; GO64! TUTORIAL ON 3-D GRAPHICS
        ; PART 5: DRAWING LINES (2)

        ; GO64! 3D-KURS
        ; TEIL 5: LINIENZEICHNEN (2)

SINCOSLO = $4A00
SINCOSHI = $4C00
LOG2TABL = $5180
LOG2TBH0 = $5200
LOG2TBH1 = $5280

VICBANK  = %00000011; $0000-$4000
V        = VICBANK($03*$4000;=$0000
SCREEN   = $0400
CHARSET0 = $2000
CHARSET1 = $2800
SPIDCOD0 = $5300
SPIDCOD1 = $7100
SPDT0OFS = $00
SPDT1OFS = $0780
SPDT2OFS = $0F00
SPDT3OFS = $1680
SPDXOFSL = $0F00
SPDXOFSH = $0F80

BASEZP   = $02
CURRCHAR = $00+BASEZP
POINTERS = $01+BASEZP
ALPHALO  = $04+BASEZP
BETALO   = $05+BASEZP
GAMMALO  = $06+BASEZP
ALPHAHI  = $07+BASEZP
BETAHI   = $08+BASEZP
GAMMAHI  = $09+BASEZP
ALPHA    = $0A+BASEZP
BETA     = $0B+BASEZP
GAMMA    = $0C+BASEZP
SINBUFL0 = $0D+BASEZP
SINBUFH0 = $0E+BASEZP
SINBUFL1 = $0F+BASEZP
SINBUFH1 = $10+BASEZP
UNITXXLO = $11+BASEZP
UNITXXHI = $12+BASEZP
UNITXYLO = $13+BASEZP
UNITXYHI = $14+BASEZP
UNITXZLO = $15+BASEZP
UNITXZHI = $16+BASEZP
UNITYXLO = $17+BASEZP
UNITYXHI = $18+BASEZP
UNITYYLO = $19+BASEZP
UNITYYHI = $1A+BASEZP
UNITYZLO = $1B+BASEZP
UNITYZHI = $1C+BASEZP
UNITZXLO = $1D+BASEZP
UNITZXHI = $1E+BASEZP
UNITZYLO = $1F+BASEZP
UNITZYHI = $20+BASEZP
UNITZZLO = $21+BASEZP
UNITZZHI = $22+BASEZP
DIVIDEND = $23+BASEZP
DIVISOR  = $25+BASEZP
X2DCRDFR = $28+BASEZP
Z2DCRDFR = $30+BASEZP
X2DCORDS = $38+BASEZP
Y2DCORDS = $40+BASEZP
Z2DCORDS = $48+BASEZP
OLDXCRDS = $50+BASEZP
OLDYCRDS = $58+BASEZP
BEGX     = $0D+BASEZP
ENDX     = $0E+BASEZP
BEGY     = $0F+BASEZP
ENDY     = $10+BASEZP
DELTAX   = $11+BASEZP
DELTAY   = $12+BASEZP
LINSLOPE = $13+BASEZP

FOREGNDC = $01
BACKGNDC = $06

XPOS     = $0C; CHAR MATRIX COORDINATES
YPOS     = $05; ZEICHENMATRIXKOORDINATEN

ALPHAADD = $FFFF+1-($0200/3)
BETAADD  = $0700/3; ANGLE ADD VALUES
GAMMAADD = $0300/3; WINKELADDITIONSWERTE

NUMPOINT = $08


         *= $4000

         SEI
         LDA #$35
         STA $01
         LDA #<RETURN;NMI
         STA $FFFA
         LDA #>RETURN;NMI
         STA $FFFB
         BIT $D011
         BPL *-3
         BIT $D011
         BMI *-3
         LDA #$00
         STA $D011
         LDA #BACKGNDC
         STA $D020
         STA $D021


         ; BUILD TABLES
         ; TABELLEN GENERIEREN

         LDA #$00
         TAX
         TAY
         .BYTE $24
MKXOFSTB PLA
         STA SPDXOFSL,Y
         PHA
         TXA
         STA SPDXOFSH,Y
         PLA
         CLC
         ADC #SPIDRAW1-SPIDRAW0
      ;= ADC #SPIDRAWE-SPIDRAW1
         BCC *+3
         INX
         INY
         BPL MKXOFSTB+1

         LDX #$00
         LDA SINCOSLO+$00,X
         STA SINCOSLO+$0100,X
         LDA SINCOSHI+$00,X
         STA SINCOSHI+$0100,X
         INX
         BNE *-13


         ; BUILD SPEEDCODE
         ; SPEEDCODE GENERIEREN

         LDA #<SPIDCOD0
         STA POINTERS+2
         LDA #>SPIDCOD0
         STA POINTERS+3
         LDA #>CHARSET0+V
         STA POINTERS+4
         JSR MAKSPEED
         LDA #<SPIDCOD1
         STA POINTERS+2
         LDA #>SPIDCOD1
         STA POINTERS+3
         LDA #>CHARSET1+V
         STA POINTERS+4
         JSR MAKSPEED


         ; CLEAR CHARSETS
         ; ZEICHENSAETZE LOESCHEN

         LDA #>CHARSET0+V
         STA POINTERS+1
         LDA #>CHARSET1+V
         STA POINTERS+3
         LDA #<CHARSET0+V
         STA POINTERS+0
         STA POINTERS+2
         LDX #$08
         TAY
CLEARCHR STA (POINTERS+0),Y
         STA (POINTERS+2),Y
         INY
         BNE CLEARCHR
         INC POINTERS+1
         INC POINTERS+3
         DEX
         BNE CLEARCHR


         ; CLEAR SCREEN
         ; BILDSCHIRM LOESCHEN

         LDA #$00
         TAX
         STA SCREEN+V+$00,X
         STA SCREEN+V+$0100,X
         STA SCREEN+V+$0200,X
         STA SCREEN+V+$0300,X
         INX
         BNE *-13


