231 lines
4.0 KiB
ArmAsm
231 lines
4.0 KiB
ArmAsm
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; projectile
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; Code and data structures related to the projectiles
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;
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; Created by Quinn Dunki on 8/13/17
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;
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projectileData:
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; gameobject data (we're a subclass, effectively)
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.word -1 ; Pos X in pixels (from left terrain edge)
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.word 0 ; Pos Y in pixels (from bottom terrain edge)
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.word 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ; Saved background
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.word 0 ; Pos X (12.4 fixed point)
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.word 0 ; Pos Y (12.4 fixed point)
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.word 0 ; Velocity X (8.8 fixed point)
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.word 0 ; Velocity Y (8.8 fixed point)
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JD_PRECISEX = 36 ; Byte offsets into projectile data structure
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JD_PRECISEY = 38
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JD_VX = 40
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JD_VY = 42
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GRAVITY = $ffff ; 8.8 fixed point
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.macro PROJECTILEPTR_Y
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tya ; Pointer to projectile structure from index
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asl
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asl
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asl
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asl
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tay
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.endmacro
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projectileParams:
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.word 0 ; Starting pos X
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.word 0 ; Starting pos Y
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.word 0 ; Initial angle
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.word 0 ; Initial power
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; fireProjectile
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;
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; Trashes SCRATCHL
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;
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fireProjectile:
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SAVE_AXY
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; Set up projectile structure
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ldy #0 ; Only one active at a time for now
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PROJECTILEPTR_Y
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lda projectileParams ; X pos
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sta projectileData+GO_POSX,y
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lda projectileParams+2 ; Y pos
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sta projectileData+GO_POSY,y
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lda projectileParams ; Fixed point version of X pos
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asl
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asl
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asl
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asl
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sta projectileData+JD_PRECISEX,y
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lda projectileParams+2 ; Fixed point version of Y pos
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asl
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asl
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asl
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asl
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sta projectileData+JD_PRECISEY,y
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lda projectileParams+4 ; Convert angle to vector
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asl
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tax
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lda angleToVectorX,x ; Velocity X
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sta projectileData+JD_VX,y
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lda projectileParams+4 ; Convert angle to vector
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asl
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tax
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lda angleToVectorY,x ; Velocity Y
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sta projectileData+JD_VY,y
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RESTORE_AXY
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; updateProjectiles
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;
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; Trashes SCRATCHL
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;
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updateProjectiles:
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SAVE_AY
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lda projectileData+GO_POSX
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bmi updateProjectilesDone
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; Integrate gravity over velocity
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lda projectileData+JD_VY
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clc
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adc #GRAVITY
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sta projectileData+JD_VY
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; Integrate X velocity over position
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lda projectileData+JD_VX
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; Convert 8.8 to 12.4
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cmp #$8000
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ror
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cmp #$8000
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ror
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cmp #$8000
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ror
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cmp #$8000
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ror
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clc
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adc projectileData+JD_PRECISEX
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sta projectileData+JD_PRECISEX
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; Convert to integral for rendering
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lsr
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lsr
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lsr
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lsr
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sta projectileData+GO_POSX
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bmi updateProjectilesDelete
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cmp #TERRAINWIDTH-GAMEOBJECTWIDTH-1
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bpl updateProjectilesDelete
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; Integrate Y velocity over position
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lda projectileData+JD_VY
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; Convert 8.8 to 12.4
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cmp #$8000
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ror
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cmp #$8000
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ror
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cmp #$8000
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ror
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cmp #$8000
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ror
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clc
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adc projectileData+JD_PRECISEY
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sta projectileData+JD_PRECISEY
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; Convert to integral for rendering
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lsr
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lsr
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lsr
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lsr
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sta projectileData+GO_POSY
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cmp #GAMEOBJECTHEIGHT
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bmi updateProjectilesDelete
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cmp #201
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bpl updateProjectilesDelete
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; Check for terrain collisions
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lda projectileData+GO_POSX
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sta rectParams
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lda projectileData+GO_POSY
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sta rectParams+2
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lda #GAMEOBJECTWIDTH
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sta rectParams+4
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lda #GAMEOBJECTHEIGHT
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sta rectParams+6
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jsr intersectRect
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cmp #0
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bne updateProjectilesDelete
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updateProjectilesDone:
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RESTORE_AY
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rts
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updateProjectilesDelete:
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ldy #0
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jsr deleteProjectile
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bra updateProjectilesDone
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; deleteProjectile
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;
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; Y = Projectile index
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; Trashes A
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;
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deleteProjectile:
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PROJECTILEPTR_Y
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lda #-1
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sta projectileData+GO_POSX,y
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; renderProjectiles
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;
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;
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renderProjectiles:
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pha
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lda projectileData
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bpl renderProjectilesDoIt
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jmp renderProjectilesDone
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renderProjectilesDoIt:
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RENDER_GAMEOBJECT projectileData
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renderProjectilesDone:
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pla
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; unrenderProjectiles
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;
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;
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unrenderProjectiles:
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pha
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lda projectileData
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bpl unrenderProjectilesDoIt
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jmp unrenderProjectilesDone
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unrenderProjectilesDoIt:
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UNRENDER_GAMEOBJECT projectileData
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unrenderProjectilesDone:
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pla
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rts
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