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Cason/c/Gouraud
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Recent acquisitions » Acorn ADFS disks » adfs_AcornUser_199312.adf » !StarInfo_StarInfo |
| Filename: | Cason/c/Gouraud |
| Read OK: | ✔ |
| File size: | 1496 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
/* c.gouraud
Gouraud shading in C
By Neil Cason
For 32-bit machines
(c) BAU December 1993
*/
#include "bbc.h"
#include "kernel.h"
#include "swis.h"
#include <stdio.h>
#include <stdlib.h>
typedef struct
{
int x0;
int y0;
int x1;
int y1;
int x2;
int y2;
} vertices;
void gouraud(vertices *, int *, int, int, int);
#define swap(arg1, arg2) { int temp=0; temp=arg1; arg1=arg2; arg2=temp; }
#define sgn(x) ((x) > 0 ? 1: ((x) == 0 ? 0: (-1)))
int xl[256], xr[256], il[256], ir[256];
int main(void)
{
vertices pts;
int cnt, cols[16];
bbc_mode(13);
pts.x0 = 12;
pts.y0 = 12;
pts.x1 = 200;
pts.y1 = 12;
pts.x2 = 100;
pts.y2 = 200;
for (cnt=0; cnt<=3; cnt++)
{
cols[cnt] = cnt;
cols[cnt+4] = cnt+44;
cols[cnt+8] = cnt+208;
cols[cnt+12] = cnt+252;
}
gouraud(&pts, &cols[0], 0, 8, 15);
}
void __nc_line(int x1, int y1, int x2, int y2, int side, int i0, int i1)
{
int dy,dx,d,incr1,incr2,inc,end,len,j, is, id;
dx = abs(x2-x1);
dy = abs(y2-y1);
if (dx > dy)
{
d = (dy<<1) - dx;
incr1 = (dy<<1);
incr2 = (dy - dx)<<1;
if (y1>=y2) inc=1; else inc=-1;
if (x1 > x2)
{
end=x1;
x1=x2;
y1=y2;
}
else
{
inc=-inc;
end = x2;
}
len = end - x1;
id = (i1 - i0) << 20;
is = id / len;
id = i0 << 20;
if (side == 0)
{
for (j=0; j<=len; j++)
{
xl[y1] = x1+j;
il[y1] = id;
id += is;
if (d<0) d+=incr1;
else
{
y1 += inc;
d += incr2;
}
}
}
if (side == 1)
{
for (j=0; j<=len; j++)
{
xr[y1] = x1+j;
ir[y1] = id;
id += is;
if (d<0) d+=incr1;
else
{
y1 += inc;
d += incr2;
}
}
}
}
else
{
d = (dx<<1) - dy;
incr1 = (dx<<1);
incr2 = (dx-dy)<<1;
if (x1 >= x2) inc = 1; else inc=-1;
if (y1 > y2)
{
end = y1;
y1 = y2;
x1 = x2;
}
else
{
inc =-inc;
end = y2;
}
len = end - y1;
id = (i1 - i0) << 20;
is = id / len;
id = i0 << 20;
if (side == 0)
{
for (j=0; j<=len; j++)
{
xl[y1+j] = x1;
il[y1+j] = id;
id += is;
if (d<0) d+=incr1;
else
{
x1+=inc;
d+=incr2;
}
}
}
if (side == 1)
{
for (j=0; j<=len; j++)
{
xr[y1+j] = x1;
ir[y1+j] = id;
id += is;
if (d<0) d+=incr1;
else
{
x1+=inc;
d+=incr2;
}
}
}
}
}
void gouraud(vertices *pts, int *colours, int i0, int i1, int i2)
{
int vdu[2], y, ys, sl, sr, screendist, istart, iend, idelta, len, x;
int screenstart, error, intens;
char *ptr;
_kernel_swi_regs r;
vdu[0] = 148;
vdu[1] = -1;
r.r[0] = r.r[1] = (int) &vdu;
_kernel_swi(OS_ReadVduVariables,&r,&r);
screenstart = vdu[0];
if (pts->y0 < pts->y1)
{
swap (pts->x0,pts->x1);
swap (pts->y0,pts->y1);
}
if (pts->y1 < pts->y2)
{
swap (pts->x1,pts->x2); /* Make triangle the right way up */
swap (pts->y1,pts->y2);
}
if (pts->y0 < pts->y1)
{
swap (pts->x0,pts->x1);
swap (pts->y0,pts->y1);
}
__nc_line(pts->x2,pts->y2,pts->x1,pts->y1,0,i2,i1);
__nc_line(pts->x1,pts->y1,pts->x0,pts->y0,0,i1,i0); /* Draw lines */
__nc_line(pts->x2,pts->y2,pts->x0,pts->y0,1,i2,i0);
ys = sgn(pts->y2 - pts->y0);
for (y=pts->y2; y<=pts->y0; y++)
{
sl = xl[y];
sr = xr[y];
istart = il[y];
iend = ir[y];
screendist = (y<<8) + (y<<6) + screenstart;
if (sl > sr)
{
sl ^= sr;
sr = sl ^ sr;
sl ^= sr;
istart ^= iend;
iend = istart ^ iend;
istart ^= iend;
}
if (sr != sl)
idelta = (iend - istart) / (sr-sl); /* Intens change for each pixel plotted */
len = screendist + sr;
