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Make DrawLine bin exact by copying from its original source.

pull/109/head
Sergey Semushin 7 years ago committed by Anders Jenbo
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c346435886
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b971d8a2cb
1 changed files with 167 additions and 199 deletions
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  1. 366
      Source/engine.cpp

366
Source/engine.cpp
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@ -2088,234 +2088,202 @@ void engine_draw_pixel(int sx, int sy)
// 52B99C: using guessed type int gbNotInView;
// 69CF0C: using guessed type int gpBufEnd;
/*
* Xiaolin Wu's anti-aliased line algorithm
*/
// Exact copy from https://github.com/erich666/GraphicsGems/blob/dad26f941e12c8bf1f96ea21c1c04cd2206ae7c9/gems/DoubleLine.c
// Except:
// * not in view checks
// * global variable instead of reverse flag
// * condition for pixels_left < 0 removed
#define GG_SWAP(A, B) \
{ \
(A) ^= (B); \
(B) ^= (A); \
(A) ^= (B); \
}
#define GG_ABSOLUTE(I, J, K) (((I) - (J)) * ((K) = (((I) - (J)) < 0 ? -1 : 1)))
void DrawLine(int x0, int y0, int x1, int y1, BYTE col)
{
int i, sx, sy, dx, dy, nx, ny, xlen, ylen, pixels, remain, xy_same, line_dir, mult_2, mult_4;
int dx, dy, incr1, incr2, D, x, y, xend, c, pixels_left;
int sign_x, sign_y, step, i;
int x1_, y1_;
gbPixelCol = col;
gbNotInView = FALSE;
if(x0 < 0 + 64 || x0 >= 640 + 64) {
if (x0 < 0 + 64 || x0 >= 640 + 64) {
gbNotInView = TRUE;
}
if(x1 < 0 + 64 || x1 >= 640 + 64) {
if (x1 < 0 + 64 || x1 >= 640 + 64) {
gbNotInView = TRUE;
}
if(y0 < 0 + 160 || y0 >= 352 + 160) {
if (y0 < 0 + 160 || y0 >= 352 + 160) {
gbNotInView = TRUE;
}
if(y1 < 0 + 160 || y1 >= 352 + 160) {
if (y1 < 0 + 160 || y1 >= 352 + 160) {
gbNotInView = TRUE;
}
if(x1 - x0 < 0) {
nx = -1;
} else {
nx = 1;
}
xlen = nx * (x1 - x0);
if(y1 - y0 < 0) {
ny = -1;
} else {
ny = 1;
}
ylen = ny * (y1 - y0);
if(ny == nx) {
xy_same = 1;
} else {
xy_same = -1;
}
dx = GG_ABSOLUTE(x1, x0, sign_x);
dy = GG_ABSOLUTE(y1, y0, sign_y);
/* decide increment sign by the slope sign */
if (sign_x == sign_y)
step = 1;
else
step = -1;
if(ylen > xlen) {
x0 ^= y0 ^= x0 ^= y0;
x1 ^= y1 ^= x1 ^= y1;
xlen ^= ylen ^= xlen ^= ylen;
if (dy > dx) { /* chooses axis of greatest movement (make
* dx) */
GG_SWAP(x0, y0);
GG_SWAP(x1, y1);
GG_SWAP(dx, dy);
gbRotateMap = TRUE;
} else {
} else
gbRotateMap = FALSE;
}
if(x0 > x1) {
sx = x1;
sy = y1;
dx = x0;
dy = y0;
/* note error check for dx==0 should be included here */
if (x0 > x1) { /* start from the smaller coordinate */
x = x1;
y = y1;
x1_ = x0;
y1_ = y0;
} else {
sx = x0;
sy = y0;
dx = x1;
dy = y1;
x = x0;
y = y0;
x1_ = x1;
y1_ = y1;
}
pixels = (xlen - 1) / 4;
remain = (xlen - 1) % 4;
engine_draw_pixel(sx, sy);
engine_draw_pixel(dx, dy);
line_dir = (ylen << 2) - xlen - xlen;
if(line_dir < 0) {
