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Radial gradient fill improvement

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Attempting to improve fading out to edges (so the
actual effect is more obvious).
This commit is contained in:
Bill Kendrick 2021-03-05 18:08:19 -08:00
parent 2b39f8cc03
commit f40dc07f37
1 changed files with 15 additions and 11 deletions
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26
src/fill.c
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@ -250,8 +250,10 @@ void draw_radial_gradient(SDL_Surface * canvas, int x_left, int y_top, int x_rig
Uint8 draw_r, draw_g, draw_b, old_r, old_g, old_b, new_r, new_g, new_b;
/* Calculate the max radius of the filled area */
xd = (x_right - x_left + 1);
yd = (y_bottom - y_top + 1);
//xd = (x_right - x_left + 1);
//yd = (y_bottom - y_top + 1);
xd = max(abs(x - x_right), abs(x - x_left));
yd = max(abs(y - y_bottom), abs(y - y_top));
rad = sqrt(xd * xd + yd * yd);
if (rad == 0) {
return;
@ -269,18 +271,20 @@ void draw_radial_gradient(SDL_Surface * canvas, int x_left, int y_top, int x_rig
xd = (float) abs(xx - x);
yd = (float) abs(yy - y);
dist = sqrt(xd * xd + yd * yd);
ratio = (dist / rad);
if (dist < rad) {
ratio = (dist / rad);
/* Get the old color, and blend it (with a distance-based ratio) with the target color */
old_colr = getpixels[canvas->format->BytesPerPixel] (canvas, xx, yy);
SDL_GetRGB(old_colr, canvas->format, &old_r, &old_g, &old_b);
/* Get the old color, and blend it (with a distance-based ratio) with the target color */
old_colr = getpixels[canvas->format->BytesPerPixel] (canvas, xx, yy);
SDL_GetRGB(old_colr, canvas->format, &old_r, &old_g, &old_b);
new_r = (Uint8) (((float) old_r) * ratio + ((float) draw_r * (1.00 - ratio)));
new_g = (Uint8) (((float) old_g) * ratio + ((float) draw_g * (1.00 - ratio)));
new_b = (Uint8) (((float) old_b) * ratio + ((float) draw_b * (1.00 - ratio)));
new_r = (Uint8) (((float) old_r) * ratio + ((float) draw_r * (1.00 - ratio)));
new_g = (Uint8) (((float) old_g) * ratio + ((float) draw_g * (1.00 - ratio)));
new_b = (Uint8) (((float) old_b) * ratio + ((float) draw_b * (1.00 - ratio)));
new_colr = SDL_MapRGB(canvas->format, new_r, new_g, new_b);
putpixels[canvas->format->BytesPerPixel] (canvas, xx, yy, new_colr);
new_colr = SDL_MapRGB(canvas->format, new_r, new_g, new_b);
putpixels[canvas->format->BytesPerPixel] (canvas, xx, yy, new_colr);
}
}
}
}