for (x=screendist+sl; x<=len; x++)
{
intens = istart>>20;
error += istart - (istart & 535822336); /* Add on error */
if (error > 1048576)
{
intens ++;
error -= 1048576; /* If overflow... */
}
ptr = (char *) x;
*ptr = (char) colours[intens]; /* Plot */
istart += idelta; /* Increment intensity */
}
}
}
00000000 2f 2a 20 63 2e 67 6f 75 72 61 75 64 20 0a 0a 20 |/* c.gouraud .. |
00000010 20 20 47 6f 75 72 61 75 64 20 73 68 61 64 69 6e | Gouraud shadin|
00000020 67 20 69 6e 20 43 0a 0a 20 20 20 42 79 20 20 4e |g in C.. By N|
00000030 65 69 6c 20 43 61 73 6f 6e 0a 20 20 20 46 6f 72 |eil Cason. For|
00000040 20 33 32 2d 62 69 74 20 6d 61 63 68 69 6e 65 73 | 32-bit machines|
00000050 0a 20 20 20 28 63 29 20 42 41 55 20 44 65 63 65 |. (c) BAU Dece|
00000060 6d 62 65 72 20 31 39 39 33 0a 2a 2f 0a 0a 23 69 |mber 1993.*/..#i|
00000070 6e 63 6c 75 64 65 20 22 62 62 63 2e 68 22 0a 23 |nclude "bbc.h".#|
00000080 69 6e 63 6c 75 64 65 20 22 6b 65 72 6e 65 6c 2e |include "kernel.|
00000090 68 22 0a 23 69 6e 63 6c 75 64 65 20 22 73 77 69 |h".#include "swi|
000000a0 73 2e 68 22 0a 23 69 6e 63 6c 75 64 65 20 3c 73 |s.h".#include <s|
000000b0 74 64 69 6f 2e 68 3e 0a 23 69 6e 63 6c 75 64 65 |tdio.h>.#include|
000000c0 20 3c 73 74 64 6c 69 62 2e 68 3e 0a 0a 74 79 70 | <stdlib.h>..typ|
000000d0 65 64 65 66 20 73 74 72 75 63 74 0a 7b 0a 20 20 |edef struct.{. |
000000e0 20 20 69 6e 74 20 78 30 3b 0a 20 20 20 20 69 6e | int x0;. in|
000000f0 74 20 79 30 3b 0a 20 20 20 20 69 6e 74 20 78 31 |t y0;. int x1|
00000100 3b 0a 20 20 20 20 69 6e 74 20 79 31 3b 0a 20 20 |;. int y1;. |
00000110 20 20 69 6e 74 20 78 32 3b 0a 20 20 20 20 69 6e | int x2;. in|
00000120 74 20 79 32 3b 0a 7d 20 76 65 72 74 69 63 65 73 |t y2;.} vertices|
00000130 3b 0a 0a 76 6f 69 64 20 67 6f 75 72 61 75 64 28 |;..void gouraud(|
00000140 76 65 72 74 69 63 65 73 20 2a 2c 20 69 6e 74 20 |vertices *, int |
00000150 2a 2c 20 69 6e 74 2c 20 69 6e 74 2c 20 69 6e 74 |*, int, int, int|
00000160 29 3b 0a 0a 23 64 65 66 69 6e 65 20 73 77 61 70 |);..#define swap|
00000170 28 61 72 67 31 2c 20 61 72 67 32 29 20 7b 20 69 |(arg1, arg2) { i|
00000180 6e 74 20 74 65 6d 70 3d 30 3b 20 74 65 6d 70 3d |nt temp=0; temp=|
00000190 61 72 67 31 3b 20 61 72 67 31 3d 61 72 67 32 3b |arg1; arg1=arg2;|
000001a0 20 61 72 67 32 3d 74 65 6d 70 3b 20 7d 0a 23 64 | arg2=temp; }.#d|
000001b0 65 66 69 6e 65 20 73 67 6e 28 78 29 20 28 28 78 |efine sgn(x) ((x|
000001c0 29 20 3e 20 30 20 3f 20 31 3a 20 28 28 78 29 20 |) > 0 ? 1: ((x) |
000001d0 3d 3d 20 30 20 3f 20 30 3a 20 28 2d 31 29 29 29 |== 0 ? 0: (-1)))|
000001e0 20 0a 0a 69 6e 74 20 78 6c 5b 32 35 36 5d 2c 20 | ..int xl[256], |
000001f0 78 72 5b 32 35 36 5d 2c 20 69 6c 5b 32 35 36 5d |xr[256], il[256]|
00000200 2c 20 69 72 5b 32 35 36 5d 3b 0a 0a 69 6e 74 20 |, ir[256];..int |
00000210 6d 61 69 6e 28 76 6f 69 64 29 0a 7b 0a 20 20 20 |main(void).{. |
00000220 20 76 65 72 74 69 63 65 73 20 70 74 73 3b 0a 20 | vertices pts;. |
00000230 20 20 20 69 6e 74 20 63 6e 74 2c 20 63 6f 6c 73 | int cnt, cols|
00000240 5b 31 36 5d 3b 0a 0a 20 20 20 20 62 62 63 5f 6d |[16];.. bbc_m|
00000250 6f 64 65 28 31 33 29 3b 0a 20 20 20 20 70 74 73 |ode(13);. pts|
00000260 2e 78 30 20 3d 20 31 32 3b 0a 20 20 20 20 70 74 |.x0 = 12;. pt|
00000270 73 2e 79 30 20 3d 20 31 32 3b 0a 20 20 20 20 70 |s.y0 = 12;. p|
00000280 74 73 2e 78 31 20 3d 20 32 30 30 3b 0a 20 20 20 |ts.x1 = 200;. |
