132 lines
2.2 KiB
ArmAsm
132 lines
2.2 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
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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 ; 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 (12.4 fixed point)
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.word 0 ; Velocity Y (12.4 fixed point)
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JD_POSX = 0 ; Byte offsets into projectile data structure
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JD_POSY = 2
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JD_PRECISEX = 4
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JD_PRECISEY = 6
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JD_VX = 8
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JD_VY = 10
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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
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lda #projectileData ; Only one active at a time for now
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sta SCRATCHL
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lda projectileParams ; X pos
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sta (SCRATCHL),y
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iny
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iny
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lda projectileParams+2 ; Y pos
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sta (SCRATCHL),y
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iny
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iny
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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 (SCRATCHL),y
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iny
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iny
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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 (SCRATCHL),y
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iny
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iny
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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 (SCRATCHL),y
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iny
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iny
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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 (SCRATCHL),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_AXY
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lda projectileData+JD_POSX
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bmi updateProjectilesDone
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; Integrate X velocity over position
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lda projectileData+JD_PRECISEX
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clc
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adc projectileData+JD_VX
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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+JD_POSX
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; Integrate Y velocity over position
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lda projectileData+JD_PRECISEY
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clc
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adc projectileData+JD_VY
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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+JD_POSY
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brk
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updateProjectilesDone:
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RESTORE_AXY
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rts
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