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Dim3Paint.Mod
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Dim3Paint.Mod
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(* OBERON System 3, Release 2.3.
Copyright 1999 ETH Zürich Institute for Computer Systems,
ETH Center, CH-8092 Zürich. e-mail: [email protected].
This module may be used under the conditions of the general Oberon
System 3 license contract. The full text can be downloaded from
"ftp://ftp.inf.ethz.ch/pub/software/Oberon/System3/license.txt;A"
Under the license terms stated it is in particular (a) prohibited to modify
the interface of this module in any way that disagrees with the style
or content of the system and (b) requested to provide all conversions
of the source code to another platform with the name OBERON. *)
MODULE Dim3Paint; (** portable *) (* David Ulrich Nov 95 - März 96 *)
(** Dim3Paint covers the basic drawing functions of the module Dim3Engine. It includes color management and
polygon drawing with and without the dynamic screen data structure **)
IMPORT
Display, Display3, Pictures, Texts, Oberon, Files, SYSTEM, Math, Dim3Base;
CONST
NoPattern = 0; Light = 1; Middle = 2; Dark = 3;
PersLimit = 2; (* maximal limit for no perspective correction *)
Ln2 = 0.693147; (* ln(2) *)
MinTexture = 2; MaxTexture = 200; (* minimal and maximal texture size for mipmaps *)
cheat = 0.9999;
TYPE
TextureMap* = POINTER TO TextureMapDesc; (** pointer to background bitmap for shaded texture **)
DSEntry* = POINTER TO DSEntryDesc; (** Pointer to a dynamic screen entry **)
TSEntry* = POINTER TO TSEntryDesc; (** Pointer to the scanline entry for a transparent texture **)
Color = POINTER TO ColorDesc;
TextureMapDesc = RECORD END;
DSEntryDesc = RECORD (* dynamic screen entry *)
min,max: INTEGER;
active: BOOLEAN;
next: DSEntry;
END;
TSEntryDesc = RECORD (* Scanline entry for transparent textures *)
texture: TextureMap;
X, Y, W: INTEGER;
u, v, uStep, vStep: REAL;
next: TSEntry;
END;
ColorDesc = RECORD (* data structure of dithering table *)
pattern: LONGINT; deltaR, deltaG, deltaB: INTEGER;
END;
Point = RECORD (* help structure for points *)
x, y, u, v, w: REAL;
END;
VAR
T: Texts.Writer;
DSPool: DSEntry;
TSPool: TSEntry;
ColorIndex: ARRAY 10, 10, 6 OF INTEGER;
DitherTab: ARRAY 4, 4, 4 OF Color;
PatternTable: ARRAY 4 OF LONGINT;
ColorTab: ARRAY 3,256 OF INTEGER;
PDots: ARRAY 4,4 OF BOOLEAN;
seed: LONGINT;
GrayIndex: ARRAY 5 OF INTEGER;
(* Random procedure for dithering *)
PROCEDURE Random (): REAL;
CONST a = 16807; m = 2147483647; q = m DIV a; r = m MOD a; (*invm = 0.025 / m;*)
BEGIN
seed := a*(seed MOD q) - r*(seed DIV q);
IF seed <= 0 THEN seed := seed + m END;
RETURN (seed * (0.025 / m) - 0.0125);
END Random;
(*--- Color Handling ---*)
(** initialize standard rembrandt colormap, initialize color and dither tables **)
PROCEDURE InitColors*;
VAR F: Files.File; R: Files.Rider;
i,h,k, pattern, iSgn, hSgn, kSgn, sum, R1, G, B: INTEGER;
r, g, b: CHAR;
PROCEDURE GetNearestColor(r,g,b : INTEGER):INTEGER;
VAR col, i: INTEGER; d, t, min: LONGINT;
BEGIN
IF (r = g) & (r = b) THEN (* use only grayscale colors *)
min := MAX(LONGINT); col := Dim3Base.White;
i := 0;
WHILE i # 256 DO
IF (ColorTab[0][i] = ColorTab[1][i]) & (ColorTab[0][i] = ColorTab[2][i]) THEN
d := (r - ColorTab[0][i]);
IF ABS(d) < min THEN min := ABS(d); col := i END;
END;
INC(i)
END;
RETURN col