00000290 20 70 74 73 2e 79 31 20 3d 20 31 32 3b 0a 20 20 | pts.y1 = 12;. |
000002a0 20 20 70 74 73 2e 78 32 20 3d 20 31 30 30 3b 0a | pts.x2 = 100;.|
000002b0 20 20 20 20 70 74 73 2e 79 32 20 3d 20 32 30 30 | pts.y2 = 200|
000002c0 3b 0a 0a 20 20 20 20 66 6f 72 20 28 63 6e 74 3d |;.. for (cnt=|
000002d0 30 3b 20 63 6e 74 3c 3d 33 3b 20 63 6e 74 2b 2b |0; cnt<=3; cnt++|
000002e0 29 0a 20 20 20 20 7b 0a 20 20 20 20 20 20 20 20 |). {. |
000002f0 63 6f 6c 73 5b 63 6e 74 5d 20 3d 20 63 6e 74 3b |cols[cnt] = cnt;|
00000300 0a 20 20 20 20 20 20 20 20 63 6f 6c 73 5b 63 6e |. cols[cn|
00000310 74 2b 34 5d 20 3d 20 63 6e 74 2b 34 34 3b 0a 20 |t+4] = cnt+44;. |
00000320 20 20 20 20 20 20 20 63 6f 6c 73 5b 63 6e 74 2b | cols[cnt+|
00000330 38 5d 20 3d 20 63 6e 74 2b 32 30 38 3b 0a 20 20 |8] = cnt+208;. |
00000340 20 20 20 20 20 20 63 6f 6c 73 5b 63 6e 74 2b 31 | cols[cnt+1|
00000350 32 5d 20 3d 20 63 6e 74 2b 32 35 32 3b 0a 20 20 |2] = cnt+252;. |
00000360 20 20 7d 0a 20 20 20 20 67 6f 75 72 61 75 64 28 | }. gouraud(|
00000370 26 70 74 73 2c 20 26 63 6f 6c 73 5b 30 5d 2c 20 |&pts, &cols[0], |
00000380 30 2c 20 38 2c 20 31 35 29 3b 0a 7d 0a 0a 76 6f |0, 8, 15);.}..vo|
00000390 69 64 20 5f 5f 6e 63 5f 6c 69 6e 65 28 69 6e 74 |id __nc_line(int|
000003a0 20 78 31 2c 20 69 6e 74 20 79 31 2c 20 69 6e 74 | x1, int y1, int|
000003b0 20 78 32 2c 20 69 6e 74 20 79 32 2c 20 69 6e 74 | x2, int y2, int|
000003c0 20 73 69 64 65 2c 20 69 6e 74 20 69 30 2c 20 69 | side, int i0, i|
000003d0 6e 74 20 69 31 29 0a 7b 0a 20 20 20 20 69 6e 74 |nt i1).{. int|
000003e0 20 64 79 2c 64 78 2c 64 2c 69 6e 63 72 31 2c 69 | dy,dx,d,incr1,i|
000003f0 6e 63 72 32 2c 69 6e 63 2c 65 6e 64 2c 6c 65 6e |ncr2,inc,end,len|
00000400 2c 6a 2c 20 69 73 2c 20 69 64 3b 0a 0a 20 20 20 |,j, is, id;.. |
00000410 20 64 78 20 3d 20 61 62 73 28 78 32 2d 78 31 29 | dx = abs(x2-x1)|
00000420 3b 0a 20 20 20 20 64 79 20 3d 20 61 62 73 28 79 |;. dy = abs(y|
00000430 32 2d 79 31 29 3b 0a 0a 20 20 20 20 69 66 20 28 |2-y1);.. if (|
00000440 64 78 20 3e 20 64 79 29 0a 20 20 20 20 7b 0a 20 |dx > dy). {. |
00000450 20 20 20 20 20 20 20 64 20 3d 20 28 64 79 3c 3c | d = (dy<<|
00000460 31 29 20 2d 20 64 78 3b 0a 20 20 20 20 20 20 20 |1) - dx;. |
00000470 20 69 6e 63 72 31 20 3d 20 28 64 79 3c 3c 31 29 | incr1 = (dy<<1)|
00000480 3b 0a 20 20 20 20 20 20 20 20 69 6e 63 72 32 20 |;. incr2 |
00000490 3d 20 28 64 79 20 2d 20 64 78 29 3c 3c 31 3b 0a |= (dy - dx)<<1;.|
000004a0 20 20 20 20 20 20 20 20 69 66 20 28 79 31 3e 3d | if (y1>=|
000004b0 79 32 29 20 69 6e 63 3d 31 3b 20 65 6c 73 65 20 |y2) inc=1; else |
000004c0 69 6e 63 3d 2d 31 3b 0a 20 20 20 20 20 20 20 20 |inc=-1;. |
000004d0 69 66 20 28 78 31 20 3e 20 78 32 29 0a 20 20 20 |if (x1 > x2). |
000004e0 20 20 20 20 20 7b 0a 20 20 20 20 20 20 20 20 20 | {. |
000004f0 20 20 20 20 65 6e 64 3d 78 31 3b 0a 20 20 20 20 | end=x1;. |
00000500 20 20 20 20 20 20 20 20 20 78 31 3d 78 32 3b 0a | x1=x2;.|
00000510 20 20 20 20 20 20 20 20 20 20 20 20 20 79 31 3d | y1=|
00000520 79 32 3b 0a 20 20 20 20 20 20 20 20 7d 0a 20 20 |y2;. }. |
00000530 20 20 20 20 20 20 65 6c 73 65 0a 20 20 20 20 20 | else. |
00000540 20 20 20 7b 0a 20 20 20 20 20 20 20 20 20 20 20 | {. |
00000550 20 69 6e 63 3d 2d 69 6e 63 3b 0a 20 20 20 20 20 | inc=-inc;. |
00000560 20 20 20 20 20 20 20 65 6e 64 20 3d 20 78 32 3b | end = x2;|
00000570 0a 20 20 20 20 20 20 20 20 7d 0a 20 20 20 20 20 |. }. |
00000580 20 20 20 6c 65 6e 20 3d 20 65 6e 64 20 2d 20 78 | len = end - x|