         ; SET UP SCREEN MATRIX
         ; BILDSCHIRMMATRIX BILDEN

         CLC
         LDA #<XPOS+(YPOS*$28)+SCREEN+V
         STA POINTERS+0
         LDA #>XPOS+(YPOS*$28)+SCREEN+V
         STA POINTERS+1
         LDX #$00
SETUPSCR TXA
         LDY #$00
         STA (POINTERS+0),Y
         ADC #$10
         INY
         CPY #$10
         BNE SETUPSCR+3
         LDA #$27
         ADC POINTERS+0
         STA POINTERS+0
         BCC *+4
         INC POINTERS+1
         INX
         CPX #$10
         BNE SETUPSCR


         ; SET FOREGROUND COLOUR
         ; VORDERGRUNDFARBE SETZEN

         LDA #FOREGNDC
         LDX #$00
         STA $D800,X
         STA $D900,X
         STA $DA00,X
         STA $DB00,X
         INX
         BNE *-13


         ; SET VIC REGISTERS
         ; VIC-REGISTER SETZEN

         BIT $D011
         BPL *-3
         BIT $D011
         BMI *-3
         LDA #%00011011
         STA $D011
         LDA #%00001000
         STA $D016
         LDA #SCREEN/64.(CHARSET0/$0400)
         STA $D018
         LDA $DD00
         AND #%11111100
         ORA #VICBANK
         STA $DD00
         LDA #$FF
         STA $D012
         LDA #$01
         STA $D01A
         LDA #$7F
         STA $DC0D
         LDA #<IRQ
         STA $FFFE
         LDA #>IRQ
         STA $FFFF
         BIT $DC0D
         DEC $D019
         CLI


         ; RESET ANGLES AND COORDINATES
         ; KOORDINATEN&WINKEL NULLSETZEN

         LDA #$00
         LDX #NUMPOINT-1
         STA OLDXCRDS,X
         STA OLDYCRDS,X
         DEX
         BPL *-5
         STA CURRCHAR
         STA ALPHALO
         STA BETALO
         STA GAMMALO
         STA ALPHAHI
         STA BETAHI
         STA GAMMAHI


         ; MAIN LOOP
         ; HAUPTSCHLEIFE

MAINLOOP ; ROTATE UNIT VECTORS
         ;  (ABSOLUTELY UNOPTIMIZED)
         ; EINHEITSVEKTOREN ROTIEREN
         ;  (ABSOLUT UNOPTIMIERT)

         SEI
         LDA ALPHAHI
         STA ALPHA
         LDA GAMMAHI
         STA GAMMA
         LDA BETAHI
         STA BETA
         CLI

          ;   COS (BETA) * COS (GAMMA)
         CLC
         ADC #$40          ; (COS)
         SEC
         SBC GAMMA
         SEC
         SBC #$40          ; (COS)
         TAX               ; BETA-GAMMA
         CLC
         LDA BETA
         ADC #$40          ; (COS)
         CLC
         ADC GAMMA
         CLC
         ADC #$40          ; (COS)
         TAY               ; BETA+GAMMA
         SEC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA UNITXXLO
         LDA SINCOSHI+$40,X;    COS(B-G)
         SBC SINCOSHI+$40,Y;  - COS(B+G)
         STA UNITXXHI

          ; - SIN(A) * SIN(B) * COS(G)
          ; - COS(A) * SIN(G)
         CLC
         LDA BETA
         ADC GAMMA
         CLC
         ADC #$40     ; (COS)
         SEC
         SBC ALPHA
         SEC
         SBC #$80     ; (-)
         TAX          ; BETA+GAMMA-ALPHA
         CLC
         LDA ALPHA
         ADC #$80     ; (-)
         CLC
         ADC GAMMA
         CLC
         ADC #$40     ; (COS)
         SEC
         SBC BETA
         TAY          ; ALPHA+GAMMA-BETA
         CLC
         LDA SINCOSLO+$00,X
         ADC SINCOSLO+$00,Y
         STA SINBUFL0
         LDA SINCOSHI+$00,X;  SIN(B+G-A)
         ADC SINCOSHI+$00,Y;+ SIN(A+G-B)
         STA SINBUFH0
         CLC
         LDA ALPHA
         ADC #$80     ; (-)
         CLC
         ADC BETA
         SEC
         SBC GAMMA
         SEC
         SBC #$40     ; (COS)
         TAX          ; ALPHA+BETA-GAMMA
         CLC
         LDA ALPHA
         ADC #$80     ; (-)
         CLC
         ADC BETA
         CLC
         ADC GAMMA
         CLC
         ADC #$40     ; (COS)
         TAY          ; ALPHA+BETA+GAMMA
         SEC
         LDA SINCOSLO+$00,X
         SBC SINCOSLO+$00,Y
         STA SINBUFL1
         LDA SINCOSHI+$00,X;  SIN(A+B-G)
         SBC SINCOSHI+$00,Y;- SIN(A+B+G)
         STA SINBUFH1
         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA SINBUFL1
         LDA SINBUFH0
         ADC SINBUFH1
         CMP #$80
         ROR A  ; - SIN(A)*SIN(B)*COS(G)
         ROR SINBUFL1
         STA SINBUFH1

         CLC
         LDA ALPHA
         ADC #$40+$80      ; (-COS)
         SEC
         SBC GAMMA
         TAX               ; ALPHA-GAMMA
         CLC
         LDA ALPHA
         ADC #$40+$80      ; (-COS)
         CLC
         ADC GAMMA
         TAY               ; ALPHA+GAMMA
         SEC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA SINBUFL0      ;    COS(A-G)
         LDA SINCOSHI+$40,X;  - COS(A+G)
         SBC SINCOSHI+$40,Y
         STA SINBUFH0  ; - COS(A)*SIN(G)

         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA UNITXYLO
         LDA SINBUFH0
         ADC SINBUFH1
         STA UNITXYHI