ELSE
min := MAX(LONGINT);
i := 0;
WHILE i # 256 DO
t := (r - ColorTab[0][i]);
IF r > ColorTab[0][i] THEN t := t*2 END; d := t * t;
t := (g - ColorTab[1][i]);
IF g > ColorTab[1][i] THEN t := t*2 END; INC(d, t * t);
t := (b - ColorTab[2][i]);
IF b > ColorTab[2][i] THEN t := t*2 END; INC(d, t * t);
IF ABS(d) < min THEN min := ABS(d); col := i END;
INC(i)
END;
RETURN col
END;
END GetNearestColor;
BEGIN
(* works only with 256 colors *)
IF Display.Depth(Display.ColLeft) # 8 THEN
Texts.WriteString(T, "3D-Engine: current implementation works on 256 color systems");
Texts.WriteLn(T); Texts.Append(Oberon.Log, T.buf);
HALT(99);
END;
FOR i := 0 TO 3 DO
IF i = 0 THEN iSgn := 0 ELSE iSgn := 1 END;
FOR h := 0 TO 3 DO
IF h = 0 THEN hSgn := 0 ELSE hSgn := 1 END;
FOR k := 0 TO 3 DO
IF k = 0 THEN kSgn := 0 ELSE kSgn := 1 END;
NEW(DitherTab[i][h][k]);
DitherTab[i][h][k].deltaR := iSgn;
DitherTab[i][h][k].deltaG := hSgn;
DitherTab[i][h][k].deltaB := kSgn;
sum := 2 * iSgn + 2 * hSgn + kSgn;
IF sum # 0 THEN pattern := (2 * i + 2 * h + k) DIV sum ELSE pattern := 0 END;
DitherTab[i][h][k].pattern := PatternTable[pattern];
END;
END;
END;
F:= Files.Old("Rembrandt0.Pal");
Files.Set(R, F, 0);
FOR i:= 0 TO 255 DO
Files.Read(R, r);
Files.Read(R, g);
Files.Read(R, b);
ColorTab[0][i] := ORD(r);
ColorTab[1][i] := ORD(g);
ColorTab[2][i] := ORD(b);
Display.SetColor(i, ORD(r), ORD(g), ORD(b));
END;
Dim3Base.CheckColorTab(ColorTab[0], ColorTab[1], ColorTab[2]);
FOR i := 0 TO 8 DO
FOR h := 0 TO 8 DO
FOR k := 0 TO 4 DO
R1 := SHORT(ENTIER(i*31.99)); G := SHORT(ENTIER(h*31.99)); B := SHORT(ENTIER(k*63.99));
ColorIndex[i][h][k] := GetNearestColor(R1, G, B);
END;
END;
END;
FOR i := 0 TO 8 DO
FOR h := 0 TO 4 DO
ColorIndex[9][i][h] := ColorIndex[8][i][h];
ColorIndex[i][9][h] := ColorIndex[i][8][h];
END;
END;
FOR i := 0 TO 8 DO
FOR h := 0 TO 8 DO
ColorIndex[i][h][5] := ColorIndex[i][h][4];
END;
END;
FOR i := 0 TO 4 DO
B := SHORT(ENTIER(i*63.99));
GrayIndex[i] := GetNearestColor(B, B, B);
END;
END InitColors;
(** get color index for colormap that matches best **)
PROCEDURE GetColor* (col: ARRAY OF REAL; light: REAL; grayscale: BOOLEAN):INTEGER;
VAR R, G, B: LONGINT;
BEGIN
IF light <= 0.0 THEN
RETURN Dim3Base.Black
END;
IF grayscale THEN
R := ENTIER(light * col[0] * 4.99);
IF R > 4 THEN R := 4 END;
RETURN GrayIndex[R]
ELSE
R := ENTIER(light * col[0] * 8.99);
IF R > 8 THEN R := 8 END;
G := ENTIER(light * col[1] * 8.99);
IF G > 8 THEN G := 8 END;
B := ENTIER(light * col[2] * 4.99);
IF B > 4 THEN B := 4 END;
RETURN ColorIndex[R][G][B]
END;
END GetColor;
(* get color indexes for colormap and dithering that matches best *)
PROCEDURE GetColorDither (col: ARRAY OF REAL; light: REAL; grayscale: BOOLEAN; VAR baseCol, patCol: INTEGER;
VAR pat: LONGINT; rand: REAL);
VAR R, G, B, R1, G1, B1, RMod, GMod, BMod: LONGINT; color: Color;
BEGIN
light := light + rand;
IF light <= 0.0 THEN
baseCol := Dim3Base.Black;
pat := NoPattern;
RETURN;
END;
IF grayscale THEN
B := ENTIER(light * 16.99 * col[2]); IF B > 16 THEN B := 16 END;
B1 := ASH(B, -2);
BMod := (B - ASH(B1, 2));
baseCol := GrayIndex[B1];
pat := BMod;
IF B1 < 4 THEN patCol := GrayIndex[B1 + 1] ELSE patCol := baseCol END
ELSE
R := ENTIER(light * 32.99 * col[0]); IF R > 32 THEN R := 32 END;
R1 := ASH(R, -2);
RMod := (R - ASH(R1, 2));
G := ENTIER(light * 32.99 * col[1]); IF G > 32 THEN G := 32 END;
G1 := ASH(G, -2);
