8bitworkshop/presets/vcs/ecs/kernel1.ecs

//#resource "vcs-ca65.h"

import "vcslib.ecs"
import "sprites.ecs"

system Kernel1Sprite
    locals 7

    on kernelsetup do with [Sprite]
---
; set player object flags
    lda {{<plyrflags}}
    sta NUSIZ0
    sta REFP0
---

    on kernelsetup do with
    [Sprite,HasBitmap,HasColormap,HasYpos]
---
; calculate screen height - ypos
    lda {{<lines}}
    clc
    adc #32
    sec
    sbc {{<ypos}}
    sta {{$5}}
; calculate bitmap pointer
    stx {{$6}}		; save X (Sprite index)
    lda {{<bitmap}}     ; deref bitmap
    tax
    lda {{<Bitmap:bitmapdata}},x
    sec
    sbc {{$5}}
    sta {{$0}}	; Y = sprite slot index
    lda {{>Bitmap:bitmapdata}},x
    sbc #0
    sta {{$1}}
; get bitmap height
    lda {{<Bitmap:height}},x
    sta {{$4}}
; calculate colormap pointer
    ldx {{$6}}		; restore X
    lda {{<colormap}}	; deref colormap
    tax
    lda {{<Colormap:colormapdata}},x
    sec
    sbc {{$5}}
    sta {{$2}}
    lda {{>Colormap:colormapdata}},x
    sbc #0
    sta {{$3}}
; save ypos
    ldx {{$6}}		; restore X
    lda {{<ypos}}
    sta {{$5}}
@nosprite:
---

// TODO: what if > 1 player? or missile?
    on kernelsetup do with [Sprite,HasXpos]
---
    ldy #0
    lda {{<xpos}}
    {{!SetHorizPos}}
    sta HMOVE
---
    on prescanline do once
---
; draw player 0
    lda {{$4}} ; height
    dcp {{$5}} ; ypos
    bcs @DoDraw1
    lda #0
    .byte $2C
@DoDraw1:
    lda ({{$0}}),y
---
    on scanline do once
---
    sta GRP0
    lda ({{$2}}),y
    sta COLUP0
---
    on kerneldone do once
---
    lda #0
    sta GRP0
    sta GRP1
    sta GRP0
    sta GRP1
---
end

system KernelMissile
    locals 1
// TODO: unroll loops
    on preframe do foreach [Missile,HasYpos] limit 1
---
    lda {{<ypos}}
    sta {{$0}}
---
    on scanline do foreach [Missile,HasYpos] limit 1
---
    dec {{$0}}
    php
    pla
    sta ENAM0+{{const index}}-2
---
    on kerneldone do foreach [Missile,HasYpos] limit 1
---
; skip 3 lines each kernel section
    lda #0
    sta ENAM0+{{const index}}-2
    dec {{$0}}
    dec {{$0}}
    dec {{$0}}
---
end

system KernelCollide
    locals 1
    on preframe do once
    ---
    lda #$ff
    sta {{$0}}		; object index if collision
    ---
    on kernelsetup do once
    ---
    sta CXCLR		; clear collision flags
    --- 
    on kerneldone do with [Sprite]
    ---
    lda CXM1P
    bpl @nocollide	; missile 1 <-> player 0?
    stx {{$0}}		; save object index
@nocollide:
    ---
// TODO: somehow avoid select? pass arg to explode?
    on postframe do select [Sprite]
    ---
    ldx {{$0}}  	; get object index
    bmi @noexplode	; was there collision?
    {{!explode}}
@noexplode:
    ---
end