          ;   COS(A) * SIN(B) * COS(G)
          ; - SIN(A) * SIN(G)
         CLC
         LDA BETA
         ADC GAMMA
         CLC
         ADC #$40     ; (COS)
         SEC
         SBC ALPHA
         SEC
         SBC #$40     ; (COS)
         TAX          ; BETA+GAMMA-ALPHA
         CLC
         LDA ALPHA
         ADC #$40     ; (COS)
         CLC
         ADC GAMMA
         CLC
         ADC #$40     ; (COS)
         SEC
         SBC BETA
         TAY          ; ALPHA+GAMMA-BETA
         CLC
         LDA SINCOSLO+$00,X
         ADC SINCOSLO+$00,Y
         STA SINBUFL0
         LDA SINCOSHI+$00,X;  SIN(B+G-A)
         ADC SINCOSHI+$00,Y;+ SIN(A+G-B)
         STA SINBUFH0
         CLC
         LDA ALPHA
         ADC #$40     ; (COS)
         CLC
         ADC BETA
         SEC
         SBC GAMMA
         SEC
         SBC #$40     ; (COS)
         TAX          ; ALPHA+BETA-GAMMA
         CLC
         LDA ALPHA
         ADC #$40     ; (COS)
         CLC
         ADC BETA
         CLC
         ADC GAMMA
         CLC
         ADC #$40     ; (COS)
         TAY          ; ALPHA+BETA+GAMMA
         SEC
         LDA SINCOSLO+$00,X
         SBC SINCOSLO+$00,Y
         STA SINBUFL1
         LDA SINCOSHI+$00,X;  SIN(A+B-G)
         SBC SINCOSHI+$00,Y;- SIN(A+B+G)
         STA SINBUFH1
         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA SINBUFL1
         LDA SINBUFH0
         ADC SINBUFH1
         CMP #$80
         ROR A    ; COS(A)*SIN(B)*COS(G)
         ROR SINBUFL1
         STA SINBUFH1

         CLC
         LDA ALPHA
         ADC #$80          ; (-)
         SEC
         SBC GAMMA
         TAX               ; ALPHA-GAMMA
         CLC
         LDA ALPHA
         ADC #$80          ; (-)
         CLC
         ADC GAMMA
         TAY               ; ALPHA+GAMMA
         SEC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA SINBUFL0      ;    COS(A-G)
         LDA SINCOSHI+$40,X;  - COS(A+G)
         SBC SINCOSHI+$40,Y
         STA SINBUFH0  ; - SIN(A)*SIN(G)

         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA UNITXZLO
         LDA SINBUFH0
         ADC SINBUFH1
         STA UNITXZHI


          ; - COS (BETA) * SIN (GAMMA)
         CLC
         LDA BETA
         ADC #$40+$80      ; (-COS)
         SEC
         SBC GAMMA
         TAX               ; BETA-GAMMA
         CLC
         LDA BETA
         ADC #$40+$80      ; (-COS)
         CLC
         ADC GAMMA
         TAY               ; BETA+GAMMA
         SEC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA UNITYXLO
         LDA SINCOSHI+$40,X;    COS(B-G)
         SBC SINCOSHI+$40,Y;  - COS(B+G)
         STA UNITYXHI

          ;   SIN(A) * SIN(B) * SIN(G)
          ; - COS(A) * COS(G)
         CLC
         LDA BETA
         ADC GAMMA
         SEC
         SBC ALPHA
         TAX          ; BETA+GAMMA-ALPHA
         CLC
         LDA ALPHA
         ADC GAMMA
         SEC
         SBC BETA
         TAY          ; ALPHA+GAMMA-BETA
         CLC
         LDA SINCOSLO+$00,X
         ADC SINCOSLO+$00,Y
         STA SINBUFL0
         LDA SINCOSHI+$00,X;  SIN(B+G-A)
         ADC SINCOSHI+$00,Y;+ SIN(A+G-B)
         STA SINBUFH0
         CLC
         LDA ALPHA
         ADC BETA
         SEC
         SBC GAMMA
         TAX          ; ALPHA+BETA-GAMMA
         CLC
         LDA ALPHA
         ADC BETA
         CLC
         ADC GAMMA
         TAY          ; ALPHA+BETA+GAMMA
         SEC
         LDA SINCOSLO+$00,X
         SBC SINCOSLO+$00,Y
         STA SINBUFL1
         LDA SINCOSHI+$00,X;  SIN(A+B-G)
         SBC SINCOSHI+$00,Y;- SIN(A+B+G)
         STA SINBUFH1
         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA SINBUFL1
         LDA SINBUFH0
         ADC SINBUFH1
         CMP #$80
         ROR A    ; SIN(A)*SIN(B)*SIN(G)
         ROR SINBUFL1
         STA SINBUFH1

         CLC
         LDA ALPHA
         ADC #$40+$80      ; (-COS)
         SEC
         SBC GAMMA
         SEC
         SBC #$40          ; (COS)
         TAX               ; ALPHA-GAMMA
         CLC
         LDA ALPHA
         ADC #$40+$80      ; (-COS)
         CLC
         ADC GAMMA
         CLC
         ADC #$40          ; (COS)
         TAY               ; ALPHA+GAMMA
         SEC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA SINBUFL0      ;    COS(A-G)
         LDA SINCOSHI+$40,X;  - COS(A+G)
         SBC SINCOSHI+$40,Y
         STA SINBUFH0  ; - COS(A)*COS(G)

         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA UNITYYLO
         LDA SINBUFH0
         ADC SINBUFH1
         STA UNITYYHI

