;EASE$$$ READ ONLY COPY of file ÒANGLES.aÓ
;¥1.5	BAL 05/29/1989 Blasting in 32-Bit QuickDraw version 1.0 Final
;¥1.4	BAL 04/12/1989 Blasting in 32-Bit QuickDraw 1.0B1
;¥1.3	BAL 04/12/1989 -d
; File Angles.a
;
; Copyright Apple Computer, Inc.  1981-1986
; All Rights Reserved
;
;

		BLANKS	ON
		STRING	ASIS

AngleFromSlope FUNC  EXPORT 		
		EXPORT SlopeFromAngle
;-----------------------------------------------------
;
;  FUNCTION AngleFromSlope(slope: Fixed): INTEGER;
;
;  Scans slope table for angle and returns angle 0..180
;
		MOVE.L	4(SP),D0				;GET SLOPE
		SMI 	D2						;REMEMBER IF IT WAS NEGATIVE
		BPL.S	NOTNEG					;CONTINUE IF POSITIVE
		NEG.L	D0						;ELSE MAKE SLOPE POS
NOTNEG	SUB.L	#500,D0 				;BIAS THE COMPARE
		MOVE.L	D0,4(SP)
		LEA 	CONTINUE,A0 			;POINT TO TABLE OF SLOPES
		MOVEQ	#-1,D1					;INIT ANGLE COUNT
SCAN	ADD.W	#1,D1
		MOVE.W	D1,D0
		CLR.L	-(SP)
		BRA.S	A2SLOPE
CONTINUE
		MOVE.L	8(SP),D0				;GET SLOPE
		CMP.L	(SP)+,D0				;SCAN THRU SLOPE TABLE
		BGT.S	SCAN
		MOVE	#180,D0
		SUB 	D1,D0					;CALC 180-ANGLE = 90..180
		TST.B	D2						;WAS DH POS ?
		BPL.S	DONE					;NO, RETURN 90..180
		MOVE	D1,D0					;YES, RETURN 0..90
DONE	MOVE.L	(SP)+,(SP)				;STRIP PARAM
		MOVE.W	D0,4(SP)				;RETURN FUNCTION RESULT
		RTS



;----------------------------------------------------------------
;
;  FUNCTION SlopeFromAngle(angle: INTEGER): Fixed;
;
;  calculate the fixed point slope of a line, DH/DV = -65536 * Tan(angle).
;  Input angle is treated MOD 180.
;
SlopeFromAngle
		MOVE.L	(SP)+,A0				;POP RETURN ADDR
		MOVE	(SP)+,D0				;GET INTEGER ANGLE
		EXT.L	D0						;SIGN EXTEND FOR DIVIDE
		DIVS	#180,D0 				;TREAT ANGLE MOD 180
		SWAP	D0						;GET THE REMAINDER
		TST 	D0						;WAS IT NEGATIVE ?
		BPL.S	OK1 					;NO, CONTINUE
		ADD 	#180,D0 				;YES, PUT IN RANGE 0..179
OK1 	MOVE	#$8000,(SP)
A2SLOPE CMP 	#90,D0
		BLE.S	OK2
		CLR.W	(SP)
		SUB 	#180,D0
		NEG 	D0
OK2 	CMP 	#45,D0
		BLT.S	SHARE
		ADD 	#1,(SP)
		CMP 	#64,D0
		BLT.S	SHARE
		MOVE.B	SLOPE-91(D0),1(SP)
		BPL.S	SHARE
		OR.B	#$7F,(SP)
SHARE	ADD 	D0,D0
		MOVE.W	SLOPE(D0),2(SP)
CHECK	BCLR	#7,(SP)
		BEQ.S	OK3
		NEG.L	(SP)
OK3 	JMP 	(A0)



;		.BYTE	$01 		;45
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01 		;50
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01 		;55
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01
;		.BYTE	$01 		;60
;		.BYTE	$01
;		.BYTE	$01
		DC.B	$01
		DC.B	$02
		DC.B	$02 		;65
		DC.B	$02
		DC.B	$02
		DC.B	$02
		DC.B	$02
		DC.B	$02 		;70
		DC.B	$02
		DC.B	$03
		DC.B	$03
		DC.B	$03
		DC.B	$03 		;75
		DC.B	$04
		DC.B	$04
		DC.B	$04
		DC.B	$05
		DC.B	$05 		;80
		DC.B	$06
		DC.B	$07
		DC.B	$08
		DC.B	$09
		DC.B	$0B 		;85
		DC.B	$0E
		DC.B	$13
		DC.B	$1C
		DC.B	$39
		DC.B	$FF 		;90
SLOPE
		DC.W	$0000		;0
		DC.W	$0478
		DC.W	$08F1
		DC.W	$0D6B
		DC.W	$11E7
		DC.W	$1666		;5
		DC.W	$1AE8
		DC.W	$1F6F
		DC.W	$23FA
		DC.W	$288C
		DC.W	$2D24		;10
		DC.W	$31C3
		DC.W	$366A
		DC.W	$3B1A
		DC.W	$3FD4
		DC.W	$4498		;15
		DC.W	$4968
		DC.W	$4E44
		DC.W	$532E
		DC.W	$5826
		DC.W	$5D2D		;20
		DC.W	$6245
		DC.W	$676E
		DC.W	$6CAA
		DC.W	$71FB
		DC.W	$7760		;25
		DC.W	$7CDC
		DC.W	$8270
		DC.W	$881E
		DC.W	$8DE7
		DC.W	$93CD		;30
		DC.W	$99D2
		DC.W	$9FF7
		DC.W	$A640
		DC.W	$ACAD
		DC.W	$B341		;35
		DC.W	$B9FF
		DC.W	$C0E9
		DC.W	$C802
		DC.W	$CF4E
		DC.W	$D6CF		;40
		DC.W	$DE8A
		DC.W	$E681
		DC.W	$EEB9
		DC.W	$F737
		DC.W	$0000		;45
		DC.W	$0919
		DC.W	$1287
		DC.W	$1C51
		DC.W	$267F
		DC.W	$3117		;50
		DC.W	$3C22
		DC.W	$47AA
		DC.W	$53B9
		DC.W	$605B
		DC.W	$6D9B		;55
		DC.W	$7B89
		DC.W	$8A35
		DC.W	$99AF
		DC.W	$AA0E
		DC.W	$BB68		;60
		DC.W	$CDD6
		DC.W	$E177
		DC.W	$F66E
		DC.W	$0CE1
		DC.W	$24FE		;65
		DC.W	$3EFC
		DC.W	$5B19
		DC.W	$799F
		DC.W	$9AE7
		DC.W	$BF5B		;70
		DC.W	$E77A
		DC.W	$13E3
		DC.W	$4556
		DC.W	$7CC7
		DC.W	$BB68		;75
		DC.W	$02C2
		DC.W	$54DB
		DC.W	$B462
		DC.W	$2501
		DC.W	$ABD9		;80
		DC.W	$5051
		DC.W	$1D88
		DC.W	$24F3
		DC.W	$83AD
		DC.W	$6E17		;85
		DC.W	$4CF5
		DC.W	$14BD
		DC.W	$A2D7
		DC.W	$4A30
		DC.W	$FFFF		;90