mult_2 = ylen << 1;
mult_4 = (mult_2 << 1) - xlen;
for(i = 0; i < pixels; i++) {
sx++;
dx--;
if(mult_4 < 0) {
engine_draw_pixel(sx, sy);
sx++;
engine_draw_pixel(sx, sy);
engine_draw_pixel(dx, dy);
dx--;
engine_draw_pixel(dx, dy);
mult_4 += mult_2 + mult_2;
} else if(mult_4 < mult_2) {
engine_draw_pixel(sx, sy);
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
engine_draw_pixel(dx, dy);
dy -= xy_same;
dx--;
engine_draw_pixel(dx, dy);
mult_4 += line_dir;
/* Note dx=n implies 0 - n or (dx+1) pixels to be set */
/* Go round loop dx/4 times then plot last 0,1,2 or 3 pixels */
/* In fact (dx-1)/4 as 2 pixels are already plotted */
xend = (dx - 1) / 4;
pixels_left = (dx - 1) % 4; /* number of pixels left over at the end */
engine_draw_pixel(x, y);
engine_draw_pixel(x1_, y1_); /* plot first two points */
incr2 = 4 * dy - 2 * dx;
if (incr2 < 0) { /* slope less than 1/2 */
c = 2 * dy;
incr1 = 2 * c;
D = incr1 - dx;
for (i = 0; i < xend; i++) { /* plotting loop */
++x;
--x1_;
if (D < 0) {
/* pattern 1 forwards */
engine_draw_pixel(x, y);
engine_draw_pixel(++x, y);
/* pattern 1 backwards */
engine_draw_pixel(x1_, y1_);
engine_draw_pixel(--x1_, y1_);
D += incr1;
} else {
sy += xy_same;
engine_draw_pixel(sx, sy);
sx++;
engine_draw_pixel(sx, sy);
dy -= xy_same;
engine_draw_pixel(dx, dy);
dx--;
engine_draw_pixel(dx, dy);
mult_4 += line_dir;
}
}
if(remain != 0) {
if(mult_4 < 0) {
sx++;
engine_draw_pixel(sx, sy);
if(remain > 1) {
sx++;
engine_draw_pixel(sx, sy);
}
if(remain > 2) {
dx--;
engine_draw_pixel(dx, dy);
}
} else if(mult_4 < mult_2) {
sx++;
engine_draw_pixel(sx, sy);
if(remain > 1) {
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
}
if(remain > 2) {
dx--;
engine_draw_pixel(dx, dy);
if (D < c) {
/* pattern 2 forwards */
engine_draw_pixel(x, y);
engine_draw_pixel(++x, y += step);
/* pattern 2 backwards */
engine_draw_pixel(x1_, y1_);
engine_draw_pixel(--x1_, y1_ -= step);
} else {
/* pattern 3 forwards */
engine_draw_pixel(x, y += step);
engine_draw_pixel(++x, y);
/* pattern 3 backwards */
engine_draw_pixel(x1_, y1_ -= step);
engine_draw_pixel(--x1_, y1_);
}
D += incr2;
}
} /* end for */
/* plot last pattern */
if (pixels_left) {
if (D < 0) {
engine_draw_pixel(++x, y); /* pattern 1 */
if (pixels_left > 1)
engine_draw_pixel(++x, y);
if (pixels_left > 2)
engine_draw_pixel(--x1_, y1_);
} else {
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
if(remain > 1) {
sx++;
engine_draw_pixel(sx, sy);
}
if(remain > 2) {
dy -= xy_same;
dx--;
engine_draw_pixel(dx, dy);
if (D < c) {
engine_draw_pixel(++x, y); /* pattern 2 */
if (pixels_left > 1)
engine_draw_pixel(++x, y += step);
if (pixels_left > 2)
engine_draw_pixel(--x1_, y1_);
} else {
/* pattern 3 */
engine_draw_pixel(++x, y += step);
if (pixels_left > 1)
engine_draw_pixel(++x, y);
if (pixels_left > 2)
engine_draw_pixel(--x1_, y1_ -= step);
}
}
}
} else {