GMod := (G - ASH(G1, 2));
B := ENTIER(light * 16.99 * col[2]); IF B > 16 THEN B := 16 END;
B1 := ASH(B, -2);
BMod := (B - ASH(B1, 2));
color := DitherTab[RMod][GMod][BMod];
baseCol := ColorIndex[R1][G1][B1];
patCol := ColorIndex[R1 + color.deltaR][G1 + color.deltaG][B1 + color.deltaB];
pat := color.pattern;
END;
END GetColorDither;
(* get color indexes for colormap and dithering that matches best, for specular reflection*)
PROCEDURE GetColorSpecular (col: ARRAY OF REAL; light, spec: REAL; grayscale: BOOLEAN; VAR baseCol, patCol: INTEGER;
VAR pat: LONGINT; rand: REAL);
VAR R, G, B, R1, G1, B1, RMod, GMod, BMod: LONGINT; color: Color;
BEGIN
light := light + rand; spec := spec + 0.001;
IF light <= 0.0 THEN
baseCol := Dim3Base.Black;
pat := NoPattern;
RETURN;
END;
IF grayscale THEN
B := ENTIER(light * 16.99 * (col[2] + spec)); IF B > 16 THEN B := 16 END;
B1 := ASH(B, -2);
BMod := (B - ASH(B1, 2));
baseCol := GrayIndex[B1];
pat := BMod;
IF B1 < 4 THEN patCol := GrayIndex[B1 + 1] ELSE patCol := baseCol END
ELSE
R := ENTIER(light * 32.99 * (col[0] + spec)); IF R > 32 THEN R := 32 END;
R1 := ASH(R, -2);
RMod := (R - ASH(R1, 2));
G := ENTIER(light * 32.99 * (col[1] + spec)); IF G > 32 THEN G := 32 END;
G1 := ASH(G, -2);
GMod := (G - ASH(G1, 2));
B := ENTIER(light * 16.99 * (col[2] + spec)); IF B > 16 THEN B := 16 END;
B1 := ASH(B, -2);
BMod := (B - ASH(B1, 2));
color := DitherTab[RMod][GMod][BMod];
baseCol := ColorIndex[R1][G1][B1];
patCol := ColorIndex[R1 + color.deltaR][G1 + color.deltaG][B1 + color.deltaB];
pat := color.pattern
END
END GetColorSpecular;
(*--- TS and DS entry mangement ---*)
(* freeing of a DSEntry to pool *)
PROCEDURE FreeDSEntry(entry: DSEntry);
BEGIN
entry.next := DSPool;
DSPool := entry
END FreeDSEntry;
(** freeing of a DSEntryArray to pool **)
PROCEDURE FreeDSList* (VAR ds: ARRAY OF DSEntry; n: INTEGER);
VAR
i: INTEGER;
entry: DSEntry;
BEGIN
FOR i := 0 TO n DO
IF ds[i] # NIL THEN
entry := ds[i];
WHILE entry.next # NIL DO
entry := entry.next;
END;
entry.next := DSPool;
DSPool := ds[i];
ds[i] := NIL
END;
END;
END FreeDSList;
(* allocating of a DSEntry from pool *)
PROCEDURE AllocDSEntry(VAR entry: DSEntry);
BEGIN
IF DSPool = NIL THEN
NEW(entry)
ELSE
entry := DSPool;
DSPool := entry.next;
END;
entry.next := NIL;
entry.active := TRUE;
END AllocDSEntry;
(* allocating of a TSEntry from pool *)
PROCEDURE AllocTSEntry(VAR entry: TSEntry);
BEGIN
IF TSPool = NIL THEN
NEW(entry)
ELSE
entry := TSPool;
TSPool := entry.next;
END;
END AllocTSEntry;
(** initialisation of the dynamic Screen datastructure, max: screen width, n: screen height **)
PROCEDURE InitDynScreen*(VAR ds: ARRAY OF DSEntry; max,n: INTEGER);
VAR
i: INTEGER;
BEGIN
FOR i := 0 TO n DO
AllocDSEntry(ds[i]);
ds[i].min := 0;
ds[i].max := max;
END;
END InitDynScreen;
(*--- Rendering ---*)
(** Fill not painted rest of the screen with color col, free dynamic screen datastructure **)
PROCEDURE DrawRest* (P: Pictures.Picture; ds: ARRAY OF DSEntry; col: INTEGER);
VAR
i,max: INTEGER;
entry, old: DSEntry;
BEGIN
Dim3Base.SetPicture(P);
max := P.height;
FOR i := 0 TO max DO
entry := ds[i];
WHILE entry # NIL DO
Dim3Base.ReplConst(col, entry.min, i, entry.max - entry.min + 1);
old := entry;
entry := entry.next;
FreeDSEntry(old);
END;
END;
END DrawRest;
(* Draw pattern using ReplConst and Dot *)
PROCEDURE DrawPattern(baseCol, patCol: INTEGER; pattern: LONGINT;