          ; - COS(A) * SIN(B) * SIN(G)
          ; - SIN(A) * COS(G)
         CLC
         LDA BETA
         ADC GAMMA
         SEC
         SBC ALPHA
         SEC
         SBC #$40+$80 ; (-COS)
         TAX          ; BETA+GAMMA-ALPHA
         CLC
         LDA ALPHA
         ADC #$40+$80 ; (-COS)
         CLC
         ADC GAMMA
         SEC
         SBC BETA
         TAY          ; ALPHA+GAMMA-BETA
         CLC
         LDA SINCOSLO+$00,X
         ADC SINCOSLO+$00,Y
         STA SINBUFL0
         LDA SINCOSHI+$00,X;  SIN(B+G-A)
         ADC SINCOSHI+$00,Y;+ SIN(A+G-B)
         STA SINBUFH0
         CLC
         LDA ALPHA
         ADC #$40+$80 ; (-COS)
         ADC BETA
         SEC
         SBC GAMMA
         TAX          ; ALPHA+BETA-GAMMA
         CLC
         LDA ALPHA
         ADC #$40+$80 ; (-COS)
         CLC
         ADC BETA
         CLC
         ADC GAMMA
         TAY          ; ALPHA+BETA+GAMMA
         SEC
         LDA SINCOSLO+$00,X
         SBC SINCOSLO+$00,Y
         STA SINBUFL1
         LDA SINCOSHI+$00,X;  SIN(A+B-G)
         SBC SINCOSHI+$00,Y;- SIN(A+B+G)
         STA SINBUFH1
         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA SINBUFL1
         LDA SINBUFH0
         ADC SINBUFH1
         CMP #$80
         ROR A  ; - COS(A)*SIN(B)*SIN(G)
         ROR SINBUFL1
         STA SINBUFH1

         CLC
         LDA ALPHA
         ADC #$80          ; (-)
         SEC
         SBC GAMMA
         SEC
         SBC #$40          ; (COS)
         TAX               ; ALPHA-GAMMA
         CLC
         LDA ALPHA
         ADC #$80          ; (-)
         CLC
         ADC GAMMA
         CLC
         ADC #$40          ; (COS)
         TAY               ; ALPHA+GAMMA
         SEC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA SINBUFL0      ;    COS(A-G)
         LDA SINCOSHI+$40,X;  - COS(A+G)
         SBC SINCOSHI+$40,Y
         STA SINBUFH0  ; - SIN(A)*COS(G)

         CLC
         LDA SINBUFL0
         ADC SINBUFL1
         STA UNITYZLO
         LDA SINBUFH0
         ADC SINBUFH1
         STA UNITYZHI


          ;   SIN (BETA)
         LDX BETA
         LDA SINCOSLO+$00,X
         ASL A
         STA UNITZXLO
         LDA SINCOSHI+$00,X
         ROL A
         STA UNITZXHI

          ;   SIN (ALPHA) * COS (BETA)
         SEC
         LDA ALPHA
         SBC BETA
         SEC
         SBC #$40          ; (COS)
         TAX               ; ALPHA-BETA
         CLC
         LDA ALPHA
         ADC BETA
         CLC
         ADC #$40          ; (COS)
         TAY               ; ALPHA+BETA
         SEC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA UNITZYLO
         LDA SINCOSHI+$40,X;    COS(A-B)
         SBC SINCOSHI+$40,Y;  - COS(A+B)
         STA UNITZYHI

          ; - COS (ALPHA) * COS (BETA)
         CLC
         LDA ALPHA
         ADC #$80+$40      ; (-COS)
         SEC
         SBC BETA
         SEC
         SBC #$40          ; (COS)
         TAX               ; ALPHA-BETA
         CLC
         LDA ALPHA
         ADC #$80+$40      ; (-COS)
         CLC
         ADC BETA
         CLC
         ADC #$40          ; (COS)
         TAY               ; ALPHA+BETA
         CLC
         LDA SINCOSLO+$40,X
         SBC SINCOSLO+$40,Y
         STA UNITZZLO
         LDA SINCOSHI+$40,X;    COS(A-B)
         SBC SINCOSHI+$40,Y;  - COS(A+B)
         STA UNITZZHI



         ; CALCULATE NEW COORDINATES,
         ;  PRETTY UNOPTIMIZED TOO
         ; NEUE KOORDINATEN BERECHNEN,
         ;  AUCH ZIEMLICH UNOPTIMIERT

          ; P(-1;+1;+1)
         SEC
         LDA UNITXYLO
         SBC UNITXXLO
         TAX
         LDA UNITXYHI
         SBC UNITXXHI
         TAY
         CLC
         TXA
         ADC UNITXZLO
         STA X2DCRDFR+$00
         TYA
         ADC UNITXZHI
         STA X2DCORDS+$00

         SEC
         LDA UNITYYLO
         SBC UNITYXLO
         TAX
         LDA UNITYYHI
         SBC UNITYXHI
         TAY
         CLC
         TXA
         ADC UNITYZLO
         TYA
         ADC UNITYZHI
         STA Y2DCORDS+$00

         SEC
         LDA UNITZYLO
         SBC UNITZXLO
         TAX
         LDA UNITZYHI
         SBC UNITZXHI
         TAY
         CLC
         TXA
         ADC UNITZZLO
         STA Z2DCRDFR+$00
         TYA
         ADC UNITZZHI
         STA Z2DCORDS+$00

          ; P(+1;+1;+1)
         CLC
         LDA UNITXXLO
         ADC UNITXYLO
         TAX
         LDA UNITXXHI
         ADC UNITXYHI
         TAY
         CLC
         TXA
         ADC UNITXZLO
         STA X2DCRDFR+$01
         TYA
         ADC UNITXZHI
         STA X2DCORDS+$01

         CLC
         LDA UNITYXLO
         ADC UNITYYLO
         TAX
         LDA UNITYXHI
         ADC UNITYYHI
         TAY
         CLC
         TXA
         ADC UNITYZLO
         TYA
         ADC UNITYZHI
         STA Y2DCORDS+$01

         CLC
         LDA UNITZXLO
         ADC UNITZYLO
         TAX
         LDA UNITZXHI
         ADC UNITZYHI
         TAY
         CLC
         TXA
         ADC UNITZZLO
         STA Z2DCRDFR+$01
         TYA
         ADC UNITZZHI
         STA Z2DCORDS+$01