00000590 31 3b 0a 20 20 20 20 20 20 20 20 69 64 20 3d 20 |1;. id = |
000005a0 28 69 31 20 2d 20 69 30 29 20 3c 3c 20 32 30 3b |(i1 - i0) << 20;|
000005b0 0a 20 20 20 20 20 20 20 20 69 73 20 3d 20 69 64 |. is = id|
000005c0 20 2f 20 6c 65 6e 3b 0a 20 20 20 20 20 20 20 20 | / len;. |
000005d0 69 64 20 3d 20 69 30 20 3c 3c 20 32 30 3b 0a 0a |id = i0 << 20;..|
000005e0 20 20 20 20 20 20 20 20 69 66 20 28 73 69 64 65 | if (side|
000005f0 20 3d 3d 20 30 29 0a 20 20 20 20 20 20 20 20 7b | == 0). {|
00000600 0a 20 20 20 20 20 20 20 20 20 20 20 20 66 6f 72 |. for|
00000610 20 28 6a 3d 30 3b 20 6a 3c 3d 6c 65 6e 3b 20 6a | (j=0; j<=len; j|
00000620 2b 2b 29 0a 20 20 20 20 20 20 20 20 20 20 20 20 |++). |
00000630 7b 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |{. |
00000640 20 20 78 6c 5b 79 31 5d 20 3d 20 78 31 2b 6a 3b | xl[y1] = x1+j;|
00000650 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. |
00000660 20 69 6c 5b 79 31 5d 20 3d 20 69 64 3b 0a 20 20 | il[y1] = id;. |
00000670 20 20 20 20 20 20 20 20 20 20 20 20 20 20 69 64 | id|
00000680 20 2b 3d 20 69 73 3b 0a 20 20 20 20 20 20 20 20 | += is;. |
00000690 20 20 20 20 20 20 20 20 69 66 20 28 64 3c 30 29 | if (d<0)|
000006a0 20 64 2b 3d 69 6e 63 72 31 3b 0a 20 20 20 20 20 | d+=incr1;. |
000006b0 20 20 20 20 20 20 20 20 20 20 20 65 6c 73 65 0a | else.|
000006c0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
000006d0 7b 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |{. |
000006e0 20 20 20 20 20 20 79 31 20 2b 3d 20 69 6e 63 3b | y1 += inc;|
000006f0 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. |
00000700 20 20 20 20 20 64 20 2b 3d 20 69 6e 63 72 32 3b | d += incr2;|
00000710 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. |
00000720 20 7d 0a 20 20 20 20 20 20 20 20 20 20 20 20 7d | }. }|
00000730 0a 20 20 20 20 20 20 20 20 7d 0a 20 20 20 20 20 |. }. |
00000740 20 20 20 69 66 20 28 73 69 64 65 20 3d 3d 20 31 | if (side == 1|
00000750 29 0a 20 20 20 20 20 20 20 20 7b 0a 20 20 20 20 |). {. |
00000760 20 20 20 20 20 20 20 20 66 6f 72 20 28 6a 3d 30 | for (j=0|
00000770 3b 20 6a 3c 3d 6c 65 6e 3b 20 6a 2b 2b 29 0a 20 |; j<=len; j++). |
00000780 20 20 20 20 20 20 20 20 20 20 20 7b 0a 20 20 20 | {. |
00000790 20 20 20 20 20 20 20 20 20 20 20 20 20 78 72 5b | xr[|
000007a0 79 31 5d 20 3d 20 78 31 2b 6a 3b 0a 20 20 20 20 |y1] = x1+j;. |
000007b0 20 20 20 20 20 20 20 20 20 20 20 20 69 72 5b 79 | ir[y|
000007c0 31 5d 20 3d 20 69 64 3b 0a 20 20 20 20 20 20 20 |1] = id;. |
000007d0 20 20 20 20 20 20 20 20 20 69 64 20 2b 3d 20 69 | id += i|
000007e0 73 3b 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 |s;. |
000007f0 20 20 20 69 66 20 28 64 3c 30 29 20 64 2b 3d 69 | if (d<0) d+=i|
00000800 6e 63 72 31 3b 0a 20 20 20 20 20 20 20 20 20 20 |ncr1;. |
00000810 20 20 20 20 20 20 65 6c 73 65 0a 20 20 20 20 20 | else. |
00000820 20 20 20 20 20 20 20 20 20 20 20 7b 0a 20 20 20 | {. |
00000830 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00000840 20 79 31 20 2b 3d 20 69 6e 63 3b 0a 20 20 20 20 | y1 += inc;. |
00000850 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00000860 64 20 2b 3d 20 69 6e 63 72 32 3b 0a 20 20 20 20 |d += incr2;. |
00000870 20 20 20 20 20 20 20 20 20 20 20 20 7d 0a 20 20 | }. |
00000880 20 20 20 20 20 20 20 20 20 20 7d 0a 20 20 20 20 | }. |
00000890 20 20 20 20 7d 0a 20 20 20 20 7d 0a 20 20 20 20 | }. }. |
