From ca6c0586750524067d2bcbbad4e559851f6b49be Mon Sep 17 00:00:00 2001
From: jacob <jacob@cagori.com>
Date: Tue, 13 Aug 2024 19:29:03 -0500
Subject: [PATCH] bullet trail testing

---
 res/graphics/bullet.ase |  4 ++--
 src/entity.h            |  6 ++++++
 src/game.c              |  8 +++++++-
 src/user.c              | 27 +++++++++++++++++++++++++++
 4 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/res/graphics/bullet.ase b/res/graphics/bullet.ase
index 13eb940e..dfc5e1df 100644
--- a/res/graphics/bullet.ase
+++ b/res/graphics/bullet.ase
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:45e5aaaab5cced39a4b4eee1cb4dad70f58dc2102d4fdcf9701c082eff41c464
-size 370
+oid sha256:1abb4e1ce9a682baa114c468381371d4d5e805231af6cde7e503ba02fad9dcd0
+size 361
diff --git a/src/entity.h b/src/entity.h
index 0c75e344..1a0043c9 100644
--- a/src/entity.h
+++ b/src/entity.h
@@ -14,6 +14,7 @@ enum entity_prop {
     ENTITY_PROP_CAMERA,
     ENTITY_PROP_CAMERA_ACTIVE,
 
+    ENTITY_PROP_BULLET,
     ENTITY_PROP_WEAPON,
     ENTITY_PROP_TRIGGERING_EQUIPPED,
     ENTITY_PROP_TRIGGERED_THIS_TICK,
@@ -122,6 +123,11 @@ struct entity {
     f32 trigger_delay;  /* Minimum time between triggers */
     f32 last_triggered;
 
+    /* ====================================================================== */
+    /* Bullet */
+
+    struct entity_handle bullet_src_ent;
+
     /* ====================================================================== */
     /* Testing */
 
diff --git a/src/game.c b/src/game.c
index 5fd5861c..ab2dd86a 100644
--- a/src/game.c
+++ b/src/game.c
@@ -557,15 +557,21 @@ INTERNAL void game_update(struct game_cmd_array game_cmds)
             struct v2 out_pos = xform_mul_v2(sprite_xform, out_slice.center);
             struct v2 out_vec = xform_basis_mul_v2(sprite_xform, out_slice.dir);
             out_vec = v2_norm(out_vec);
-            out_vec = v2_mul(out_vec, 5);
+            out_vec = v2_mul(out_vec, 25);
 
             {
+                /* FIXME: Weapon velocity should affect bullet velocity
+                 * (This should also make bullet_src_ent unnecessary for
+                 * drawing bullet trails) */
+
                 /* Spawn bullet */
                 struct entity *bullet = entity_alloc(root);
                 bullet->sprite = sprite_tag_from_path(STR("res/graphics/bullet.ase"));
                 struct xform bullet_xf = XFORM_POS(out_pos);
                 entity_set_xform(bullet, bullet_xf);
                 bullet->velocity = out_vec;
+                bullet->bullet_src_ent = ent->handle;
+                entity_enable_prop(bullet, ENTITY_PROP_BULLET);
             }
         }
     }
diff --git a/src/user.c b/src/user.c
index 6d105432..d99f47b6 100644
--- a/src/user.c
+++ b/src/user.c
@@ -809,6 +809,33 @@ INTERNAL void user_update(void)
 
         struct xform sprite_xform = xf;
 
+        /* Draw bullet trail */
+        if (entity_has_prop(ent, ENTITY_PROP_BULLET)) {
+            f32 max_len = 0.75;
+
+            f32 thickness = 0.0025;
+            u32 color = RGBA_32_F(1, 1, 1, 1);
+
+            struct v2 end = xf.og;
+
+            struct v2 start;
+            struct entity *src = entity_from_handle(store, ent->bullet_src_ent);
+            if (src->valid) {
+                start = xform_mul_v2(src->sprite_local_xform, sprite_sheet_get_slice(sprite_sheet_from_tag_await(sprite_frame_scope, src->sprite), STR("out"), src->animation_frame).center);
+                start = xform_mul_v2(entity_get_xform(src), start);
+            } else {
+                start = v2_sub(end, v2_div(ent->velocity, 50));
+            }
+
+            struct v2 rel = v2_sub(start, end);
+            if (v2_len(rel) > max_len) {
+                rel = v2_mul(v2_norm(rel), max_len);
+                start = v2_add(end, rel);
+            }
+
+            draw_solid_line(G.world_canvas, start, end, thickness, color);
+        }
+
         /* Draw sprite */
         if (!sprite_tag_is_nil(sprite)) {
             /* Calculate sprite xform */