          ; P(-1;+1;-1)
         SEC
         LDA UNITXYLO
         SBC UNITXXLO
         TAX
         LDA UNITXYHI
         SBC UNITXXHI
         TAY
         SEC
         TXA
         SBC UNITXZLO
         STA X2DCRDFR+$02
         TYA
         SBC UNITXZHI
         STA X2DCORDS+$02

         SEC
         LDA UNITYYLO
         SBC UNITYXLO
         TAX
         LDA UNITYYHI
         SBC UNITYXHI
         TAY
         SEC
         TXA
         SBC UNITYZLO
         TYA
         SBC UNITYZHI
         STA Y2DCORDS+$02

         SEC
         LDA UNITZYLO
         SBC UNITZXLO
         TAX
         LDA UNITZYHI
         SBC UNITZXHI
         TAY
         SEC
         TXA
         SBC UNITZZLO
         STA Z2DCRDFR+$02
         TYA
         SBC UNITZZHI
         STA Z2DCORDS+$02

          ; P(+1;+1;-1)
         CLC
         LDA UNITXXLO
         ADC UNITXYLO
         TAX
         LDA UNITXXHI
         ADC UNITXYHI
         TAY
         SEC
         TXA
         SBC UNITXZLO
         STA X2DCRDFR+$03
         TYA
         SBC UNITXZHI
         STA X2DCORDS+$03

         CLC
         LDA UNITYXLO
         ADC UNITYYLO
         TAX
         LDA UNITYXHI
         ADC UNITYYHI
         TAY
         SEC
         TXA
         SBC UNITYZLO
         TYA
         SBC UNITYZHI
         STA Y2DCORDS+$03

         CLC
         LDA UNITZXLO
         ADC UNITZYLO
         TAX
         LDA UNITZXHI
         ADC UNITZYHI
         TAY
         SEC
         TXA
         SBC UNITZZLO
         STA Z2DCRDFR+$03
         TYA
         SBC UNITZZHI
         STA Z2DCORDS+$03

          ; P(-1;-1;+1)
         SEC
         LDA UNITXZLO
         SBC UNITXXLO
         TAX
         LDA UNITXZHI
         SBC UNITXXHI
         TAY
         SEC
         TXA
         SBC UNITXYLO
         STA X2DCRDFR+$04
         TYA
         SBC UNITXYHI
         STA X2DCORDS+$04

         SEC
         LDA UNITYZLO
         SBC UNITYXLO
         TAX
         LDA UNITYZHI
         SBC UNITYXHI
         TAY
         SEC
         TXA
         SBC UNITYYLO
         TYA
         SBC UNITYYHI
         STA Y2DCORDS+$04

         SEC
         LDA UNITZZLO
         SBC UNITZXLO
         TAX
         LDA UNITZZHI
         SBC UNITZXHI
         TAY
         SEC
         TXA
         SBC UNITZYLO
         STA Z2DCRDFR+$04
         TYA
         SBC UNITZYHI
         STA Z2DCORDS+$04

          ; P(+1;-1;+1)
         SEC
         LDA UNITXXLO
         SBC UNITXYLO
         TAX
         LDA UNITXXHI
         SBC UNITXYHI
         TAY
         CLC
         TXA
         ADC UNITXZLO
         STA X2DCRDFR+$05
         TYA
         ADC UNITXZHI
         STA X2DCORDS+$05

         SEC
         LDA UNITYXLO
         SBC UNITYYLO
         TAX
         LDA UNITYXHI
         SBC UNITYYHI
         TAY
         CLC
         TXA
         ADC UNITYZLO
         TYA
         ADC UNITYZHI
         STA Y2DCORDS+$05

         SEC
         LDA UNITXZLO
         SBC UNITZYLO
         TAX
         LDA UNITZXHI
         SBC UNITZYHI
         TAY
         CLC
         TXA
         ADC UNITZZLO
         STA Z2DCRDFR+$05
         TYA
         ADC UNITZZHI
         STA Z2DCORDS+$05

          ; P(-1;-1;-1)
         SEC
         LDA #$00
         SBC UNITXXLO
         TAX
         LDA #$00
         SBC UNITXXHI
         TAY
         SEC
         TXA
         SBC UNITXYLO
         TAX
         TYA
         SBC UNITXYHI
         TAY
         SEC
         TXA
         SBC UNITXZLO
         STA X2DCRDFR+$06
         TYA
         SBC UNITXZHI
         STA X2DCORDS+$06

         SEC
         LDA #$00
         SBC UNITYXLO
         TAX
         LDA #$00
         SBC UNITYXHI
         TAY
         SEC
         TXA
         SBC UNITYYLO
         TAX
         TYA
         SBC UNITYYHI
         TAY
         SEC
         TXA
         SBC UNITYZLO
         TYA
         SBC UNITYZHI
         STA Y2DCORDS+$06

         SEC
         LDA #$00
         SBC UNITZXLO
         TAX
         LDA #$00
         SBC UNITZXHI
         TAY
         SEC
         TXA
         SBC UNITZYLO
         TAX
         TYA
         SBC UNITZYHI
         TAY
         SEC
         TXA
         SBC UNITZZLO
         STA Z2DCRDFR+$06
         TYA
         SBC UNITZZHI
         STA Z2DCORDS+$06

          ; P(+1;-1;-1)
         SEC
         LDA UNITXXLO
         SBC UNITXYLO
         TAX
         LDA UNITXXHI
         SBC UNITXYHI
         TAY
         SEC
         TXA
         SBC UNITXZLO
         STA X2DCRDFR+$07
         TYA
         SBC UNITXZHI
         STA X2DCORDS+$07

         SEC
         LDA UNITYXLO
         SBC UNITYYLO
         TAX
         LDA UNITYXHI
         SBC UNITYYHI
         TAY
         SEC
         TXA
         SBC UNITYZLO
         TYA
         SBC UNITYZHI
         STA Y2DCORDS+$07

