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Magic Emitters: Motion, gravity, & spawning

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Hearts float up, sparkles float down (and sometimes spawn).
Everyone gets random initial movement.
This commit is contained in:
Bill Kendrick 2024-12-26 20:29:44 -08:00
parent 51e28bdfb0
commit e1b9f29c2f
1 changed files with 59 additions and 2 deletions
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61
magic/src/emitter.c
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@ -34,8 +34,8 @@
#include "SDL_mixer.h"
#include "SDL2_rotozoom.h"
#define EMITTER_QUEUE_SIZE 32
#define EMITTER_QUEUE_SIZE_SCALE 4
#define EMITTER_QUEUE_SIZE 64
#define EMITTER_QUEUE_SIZE_SCALE 8
#define EMITTER_DRAW_THRESHOLD 16
@ -74,6 +74,30 @@ int emitter_rotate[NUM_EMITTERS] = {
180,
};
/* Scale of emitter xm/ym speeds */
#define EMITTER_SPEED 64
/* Max random-direction speed for each emitter type */
int emitter_speed[NUM_EMITTERS] = {
16,
8,
4,
};
/* Gravity (if any) of the emitter */
int emitter_gravity[NUM_EMITTERS] = {
-2,
2,
0,
};
/* Whether emitter duplicates itself */
int emitter_duplicate[NUM_EMITTERS] = {
0,
1,
0,
};
/* Our globals: */
static Mix_Chunk *emitter_snds[NUM_EMITTERS];
@ -82,6 +106,7 @@ Uint8 emitter_r, emitter_g, emitter_b;
int emitter_max_trail_length;
int emitter_cur_trail_length;
int emitter_queue_x[EMITTER_QUEUE_SIZE], emitter_queue_y[EMITTER_QUEUE_SIZE];
int emitter_queue_xm[EMITTER_QUEUE_SIZE], emitter_queue_ym[EMITTER_QUEUE_SIZE];
SDL_Surface * * emitter_images[NUM_EMITTERS][EMITTER_QUEUE_SIZE];
/* Function prototypes: */
@ -264,28 +289,58 @@ void emitter_drag(magic_api *api, int which, SDL_Surface *canvas,
SDL_BlitSurface(last, NULL, canvas, NULL);
/* Move all of the objects */
for (i = 0; i < emitter_cur_trail_length; i++)
{
emitter_queue_x[i] += emitter_queue_xm[i] / EMITTER_SPEED;
emitter_queue_y[i] += emitter_queue_ym[i] / EMITTER_SPEED;
emitter_queue_ym[i] += emitter_gravity[which];
if (emitter_duplicate[which] && (rand() % 16) == 0)
{
int d;
d = (rand() % (i + 1));
emitter_queue_x[d] = emitter_queue_x[i];
emitter_queue_y[d] = emitter_queue_y[i];
emitter_queue_xm[d] = emitter_queue_xm[i];
emitter_queue_ym[d] = emitter_queue_ym[i] * 2;
}
}
/* If we've moved a significant distance, emit another object */
if (abs(x - last_x) > EMITTER_DRAW_THRESHOLD || abs(y - last_y) > EMITTER_DRAW_THRESHOLD)
{
if (emitter_cur_trail_length < emitter_max_trail_length - 1)
{
/* Trail not full, add another */
emitter_cur_trail_length++;
}
else
{
/* Trail is full, rotate queue */
for (i = 0; i < emitter_cur_trail_length; i++)
{
emitter_queue_x[i] = emitter_queue_x[i + 1];
emitter_queue_y[i] = emitter_queue_y[i + 1];
emitter_queue_xm[i] = emitter_queue_xm[i + 1];
emitter_queue_ym[i] = emitter_queue_ym[i + 1];
}
}
/* Add the new object */
emitter_queue_x[emitter_cur_trail_length] = x;
emitter_queue_y[emitter_cur_trail_length] = y;
emitter_queue_xm[emitter_cur_trail_length] = (rand() % emitter_speed[which] * 2) - emitter_speed[which];
emitter_queue_ym[emitter_cur_trail_length] = (rand() % emitter_speed[which] * 2) - emitter_speed[which];
last_x = x;
last_y = y;
}
/* Draw all of them */
for (i = 0; i < emitter_cur_trail_length + 1; i++)
{
img = (emitter_cur_trail_length - i);
@ -384,6 +439,8 @@ void emitter_click(magic_api *api, int which, int mode ATTRIBUTE_UNUSED,
{
emitter_queue_x[0] = x;
emitter_queue_y[0] = y;
emitter_queue_xm[0] = (rand() % emitter_speed[which] * 2) - emitter_speed[which];
emitter_queue_ym[0] = (rand() % emitter_speed[which] * 2) - emitter_speed[which];
emitter_cur_trail_length = 0;
last_x = -100;
last_y = -100;