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Polyfill filling polygons now

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Scanline polygon fill routine based on public-domain code
by Darel Rex Finley, 2007 <https://alienryderflex.com/polygon_fill/
This commit is contained in:
Bill Kendrick 2024-03-28 00:26:05 -07:00
parent 608564b00f
commit da837a35a2
3 changed files with 104 additions and 12 deletions
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99
magic/src/polyfill.c
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@ -3,7 +3,10 @@
A Magic tool for Tux Paint that creates a filled polygon.
by Bill Kendrick <bill@newbreedsoftware.com>
Last updated: March 27, 2024
Scanline polygon fill routine based on public-domain code
by Darel Rex Finley, 2007 <https://alienryderflex.com/polygon_fill/>
Last updated: March 28, 2024
*/
@ -60,6 +63,7 @@ void polyfill_line_callback(void *pointer, int which, SDL_Surface * canvas,
SDL_Surface * snapshot, int x, int y);
void polyfill_draw_preview(magic_api * api, SDL_Surface * canvas, int show_handles);
void polyfill_draw_final(magic_api * api, SDL_Surface * canvas);
Uint32 polyfill_api_version(void)
@ -234,6 +238,7 @@ void polyfill_draw_preview(magic_api * api, SDL_Surface * canvas, int show_handl
return;
SDL_BlitSurface(polyfill_snapshot, NULL, canvas, NULL);
for (i = 0; i < polyfill_num_pts - 1; i++) {
api->line((void *) api, 0 /* which */, canvas, NULL /* snapshot */,
polyfill_pt_x[i], polyfill_pt_y[i],
@ -284,10 +289,9 @@ polyfill_release(magic_api * api, int which,
printf("Release while editing %d\n", polyfill_editing);
// if (polyfill_editing == polyfill_num_pts) {
// printf("Finalizing it...\n");
// polyfill_num_pts++;
// }
/* FIXME: If they simply clicked the first point (without
drawing to move it), and there are enough points, consider
it a final placement of a new point! */
/* Moved (or placed) the final spot at the beginning? */
if (polyfill_num_pts > 2 &&
@ -311,8 +315,7 @@ polyfill_release(magic_api * api, int which,
polyfill_pt_y[polyfill_num_pts - 1] = polyfill_pt_y[0];
}
// FIXME
polyfill_draw_preview(api, canvas, 0);
polyfill_draw_final(api, canvas);
polyfill_num_pts = 0;
polyfill_editing = MAX_PTS;
@ -358,6 +361,7 @@ polyfill_release(magic_api * api, int which,
void polyfill_set_color(magic_api * api, int which, SDL_Surface * canvas, SDL_Surface * snapshot, Uint8 r, Uint8 g, Uint8 b, SDL_Rect * update_rect)
{
polyfill_color = SDL_MapRGB(canvas->format, r, g, b);
polyfill_draw_preview(api, canvas, 1);
}
void polyfill_set_size(magic_api * api, int which, int mode, SDL_Surface * canvas, SDL_Surface * snapshot, Uint8 size, SDL_Rect * update_rect)
@ -401,7 +405,82 @@ void polyfill_switchin(magic_api * api, int which, int mode,
void polyfill_switchout(magic_api * api, int which, int mode,
SDL_Surface * canvas)
{
/* FIXME: Do we want to do this? */
// polyfill_num_pts = 0;
// polyfill_editing = MAX_PTS;
polyfill_num_pts = 0;
polyfill_editing = MAX_PTS;
}
/* Based on public-domain code by Darel Rex Finley, 2007
https://alienryderflex.com/polygon_fill/
*/
void polyfill_draw_final(magic_api * api, SDL_Surface * canvas) {
int i, j, ymin, ymax, y, nodes, swap;
int nodeX[256];
SDL_Rect rect;
SDL_BlitSurface(polyfill_snapshot, NULL, canvas, NULL);
ymin = canvas->w;
ymax = 0;
for (i = 0; i < polyfill_num_pts; i++) {
if (polyfill_pt_y[i] < ymin) {
ymin = polyfill_pt_y[i];
}
if (polyfill_pt_y[i] > ymax) {
ymax = polyfill_pt_y[i];
}
}
printf("ymin %d -> ymax %d\n", ymin, ymax);
for (y = ymin; y <= ymax; y++) {
nodes = 0;
j = polyfill_num_pts - 2;
for (i = 0; i < polyfill_num_pts - 1; i++) {
if ((polyfill_pt_y[i] < y && polyfill_pt_y[j] >= y) ||
(polyfill_pt_y[j] < y && polyfill_pt_y[i] >= y)) {
nodeX[nodes++] = (int)
(
(double) polyfill_pt_x[i] +
(double) (y - polyfill_pt_y[i]) /
(double) (polyfill_pt_y[j] - polyfill_pt_y[i]) *
(double) (polyfill_pt_x[j] - polyfill_pt_x[i])
);
}
j = i;
}
// Sort the nodes, via a simple “Bubble” sort.
i = 0;
while (i < nodes - 1) {
if (nodeX[i] > nodeX[i+1]) {
swap = nodeX[i];
nodeX[i] = nodeX[i + 1];
nodeX[i + 1] = swap;
if (i)
i--;
} else {
i++;
}
}
// Fill the pixels between node pairs.
for (i = 0; i < nodes; i += 2) {
if (nodeX[i] >= canvas->w)
break;
if (nodeX[i + 1] > 0) {
if (nodeX[i] < 0)
nodeX[i] = 0;
if (nodeX[i + 1] > canvas->w - 1)
nodeX[i + 1] = canvas->w - 1;
rect.x = nodeX[i];
rect.y = y;
rect.w = nodeX[i + 1] - nodeX[i] + 1;
rect.h = 1;
SDL_FillRect(canvas, &rect, polyfill_color);
}
}
}
}