         SEC
         LDA UNITZXLO
         SBC UNITZYLO
         TAX
         LDA UNITZXHI
         SBC UNITZYHI
         TAY
         SEC
         TXA
         SBC UNITZZLO
         STA Z2DCRDFR+$07
         TYA
         SBC UNITZZHI
         STA Z2DCORDS+$07


         ; CONVERT COORDINATES TO 2-D
         ; KOORDINATEN NACH 2D WANDELN

         LDX #NUMPOINT-1
CONVTO2D LDY X2DCRDFR,X
         LDA X2DCORDS,X
         JSR PERSPECT
         STA X2DCORDS,X
         LDY Z2DCRDFR,X
         LDA Z2DCORDS,X
         JSR PERSPECT
         STA Y2DCORDS,X
         DEX
         BPL CONVTO2D


         ; TOGGLE VISIBLE SCREEN
         ; SICHTBAREN BILDSCHIRM
         ;  UMSCHALTEN

         LDA $D012
         CMP #$D6
         BCS *+13
         CMP #$53
         BCC *+9
         LDA #$D6
         CMP $D012
         BCS *-3
         LDA #$01
         EOR CURRCHAR
         STA CURRCHAR
         LDA #CHARSET0(CHARSET1/$0400
         EOR $D018
         STA $D018


         ; CLEAR THE INVISIBLE CHARSET
         ; DEN UNSICHTBAREN ZEICHENSATZ
         ;  LOESCHEN

         LDA #$00
         TAX
         LDY CURRCHAR
         BEQ CLIRCHR1
CLIRCHR0 STA CHARSET0+V+$00,X
         STA CHARSET0+V+$80,X
         STA CHARSET0+V+$0100,X
         STA CHARSET0+V+$0180,X
         STA CHARSET0+V+$0200,X
         STA CHARSET0+V+$0280,X
         STA CHARSET0+V+$0300,X
         STA CHARSET0+V+$0380,X
         STA CHARSET0+V+$0400,X
         STA CHARSET0+V+$0480,X
         STA CHARSET0+V+$0500,X
         STA CHARSET0+V+$0580,X
         STA CHARSET0+V+$0600,X
         STA CHARSET0+V+$0680,X
         STA CHARSET0+V+$0700,X
         STA CHARSET0+V+$0780,X
         INX
         BPL CLIRCHR0
         BMI DRAWLOOP-2
CLIRCHR1 STA CHARSET1+V+$00,X
         STA CHARSET1+V+$80,X
         STA CHARSET1+V+$0100,X
         STA CHARSET1+V+$0180,X
         STA CHARSET1+V+$0200,X
         STA CHARSET1+V+$0280,X
         STA CHARSET1+V+$0300,X
         STA CHARSET1+V+$0380,X
         STA CHARSET1+V+$0400,X
         STA CHARSET1+V+$0480,X
         STA CHARSET1+V+$0500,X
         STA CHARSET1+V+$0580,X
         STA CHARSET1+V+$0600,X
         STA CHARSET1+V+$0680,X
         STA CHARSET1+V+$0700,X
         STA CHARSET1+V+$0780,X
         INX
         BPL CLIRCHR1


         ; DRAW VECTOR OBJECT
         ; VEKTOROBJEKT ZEICHNEN

         LDY #LINEPNT1-LINEPNT0-1
DRAWLOOP STY POINTERS+2
         LDX LINEPNT0,Y
         LDA X2DCORDS,X
         STA BEGX
         LDA Y2DCORDS,X
         STA BEGY
         LDX LINEPNT1,Y
         LDA X2DCORDS,X
         LDY Y2DCORDS,X
         TAX
         JSR DRAWLINE
         LDY POINTERS+2
         DEY
         BPL DRAWLOOP
         JMP MAINLOOP


         ; IRQ ROUTINE
         ; IRQ-ROUTINE

IRQ      PHA


         ; ADVANCE ANGLES
         ; WINKEL ERHOEHEN

         CLC
         LDA #<ALPHAADD
         ADC ALPHALO
         STA ALPHALO
         LDA #>ALPHAADD
         ADC ALPHAHI
         STA ALPHAHI
         CLC
         LDA #<BETAADD
         ADC BETALO
         STA BETALO
         LDA #>BETAADD
         ADC BETAHI
         STA BETAHI
         CLC
         LDA #<GAMMAADD
         ADC GAMMALO
         STA GAMMALO
         LDA #>GAMMAADD
         ADC GAMMAHI
         STA GAMMAHI

         DEC $D019
         PLA
         RTI


         ;PERFORM PERSPECTIVE DIVISION
         ;PERSPEKTIVDIVISION VOLLFUEHREN

PERSPECT PHA
         BPL NONEGCRD
         PHA
         TYA
         CLC
         EOR #$FF
         ADC #$01
         TAY
         PLA
         EOR #$FF
         ADC #$00
NONEGCRD STA DIVIDEND+0
         STY DIVIDEND+1
         CLC
         LDA #$50; ONLY POSITIVE DEPTH
                 ;  VALUES
                 ; NUR POSITIVE TIEFEN-
                 ;  WERTE
         ADC Y2DCORDS,X
         STA DIVISOR+0
         LDY #$00
         STY DIVISOR+1
         INY
         STY DIVISOR+2
         SEC
DIVLOOP  ROR DIVISOR+0
         ROR DIVISOR+1
         SEC
         LDA DIVIDEND+1
         SBC DIVISOR+1
         TAY
         LDA DIVIDEND+0
         SBC DIVISOR+0
         BCC *+6
         STA DIVIDEND+0
         STY DIVIDEND+1
         ROL DIVISOR+2
         BCC DIVLOOP
         PLA
         ASL A
         LDA DIVISOR+2
         BCC *+4
         EOR #$FF
         ADC #$40;ORIGIN IS AT ($40;$40)
                 ;URSPRUNG BEI ($40;$40)
         RTS