PtToAngle PROC	  EXPORT	
		IMPORT	AngleFromSlope
;--------------------------------------------------------------
;
;  PROCEDURE PtToAngle(r: Rect; pt: Point; VAR angle: INTEGER);
;
;  Given a rectangle and a point, return the angle subtended by pt.
;
;  A6 OFFSETS OF PARAMETERS AFTER LINK:
;
PARAMSIZE		EQU 	12				;TOTAL BYTES OF PARAMS
RECT			EQU 	PARAMSIZE+8-4	;ADDR OF RECT
PT				EQU 	RECT-4			;POINT
ANGLE			EQU 	PT-4			;ADDR OF INTEGER;

		LINK	A6,#0					;NO LOCALS
		MOVEM.L D6-D7/A4,-(SP)			;SAVE REGS
		MOVE.L	RECT(A6),A4 			;POINT TO RECT

		MOVE	BOTTOM(A4),D0
		ADD 	TOP(A4),D0
		ASR 	#1,D0					;CENTER.V := (TOP+BOTTOM)/2
		MOVE	PT+V(A6),D1
		SUB 	D0,D1					;DV := PT.V - CENTER.V

		MOVE	RIGHT(A4),D0
		ADD 	LEFT(A4),D0
		ASR 	#1,D0					;CENTER.H := (LEFT+RIGHT)/2
		MOVE	PT+H(A6),D7
		SUB 	D0,D7					;DH := PT.H - CENTER.H
		BNE.S	DHOK					;CONTINUE IF DH <> 0
		TST 	D1						;WAS DV > 0 ?
		BLE.S	ZERO					;NO, RETURN ANGLE = 0
		MOVE	#180,D0 				;YES, RETURN ANGLE = 180
		BRA.S	DONE

DHOK	CLR.L	-(SP)					;ROOM FOR FCN RESULT
		MOVE	D7,-(SP)				;PUSH DH
		MOVE	D1,-(SP)				;PUSH DV
		_FixRatio						;CALC SLOPE := DH/DV
		MOVE.L	(SP)+,D6				;GET SLOPE RESULT

		CLR.L	-(SP)					;ROOM FOR FCN RESULT
		MOVE	BOTTOM(A4),D0
		SUB 	TOP(A4),D0
		MOVE	D0,-(SP)				;PUSH HEIGHT
		MOVE	RIGHT(A4),D0
		SUB 	LEFT(A4),D0
		MOVE	D0,-(SP)				;PUSH WIDTH
		_FixRatio						;CALC ASPECT := HT/WD
		MOVE.L	(SP)+,D0				;GET ASPECT RESULT

		CLR.L	-(SP)					;ROOM FOR FCN RESULT
		MOVE.L	D6,-(SP)				;PUSH SLOPE
		MOVE.L	D0,-(SP)				;PUSH ASPECT
		_FixMul 						;CALC SLOPE*ASPECT
		MOVE.L	(SP)+,D0				;GET RESULT SLOPE2

		CLR.W	-(SP)					;ROOM FOR FCN RESULT
		MOVE.L	D0,-(SP)				;PUSH SLOPE2
		_AngleFromSlope					;SCAN FOR ARCTAN
		MOVE	(SP)+,D0				;GET RESULT ANGLE

		TST 	D7						;WAS DH POSITIVE ?
		BPL.S	DONE					;YES, CONTINUE
		ADD 	#180,D0 				;NO, ADD 180 TO ANG
		CMP 	#360,D0 				;IS RESULT = 360 ?
		BNE.S	DONE					;NO, CONTINUE
ZERO	CLR 	D0						;YES, ANGLE := 0
DONE	MOVE.L	ANGLE(A6),A0			;GET VAR ADDR
		MOVE	D0,(A0) 				;STORE INTO ANGLE
		MOVEM.L (SP)+,D6-D7/A4			;RESTORE REGS
		UNLINK	PARAMSIZE,'PTTOANGL'



		ENDPROC