GameDev.net3d Solids

3D Solids ÕÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ¸ ³ W E L C O M E ³ ³ To the VGA Trainer Program ³ ³ ³ By ³ ³ ³ DENTHOR of ASPHYXIA ³ ³ ³ ÔÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ¾ ³ ³ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ --==[ PART 9 ]==-- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= þ Introduction Hi there! ASPHYXIA is BACK with our first MegaDemo, Psycho Neurosis! A paltry 1.3MB download is all it takes to see the group from Durbs first major production! We are quite proud of it, and think you should see it ;) Secondly, I released a small little trainer (a trainerette ;-)) on RsaPROG and Connexctix BBS mail, also on the ASPHYXIA BBS as COPPERS.ZIP It is a small Pascal program demonstrating how to display copper bars in text mode. Also includes a check for horizontal retrace (A lot of people wanted it, that is why I wrote the program) (ASPHYXIA ... first with the trainer goodies ;-) aargh, sorry, had to be done )) Thirdly, sorry about the problems with Tut 8! If you had all the checking on, the tutorial would probably die on the first points. The reason is this : in the first loop, we have DrawPoints then RotatePoints. The variables used in DrawPoints are set in RotatePoints, so if you put RotatePoints before DrawPoints, the program should work fine. Alternatively, turn off error checking 8-) Fourthly, I have had a surprisingly large number of people saying that "I get this, like, strange '286 instructions not enabled' message! What's wrong with your code, dude?" To all of you, get into Pascal, hit Alt-O (for options), hit enter and a 2 (for Enable 286 instructions). Hard hey? Doesn't anyone EVER set up their version of Pascal? Now, on to todays tutorial! 3D solids. That is what the people wanted, that is what the people get! This tutorial is mainly on how to draw the polygon on screen. For details on how the 3D stuff works, check out tut 8. If you would like to contact me, or the team, there are many ways you can do it : 1) Write a message to Grant Smith/Denthor/Asphyxia in private mail on the ASPHYXIA BBS. 2) Write to Denthor, EzE or Goth on Connectix. 3) Write to : Grant Smith P.O.Box 270 Kloof 3640 Natal 4) Call me (Grant Smith) at (031) 73 2129 (leave a message if you call during varsity) 5) Write to mcphail@beastie.cs.und.ac.za on InterNet, and mention the word Denthor near the top of the letter. NB : If you are a representative of a company or BBS, and want ASPHYXIA to do you a demo, leave mail to me; we can discuss it. NNB : If you have done/attempted a demo, SEND IT TO ME! We are feeling quite lonely and want to meet/help out/exchange code with other demo groups. What do you have to lose? Leave a message here and we can work out how to transfer it. We really want to hear from you! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= þ How to draw a polygon Sounds easy enough, right? WRONG! There are many, many different ways to go about this, and today I'll only be showing you one. Please don't take what is written here as anything approaching the best method, it is just here to get you on your way... The procedure I will be using here is based on something most of us learned in standard eight ... I think. I seem to recall doing something like this in Mrs. Reids maths class all those years ago ;) Take two points, x1,y1 and x2,y2. Draw them : + (x1,y1) \ \ <-- Point a somewhere along the line \ + (x2,y2) Right, so what we have to do is this : if we know the y-coord of a, what is it's x-coord? To prove the method we will give the points random values. + (2,10) \ \ <-- a.y = 12 \ + (15,30) Right. Simple enough problem. This is how we do it : (a.y-y1) = (12 - 10) {to get a.y as though y1 was zero} *(x2-x1) = *(15 - 2) {the total x-length of the line} /(y2-y1) = /(30 - 10) {the total y-length of the line} +x1 = +2 { to get the equation