         ; DRAW A LINE
         ; EINE LINIE ZEICHNEN

DRAWLINE STX ENDX
         STY ENDY
         CPX BEGX
         BCS *+14; SWAP LINE END POINTS
         LDA BEGX;  IF THE LINE RUNS
         STA ENDX;  FROM RIGHT TO LEFT
         LDA BEGY; LINIENENDPUNKTE VER-
         STA ENDY;  TAUSCHEN, WENN DIE
         STX BEGX;  LINIE VON RECHTS
         STY BEGY;  NACH LINKS VERLAEUFT
         SEC
         LDA ENDX
         SBC BEGX
         STA DELTAX
         LDA BEGY
         SBC ENDY
         BCC LINTYPE2
         STA DELTAY
         CMP DELTAX
         BCC LINTYPE1


          ; LINE ANGLES FROM -90 TO -45
          ;  DEGREES
          ; LINIENWINKEL VON -90 BIS -45
          ;  GRAD

         DEC ENDY
         LDA #<SPDT0OFS
         PHA
         LDA #>SPDT0OFS
         BCS PUTLINE0


          ; LINE ANGLES FROM -45 TO 0
          ;  DEGREES
          ; LINIENWINKEL VON -45 BIS 0
          ;  GRAD

LINTYPE1 LDA #<SPDT1OFS
         PHA
         LDA #>SPDT1OFS
         BCC PUTLINE0

LINTYPE2 EOR #$FF
         ADC #$01
         STA DELTAY
         CMP DELTAX
         BCS LINTYPE3


          ; LINE ANGLES FROM 0 TO 45
          ;  DEGREES
          ; LINIENWINKEL VON 0 BIS 45
          ;  GRAD

         LDA #<SPDT2OFS
         PHA
         LDA #>SPDT2OFS
         BCC PUTLINE0


          ; LINE ANGLES FROM 45 TO 90
          ;  DEGREES
          ; LINIENWINKEL VON 45 BIS 90
          ;  GRAD

LINTYPE3 INC ENDY
         LDA #<SPDT3OFS
         PHA
         LDA #>SPDT3OFS

PUTLINE0 LDX DELTAX
         LDY DELTAY
         BCS *+6
         LDX DELTAY
         LDY DELTAX
         PHA

         SEC           ; PERFORM DIVI-
         LDA LOG2TABL,Y;  SION TO CALC-
         SBC LOG2TABL,X;  ULATE THE
         STA CLCSLOPE+1;  LINE SLOPE
         LDA LOG2TBH0,Y; DIVISION VOLL-
         SBC LOG2TBH1,X;  FUEHREN, UM
         STA CLCSLOPE+2;  DEN LINIEN-
CLCSLOPE LDA !$00      ;  ANSTIEG ZU
         STA LINSLOPE  ;  BERECHNEN

         CLC
         PLA
         TAY
         PLA
         PHA
         LDA CURRCHAR
         BEQ DRWLNCH1
         PLA
         ADC #<SPIDCOD0
         STA POINTERS+0
         TYA
         ADC #>SPIDCOD0
         STA POINTERS+1
         BNE PUTLINE2
DRWLNCH1 PLA
         ADC #<SPIDCOD1
         STA POINTERS+0
         TYA
         ADC #>SPIDCOD1
         STA POINTERS+1

PUTLINE2 LDY BEGX      ; DETERMINE
         LDA POINTERS+0;  JUMP-IN
         ADC SPDXOFSL,Y;  ADDRESS
         STA SPIDJSR0+1
         STA SPIDJSR1+1
         LDA POINTERS+1; EINSPRUNG-
         ADC SPDXOFSH,Y;  ADRESSE
         STA SPIDJSR0+2;  BESTIMMEN
         STA SPIDJSR1+2
         LDY ENDX
         LDA SPDXOFSL,Y; DETERMINE
         ADC POINTERS+0;  RETURN ADDRESS
         STA POINTERS+0
         LDA SPDXOFSH,Y; RUECKKEHR-
         ADC POINTERS+1;  ADRESSE
         STA POINTERS+1;  BESTIMMEN

         LDA DELTAY
         CMP DELTAX
         BCS BIGSLOPE

         LDY #$08
         LDA #$60; OP-CODE FOR RTS
         STA (POINTERS+0),Y; OP-CODE
                           ;  FUER RTS
         LDX #$80
         LDY BEGY
SPIDJSR0 JSR !$00; DRAW THE LINE
                 ; DIE LINIE ZEICHNEN

         LDY #$08
         LDA #$8A; OP-CODE FOR TXA
         STA (POINTERS+0),Y; OP-CODE
                           ;  FUER TXA
         RTS

BIGSLOPE LDY #$09
         LDA #$C0; OP-CODE FOR CPY #$
                 ; OP-CODE FUER CPY #$
         STA (POINTERS+0),Y
         INY
         LDA ENDY
         STA (POINTERS+0),Y
         INY
         LDA #$D0; OP-CODE FOR BNE
                 ; OP-CODE FUER BNE
         STA (POINTERS+0),Y
         INY
         LDA #$F3; *-11
         STA (POINTERS+0),Y
         INY
         LDA #$60; OP-CODE FOR RTS
                 ; OP-CODE FUER RTS
         STA (POINTERS+0),Y

         CLC
         LDX #$80
         LDY BEGY
SPIDJSR1 JSR !$00; FINALLY DRAW THE LINE
                 ; DIE LINIE ENDLICH
                 ;  ZEICHNEN

         LDY #$09
         LDA #$8A; RESTORE THE SPEEDCODE
         STA (POINTERS+0),Y; DEN SPEED-
         INY     ; CODE WIEDERHERSTELLEN
         LDA #$65
         STA (POINTERS+0),Y
         INY
         LDA #LINSLOPE
         STA (POINTERS+0),Y
         INY
         LDA #$AA
         STA (POINTERS+0),Y
         INY
         LDA #$90
         STA (POINTERS+0),Y
         RTS