000008a0 65 6c 73 65 0a 20 20 20 20 7b 0a 20 20 20 20 20 |else. {. |
000008b0 20 20 20 64 20 3d 20 28 64 78 3c 3c 31 29 20 2d | d = (dx<<1) -|
000008c0 20 64 79 3b 0a 20 20 20 20 20 20 20 20 69 6e 63 | dy;. inc|
000008d0 72 31 20 3d 20 28 64 78 3c 3c 31 29 3b 0a 20 20 |r1 = (dx<<1);. |
000008e0 20 20 20 20 20 20 69 6e 63 72 32 20 3d 20 28 64 | incr2 = (d|
000008f0 78 2d 64 79 29 3c 3c 31 3b 0a 20 20 20 20 20 20 |x-dy)<<1;. |
00000900 20 20 69 66 20 28 78 31 20 3e 3d 20 78 32 29 20 | if (x1 >= x2) |
00000910 69 6e 63 20 3d 20 31 3b 20 65 6c 73 65 20 69 6e |inc = 1; else in|
00000920 63 3d 2d 31 3b 0a 20 20 20 20 20 20 20 20 69 66 |c=-1;. if|
00000930 20 28 79 31 20 3e 20 79 32 29 0a 20 20 20 20 20 | (y1 > y2). |
00000940 20 20 20 7b 0a 20 20 20 20 20 20 20 20 20 20 20 | {. |
00000950 20 65 6e 64 20 3d 20 79 31 3b 0a 20 20 20 20 20 | end = y1;. |
00000960 20 20 20 20 20 20 20 79 31 20 3d 20 79 32 3b 0a | y1 = y2;.|
00000970 20 20 20 20 20 20 20 20 20 20 20 20 78 31 20 3d | x1 =|
00000980 20 78 32 3b 0a 20 20 20 20 20 20 20 20 7d 0a 20 | x2;. }. |
00000990 20 20 20 20 20 20 20 65 6c 73 65 0a 20 20 20 20 | else. |
000009a0 20 20 20 20 7b 0a 20 20 20 20 20 20 20 20 20 20 | {. |
000009b0 20 20 69 6e 63 20 3d 2d 69 6e 63 3b 0a 20 20 20 | inc =-inc;. |
000009c0 20 20 20 20 20 20 20 20 20 65 6e 64 20 3d 20 79 | end = y|
000009d0 32 3b 0a 20 20 20 20 20 20 20 20 7d 0a 20 20 20 |2;. }. |
000009e0 20 20 20 20 20 6c 65 6e 20 3d 20 65 6e 64 20 2d | len = end -|
000009f0 20 79 31 3b 0a 0a 20 20 20 20 20 20 20 20 69 64 | y1;.. id|
00000a00 20 3d 20 28 69 31 20 2d 20 69 30 29 20 3c 3c 20 | = (i1 - i0) << |
00000a10 32 30 3b 0a 20 20 20 20 20 20 20 20 69 73 20 3d |20;. is =|
00000a20 20 69 64 20 2f 20 6c 65 6e 3b 0a 20 20 20 20 20 | id / len;. |
00000a30 20 20 20 69 64 20 3d 20 69 30 20 3c 3c 20 32 30 | id = i0 << 20|
00000a40 3b 0a 0a 20 20 20 20 20 20 20 20 69 66 20 28 73 |;.. if (s|
00000a50 69 64 65 20 3d 3d 20 30 29 0a 20 20 20 20 20 20 |ide == 0). |
00000a60 20 20 7b 0a 20 20 20 20 20 20 20 20 20 20 20 20 | {. |
00000a70 66 6f 72 20 28 6a 3d 30 3b 20 6a 3c 3d 6c 65 6e |for (j=0; j<=len|
00000a80 3b 20 6a 2b 2b 29 0a 20 20 20 20 20 20 20 20 20 |; j++). |
00000a90 20 20 20 7b 0a 20 20 20 20 20 20 20 20 20 20 20 | {. |
00000aa0 20 20 20 20 20 78 6c 5b 79 31 2b 6a 5d 20 3d 20 | xl[y1+j] = |
00000ab0 78 31 3b 0a 20 20 20 20 20 20 20 20 20 20 20 20 |x1;. |
00000ac0 20 20 20 20 69 6c 5b 79 31 2b 6a 5d 20 3d 20 69 | il[y1+j] = i|
00000ad0 64 3b 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 |d;. |
00000ae0 20 20 20 69 64 20 2b 3d 20 69 73 3b 0a 20 20 20 | id += is;. |
00000af0 20 20 20 20 20 20 20 20 20 20 20 20 20 69 66 20 | if |
00000b00 28 64 3c 30 29 20 64 2b 3d 69 6e 63 72 31 3b 0a |(d<0) d+=incr1;.|
00000b10 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00000b20 65 6c 73 65 0a 20 20 20 20 20 20 20 20 20 20 20 |else. |
00000b30 20 20 20 20 20 7b 0a 20 20 20 20 20 20 20 20 20 | {. |
00000b40 20 20 20 20 20 20 20 20 20 20 20 78 31 2b 3d 69 | x1+=i|
00000b50 6e 63 3b 0a 20 20 20 20 20 20 20 20 20 20 20 20 |nc;. |
00000b60 20 20 20 20 20 20 20 20 64 2b 3d 69 6e 63 72 32 | d+=incr2|
00000b70 3b 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |;. |
00000b80 20 20 7d 0a 20 20 20 20 20 20 20 20 20 20 20 20 | }. |
00000b90 7d 0a 20 20 20 20 20 20 20 20 7d 0a 20 20 20 20 |}. }. |
00000ba0 20 20 20 20 69 66 20 28 73 69 64 65 20 3d 3d 20 | if (side == |
