1 files changed, 55 insertions, 0 deletions
diff --git a/gst/fxs.c b/gst/fxs.c
new file mode 100644
index 0000000..2078a89
--- /dev/null
+++ b/gst/fxs.c
@@ -0,0 +1,55 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <units.h>
+#include <vec.h>
+
+#include <fxs.h>
+
+void fx_init (fxs *fx) {
+    fx->bullets = (bullet*)malloc(sizeof(bullet)*1024);
+    fx->bulletslen = 0;
+}
+
+void fx_add_bullet (fxs *fx, bullet *b) {
+    fx->bullets[fx->bulletslen] = *b;
+    fx->bulletslen++;
+}
+
+void fx_process (fxs *fx, float time) {
+    for (int i=0; i<fx->bulletslen; i++) {
+        bullet *b = fx->bullets+i;
+        if (time > b->endtime) {
+            // remove by replacing with last, dont care for order
+            *b = fx->bullets[fx->bulletslen-1];
+            fx->bulletslen--;
+        }
+    }
+}
+
+
+void fx_render (SDL_Renderer *rend, fxs *fx, float cam[], float time) {
+    for (int i=0; i<fx->bulletslen; i++) {
+        bullet *b = fx->bullets+i;
+        float travel_time = b->endtime - b->starttime;
+        float interval_time = time - b->starttime;
+        float amt = interval_time / travel_time;
+        if (amt < 0) amt = 0; if (amt > 1) amt = 1;
+        float pos[2] = {
+            b->from[0] *(1-amt) + b->to[0] *amt,
+            b->from[1] *(1-amt) + b->to[1] *amt
+        };
+        float head[2]; vec2_sub(head, b->from, b->to);
+        vec2_norm(head); vec2_mul(head, head, 10);
+        SDL_SetRenderDrawColor(rend, 
+            b->color[0], 
+            b->color[1], 
+            b->color[2],
+            255);
+        SDL_RenderDrawLine(rend, 
+            -cam[0] + pos[0], 
+            -cam[1] + pos[1],
+            -cam[0] + pos[0] + head[0], 
+            -cam[1] + pos[1] + head[1]
+        );
+    }
+}