From 573891918b6d86693767a915b0831bfdbf6dd215 Mon Sep 17 00:00:00 2001
From: Joseph Ferano <joseph@ferano.io>
Date: Mon, 26 Aug 2024 18:04:41 +0700
Subject: [PATCH] Replace swap n pop for unordered_remove and check
 bullet/asteroid collisions even if dead

---
 game.odin | 69 +++++++++++++++----------------------------------------
 1 file changed, 18 insertions(+), 51 deletions(-)

diff --git a/game.odin b/game.odin
index 5959247..aa12f3c 100644
--- a/game.odin
+++ b/game.odin
@@ -13,7 +13,6 @@ SCREEN_HEIGHT : i32 = 800
 BW := f32(SCREEN_WIDTH)
 BH := f32(SCREEN_HEIGHT)
 
-
 SCALE: f32 = 0.37
 SHIP_W: f32 = 70 * SCALE
 SHIP_H: f32 = 100 * SCALE
@@ -63,8 +62,6 @@ GameState :: struct {
     player_state: PlayerState,
     bullets:   [dynamic]Bullet,
     asteroids: [dynamic]Asteroid,
-    bullet_pop_idxs: [dynamic]int,
-    asteroid_pop_idxs: [dynamic]int,
 }
 
 update_ship_shape :: proc(p : ^Player) {
@@ -79,16 +76,6 @@ random_direction :: proc() -> Vec2 {
     return {math.cos(angle), math.sin(angle)}
 }
 
-swap_n_pop :: proc(bullets: ^[dynamic]$T, idx: int) {
-    last := len(bullets) - 1
-    if last == 0 {
-        clear(bullets)
-    } else {
-        bullets[last], bullets[idx] = bullets[idx], bullets[last]
-        pop(bullets)
-    }
-}
-
 init_state :: proc() -> ^GameState {
     start_pos := Vec2{BW / 2 - SHIP_W / 2, BH / 2 - SHIP_H / 2}
     player_state := Player {
@@ -101,8 +88,6 @@ init_state :: proc() -> ^GameState {
         player_state = player_state,
         bullets           = make([dynamic]Bullet, 0, 64),
         asteroids         = make([dynamic]Asteroid, 0, 64),
-        asteroid_pop_idxs = make([dynamic]int, 0, 64),
-        bullet_pop_idxs   = make([dynamic]int, 0, 64),
     }
 
     get_rand_angle :: proc(min: i32, max: i32) -> f32 {
@@ -163,35 +148,6 @@ update :: proc(s: ^GameState) {
                 }
             }
         }
-        for i := 0; i < len(s.bullets); i += 1 {
-            if (   s.bullets[i].pos.x < 0 || s.bullets[i].pos.x > BW
-                || s.bullets[i].pos.y < 0 || s.bullets[i].pos.y > BH) {
-                append(&s.bullet_pop_idxs, i)
-            }
-            s.bullets[i].pos += s.bullets[i].vel
-            for j := 0; j < len(s.asteroids); j += 1 {
-                if rl.CheckCollisionCircleRec(s.bullets[i].pos, BULLET_RADIUS, s.asteroids[j].rect) {
-                    append(&s.bullet_pop_idxs, i)
-                    append(&s.asteroid_pop_idxs, j)
-                }
-            }
-        }
-
-        bpi_len := len(s.bullet_pop_idxs)
-        for i := 0; i < bpi_len; i += 1 {
-            swap_n_pop(&s.bullets, s.bullet_pop_idxs[i])
-        }
-        if bpi_len > 0 {
-            clear(&s.bullet_pop_idxs)
-        }
-        api_len := len(s.asteroid_pop_idxs)
-        for i := 0; i < api_len; i += 1 {
-            swap_n_pop(&s.asteroids, s.asteroid_pop_idxs[i])
-        }
-        if bpi_len > 0 {
-            clear(&s.asteroid_pop_idxs)
-        }
-
         if ship_collision {
             // Randomize everything
             s.player_state = Death {
@@ -214,18 +170,29 @@ update :: proc(s: ^GameState) {
             part.points[0] += part.vel
             part.points[1] += part.vel
         }
-        for i := 0; i < len(s.bullets); i += 1 {
-            if (   s.bullets[i].pos.x < 0 || s.bullets[i].pos.x > BW
-                || s.bullets[i].pos.y < 0 || s.bullets[i].pos.y > BH) {
-                append(&s.bullet_pop_idxs, i)
-            }
-            s.bullets[i].pos += s.bullets[i].vel
-        }
         for i := 0; i < len(s.asteroids); i += 1 {
             s.asteroids[i].rect.x += s.asteroids[i].vel.x * s.dt
             s.asteroids[i].rect.y += s.asteroids[i].vel.y * s.dt
         }
     }
+    for i := len(s.bullets) - 1; i >= 0; i -= 1 {
+        if (   s.bullets[i].pos.x < 0 || s.bullets[i].pos.x > BW
+            || s.bullets[i].pos.y < 0 || s.bullets[i].pos.y > BH) {
+            unordered_remove(&s.bullets, i)
+            continue
+        }
+        s.bullets[i].pos += s.bullets[i].vel
+        collided := false
+        for j := len(s.asteroids) - 1; j >= 0; j -= 1 {
+            if rl.CheckCollisionCircleRec(s.bullets[i].pos, BULLET_RADIUS, s.asteroids[j].rect) {
+                collided = true
+                unordered_remove(&s.asteroids, j)
+            }
+        }
+        if collided {
+            unordered_remove(&s.bullets, i)
+        }
+    }
 }
 
 draw2d :: proc(s: ^GameState) {