         ; SUBROUTINE TO BUILD
         ;  THE SPEEDCODE
         ; UNTERROUTINE ZUM GENERIEREN
         ;  DES SPEEDCODES

MAKSPEED LDA #$88; OP-CODE FOR DEY
                 ; OP-CODE FUER DEY
         STA SPRW0DIR
         STA SPRW1DIR

         LDA #<SPDT0OFS
         LDX #>SPDT0OFS
         JSR MKSPT0SB
         LDA #<SPDT1OFS
         LDX #>SPDT1OFS
         JSR MKSPT1SB

         LDA #$C8; OP-CODE FOR INY
                 ; OP-CODE FUER INY
         STA SPRW0DIR
         STA SPRW1DIR

         LDA #<SPDT2OFS
         LDX #>SPDT2OFS
         JSR MKSPT1SB
         LDA #<SPDT3OFS
         LDX #>SPDT3OFS
         JMP MKSPT0SB

MKSPT0SB CLC
         ADC POINTERS+2
         STA POINTERS+0
         TXA
         ADC POINTERS+3
         STA POINTERS+1
         LDA #%10000000
         STA SPIDRAW0+1
         LDA POINTERS+4
         STA SPIDRAW0+4
         STA SPIDRAW0+7
         LDX #$80; 128 PIXELS WIDTH
                 ; 128 PIXEL BREITE
MKSPT0LP LDY #SPIDRAW1-SPIDRAW0-1
         LDA SPIDRAW0,Y
         STA (POINTERS+0),Y
         DEY
         BPL MKSPT0LP+2
         LDA #SPIDRAW1-SPIDRAW0
         LDY #SPIDRAW0-SPIDRAW0
         JSR NEXTSPID
         BNE MKSPT0LP+0
         RTS

MKSPT1SB CLC
         ADC POINTERS+2
         STA POINTERS+0
         TXA
         ADC POINTERS+3
         STA POINTERS+1
         LDA #%10000000
         STA SPIDRAW1+1
         LDA POINTERS+4
         STA SPIDRAW1+4
         STA SPIDRAW1+7
         LDX #$80; 128 PIXELS WIDTH
                 ; 128 PIXEL BREITE
MKSPT1LP LDY #SPIDRAWE-SPIDRAW1-1
         LDA SPIDRAW1,Y
         STA (POINTERS+0),Y
         DEY
         BPL MKSPT1LP+2
         LDA #SPIDRAWE-SPIDRAW1
         LDY #SPIDRAW1-SPIDRAW0
         JSR NEXTSPID
         BNE MKSPT1LP+0
         RTS

NEXTSPID CLC
         ADC POINTERS+0
         STA POINTERS+0
         BCC *+4
         INC POINTERS+1
         LDA SPIDRAW0+1,Y
         PHA
         LSR A
         PLA
         ROR A
         STA SPIDRAW0+1,Y
         BCC NXTSPRET
         CLC
         LDA #$80; 1 CHAR COLUMN IS 128
                 ;  (16X8) BYTES
                 ; 1 ZEICHENSPALTE SIND
                 ;  128 (16*8) BYTES
         ADC SPIDRAW0+3,Y
         STA SPIDRAW0+3,Y
         STA SPIDRAW0+6,Y
         LDA #$00
         ADC SPIDRAW0+4,Y
         STA SPIDRAW0+4,Y
         STA SPIDRAW0+7,Y
NXTSPRET DEX
         RTS


         ; SPEEDCODE ELEMENT FOR A
         ;  SLOPE ANGLE OF +/-90 TO  
         ;  +/-45 DEGREES
         ; SPEEDCODEELEMENT FUER EINEN
         ;  STEIGUNGSWINKEL VON +/-90
         ;  BIS +/-45 GRAD

SPIDRAW0 LDA #$00
         ORA !$00,Y
         STA !$00,Y
SPRW0DIR .BYTE $00
         TXA
         ADC LINSLOPE
         TAX
         BCC SPIDRAW0


         ; SPEEDCODE ELEMENT FOR A
         ;  SLOPE ANGLE OF +/-45 TO 0
         ;  DEGREES
         ; SPEEDCODEELEMENT FUER EINEN
         ;  STEIGUNGSWINKEL VON +/-45
         ;  BIS 0 GRAD

SPIDRAW1 LDA #$00
         ORA !$00,Y
         STA !$00,Y
         TXA
         ADC LINSLOPE
         TAX
         BCC *+3
SPRW1DIR .BYTE $00

SPIDRAWE

         ; TABLE WITH THE LINE BEGIN
         ;  AND END POINTS
         ; TABELLE DER LINIENANFANGS-
         ;  UND ENDPUNKTE

LINEPNT0 .BYTE 0,1,3,2,0,1,2,3,4,5,7,6
LINEPNT1 .BYTE 1,3,2,0,4,5,6,7,5,7,6,4


NMI      RTI


         *= $0800

RETURN   SEI
         LDA #$37
         STA $01
         LDX #$FF
         TXS
         JSR $FDA3
         LDA #$00
         TAY
         STA $02,Y
         STA $0200,Y
         STA $0300,Y
         INY
         BNE *-10
         LDX #$3C
         LDY #$03
         STX $B2
         STY $B3
         LDX #$00
         LDY #$A0
         JSR $FD8C
         JSR $FD15
         JSR $FF5B
         JSR $E453
         JSR $E3BF
         LDX #$01
         STX $DF06
         DEX
         STX $DF02
         STX $DF04
         LDY #$08
         STY $DF03
         STY $DF05
         LDY #$F8
         STY $DF07
         DEY
         STY $DF08
         STX $DF0A
         LDA #$EC
         STA $DF01
         LDY #$1F
         LDA DORETURN,Y
         STA $0340,Y
         DEY
         BPL *-7
         JSR $0340
         STX $DF06
         LDA #$ED
         STA $DF01
         LDA #$8F
         PHA
         LDA #$FF
         PHA
         JMP $0340
DORETURN SEI
         LDA #$30
         STA $01
         LDA $FF00
         STA $FF00
         LDA #$37
         STA $01
         RTS