X, Y, W: INTEGER);
VAR oddY, oddX: BOOLEAN; index: INTEGER; pictAdr: LONGINT;
BEGIN
oddY := ODD(Y); oddX := ODD(X);
IF ((pattern = Light) & oddY) OR (pattern = NoPattern) THEN
Dim3Base.ReplConst(baseCol, X, Y, W);
RETURN;
ELSIF (pattern = Dark) & (~oddY) THEN
Dim3Base.ReplConst(patCol, X, Y, W);
RETURN;
ELSIF oddY THEN
IF oddX THEN index := 1 ELSE index := 0 END;
ELSE
IF oddX THEN index := 0 ELSE index := 1 END;
END;
Dim3Base.ReplConst(baseCol, X, Y, W);
pictAdr := Dim3Base.GetAddress(X, Y);
WHILE index < W DO
SYSTEM.PUT(pictAdr + index, CHR(patCol));
INC(index,2)
END;
END DrawPattern;
(* split dynamic screen entry into two entries *)
PROCEDURE SplitSegment(i,j: INTEGER; k: DSEntry);
VAR
newEntry: DSEntry;
BEGIN
AllocDSEntry(newEntry);
newEntry.min := j + 1;
newEntry.max := k.max;
k.max := i - 1;
newEntry.next := k.next;
k.next := newEntry;
END SplitSegment;
(* draw a gouraud shaded polygon scanline, with dithering and specular reflection *)
PROCEDURE DrawSpecularSegment(sel: BOOLEAN; col: ARRAY OF REAL; planeCol: INTEGER; grayscale: BOOLEAN; entry: DSEntry;
xL, xR: REAL; Y, botL, botR, topL, topR: INTEGER; y, i, s: ARRAY OF REAL);
VAR XL, XR, W: INTEGER; t1, t3, iL, iR, dInten, dSpec, sL, sR: REAL;
PROCEDURE Display(X, W: INTEGER; iLeft, sLeft: REAL);
VAR x, color, oddY, oddX, patCol: INTEGER; inten, spec: REAL; pat, pictAdr: LONGINT; rand: REAL;
BEGIN
IF W > 2 THEN rand := Random() ELSE rand := 0 END;
IF ODD(Y) THEN oddY := 0 ELSE oddY := 2 END;
oddX := 0;
inten := iLeft; spec := sLeft;
pictAdr := Dim3Base.GetAddress(X, Y);
WHILE W >= 15 DO
FOR x := 1 TO 15 DO
GetColorSpecular(col, inten, spec, grayscale, color, patCol, pat, rand);
inten := inten + dInten; spec := spec +dSpec;
IF PDots[pat][oddY + oddX] THEN
SYSTEM.PUT(pictAdr, CHR(patCol))
ELSE
SYSTEM.PUT(pictAdr, CHR(color))
END;
INC(pictAdr);
oddX := (oddX + 1) MOD 2
END;
rand := Random(); DEC(W, 15);
END;
WHILE W > 0 DO
GetColorSpecular(col, inten, spec, grayscale, color, patCol, pat, rand);
inten := inten + dInten; spec := spec + dSpec;
IF PDots[pat][oddY + oddX] THEN
SYSTEM.PUT(pictAdr, CHR(patCol))
ELSE
SYSTEM.PUT(pictAdr, CHR(color))
END;
INC(pictAdr);
oddX := (oddX + 1) MOD 2;
DEC(W);
END;
END Display;
BEGIN
IF xL <= xR THEN
XL := SHORT(ENTIER(xL)) + 1;
XR := SHORT(ENTIER(xR));
W := XR - XL + 1;
t1 := (y[topL] - Y) / (y[topL] - y[botL]);
t3 := i[botL] - i[topL]; iL := i[topL] + t1 * t3;
t3 := s[botL] - s[topL]; sL := s[topL] + t1 * t3;
t1 := (y[topR] - Y) / (y[topR] - y[botR]);
t3 := i[botR] - i[topR]; iR := i[topR] + t1 * t3;
t3 := s[botR] - s[topR]; sR := s[topR] + t1 * t3;
ELSE
XL := SHORT(ENTIER(xR)) + 1;
XR := SHORT(ENTIER(xL));
W := XR - XL + 1;
t1 := (y[topL] - Y) / (y[topL] - y[botL]);
t3 := i[botL] - i[topL]; iR := i[topL] + t1 * t3;
t3 := s[botL] - s[topL]; sR := s[topL] + t1 * t3;
t1 := (y[topR] - Y) / (y[topR] - y[botR]);
t3 := i[botR] - i[topR]; iL := i[topR] + t1 * t3;
t3 := s[botR] - s[topR]; sL := s[topR] + t1 * t3;
END;
dInten := (iR - iL) / (W - cheat);
dSpec := (sR - sL) / (W - cheat);
(* Loop for merging *)
LOOP
IF W <= 0 THEN EXIT END;
IF ~entry.active THEN
entry := entry.next
ELSIF XR < entry.min THEN (* case 1 *)
EXIT;
ELSIF XL > entry.max THEN (* case 8 *)
entry := entry.next;
ELSE
IF XR < entry.max THEN
IF XL <= entry.min THEN (* case 2 *)
Display(entry.min, XR - entry.min + 1, iL + (entry.min - XL) * dInten, sL + (entry.min - XL) * dSpec);