00000bb0 31 29 0a 20 20 20 20 20 20 20 20 7b 0a 20 20 20 |1). {. |
00000bc0 20 20 20 20 20 20 20 20 20 66 6f 72 20 28 6a 3d | for (j=|
00000bd0 30 3b 20 6a 3c 3d 6c 65 6e 3b 20 6a 2b 2b 29 0a |0; j<=len; j++).|
00000be0 20 20 20 20 20 20 20 20 20 20 20 20 7b 0a 20 20 | {. |
00000bf0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 78 72 | xr|
00000c00 5b 79 31 2b 6a 5d 20 3d 20 78 31 3b 0a 20 20 20 |[y1+j] = x1;. |
00000c10 20 20 20 20 20 20 20 20 20 20 20 20 20 69 72 5b | ir[|
00000c20 79 31 2b 6a 5d 20 3d 20 69 64 3b 0a 20 20 20 20 |y1+j] = id;. |
00000c30 20 20 20 20 20 20 20 20 20 20 20 20 69 64 20 2b | id +|
00000c40 3d 20 69 73 3b 0a 20 20 20 20 20 20 20 20 20 20 |= is;. |
00000c50 20 20 20 20 20 20 69 66 20 28 64 3c 30 29 20 64 | if (d<0) d|
00000c60 2b 3d 69 6e 63 72 31 3b 0a 20 20 20 20 20 20 20 |+=incr1;. |
00000c70 20 20 20 20 20 20 20 20 20 65 6c 73 65 0a 20 20 | else. |
00000c80 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7b 0a | {.|
00000c90 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00000ca0 20 20 20 20 78 31 2b 3d 69 6e 63 3b 0a 20 20 20 | x1+=inc;. |
00000cb0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00000cc0 20 64 2b 3d 69 6e 63 72 32 3b 0a 20 20 20 20 20 | d+=incr2;. |
00000cd0 20 20 20 20 20 20 20 20 20 20 20 7d 0a 20 20 20 | }. |
00000ce0 20 20 20 20 20 20 20 20 20 7d 0a 20 20 20 20 20 | }. |
00000cf0 20 20 20 7d 0a 20 20 20 20 7d 0a 7d 0a 0a 76 6f | }. }.}..vo|
00000d00 69 64 20 67 6f 75 72 61 75 64 28 76 65 72 74 69 |id gouraud(verti|
00000d10 63 65 73 20 2a 70 74 73 2c 20 69 6e 74 20 2a 63 |ces *pts, int *c|
00000d20 6f 6c 6f 75 72 73 2c 20 69 6e 74 20 69 30 2c 20 |olours, int i0, |
00000d30 69 6e 74 20 69 31 2c 20 69 6e 74 20 69 32 29 0a |int i1, int i2).|
00000d40 7b 0a 20 20 20 20 69 6e 74 20 76 64 75 5b 32 5d |{. int vdu[2]|
00000d50 2c 20 79 2c 20 79 73 2c 20 73 6c 2c 20 73 72 2c |, y, ys, sl, sr,|
00000d60 20 73 63 72 65 65 6e 64 69 73 74 2c 20 69 73 74 | screendist, ist|
00000d70 61 72 74 2c 20 69 65 6e 64 2c 20 69 64 65 6c 74 |art, iend, idelt|
00000d80 61 2c 20 6c 65 6e 2c 20 78 3b 0a 20 20 20 20 69 |a, len, x;. i|
00000d90 6e 74 20 73 63 72 65 65 6e 73 74 61 72 74 2c 20 |nt screenstart, |
00000da0 65 72 72 6f 72 2c 20 69 6e 74 65 6e 73 3b 0a 20 |error, intens;. |
00000db0 20 20 20 63 68 61 72 20 2a 70 74 72 3b 0a 20 20 | char *ptr;. |
00000dc0 20 20 5f 6b 65 72 6e 65 6c 5f 73 77 69 5f 72 65 | _kernel_swi_re|
00000dd0 67 73 20 72 3b 0a 0a 20 20 20 20 76 64 75 5b 30 |gs r;.. vdu[0|
00000de0 5d 20 3d 20 31 34 38 3b 0a 20 20 20 20 76 64 75 |] = 148;. vdu|
00000df0 5b 31 5d 20 3d 20 2d 31 3b 0a 20 20 20 20 72 2e |[1] = -1;. r.|
00000e00 72 5b 30 5d 20 3d 20 72 2e 72 5b 31 5d 20 3d 20 |r[0] = r.r[1] = |
00000e10 28 69 6e 74 29 20 26 76 64 75 3b 0a 20 20 20 20 |(int) &vdu;. |
00000e20 5f 6b 65 72 6e 65 6c 5f 73 77 69 28 4f 53 5f 52 |_kernel_swi(OS_R|
00000e30 65 61 64 56 64 75 56 61 72 69 61 62 6c 65 73 2c |eadVduVariables,|
00000e40 26 72 2c 26 72 29 3b 0a 0a 20 20 20 20 73 63 72 |&r,&r);.. scr|
00000e50 65 65 6e 73 74 61 72 74 20 3d 20 76 64 75 5b 30 |eenstart = vdu[0|
00000e60 5d 3b 0a 0a 20 20 20 20 69 66 20 28 70 74 73 2d |];.. if (pts-|
00000e70 3e 79 30 20 3c 20 70 74 73 2d 3e 79 31 29 0a 20 |>y0 < pts->y1). |
00000e80 20 20 20 7b 0a 20 20 20 20 20 20 20 20 73 77 61 | {. swa|
00000e90 70 20 28 70 74 73 2d 3e 78 30 2c 70 74 73 2d 3e |p (pts->x0,pts->|
00000ea0 78 31 29 3b 0a 20 20 20 20 20 20 20 20 73 77 61 |x1);. swa|
