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improve blur effect

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This commit is contained in:
Albert Cahalan 2004-12-07 05:24:07 +00:00
parent 5c67b05102
commit 6d9f9999ec
2 changed files with 54 additions and 30 deletions
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4
docs/CHANGES.txt
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@ -8,6 +8,10 @@ http://www.newbreedsoftware.com/tuxpaint/
2004.December.5 (0.9.15)
* Magic blur effect now gamma-aware, circular, and modifying all points
within the brush instead of just 25% of them.
Albert Cahalan <albert@users.sf.net>
* fixed display corruption in load dialog when saved images are
from a larger display size
Albert Cahalan <albert@users.sf.net>

80
src/tuxpaint.c
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@ -4063,41 +4063,61 @@ static void blit_magic(int x, int y, int button_down)
if (cur_magic == MAGIC_BLUR)
{
/* FIXME: Circular "brush?" */
double state[32][32][3];
unsigned i = 32*32;
SDL_LockSurface(canvas);
for (yy = y - 16; yy < y + 16; yy = yy + 2)
while (i--)
{
for (xx = x - 16; xx < x + 16; xx = xx + 2)
{
SDL_GetRGB(getpixel(canvas, clamp(0, xx, canvas->w - 1),
clamp(0, yy - 1, canvas->h - 1)),
canvas->format,
&r1, &g1, &b1);
SDL_GetRGB(getpixel(canvas, clamp(0, xx - 1, canvas->w - 1),
clamp(0, yy, canvas->h - 1)),
canvas->format,
&r2, &g2, &b2);
SDL_GetRGB(getpixel(canvas, clamp(0, xx + 1, canvas->w - 1),
clamp(0, yy, canvas->h - 1)),
canvas->format,
&r3, &g3, &b3);
SDL_GetRGB(getpixel(canvas, clamp(0, xx, canvas->w - 1),
clamp(0, yy + 1, canvas->h - 1)),
canvas->format,
&r4, &g4, &b4);
int iy = i>>5;
int ix = i&0x1f;
// is it not on the circle of radius sqrt(220) at location 16,16?
if ( (ix-16)*(ix-16) + (iy-16)*(iy-16) > 220)
continue;
// it is on the circle, so grab it
r = (r1 + r2 + r3 + r4) >> 2;
g = (g1 + g2 + g3 + g4) >> 2;
b = (b1 + b2 + b3 + b4) >> 2;
SDL_GetRGB(getpixel(canvas, x+ix-16, y+iy-16), last->format, &r, &g, &b);
state[ix][iy][0] = sRGB_to_linear_table[r];
state[ix][iy][1] = sRGB_to_linear_table[g];
state[ix][iy][2] = sRGB_to_linear_table[b];
}
i = 32*32;
while (i--)
{
double lr, lg, lb; // linear red,green,blue
double weight;
int iy = i>>5;
int ix = i&0x1f;
int r2 = (ix-16)*(ix-16) + (iy-16)*(iy-16); // radius squared
putpixel(canvas, xx, yy,
SDL_MapRGB(canvas->format, r, g, b));
}
// is it not on the circle of radius sqrt(140) at location 16,16?
if ( r2 > 140)
continue;
// It is on the circle, but how strongly will it be affected?
// This is lame; we should use something like a gaussian or cosine
// via a lookup table. (inverted, because this is the center weight)
weight = r2/16.0+3.0;
// Sampling more points would be good too, though it'd be slower.
lr = state[ix][iy-1][0]
+ state[ix-1][iy][0] + state[ix][iy ][0]*weight + state[ix+1][iy][0]
+ state[ix][iy+1][0];
lg = state[ix][iy-1][1]
+ state[ix-1][iy][1] + state[ix][iy ][1]*weight + state[ix+1][iy][1]
+ state[ix][iy+1][1];
lb = state[ix][iy-1][2]
+ state[ix-1][iy][2] + state[ix][iy ][2]*weight + state[ix+1][iy][2]
+ state[ix][iy+1][2];
lr /= weight+4.0;
lg /= weight+4.0;
lb /= weight+4.0;
putpixel(canvas, x+ix-16, y+iy-16, SDL_MapRGB(canvas->format, linear_to_sRGB(lr), linear_to_sRGB(lg), linear_to_sRGB(lb)));
}
SDL_UnlockSurface(canvas);
}