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Angle calculation for WIP Lightning effect

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This commit is contained in:
Bill Kendrick 2021-09-26 23:34:49 -07:00
parent 2bd9b74dd6
commit 4965cc95f1
1 changed files with 18 additions and 10 deletions
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28
magic/src/lightning.c
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@ -9,6 +9,7 @@
#include <stdio.h>
#include <string.h>
#include <libintl.h>
#include <math.h>
#include "tp_magic_api.h"
#include "SDL_image.h"
@ -22,7 +23,6 @@ int sx, sy;
void lightning_drag(magic_api * api, int which, SDL_Surface * canvas,
SDL_Surface * snapshot, int ox, int oy, int x, int y, SDL_Rect * update_rect);
void lightning_line_callback_drag(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y);
void lightning_line_callback_release(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y);
Uint32 lightning_api_version(void)
@ -120,6 +120,8 @@ void
lightning_release(magic_api * api, int which,
SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y, SDL_Rect * update_rect)
{
float a, b, len, angle;
/* FIXME: This could be made more efficient
(only blit and update between (sx,sy) and (x,y), though
it should also cover the area extending to (ox,oy),
@ -131,9 +133,23 @@ lightning_release(magic_api * api, int which,
SDL_BlitSurface(snapshot, update_rect, canvas, update_rect);
api->line((void *)api, which, canvas, snapshot, sx, sy, x, y, 1, lightning_line_callback_release);
api->stopsound();
api->playsound(snd_effect, (x * 255) / canvas->w, 255);
a = (x - sx);
b = (y - sy);
len = sqrt((a * a) + (b * b));
angle = acos((x - sx) / len);
if (y < sy)
angle = -angle;
#ifdef DEBUG
printf("(%d,%d)->(%d,%d) => a = %.2f, b = %.2f, c (len) = %.2f; angle = %.2f degrees\n",
sx, sy, x, y, a, b, len, (angle * 180.0) / M_PI);
#endif
// FIXME: Do something
}
void lightning_set_color(magic_api * api, Uint8 r, Uint8 g, Uint8 b)
@ -151,14 +167,6 @@ void lightning_line_callback_drag(void *ptr, int which, SDL_Surface * canvas, SD
api->xorpixel(canvas, x, y);
}
void lightning_line_callback_release(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y)
{
magic_api *api = (magic_api *) ptr;
// FIXME
api->putpixel(canvas, x, y, SDL_MapRGB(canvas->format, lightning_r, lightning_g, lightning_b));
}
void lightning_switchin(magic_api * api, int which, int mode, SDL_Surface * canvas)
{
}