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https://github.com/deater/dos33fsprogs.git
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204 lines
2.2 KiB
ArmAsm
204 lines
2.2 KiB
ArmAsm
; particle effect? -- Apple II Lores
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; by Vince `deater` Weaver
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PARTICLES = 64
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SCALE = 2
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HGR_BITS = $1C
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COLOR = $30
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SEEDLO = $43
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SEEDHI = $44
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HGR_COLOR = $E4
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QUOTIENT = $FA
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DIVISOR = $FB
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DIVIDEND = $FC
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XX = $FD
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YY = $FE
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FRAME = $FF
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FULLGR = $C052
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LORES = $C056 ; Enable LORES graphics
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HGR2 = $F3D8
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HGR = $F3E2
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HPLOT0 = $F457 ; plot at (Y,X), (A)
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PLOT = $F800 ; PLOT AT Y,A (A colors output, Y preserved)
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SETGR = $FB40
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WAIT = $FCA8 ; delay 1/2(26+27A+5A^2) us
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particle_x = $2000
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particle_y = $2100
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particle_life = $2200
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particle_vx = $2300
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particle_vy = $2400
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particle:
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jsr HGR ; clear $2000 for data struct
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jsr HGR2 ; clear/display HGR2
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; init
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ldx #PARTICLES
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init_particles_loop:
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jsr init_particle
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dex
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bpl init_particles_loop
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main_loop:
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lda #100
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jsr WAIT
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lda #0
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sta HGR_COLOR
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ldx #PARTICLES
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clear_loop:
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txa
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pha
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tay
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ldx particle_x,Y
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lda particle_y,Y
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ldy #0
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jsr HPLOT0 ; plot at (Y,X), (A)
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pla
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tax
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dex
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bpl clear_loop
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; move particles
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; draw particles
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ldx #PARTICLES
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draw_particles_loop:
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; adjust x
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lda particle_x,X
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clc
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adc particle_vx,X
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sta particle_x,X
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; bmi redo_particle
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; cmp #40*SCALE
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; bcs redo_particle
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; adjust y
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; first adjust for gravity
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inc particle_vy,X
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; inc particle_vy,X
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lda particle_y,X
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clc
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adc particle_vy,X
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sta particle_y,X
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; bmi redo_particle
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cmp #191
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bcc y_good
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redo_particle:
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jsr init_particle
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y_good:
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dec particle_life,X
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beq redo_particle
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lda #$ff
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sta HGR_COLOR
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; lda particle_life,X
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; sta HGR_COLOR
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; sec
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; sbc #$11
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; sta particle_life,X
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; cmp #$ef
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; beq redo_particle
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txa
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pha
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tay
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ldx particle_x,Y
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lda particle_y,Y
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ldy #0
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jsr HPLOT0 ; plot at (Y,X), (A)
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pla
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tax
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dex
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bpl draw_particles_loop
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jmp main_loop
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; init particle
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; particle in X
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init_particle:
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; source
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lda #128 ; init x
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sta particle_x,X
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lda #100 ; init y
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sta particle_y,X
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; color
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lda #$ff
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sta particle_life,X
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; velocities
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; -8 to 8?
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jsr random
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cmp #$80
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ror
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sta particle_vx,X
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jsr random
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ora #$f0
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sta particle_vy,X
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rts
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; -8 to 8
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; batari RNG
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random:
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lda SEEDHI
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lsr
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rol SEEDLO
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bcc noeor
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eor #$B4
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noeor:
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sta SEEDHI
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eor SEEDLO
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and #$f
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sec
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sbc #$8
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rts
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; need this to be at $3F5
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jmp particle
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