mult_2 = (ylen - xlen) << 1;
mult_4 = (mult_2 << 1) + xlen;
for(i = 0; i < pixels; i++) {
sx++;
dx--;
if(mult_4 > 0) {
sy += xy_same;
engine_draw_pixel(sx, sy);
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
dy -= xy_same;
engine_draw_pixel(dx, dy);
dy -= xy_same;
dx--;
engine_draw_pixel(dx, dy);
mult_4 += mult_2 + mult_2;
} else if(mult_4 < mult_2) {
engine_draw_pixel(sx, sy);
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
engine_draw_pixel(dx, dy);
dy -= xy_same;
dx--;
engine_draw_pixel(dx, dy);
mult_4 += line_dir;
} /* end if pixels_left */
}
/* end slope < 1/2 */
else { /* slope greater than 1/2 */
c = 2 * (dy - dx);
incr1 = 2 * c;
D = incr1 + dx;
for (i = 0; i < xend; i++) {
++x;
--x1_;
if (D > 0) {
/* pattern 4 forwards */
engine_draw_pixel(x, y += step);
engine_draw_pixel(++x, y += step);
/* pattern 4 backwards */
engine_draw_pixel(x1_, y1_ -= step);
engine_draw_pixel(--x1_, y1_ -= step);
D += incr1;
} else {
sy += xy_same;
engine_draw_pixel(sx, sy);
sx++;
engine_draw_pixel(sx, sy);
dy -= xy_same;
engine_draw_pixel(dx, dy);
dx--;
engine_draw_pixel(dx, dy);
mult_4 += line_dir;
}
}
if(remain != 0) {
if(mult_4 > 0) {
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
if(remain > 1) {
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
}
if(remain > 2) {
dy -= xy_same;
dx--;
engine_draw_pixel(dx, dy);
}
} else if(mult_4 < mult_2) {
sx++;
engine_draw_pixel(sx, sy);
if(remain > 1) {
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
}
if(remain > 2) {
dx--;
engine_draw_pixel(dx, dy);
if (D < c) {
/* pattern 2 forwards */
engine_draw_pixel(x, y);
engine_draw_pixel(++x, y += step);
/* pattern 2 backwards */
engine_draw_pixel(x1_, y1_);
engine_draw_pixel(--x1_, y1_ -= step);
} else {
/* pattern 3 forwards */
engine_draw_pixel(x, y += step);
engine_draw_pixel(++x, y);
/* pattern 3 backwards */
engine_draw_pixel(x1_, y1_ -= step);
engine_draw_pixel(--x1_, y1_);
}
D += incr2;
}
} /* end for */
/* plot last pattern */
if (pixels_left) {
if (D > 0) {
engine_draw_pixel(++x, y += step); /* pattern 4 */
if (pixels_left > 1)
engine_draw_pixel(++x, y += step);
if (pixels_left > 2)
engine_draw_pixel(--x1_, y1_ -= step);
} else {
sy += xy_same;
sx++;
engine_draw_pixel(sx, sy);
if(remain > 1) {
sx++;
engine_draw_pixel(sx, sy);
}
if(remain > 2) {
if(mult_4 > mult_2) {
dy -= xy_same;
dx--;
engine_draw_pixel(dx, dy);
} else {
dx--;
engine_draw_pixel(dx, dy);
if (D < c) {
engine_draw_pixel(++x, y); /* pattern 2 */
if (pixels_left > 1)
engine_draw_pixel(++x, y += step);
if (pixels_left > 2)
engine_draw_pixel(--x1_, y1_);
} else {
/* pattern 3 */
engine_draw_pixel(++x, y += step);
if (pixels_left > 1)
engine_draw_pixel(++x, y);
if (pixels_left > 2) {
if (D > c) /* step 3 */
engine_draw_pixel(--x1_, y1_ -= step);
else /* step 2 */
engine_draw_pixel(--x1_, y1_);
}
}
}

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