entry.min := XR + 1;
EXIT;
ELSE (* case 3 *)
Display( XL, W, iL, sL);
SplitSegment(XL, XR, entry);
EXIT;
END;
ELSIF XR > entry.max THEN
IF XL <= entry.min THEN (* case 6 *)
Display(entry.min, entry.max - entry.min + 1, iL + (entry.min - XL) * dInten, sL + (entry.min - XL) * dSpec);
entry.active := FALSE;
entry := entry.next;
ELSE (* case 7 *)
Display(XL, entry.max - XL + 1, iL, sL);
entry.max := XL - 1;
entry := entry.next;
END;
ELSE
IF XL <= entry.min THEN (* case 4 *)
Display(entry.min, entry.max - entry.min + 1, iL + (entry.min - XL) * dInten, sL + (entry.min - XL) * dSpec);
entry.active := FALSE;
EXIT;
ELSE (* case 5 *)
Display(XL, W, iL, sL);
entry.max := XL - 1;
EXIT;
END;
END;
END;
END;
END DrawSpecularSegment;
(* draw a gouraud shaded polygon scanline, with dithering *)
PROCEDURE DrawDitherSegment(sel: BOOLEAN; col: ARRAY OF REAL; planeCol: INTEGER; grayscale: BOOLEAN; entry: DSEntry;
xL, xR: REAL; Y, botL, botR, topL, topR: INTEGER; y, i, s: ARRAY OF REAL);
VAR XL, XR, W: INTEGER; t1, t2, t3, iL, iR, dInten: REAL;
PROCEDURE Display(X, W: INTEGER; iLeft: REAL);
VAR x, color, oddY, oddX, patCol: INTEGER; inten: REAL; pat, pictAdr: LONGINT; rand: REAL;
BEGIN
IF W > 2 THEN rand := Random() ELSE rand := 0 END;
IF ODD(Y) THEN oddY := 0 ELSE oddY := 2 END;
oddX := 0;
inten := iLeft;
pictAdr := Dim3Base.GetAddress(X, Y);
WHILE W >= 15 DO
FOR x := 1 TO 15 DO
GetColorDither(col, inten, grayscale, color, patCol, pat, rand);
inten := inten + dInten;
IF PDots[pat][oddY + oddX] THEN
SYSTEM.PUT(pictAdr, CHR(patCol))
ELSE
SYSTEM.PUT(pictAdr, CHR(color))
END;
INC(pictAdr);
oddX := (oddX + 1) MOD 2
END;
rand := Random(); DEC(W, 15);
END;
WHILE W > 0 DO
GetColorDither(col, inten, grayscale, color, patCol, pat, rand);
inten := inten + dInten;
IF PDots[pat][oddY + oddX] THEN
SYSTEM.PUT(pictAdr, CHR(patCol))
ELSE
SYSTEM.PUT(pictAdr, CHR(color))
END;
INC(pictAdr);
oddX := (oddX + 1) MOD 2;
DEC(W);
END;
END Display;
BEGIN
IF xL <= xR THEN
XL := SHORT(ENTIER(xL)) + 1;
XR := SHORT(ENTIER(xR));
W := XR - XL + 1;
t1 := y[topL] - Y; t2 := y[topL] - y[botL]; t3 := i[botL] - i[topL];
iL := i[topL] + t1 / t2 * t3;
t1 := y[topR] - Y; t2 := y[topR] - y[botR]; t3 := i[botR] - i[topR];
iR := i[topR] + t1 / t2 * t3;
dInten := (iR - iL) / (W - cheat);
ELSE
XL := SHORT(ENTIER(xR)) + 1;
XR := SHORT(ENTIER(xL));
W := XR - XL + 1;
t1 := y[topL] - Y; t2 := y[topL] - y[botL]; t3 := i[botL] - i[topL];
iR := i[topL] + t1 / t2 * t3;
t1 := y[topR] - Y; t2 := y[topR] - y[botR]; t3 := i[botR] - i[topR];
iL := i[topR] + t1 / t2 * t3;
dInten := (iR - iL) / (W - cheat);
END;
(* Loop for merging *)
LOOP
IF W <= 0 THEN EXIT END;
IF ~entry.active THEN
entry := entry.next
ELSIF XR < entry.min THEN (* case 1 *)
EXIT;
ELSIF XL > entry.max THEN (* case 8 *)
entry := entry.next;
ELSE
IF XR < entry.max THEN
IF XL <= entry.min THEN (* case 2 *)
Display(entry.min, XR - entry.min + 1,iL + (entry.min - XL) * dInten);
entry.min := XR + 1;
EXIT;
ELSE (* case 3 *)
Display( XL, W, iL);
SplitSegment(XL, XR, entry);
EXIT;
END;
ELSIF XR > entry.max THEN
IF XL <= entry.min THEN (* case 6 *)
Display(entry.min, entry.max - entry.min + 1, iL + (entry.min - XL) * dInten);
entry.active := FALSE;
entry := entry.next;
ELSE (* case 7 *)
Display(XL, entry.max - XL + 1, iL);
entry.max := XL - 1;
entry := entry.next;
END;
ELSE
IF XL <= entry.min THEN (* case 4 *)