back to real coords} So our equation is : (a.y-y1)*(x2-x1)/(y2-y1)+x4 or (12-10)*(15-2)/(30-10)+2 which gives you : 2*13/20+2 = 26/20+2 = 3.3 That means that along the line with y=12, x is equal to 3.3. Since we are not concerned with the decimal place, we replace the / with a div, which in Pascal gives us an integer result, and is faster too. All well and good, I hear you cry, but what does this have to do with life and how it relates to polygons in general. The answer is simple. For each of the four sides of the polygon we do the above test for each y line. We store the smallest and the largest x values into separate variables for each line, and draw a horizontal line between them. Ta-Dah! We have a cool polygon! For example : Two lines going down : + + / <-x1 x2->| <--For this y line / | + + Find x1 and x2 for that y, then draw a line between them. Repeat for all y values. Of course, it's not as simple as that. We have to make sure we only check those y lines that contain the polygon (a simple min y, max y test for all the points). We also have to check that the line we are calculating actually extends as far as where our current y is (check that the point is between both y's). We have to compare each x to see weather it is smaller then the minimum x value so far, or bigger then the maximum (the original x min is set as a high number, and the x max is set as a small number). We must also check that we only draw to the place that we can see ( 0-319 on the x ; 0-199 on the y (the size of the MCGA screen)) To see how this looks in practice, have a look at the sample code provided. (Mrs. Reid would probably kill me for the above explanation, so when you learn it in school, split it up into thousands of smaller equations to get the same answer ;)) Okay, that's it! What's that? How do you draw a vertical line? Thats simple ... =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= þ Drawing a vertical line Right, this is a lot easier than drawing a normal line (Tut 5 .. I think), because you stay on the same y value. So, what you do is you set ES to the screen you want to write to, and get DI to the start of the y-line (see earlier trainers for a description of how SEGMENT:OFFSET works. IN : x1 , x2, y, color, where asm mov ax,where mov es,ax mov di,y mov ax,y shl di,8 { di:=di*256 } shl ax,6 { ax:=ax*64 } add di,ax { di := (y*256)+(y*64) := y*320 Faster then a straight multiplication } Right, now you add the first x value to get your startoff. add di,x1 Move the color to store into ah and al mov al,color mov ah,al { ah:=al:=color } then get CX equal to how many pixels across you want to go mov cx,x2 sub cx,x1 { cx:=x2-x1 } Okay, as we all know, moving a word is a lot faster then moving a byte, so we halve CX shr cx,1 { cx:=cx/2 } but what happens if CX was an odd number. After a shift, the value of the last number is placed in the carry flag, so what we do is jump over a single byte move if the carry flag is zero, or execute it if it is one. jnc @Start { If there is no carry, jump to label Start } stosb { ES:[DI]:=al ; increment DI } @Start : { Label Start } rep stosw { ES:[DI]:=ax ; DI:=DI+2; repeat CX times } Right, the finished product looks like this : Procedure Hline (x1,x2,y:word;col:byte;where:word); assembler; { This draws a horizontal line from x1 to x2 on line y in color col } asm mov ax,where mov es,ax mov ax,y mov di,ax shl ax,8 shl di,6 add di,ax add di,x1 mov al,col mov ah,al mov cx,x2 sub cx,x1 shr cx,1 jnc @start stosb @Start : rep stosw end; Done! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= þ In closing This 3D system is still not perfect. It needs to be faster, and now I have also dumped the problem of face-sorting on you! Nyahahahaha! [ My sister and I were driving along the other day when she asked me, what would I like for my computer. I thought long and hard about it, and came up with the following hypothesis. When a girl gets a Barbie doll, she then wants the extra ballgown for the doll, then the hairbrush, and the car, and the house, and the friends etc. When a guy gets a computer, he wants the extra memory, the bigger hard drive, the maths co-pro, the better motherboard, the latest software, and the bigger monitor etc. I told my sister all of this, and finished up with : "So as you can see, computers are Barbie dolls for MEN!" She called me a chauvinist. And hit me. Hard. ] - Grant Smith 19:24 26/2/94 See you next time! - Denthor These fine BBS's carry the ASPHYXIA DEMO TRAINER SERIES : (alphabetical) ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍËÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍËÍÍÍÍÍËÍÍÍËÍÍÍÍËÍÍÍÍ» ºBBS Name ºTelephone No. ºOpen ºMsgºFileºPastº ÌÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÎÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÎÍÍÍÍÍÎÍÍÍÎÍÍÍÍÎÍÍÍÍ¹ ºASPHYXIA BBS #1 º(031) 765-5312 ºALL º * º * º * º ºASPHYXIA BBS #2 º(031) 765-6293 ºALL º * º * º * º ºConnectix BBS º(031) 266-9992 ºALL º º * º * º ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÊÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÊÍÍÍÍÍÊÍÍÍÊÍÍÍÍÊÍÍÍÍ¼ Open = Open at all times or only A/H Msg = Available in message base File = Available in file base Past = Previous Parts available Does no other BBS's ANYWHERE carry the trainer? Am I writing this for three people who get it from one of these BBS's each week? Should I go on? (Hehehehe ... I was pleased to note that Tut 8 was THE most downloaded file from ASPHYXIA BBS last month ... ) {$X+} USES Crt; CONST VGA = $A000; maxpolys = 5; A : Array [1..maxpolys,1..4,1..3] of integer = ( ((-10,10,0),(-2,-10,0),(0,-10,0),(-5,10,0)), ((10,10,0),(2,-10,0),(0,-10,0),(5,10,0)), ((-2,-10,0),(2,-10,0),(2,-5,0),(-2,-5,0)), ((-6,0,0),(6,0,0),(7,5,0),(-7,5,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)) ); { The 3-D coordinates of our object ... stored as (X1,Y1,Z1), } { (X2,Y2,Z2) ... for the 4 points of a poly } S : Array [1..maxpolys,1..4,1..3] of integer = ( ((-10,-10,0),(10,-10,0),(10,-7,0),(-10,-7,0)), ((-10,10,0),(10,10,0),(10,7,0),(-10,7,0)), ((-10,1,0),(10,1,0),(10,-2,0),(-10,-2,0)), ((-10,-8,0),(-7,-8,0),(-7,0,0),(-10,0,0)), ((10,8,0),(7,8,0),(7,0,0),(10,0,0)) ); { The 3-D coordinates of our object ... stored as (X1,Y1,Z1), } { (X2,Y2,Z2) ... for the 4 points of a poly } P : Array [1..maxpolys,1..4,1..3] of integer = ( ((-10,-10,0),(-7,-10,0),(-7,10,0),(-10,10,0)), ((10,-10,0),(7,-10,0),(7,0,0),(10,0,0)), ((-9,-10,0),(9,-10,0),(9,-7,0),(-9,-7,0)), ((-9,-1,0),(9,-1,0),(9,2,0),(-9,2,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)) ); { The 3-D coordinates of our object ... stored as (X1,Y1,Z1), } { (X2,Y2,Z2) ... for the 4 points of a poly } H : Array [1..maxpolys,1..4,1..3] of integer = ( ((-10,-10,0),(-7,-10,0),(-7,10,0),(-10,10,0)), ((10,-10,0),(7,-10,0),(7,10,0),(10,10,0)), ((-9,-1,0),(9,-1,0),(9,2,0),(-9,2,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)) ); { The 3-D coordinates of our object ... stored as (X1,Y1,Z1), } { (X2,Y2,Z2) ... for the 4 points of a poly } Y : Array [1..maxpolys,1..4,1..3] of integer = ( ((-7,-10,0),(0,-3,0),(0,0,0),(-10,-7,0)), ((7,-10,0),(0,-3,0),(0,0,0),(10,-7,0)), ((-2,-3,0),(2,-3,0),(2,10,0),(-2,10,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)) ); { The 3-D coordinates of our object ... stored as (X1,Y1,Z1), } { (X2,Y2,Z2) ... for the 4 points of a poly } X : Array [1..maxpolys,1..4,1..3] of integer = ( ((-7,-10,0),(10,7,0),(7,10,0),(-10,-7,0)), ((7,-10,0),(-10,7,0),(-7,10,0),(10,-7,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)) ); { The 3-D coordinates of our object ... stored as (X1,Y1,Z1), } { (X2,Y2,Z2) ... for the 4 points of a poly } I : Array [1..maxpolys,1..4,1..3] of integer = ( ((-10,-10,0),(10,-10,0),(10,-7,0),(-10,-7,0)), ((-10,10,0),(10,10,0),(10,7,0),(-10,7,0)), ((-2,-9,0),(2,-9,0),(2,9,0),(-2,9,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)), ((0,0,0),(0,0,0),(0,0,0),(0,0,0)) ); { The 3-D coordinates of our object ... stored as (X1,Y1,Z1), } { (X2,Y2,Z2) ... for the 4 points of a poly } Type Point = Record x,y,z:real; { The data on every point we rotate} END; Virtual = Array [1..64000] of byte; { The size of our Virtual Screen } VirtPtr = ^Virtual; { Pointer to the virtual screen } VAR Lines : Array [1..maxpolys,1..4] of Point; { The base object rotated } Translated : Array [1..maxpolys,1..4] of Point; { The rotated object } Xoff,Yoff,Zoff:Integer; { Used for movement of the object } lookup : Array [0..360,1..2] of real; { Our sin and cos lookup table } Virscr : VirtPtr; { Our first Virtual screen } Vaddr : word; { The segment of our virtual screen} {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure SetMCGA; { This procedure gets you into 320x200x256 mode. } BEGIN asm mov ax,0013h int 10h end; END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure SetText; { This procedure returns you to text mode. } BEGIN asm mov ax,0003h int 10h end; END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure Cls (Where:word;Col : Byte); { This clears the screen to the specified color } BEGIN asm push es mov cx, 32000; mov es,[where] xor di,di mov al,[col] mov ah,al rep stosw pop es End; END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure SetUpVirtual; { This sets up the memory needed for the virtual screen } BEGIN GetMem (VirScr,64000); vaddr := seg (virscr^); END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure ShutDown; { This frees the memory used by the virtual screen } BEGIN FreeMem (VirScr,64000); END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} procedure flip(source,dest:Word); { This copies the entire screen at "source" to destination } begin asm push ds mov ax, [Dest] mov es, ax mov ax, [Source] mov ds, ax xor si, si xor di, di mov cx, 32000 rep movsw pop ds end; end; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure Pal(Col,R,G,B : Byte); { This sets the Red, Green and Blue values of a certain color } Begin asm mov dx,3c8h mov al,[col] out dx,al inc dx mov al,[r] out dx,al mov al,[g] out dx,al mov al,[b] out dx,al end; End; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure Hline (x1,x2,y:word;col:byte;where:word); assembler; { This draws a horizontal line from x1 to x2 on line y in color col } asm mov ax,where mov es,ax mov ax,y mov di,ax shl ax,8 shl di,6 add di,ax add di,x1 mov al,col mov ah,al mov cx,x2 sub cx,x1 shr cx,1 jnc @start stosb @Start : rep stosw end; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure DrawPoly(x1,y1,x2,y2,x3,y3,x4,y4:integer;color:byte;where:word); { This draw a polygon with 4 points at x1,y1 , x2,y2 , x3,y3 , x4,y4 in color col } var x:integer; mny,mxy:integer; mnx,mxx,yc:integer; mul1,div1, mul2,div2, mul3,div3, mul4,div4:integer; begin mny:=y1; mxy:=y1; if y2mxy then mxy:=y2; if y3mxy then mxy:=y3; { Choose the min y mny and max y mxy } if y4mxy then mxy:=y4; if mny<0 then mny:=0; if mxy>199 then mxy:=199; if mny>199 then exit; if mxy<0 then exit; { Verticle range checking } mul1:=x1-x4; div1:=y1-y4; mul2:=x2-x1; div2:=y2-y1; mul3:=x3-x2; div3:=y3-y2; mul4:=x4-x3; div4:=y4-y3; { Constansts needed for intersection calc } for yc:=mny to mxy do begin mnx:=320; mxx:=-1; if (y4>=yc) or (y1>=yc) then if (y4<=yc) or (y1<=yc) then { Check that yc is between y1 and y4 } if not(y4=y1) then begin x:=(yc-y4)*mul1 div div1+x4; { Point of intersection on x axis } if xmxx then mxx:=x; { Set point as start or end of horiz line } end; if (y1>=yc) or (y2>=yc) then if (y1<=yc) or (y2<=yc) then { Check that yc is between y1 and y2 } if not(y1=y2) then begin x:=(yc-y1)*mul2 div div2+x1; { Point of intersection on x axis } if xmxx then mxx:=x; { Set point as start or end of horiz line } end; if (y2>=yc) or (y3>=yc) then if (y2<=yc) or (y3<=yc) then { Check that yc is between y2 and y3 } if not(y2=y3) then begin x:=(yc-y2)*mul3 div div3+x2; { Point of intersection on x axis } if xmxx then mxx:=x; { Set point as start or end of horiz line } end; if (y3>=yc) or (y4>=yc) then if (y3<=yc) or (y4<=yc) then { Check that yc is between y3 and y4 } if not(y3=y4) then begin x:=(yc-y3)*mul4 div div4+x3; { Point of intersection on x axis } if xmxx then mxx:=x; { Set point as start or end of horiz line } end; if mnx<0 then mnx:=0; if mxx>319 then mxx:=319; { Range checking on horizontal line } if mnx<=mxx then hline (mnx,mxx,yc,color,where); { Draw the horizontal line } end; end; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Function rad (theta : real) : real; { This calculates the degrees of an angle } BEGIN rad := theta * pi / 180 END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure SetUpPoints; { This creates the lookup table } VAR loop1,loop2:integer; BEGIN For loop1:=0 to 360 do BEGIN lookup [loop1,1]:=sin (rad (loop1)); lookup [loop1,2]:=cos (rad (loop1)); END; END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure Putpixel (X,Y : Integer; Col : Byte; where:word); { This puts a pixel on the screen by writing directly to memory. } BEGIN Asm mov ax,[where] mov es,ax mov bx,[X] mov dx,[Y] mov di,bx mov bx, dx {; bx = dx} shl dx, 8 shl bx, 6 add dx, bx {; dx = dx + bx (ie y*320)} add di, dx {; finalise location} mov al, [Col] stosb End; END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure RotatePoints (X,Y,Z:Integer); { This rotates object lines by X,Y and Z; then places the result in TRANSLATED } VAR loop1,loop2:integer; temp:point; BEGIN For loop1:=1 to maxpolys do BEGIN For loop2:=1 to 4 do BEGIN temp.x:=lines[loop1,loop2].x; temp.y:=lookup[x,2]*lines[loop1,loop2].y - lookup[x,1]*lines[loop1,loop2].z; temp.z:=lookup[x,1]*lines[loop1,loop2].y + lookup[x,2]*lines[loop1,loop2].z; translated[loop1,loop2]:=temp; If y>0 then BEGIN temp.x:=lookup[y,2]*translated[loop1,loop2].x - lookup[y,1]*translated[loop1,loop2].y; temp.y:=lookup[y,1]*translated[loop1,loop2].x + lookup[y,2]*translated[loop1,loop2].y; temp.z:=translated[loop1,loop2].z; translated[loop1,loop2]:=temp; END; If z>0 then BEGIN temp.x:=lookup[z,2]*translated[loop1,loop2].x + lookup[z,1]*translated[loop1,loop2].z; temp.y:=translated[loop1,loop2].y; temp.z:=-lookup[z,1]*translated[loop1,loop2].x + lookup[z,2]*translated[loop1,loop2].z; translated[loop1,loop2]:=temp; END; END; END; END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure DrawPoints; { This draws the translated object to the virtual screen } VAR loop1:Integer; nx,ny,nx2,ny2,nx3,ny3,nx4,ny4:integer; temp:integer; BEGIN For loop1:=1 to maxpolys do BEGIN If (translated[loop1,1].z+zoff<0) and (translated[loop1,2].z+zoff<0) and (translated[loop1,3].z+zoff<0) and (translated[loop1,4].z+zoff<0) then BEGIN temp:=round (translated[loop1,1].z+zoff); nx :=round (256*translated[loop1,1].X) div temp+xoff; ny :=round (256*translated[loop1,1].Y) div temp+yoff; temp:=round (translated[loop1,2].z+zoff); nx2:=round (256*translated[loop1,2].X) div temp+xoff; ny2:=round (256*translated[loop1,2].Y) div temp+yoff; temp:=round (translated[loop1,3].z+zoff); nx3:=round (256*translated[loop1,3].X) div temp+xoff; ny3:=round (256*translated[loop1,3].Y) div temp+yoff; temp:=round (translated[loop1,4].z+zoff); nx4:=round (256*translated[loop1,4].X) div temp+xoff; ny4:=round (256*translated[loop1,4].Y) div temp+yoff; drawpoly (nx,ny,nx2,ny2,nx3,ny3,nx4,ny4,13,vaddr); END; END; END; {ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ} Procedure MoveAround; { This is the main display procedure. Firstly it brings the object towards the viewer by increasing the Zoff, then passes control to the user } VAR deg,loop1,loop2:integer; ch:char; Procedure Whizz (sub:boolean); VAR loop1:integer; BEGIN For