00000eb0 70 20 28 70 74 73 2d 3e 79 30 2c 70 74 73 2d 3e |p (pts->y0,pts->|
00000ec0 79 31 29 3b 0a 20 20 20 20 7d 0a 0a 20 20 20 20 |y1);. }.. |
00000ed0 69 66 20 28 70 74 73 2d 3e 79 31 20 3c 20 70 74 |if (pts->y1 < pt|
00000ee0 73 2d 3e 79 32 29 0a 20 20 20 20 7b 0a 20 20 20 |s->y2). {. |
00000ef0 20 20 20 20 20 73 77 61 70 20 28 70 74 73 2d 3e | swap (pts->|
00000f00 78 31 2c 70 74 73 2d 3e 78 32 29 3b 20 2f 2a 20 |x1,pts->x2); /* |
00000f10 4d 61 6b 65 20 74 72 69 61 6e 67 6c 65 20 74 68 |Make triangle th|
00000f20 65 20 72 69 67 68 74 20 77 61 79 20 75 70 20 2a |e right way up *|
00000f30 2f 0a 20 20 20 20 20 20 20 20 73 77 61 70 20 28 |/. swap (|
00000f40 70 74 73 2d 3e 79 31 2c 70 74 73 2d 3e 79 32 29 |pts->y1,pts->y2)|
00000f50 3b 0a 20 20 20 20 7d 0a 0a 20 20 20 20 69 66 20 |;. }.. if |
00000f60 28 70 74 73 2d 3e 79 30 20 3c 20 70 74 73 2d 3e |(pts->y0 < pts->|
00000f70 79 31 29 0a 20 20 20 20 7b 0a 20 20 20 20 20 20 |y1). {. |
00000f80 20 20 73 77 61 70 20 28 70 74 73 2d 3e 78 30 2c | swap (pts->x0,|
00000f90 70 74 73 2d 3e 78 31 29 3b 0a 20 20 20 20 20 20 |pts->x1);. |
00000fa0 20 20 73 77 61 70 20 28 70 74 73 2d 3e 79 30 2c | swap (pts->y0,|
00000fb0 70 74 73 2d 3e 79 31 29 3b 0a 20 20 20 20 7d 0a |pts->y1);. }.|
00000fc0 0a 20 20 20 20 5f 5f 6e 63 5f 6c 69 6e 65 28 70 |. __nc_line(p|
00000fd0 74 73 2d 3e 78 32 2c 70 74 73 2d 3e 79 32 2c 70 |ts->x2,pts->y2,p|
00000fe0 74 73 2d 3e 78 31 2c 70 74 73 2d 3e 79 31 2c 30 |ts->x1,pts->y1,0|
00000ff0 2c 69 32 2c 69 31 29 3b 0a 20 20 20 20 5f 5f 6e |,i2,i1);. __n|
00001000 63 5f 6c 69 6e 65 28 70 74 73 2d 3e 78 31 2c 70 |c_line(pts->x1,p|
00001010 74 73 2d 3e 79 31 2c 70 74 73 2d 3e 78 30 2c 70 |ts->y1,pts->x0,p|
00001020 74 73 2d 3e 79 30 2c 30 2c 69 31 2c 69 30 29 3b |ts->y0,0,i1,i0);|
00001030 20 2f 2a 20 44 72 61 77 20 6c 69 6e 65 73 20 2a | /* Draw lines *|
00001040 2f 0a 20 20 20 20 5f 5f 6e 63 5f 6c 69 6e 65 28 |/. __nc_line(|
00001050 70 74 73 2d 3e 78 32 2c 70 74 73 2d 3e 79 32 2c |pts->x2,pts->y2,|
00001060 70 74 73 2d 3e 78 30 2c 70 74 73 2d 3e 79 30 2c |pts->x0,pts->y0,|
00001070 31 2c 69 32 2c 69 30 29 3b 0a 0a 20 20 20 20 79 |1,i2,i0);.. y|
00001080 73 20 3d 20 73 67 6e 28 70 74 73 2d 3e 79 32 20 |s = sgn(pts->y2 |
00001090 2d 20 70 74 73 2d 3e 79 30 29 3b 0a 0a 20 20 20 |- pts->y0);.. |
000010a0 20 66 6f 72 20 28 79 3d 70 74 73 2d 3e 79 32 3b | for (y=pts->y2;|
000010b0 20 79 3c 3d 70 74 73 2d 3e 79 30 3b 20 79 2b 2b | y<=pts->y0; y++|
000010c0 29 0a 20 20 20 20 7b 0a 20 20 20 20 20 20 20 20 |). {. |
000010d0 73 6c 20 3d 20 78 6c 5b 79 5d 3b 0a 20 20 20 20 |sl = xl[y];. |
000010e0 20 20 20 20 73 72 20 3d 20 78 72 5b 79 5d 3b 0a | sr = xr[y];.|
000010f0 20 20 20 20 20 20 20 20 69 73 74 61 72 74 20 3d | istart =|
00001100 20 69 6c 5b 79 5d 3b 0a 20 20 20 20 20 20 20 20 | il[y];. |
00001110 69 65 6e 64 20 3d 20 69 72 5b 79 5d 3b 0a 0a 20 |iend = ir[y];.. |
00001120 20 20 20 20 20 20 20 73 63 72 65 65 6e 64 69 73 | screendis|
00001130 74 20 3d 20 28 79 3c 3c 38 29 20 2b 20 28 79 3c |t = (y<<8) + (y<|
00001140 3c 36 29 20 2b 20 73 63 72 65 65 6e 73 74 61 72 |<6) + screenstar|
00001150 74 3b 0a 0a 20 20 20 20 20 20 20 20 69 66 20 28 |t;.. if (|
00001160 73 6c 20 3e 20 73 72 29 0a 20 20 20 20 20 20 20 |sl > sr). |
00001170 20 7b 0a 20 20 20 20 20 20 20 20 20 20 20 20 73 | {. s|
00001180 6c 20 5e 3d 20 73 72 3b 0a 20 20 20 20 20 20 20 |l ^= sr;. |
00001190 20 20 20 20 20 73 72 20 3d 20 73 6c 20 5e 20 73 | sr = sl ^ s|