Display(entry.min, entry.max - entry.min + 1, iL + (entry.min - XL) * dInten);
entry.active := FALSE;
EXIT;
ELSE (* case 5 *)
Display(XL, W, iL);
entry.max := XL - 1;
EXIT;
END;
END;
END;
END;
END DrawDitherSegment;
(* draw a gouraud shaded polygon scanline, no dithering *)
PROCEDURE DrawGouraudSegment(sel: BOOLEAN; col: ARRAY OF REAL; planeCol: INTEGER; grayscale: BOOLEAN; entry: DSEntry;
xL, xR: REAL; Y, botL, botR, topL, topR: INTEGER; y, i, s: ARRAY OF REAL);
VAR XL, XR, W: INTEGER; t1, t2, t3, iL, iR, dInten: REAL;
PROCEDURE Display(X, W: INTEGER; iLeft: REAL);
VAR x, color: INTEGER; inten, dInt: REAL; pictAdr: LONGINT;
BEGIN
DEC(W);
inten := iLeft;
dInt := dInten;
pictAdr := Dim3Base.GetAddress(X, Y);
FOR x := 0 TO W DO
color := GetColor(col, inten, grayscale);
inten := inten + dInt;
SYSTEM.PUT(pictAdr, CHR(color));
INC(pictAdr);
END;
END Display;
BEGIN
IF xL <= xR THEN
XL := SHORT(ENTIER(xL)) + 1;
XR := SHORT(ENTIER(xR));
W := XR - XL + 1;
t1 := y[topL] - Y; t2 := y[topL] - y[botL]; t3 := i[botL] - i[topL];
iL := i[topL] + t1 / t2 * t3;
t1 := y[topR] - Y; t2 := y[topR] - y[botR]; t3 := i[botR] - i[topR];
iR := i[topR] + t1 / t2 * t3;
dInten := (iR - iL) / (W - cheat);
ELSE
XL := SHORT(ENTIER(xR)) + 1;
XR := SHORT(ENTIER(xL));
W := XR - XL + 1;
t1 := y[topL] - Y; t2 := y[topL] - y[botL]; t3 := i[botL] - i[topL];
iR := i[topL] + t1 / t2 * t3;
t1 := y[topR] - Y; t2 := y[topR] - y[botR]; t3 := i[botR] - i[topR];
iL := i[topR] + t1 / t2 * t3;
dInten := (iR - iL) / (W - cheat);
END;
(* Loop for merging *)
LOOP
IF W <= 0 THEN EXIT END;
IF ~entry.active THEN
entry := entry.next
ELSIF XR < entry.min THEN (* case 1 *)
EXIT;
ELSIF XL > entry.max THEN (* case 8 *)
entry := entry.next;
ELSE
IF XR < entry.max THEN
IF XL <= entry.min THEN (* case 2 *)
Display(entry.min, XR - entry.min + 1,iL + (entry.min - XL) * dInten);
entry.min := XR + 1;
EXIT;
ELSE (* case 3 *)
Display( XL, W, iL);
SplitSegment(XL, XR, entry);
EXIT;
END;
ELSIF XR > entry.max THEN
IF XL <= entry.min THEN (* case 6 *)
Display(entry.min, entry.max - entry.min + 1, iL + (entry.min - XL) * dInten);
entry.active := FALSE;
entry := entry.next;
ELSE (* case 7 *)
Display(XL, entry.max - XL + 1, iL);
entry.max := XL - 1;
entry := entry.next;
END;
ELSE
IF XL <= entry.min THEN (* case 4 *)
Display(entry.min, entry.max - entry.min + 1, iL + (entry.min - XL) * dInten);
entry.active := FALSE;
EXIT;
ELSE (* case 5 *)
Display(XL, W, iL);
entry.max := XL - 1;
EXIT;
END;
END;
END;
END;
END DrawGouraudSegment;
(* draw a constant shaded polygon scanline *)
PROCEDURE DrawUniSegment(sel: BOOLEAN; col: ARRAY OF REAL; planeCol: INTEGER; grayscale: BOOLEAN;
entry: DSEntry; xL, xR: REAL; Y, botL, botR, topL, topR: INTEGER; y, i, s: ARRAY OF REAL);
VAR XL, XR, W: INTEGER;
PROCEDURE Display(X, W: INTEGER);
BEGIN
IF sel THEN
DrawPattern(planeCol, Display3.BG, Middle, X, Y, W)
ELSE
Dim3Base.ReplConst(planeCol, X, Y, W)
END;
END Display;
BEGIN
IF xL <= xR THEN
XL := SHORT(ENTIER(xL)) + 1;
XR := SHORT(ENTIER(xR));
W := XR - XL + 1;
ELSE
XL := SHORT(ENTIER(xR)) + 1;
XR := SHORT(ENTIER(xL));
W := XR - XL + 1;
END;
(* Loop for merging *)
LOOP
IF W <= 0 THEN EXIT END;
IF ~entry.active THEN
entry := entry.next
ELSIF XR < entry.min THEN (* case 1 *)
EXIT;
ELSIF XL > entry.max THEN (* case 8 *)
entry := entry.next;
ELSE
IF XR < entry.max THEN
IF XL <= entry.min THEN (* case 2 *)
Display(entry.min, XR - entry.min + 1);