loop1:=-64 to -5 do BEGIN zoff:=loop1*8; if sub then xoff:=xoff-7 else xoff:=xoff+7; RotatePoints (deg,deg,deg); DrawPoints; flip (vaddr,vga); Cls (vaddr,0); deg:=(deg+5) mod 360; END; END; BEGIN deg:=0; ch:=#0; Yoff:=100; Xoff:=350; Cls (vaddr,0); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=a [loop1,loop2,1]; Lines [loop1,loop2].y:=a [loop1,loop2,2]; Lines [loop1,loop2].z:=a [loop1,loop2,3]; END; Whizz (TRUE); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=s [loop1,loop2,1]; Lines [loop1,loop2].y:=s [loop1,loop2,2]; Lines [loop1,loop2].z:=s [loop1,loop2,3]; END; Whizz (FALSE); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=p [loop1,loop2,1]; Lines [loop1,loop2].y:=p [loop1,loop2,2]; Lines [loop1,loop2].z:=p [loop1,loop2,3]; END; Whizz (TRUE); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=h [loop1,loop2,1]; Lines [loop1,loop2].y:=h [loop1,loop2,2]; Lines [loop1,loop2].z:=h [loop1,loop2,3]; END; Whizz (FALSE); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=y [loop1,loop2,1]; Lines [loop1,loop2].y:=y [loop1,loop2,2]; Lines [loop1,loop2].z:=y [loop1,loop2,3]; END; Whizz (TRUE); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=x [loop1,loop2,1]; Lines [loop1,loop2].y:=x [loop1,loop2,2]; Lines [loop1,loop2].z:=x [loop1,loop2,3]; END; Whizz (FALSE); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=i [loop1,loop2,1]; Lines [loop1,loop2].y:=i [loop1,loop2,2]; Lines [loop1,loop2].z:=i [loop1,loop2,3]; END; Whizz (TRUE); For loop1:=1 to maxpolys do For loop2:=1 to 4 do BEGIN Lines [loop1,loop2].x:=a [loop1,loop2,1]; Lines [loop1,loop2].y:=a [loop1,loop2,2]; Lines [loop1,loop2].z:=a [loop1,loop2,3]; END; Whizz (FALSE); cls (vaddr,0); cls (vga,0); Xoff := 160; Repeat if keypressed then BEGIN ch:=upcase (Readkey); Case ch of 'A' : zoff:=zoff+5; 'Z' : zoff:=zoff-5; ',' : xoff:=xoff-5; '.' : xoff:=xoff+5; 'S' : yoff:=yoff-5; 'X' : yoff:=yoff+5; END; END; DrawPoints; flip (vaddr,vga); cls (vaddr,0); RotatePoints (deg,deg,deg); deg:=(deg+5) mod 360; Until ch=#27; END; BEGIN SetUpVirtual; clrscr; Writeln ('Hello there! Varsity has begun once again, so it is once again'); Writeln ('back to the grindstone ;-) ... anyway, this tutorial is, by'); Writeln ('popular demand, on poly-filling, in relation to 3-D solids.'); Writeln; Writeln ('In this program, the letters of ASPHYXIA will fly past you. As you'); Writeln ('will see, they are solid, not wireframe. After the last letter has'); Writeln ('flown by, a large A will be left in the middle of the screen.'); Writeln; Writeln ('You will be able to move it around the screen, and you will notice'); Writeln ('that it may have bits only half on the screen, i.e. clipping is'); Writeln ('perfomed. To control it use the following : "A" and "Z" control the Z'); Writeln ('movement, "," and "." control the X movement, and "S" and "X"'); Writeln ('control the Y movement. I have not included rotation control, but'); Writeln ('it should be easy enough to put in yourself ... if you have any'); Writeln ('hassles, leave me mail.'); Writeln; Writeln ('I hope this is what you wanted...leave me mail for new ideas.'); writeln; writeln; Write (' Hit any key to contine ...'); Readkey; SetMCGA; SetUpPoints; MoveAround; SetText; ShutDown; Writeln ('All done. This concludes the ninth sample program in the ASPHYXIA'); Writeln ('Training series. You may reach DENTHOR under the names of GRANT'); Writeln ('SMITH/DENTHOR/ASPHYXIA on the ASPHYXIA BBS. I am also an avid'); Writeln ('Connectix BBS user, and occasionally read RSAProg.'); Writeln ('The numbers are available in the main text. You may also write to me at:'); Writeln (' Grant Smith'); Writeln (' P.O. Box 270'); Writeln (' Kloof'); Writeln (' 3640'); Writeln ('I hope to hear from you soon!'); Writeln; Writeln; Write ('Hit any key to exit ...'); Readkey; END. [BACK] Back
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