000011a0 72 3b 0a 20 20 20 20 20 20 20 20 20 20 20 20 73 |r;. s|
000011b0 6c 20 5e 3d 20 73 72 3b 0a 20 20 20 20 20 20 20 |l ^= sr;. |
000011c0 20 20 20 20 20 69 73 74 61 72 74 20 5e 3d 20 69 | istart ^= i|
000011d0 65 6e 64 3b 0a 20 20 20 20 20 20 20 20 20 20 20 |end;. |
000011e0 20 69 65 6e 64 20 3d 20 69 73 74 61 72 74 20 5e | iend = istart ^|
000011f0 20 69 65 6e 64 3b 0a 20 20 20 20 20 20 20 20 20 | iend;. |
00001200 20 20 20 69 73 74 61 72 74 20 5e 3d 20 69 65 6e | istart ^= ien|
00001210 64 3b 0a 20 20 20 20 20 20 20 20 7d 0a 0a 20 20 |d;. }.. |
00001220 20 20 20 20 20 20 69 66 20 28 73 72 20 21 3d 20 | if (sr != |
00001230 73 6c 29 0a 20 20 20 20 20 20 20 20 20 20 20 20 |sl). |
00001240 69 64 65 6c 74 61 20 3d 20 28 69 65 6e 64 20 2d |idelta = (iend -|
00001250 20 69 73 74 61 72 74 29 20 2f 20 28 73 72 2d 73 | istart) / (sr-s|
00001260 6c 29 3b 20 2f 2a 20 49 6e 74 65 6e 73 20 63 68 |l); /* Intens ch|
00001270 61 6e 67 65 20 66 6f 72 20 65 61 63 68 20 70 69 |ange for each pi|
00001280 78 65 6c 20 70 6c 6f 74 74 65 64 20 2a 2f 0a 20 |xel plotted */. |
00001290 20 20 20 20 20 20 20 6c 65 6e 20 3d 20 73 63 72 | len = scr|
000012a0 65 65 6e 64 69 73 74 20 2b 20 73 72 3b 0a 0a 20 |eendist + sr;.. |
000012b0 20 20 20 20 20 20 20 66 6f 72 20 28 78 3d 73 63 | for (x=sc|
000012c0 72 65 65 6e 64 69 73 74 2b 73 6c 3b 20 78 3c 3d |reendist+sl; x<=|
000012d0 6c 65 6e 3b 20 78 2b 2b 29 0a 20 20 20 20 20 20 |len; x++). |
000012e0 20 20 7b 0a 20 20 20 20 20 20 20 20 20 20 20 20 | {. |
000012f0 69 6e 74 65 6e 73 20 3d 20 69 73 74 61 72 74 3e |intens = istart>|
00001300 3e 32 30 3b 0a 20 20 20 20 20 20 20 20 20 20 20 |>20;. |
00001310 20 65 72 72 6f 72 20 2b 3d 20 69 73 74 61 72 74 | error += istart|
00001320 20 2d 20 28 69 73 74 61 72 74 20 26 20 35 33 35 | - (istart & 535|
00001330 38 32 32 33 33 36 29 3b 20 2f 2a 20 41 64 64 20 |822336); /* Add |
00001340 6f 6e 20 65 72 72 6f 72 20 2a 2f 0a 20 20 20 20 |on error */. |
00001350 20 20 20 20 20 20 20 20 69 66 20 28 65 72 72 6f | if (erro|
00001360 72 20 3e 20 31 30 34 38 35 37 36 29 0a 20 20 20 |r > 1048576). |
00001370 20 20 20 20 20 20 20 20 20 7b 0a 20 20 20 20 20 | {. |
00001380 20 20 20 20 20 20 20 20 20 20 20 69 6e 74 65 6e | inten|
00001390 73 20 2b 2b 3b 0a 20 20 20 20 20 20 20 20 20 20 |s ++;. |
000013a0 20 20 20 20 20 20 65 72 72 6f 72 20 2d 3d 20 31 | error -= 1|
000013b0 30 34 38 35 37 36 3b 20 20 20 20 20 20 20 20 20 |048576; |
000013c0 20 20 20 20 20 20 20 20 20 20 2f 2a 20 49 66 20 | /* If |
000013d0 6f 76 65 72 66 6c 6f 77 2e 2e 2e 20 2a 2f 0a 20 |overflow... */. |
000013e0 20 20 20 20 20 20 20 20 20 20 20 7d 0a 20 20 20 | }. |
000013f0 20 20 20 20 20 20 20 20 20 70 74 72 20 3d 20 28 | ptr = (|
00001400 63 68 61 72 20 2a 29 20 78 3b 0a 20 20 20 20 20 |char *) x;. |
00001410 20 20 20 20 20 20 20 2a 70 74 72 20 3d 20 28 63 | *ptr = (c|
00001420 68 61 72 29 20 63 6f 6c 6f 75 72 73 5b 69 6e 74 |har) colours[int|
00001430 65 6e 73 5d 3b 20 20 20 20 20 20 20 20 20 20 2f |ens]; /|
00001440 2a 20 50 6c 6f 74 20 2a 2f 0a 20 20 20 20 20 20 |* Plot */. |
00001450 20 20 20 20 20 20 69 73 74 61 72 74 20 2b 3d 20 | istart += |
00001460 69 64 65 6c 74 61 3b 20 20 20 2f 2a 20 49 6e 63 |idelta; /* Inc|
00001470 72 65 6d 65 6e 74 20 69 6e 74 65 6e 73 69 74 79 |rement intensity|
00001480 20 2a 2f 0a 20 20 20 20 20 20 20 20 7d 0a 20 20 | */. }. |
00001490 20 20 7d 0a 7d 0a | }.}.|
00001496 
.