entry.min := XR + 1;
EXIT;
ELSE (* case 3 *)
Display(XL, W);
SplitSegment(XL, XR, entry);
EXIT;
END;
ELSIF XR > entry.max THEN
IF XL <= entry.min THEN (* case 6 *)
Display(entry.min, entry.max - entry.min + 1);
entry.active := FALSE;
entry := entry.next;
ELSE (* case 7 *)
Display(XL, entry.max - XL + 1);
entry.max := XL - 1;
entry := entry.next;
END;
ELSE
IF XL <= entry.min THEN (* case 4 *)
Display(entry.min, entry.max - entry.min + 1);
entry.active := FALSE;
EXIT;
ELSE (* case 5 *)
Display(XL, W);
entry.max := XL - 1;
EXIT;
END;
END;
END;
END;
END DrawUniSegment;
(** Draw polygon with the dynamic screen method as following:
uni = TRUE : draw a constant shaded polygon;
uni = FALSE & dither = FALSE & specular = FALSE : draw a gouraud shaded polygon without dithering and without specular reflection;
uni = FALSE & dither = FALSE & specular = TRUE : not allowed;
uni = FALSE & dither = TRUE & specular = FALSE : draw a gouraud shaded polygon with 2*2 dithering and without specular reflection;
uni = FALSE & dither = TRUE & specular = TRUE : draw a gouraud shaded polygon with 2*2 dithering and with specular reflection; **)
PROCEDURE DrawShadePoly* (P: Pictures.Picture; VAR ds: ARRAY OF DSEntry; col: ARRAY OF REAL; planeCol: INTEGER;
grayscale, uni, sel, dither, specular: BOOLEAN; VAR x, y, i, s: ARRAY OF REAL; n: INTEGER);
VAR
xL, xR, mL, mR, dxL, dxR, dyL, dyR, yt, pw, ph: REAL;
sy, topY, stopL, stopR: LONGINT;
topL, topR, botL, botR, t, Y: INTEGER;
drawScanline: PROCEDURE(sel: BOOLEAN; col: ARRAY OF REAL; planeCol: INTEGER; grayscale: BOOLEAN;
entry: DSEntry; xL, xR: REAL; Y, botL, botR, topL, topR: INTEGER; y, i, s: ARRAY OF REAL);
BEGIN
seed := 1235; DEC(n);
Dim3Base.SetPicture(P);
IF uni OR sel THEN
drawScanline := DrawUniSegment
ELSIF ~dither THEN (* draw with dithering or not *)
drawScanline := DrawGouraudSegment
ELSIF ~specular THEN
drawScanline := DrawDitherSegment
ELSE
drawScanline := DrawSpecularSegment;
END;
(* find bottommost point and highest y value *)
botL := 0; topL := 0;
pw := ASH(P.width, -1); ph := ASH(P.height, -1);
x[0] := pw * (cheat + x[0]);
y[0] := ph * (cheat + y[0]);
FOR t := 1 TO n DO
x[t] := pw * (cheat +x[t]);
yt := ph * (cheat + y[t]);
y[t] := yt;
IF yt < y[botL] THEN botL := t END;
IF yt > y[topL] THEN topL := t END
END;
sy := ENTIER(y[botL]) + 1; (* initialize current scanline *)
IF sy > ENTIER(y[topL]) THEN (* polygon lies between scanlines *)
RETURN
END;
topY := ENTIER(y[topL]); (* last scanline to be considered *)
botR := botL;
IF botL = 0 THEN topL := n ELSE topL := botL - 1 END;
IF botR = n THEN topR := 0 ELSE topR := botR + 1 END;
(* set up parameters for first two edges *)
dxL := x[topL] - x[botL]; dyL := y[topL] - y[botL];
stopL := ENTIER(y[topL]);
WHILE stopL < sy DO
botL := topL;
IF topL = 0 THEN topL := n ELSE DEC(topL) END;
dxL := x[topL] - x[botL]; dyL := y[topL] - y[botL];
stopL := ENTIER(y[topL])
END;
mL := dxL / dyL;
xL := x[botL] + (sy - y[botL]) * mL;
dxR := x[topR] - x[botR]; dyR := y[topR] - y[botR];
stopR := ENTIER(y[topR]);
WHILE stopR < sy DO
botR := topR;
IF topR = n THEN topR := 0 ELSE INC(topR) END;
dxR := x[topR] - x[botR]; dyR := y[topR] - y[botR];
stopR := ENTIER(y[topR])
END;
mR := dxR / dyR;
xR := x[botR] + (sy - y[botR]) * mR;
LOOP
(* draw current scanline *)
Y := SHORT(sy);
drawScanline(sel, col, planeCol, grayscale, ds[sy], xL, xR, Y, botL, botR, topL, topR, y, i, s);
