;;;;;;;;;;;;
;;;;;;; Perspective Line Segment Clipper
;;;;;;;;;;;

;; TODO? start interpolating earlier and test the clipping flags later

;;;; Uses the following registers
;;
;; vi01         tmp
;; vi15         tmp (return address)
;;
;; vf01		p1 pos		input
;; vf02		p1 bary		input
;; vf03		p2 pos		input
;; vf04		p2 bary		input
;; vf05		interp pos
;; vf06		interp bary
;; vf07.w	d2
;; vf08.w	d1
;; vf09.w	d1-d2
ClipLine:

.if 1
;;; ====== w = near plane ======
	nop				fcor vi01,negZo2		; test if both out
	sub.w vf09,vf01,vf03		ibne vi01,vi00,CullLine		; d1-d2 - yes, skip this segment completely
	subz.w vf07,vf01,vf24		fcand vi01,negZn2		; d1 - test if both in
	subz.w vf08,vf03,vf24		ibeq vi01,vi00,LClipNegZ_End	; d2 - yes, no need to clip against this plane
	;; So we need to interpolate
	nop				nop
	nop				div q,vf00w,vf09w
	mulaw acc,vf03,vf07		nop				; interp pos (acc = p2*d1)
	msubw vf05,vf01,vf08		nop				; interp pos (acc - p1*d2)
	mulaw acc,vf04,vf07		nop				; interp bary (acc = p2*d1)
	msubw vf06,vf02,vf08		nop				; interp bary (acc - p1*d2)
	nop				nop
	nop				nop
	mulq vf05,vf05,q		nop				; interp pos
	mulq vf06,vf06,q		nop				; interp bary
	nop				fcand vi01,negZn1		; test p2's cliping
	nop				ibeq vi01,vi00,LClipNegZ_p1	; it's in, so p1 is out
	;; p2 is out, so replace it
	nop				nop
	clipw.xyz vf01,vf01		move vf03,vf05
	nop				b LClipNegZ_Done
	clipw.xyz vf05,vf05		move vf04,vf06
LClipNegZ_p1:			;; p1 is out, so replace it
	clipw.xyz vf05,vf05		move vf01,vf05
	clipw.xyz vf03,vf03		move vf02,vf06
LClipNegZ_Done:
	nop				nop				; wait for clipping flags
	nop				nop
	nop				nop
LClipNegZ_End:
.endif

.if 1
;;; ====== w = far plane ======
	nop				fcor vi01,posZo2		; test if both out
	sub.w vf09,vf03,vf01		ibne vi01,vi00,CullLine		; d1-d2 - yes, skip this segment completely
	sub.w vf07,vf24,vf01		fcand vi01,posZn2		; d1 - test if both in
	sub.w vf08,vf24,vf03		ibeq vi01,vi00,LClipPosZ_End	; d2 - yes, no need to clip against this plane
	;; So we need to interpolate
	nop				nop
	nop				div q,vf00w,vf09w
	mulaw acc,vf03,vf07		nop				; interp pos (acc = p2*d1)
	msubw vf05,vf01,vf08		nop				; interp pos (acc - p1*d2)
	mulaw acc,vf04,vf07		nop				; interp bary (acc = p2*d1)
	msubw vf06,vf02,vf08		nop				; interp bary (acc - p1*d2)
	nop				nop
	nop				nop
	mulq vf05,vf05,q		nop				; interp pos
	mulq vf06,vf06,q		nop				; interp bary
	nop				fcand vi01,posZn1		; test p2's cliping
	nop				ibeq vi01,vi00,LClipPosZ_p1	; it's in, so p1 is out
	;; p2 is out, so replace it
	nop				nop
	clipw.xyz vf01,vf01		move vf03,vf05
	nop				b LClipPosZ_Done
	clipw.xyz vf05,vf05		move vf04,vf06
LClipPosZ_p1:			;; p1 is out, so replace it
	clipw.xyz vf05,vf05		move vf01,vf05
	clipw.xyz vf03,vf03		move vf02,vf06
LClipPosZ_Done:
	nop				nop				; wait for clipping flags
	nop				nop
	nop				nop
LClipPosZ_End:
.endif

.if 1
;;; ====== w = -x ======
	addax.w acc,vf01,vf01		fcor vi01,negXo2		; test if both out
	msubax.w acc,vf00,vf03		ibne vi01,vi00,CullLine		; yes, skip this segment completely
	msub.w vf09,vf00,vf03		fcand vi01,negXn2		; d1-d2 test if both in
	addx.w vf07,vf01,vf01		ibeq vi01,vi00,LClipNegX_End	; d1 yes, no need to clip against this plane
	;; So we need to interpolate
	addx.w vf08,vf03,vf03		nop				; d2
	nop				nop
	nop				div q,vf00w,vf09w
	mulaw acc,vf03,vf07		nop				; interp pos (acc = p2*d1)
	msubw vf05,vf01,vf08		nop				; interp pos (acc - p1*d2)
	mulaw acc,vf04,vf07		nop				; interp bary (acc = p2*d1)
	msubw vf06,vf02,vf08		nop				; interp bary (acc - p1*d2)
	nop				nop
	nop				nop
	mulq vf05,vf05,q		nop				; interp pos
	mulq vf06,vf06,q		nop				; interp bary
	nop				fcand vi01,negXn1		; test p2's cliping
	nop				ibeq vi01,vi00,LClipNegX_p1	; it's in, so p1 is out
	;; p2 is out, so replace it
	nop				nop
	clipw.xyz vf01,vf01		move vf03,vf05
	nop				b LClipNegX_Done
	clipw.xyz vf05,vf05		move vf04,vf06
LClipNegX_p1:			;; p1 is out, so replace it
	clipw.xyz vf05,vf05		move vf01,vf05
	clipw.xyz vf03,vf03		move vf02,vf06
LClipNegX_Done:
	nop				nop				; wait for clipping flags
	nop				nop
	nop				nop
LClipNegX_End:
.endif

