSprite:
        .byte %00000000
@@ -733,6 +777,17 @@ BirdSprite:
        .byte %00100100
 BIRDHEIGHT = * - BirdSprite
 
+BirdSprite2:
+       .byte %00000000
+       .byte %00011000
+       .byte %00011000
+       .byte %00100100
+       .byte %01011010
+       .byte %10011001
+       .byte %00011000
+       .byte %00100100
+BIRDHEIGHT2 = * - BirdSprite2
+
        align 256
 DigitGfx:
        .byte %01110111