(* exit from loop if topmost scanline has just been drawn *)
IF sy = topY THEN EXIT END;
(* update left edge *)
IF sy = stopL THEN
REPEAT
botL := topL;
IF topL = 0 THEN topL := n ELSE DEC(topL) END;
dxL := x[topL] - x[botL]; dyL := y[topL] - y[botL];
stopL := ENTIER(y[topL])
UNTIL stopL > sy;
mL := dxL / dyL;
xL := x[botL] + (sy+1 - y[botL]) * mL;
ELSE
xL := xL + mL
END;
(* update right edge *)
IF sy = stopR THEN
REPEAT
botR := topR;
IF topR = n THEN topR := 0 ELSE INC(topR) END;
dxR := x[topR] - x[botR]; dyR := y[topR] - y[botR];
stopR := ENTIER(y[topR])
UNTIL stopR > sy;
mR := dxR / dyR;
xR := x[botR] + (sy+1 - y[botR]) * mR;
ELSE
xR := xR + mR
END;
INC(sy)
END (* End outer loop *)
END DrawShadePoly;
(** Draw constant shaded polygon without the dynamic screen method **)
PROCEDURE DrawPolygon* (P: Pictures.Picture; col: INTEGER; sel: BOOLEAN; VAR x, y: ARRAY OF REAL; n: INTEGER);
VAR
xL, xR, mL, mR, dxL, dxR, dyL, dyR, yt, pw, ph: REAL;
sy, topY, stopL, stopR: LONGINT;
topL, topR, botL, botR, t, X, W: INTEGER;
BEGIN
Dim3Base.SetPicture(P); DEC(n);
(* find bottommost point and highest y value *)
botL := 0; topL := 0;
pw := ASH(P.width, -1); ph := ASH(P.height, -1);
x[0] := pw * (cheat + x[0]);
y[0] := ph * (cheat + y[0]);
FOR t := 1 TO n DO
x[t] := pw * (cheat +x[t]);
yt := ph * (cheat + y[t]);
y[t] := yt;
IF yt < y[botL] THEN botL := t END;
IF yt > y[topL] THEN topL := t END
END;
sy := ENTIER(y[botL]) + 1; (* initialize current scanline *)
IF sy > ENTIER(y[topL]) THEN (* polygon lies between scanlines *)
RETURN
END;
topY := ENTIER(y[topL]); (* last scanline to be considered *)
botR := botL;
IF botL = 0 THEN topL := n ELSE topL := botL - 1 END;
IF botR = n THEN topR := 0 ELSE topR := botR + 1 END;
(* set up parameters for first two edges *)
dxL := x[topL] - x[botL]; dyL := y[topL] - y[botL];
stopL := ENTIER(y[topL]);
WHILE stopL < sy DO
botL := topL;
IF topL = 0 THEN topL := n ELSE DEC(topL) END;
dxL := x[topL] - x[botL]; dyL := y[topL] - y[botL];
stopL := ENTIER(y[topL])
END;
mL := dxL / dyL;
xL := x[botL] + (sy - y[botL]) * mL;
dxR := x[topR] - x[botR]; dyR := y[topR] - y[botR];
stopR := ENTIER(y[topR]);
WHILE stopR < sy DO
botR := topR;
IF topR = n THEN topR := 0 ELSE INC(topR) END;
dxR := x[topR] - x[botR]; dyR := y[topR] - y[botR];
stopR := ENTIER(y[topR])
END;
mR := dxR / dyR;
xR := x[botR] + (sy - y[botR]) * mR;
LOOP
(* draw current scanline *)
IF xL <= xR THEN
X := SHORT(ENTIER(xL));
W := SHORT(ENTIER(xR)) - X
ELSE
X := SHORT(ENTIER(xR));
W := SHORT(ENTIER(xL)) - X
END;
IF sel THEN
DrawPattern(col, Display3.BG, Middle, X + 1, SHORT(sy), W)
ELSE
Dim3Base.ReplConst(col, X + 1, SHORT(sy), W);
END;
(* exit from loop if topmost scanline has just been drawn *)
IF sy = topY THEN EXIT END;
(* update left edge *)
IF sy = stopL THEN
REPEAT
botL := topL;
IF topL = 0 THEN topL := n ELSE DEC(topL) END;
dxL := x[topL] - x[botL]; dyL := y[topL] - y[botL];
stopL := ENTIER(y[topL])
UNTIL stopL > sy;
mL := dxL / dyL;
xL := x[botL] + (sy+1 - y[botL]) * mL
ELSE
xL := xL + mL
END;
(* update right edge *)
IF sy = stopR THEN
REPEAT
botR := topR;
IF topR = n THEN topR := 0 ELSE INC(topR) END;
dxR := x[topR] - x[botR]; dyR := y[topR] - y[botR];
stopR := ENTIER(y[topR])
UNTIL stopR > sy;
mR := dxR / dyR;
xR := x[botR] + (sy+1 - y[botR]) * mR
ELSE
xR := xR + mR
END;
INC(sy)
END
END DrawPolygon;