.if 1
;;; ====== w = x ======
	subax.w acc,vf01,vf01		fcor vi01,posXo2		; test if both out
	maddax.w acc,vf00,vf03		ibne vi01,vi00,CullLine		; yes, skip this segment completely
	msub.w vf09,vf00,vf03		fcand vi01,posXn2		; d1-d2 - test if both in
	subx.w vf07,vf01,vf01		ibeq vi01,vi00,LClipPosX_End	; d1 - yes, no need to clip against this plane
	;; So we need to interpolate
	subx.w vf08,vf03,vf03		nop				; d2
	nop				nop
	nop				div q,vf00w,vf09w
	mulaw acc,vf03,vf07		nop				; interp pos (acc = p2*d1)
	msubw vf05,vf01,vf08		nop				; interp pos (acc - p1*d2)
	mulaw acc,vf04,vf07		nop				; interp bary (acc = p2*d1)
	msubw vf06,vf02,vf08		nop				; interp bary (acc - p1*d2)
	nop				nop
	nop				nop
	mulq vf05,vf05,q		nop				; interp pos
	mulq vf06,vf06,q		nop				; interp bary
	nop				fcand vi01,posXn1		; test p2's cliping
	nop				ibeq vi01,vi00,LClipPosX_p1	; it's in, so p1 is out
	;; p2 is out, so replace it
	nop				nop
	clipw.xyz vf01,vf01		move vf03,vf05
	nop				b LClipPosX_Done
	clipw.xyz vf05,vf05		move vf04,vf06
LClipPosX_p1:			;; p1 is out, so replace it
	clipw.xyz vf05,vf05		move vf01,vf05
	clipw.xyz vf03,vf03		move vf02,vf06
LClipPosX_Done:
	nop				nop				; wait for clipping flags
	nop				nop
	nop				nop
LClipPosX_End:
.endif

.if 1
;;; ====== w = -y ======
	adday.w acc,vf01,vf01		fcor vi01,negYo2		; test if both out
	msubay.w acc,vf00,vf03		ibne vi01,vi00,CullLine		; yes, skip this segment completely
	msub.w vf09,vf00,vf03		fcand vi01,negYn2		; d1-d2 - test if both in
	addy.w vf07,vf01,vf01		ibeq vi01,vi00,LClipNegY_End	; d1 - yes, no need to clip against this plane
	;; So we need to interpolate
	addy.w vf08,vf03,vf03		nop				; d2
	nop				nop
	nop				div q,vf00w,vf09w
	mulaw acc,vf03,vf07		nop				; interp pos (acc = p2*d1)
	msubw vf05,vf01,vf08		nop				; interp pos (acc - p1*d2)
	mulaw acc,vf04,vf07		nop				; interp bary (acc = p2*d1)
	msubw vf06,vf02,vf08		nop				; interp bary (acc - p1*d2)
	nop				nop
	nop				nop
	mulq vf05,vf05,q		nop				; interp pos
	mulq vf06,vf06,q		nop				; interp bary
	nop				fcand vi01,negYn1		; test p2's cliping
	nop				ibeq vi01,vi00,LClipNegY_p1	; it's in, so p1 is out
	;; p2 is out, so replace it
	nop				nop
	clipw.xyz vf01,vf01		move vf03,vf05
	nop				b LClipNegY_Done
	clipw.xyz vf05,vf05		move vf04,vf06
LClipNegY_p1:			;; p1 is out, so replace it
	clipw.xyz vf05,vf05		move vf01,vf05
	clipw.xyz vf03,vf03		move vf02,vf06
LClipNegY_Done:
	nop				nop				; wait for clipping flags
	nop				nop
	nop				nop
LClipNegY_End:
.endif

.if 1
;;; ====== w = y ======
	subay.w acc,vf01,vf01		fcor vi01,posYo2		; test if both out
	madday.w acc,vf00,vf03		ibne vi01,vi00,CullLine		; yes, skip this segment completely
	msub.w vf09,vf00,vf03		fcand vi01,posYn2		; d1-d2 - test if both in
	suby.w vf07,vf01,vf01		ibeq vi01,vi00,LClipPosY_End	; d2 - yes, no need to clip against this plane
	;; So we need to interpolate
	suby.w vf08,vf03,vf03		nop				; d2
	nop				nop
	nop				div q,vf00w,vf09w
	mulaw acc,vf03,vf07		nop				; interp pos (acc = p2*d1)
	msubw vf05,vf01,vf08		nop				; interp pos (acc - p1*d2)
	mulaw acc,vf04,vf07		nop				; interp bary (acc = p2*d1)
	msubw vf06,vf02,vf08		nop				; interp bary (acc - p1*d2)
	nop				nop
	nop				nop
	mulq vf05,vf05,q		nop				; interp pos
	mulq vf06,vf06,q		nop				; interp bary
	nop				fcand vi01,posYn1		; test p2's cliping
	nop				ibeq vi01,vi00,LClipPosY_p1	; it's in, so p1 is out
	;; p2 is out, so replace it
	nop				nop
	clipw.xyz vf01,vf01		move vf03,vf05
	nop				b LClipPosY_End
	clipw.xyz vf05,vf05		move vf04,vf06
LClipPosY_p1:			;; p1 is out, so replace it
	clipw.xyz vf05,vf05		move vf01,vf05
	clipw.xyz vf03,vf03		move vf02,vf06
LClipPosY_End:
.endif

	nop				iaddiu vi15,vi15,2
CullLine:
	nop				jr vi15
	nop				nop