From 85984a0a07f2ea45eb4c0df2cc89649623067d59 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cobrien@witekio.com>
Date: Tue, 14 Oct 2025 16:13:46 +0100
Subject: [PATCH] Add collision info to entities

---
 game.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/game.c b/game.c
index cd71ccb..9aa8b69 100644
--- a/game.c
+++ b/game.c
@@ -9,6 +9,8 @@
 #include <math.h>
 #include <string.h>
 
+#define SHIP_COLLIDE_R 0.05
+
 #define FIRE_MEAN -0.15
 #define FIRE_JITTER 0.01
 
@@ -29,6 +31,7 @@
 #define ROT_PWR 0.002
 
 #define SHOT_VEL 0.04
+#define SHOT_COLLIDE_R 0.005
 
 #define MAX_SHAPES 256U
 #define MAX_ENTITIES 128U
@@ -36,6 +39,12 @@
 
 #define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))
 
+typedef enum {
+	COLLISION_SHIP,
+	COLLISION_SHOT,
+	COLLISION_ASTEROID,
+} collision_tag_t;
+
 typedef struct {
 	vec2_t pos;
 	vec2_t vel;
@@ -43,6 +52,8 @@ typedef struct {
 	float omg;
 	unsigned shapes[MAX_SHAPES_PER_ENTITY];
 	unsigned shape_count;
+	float collision_radius;
+	collision_tag_t tag;
 	bool wrap;
 } entity_t;
 
@@ -118,6 +129,8 @@ static void shoot()
 	    ship->pos, mat2_mul_vec2(ship->dir, ship_shape->verts[0]));
 	e->vel = vec2_add(
 	    ship->vel, mat2_mul_vec2(ship->dir, (vec2_t) { 0, SHOT_VEL }));
+	e->collision_radius = SHIP_COLLIDE_R;
+	e->tag = COLLISION_SHOT;
 
 	shape_t *s = add_shape(id, nullptr);
 	s->visible = true;
@@ -130,6 +143,8 @@ static entity_t *gen_asteroid(float r_mean)
 	unsigned id;
 	entity_t *e = add_entity(&id);
 	e->wrap = true;
+	e->collision_radius = r_mean;
+	e->tag = COLLISION_ASTEROID;
 
 	shape_t *s = add_shape(id, nullptr);
 	s->visible = true;
@@ -177,7 +192,7 @@ static void remove_shape(unsigned id)
 {
 	if (id < shape_count - 1) {
 		const shape_t *last = shapes + shape_count - 1;
-		memcpy(shapes + id, shapes + shape_count - 1, sizeof(shape_t));
+		memcpy(shapes + id, last, sizeof(shape_t));
 		for (unsigned i = 0; i < entities[last->entity].shape_count; ++i) {
 			if (entities[last->entity].shapes[i] == shape_count - 1) {
 				entities[last->entity].shapes[i] = id;
@@ -227,9 +242,12 @@ void game_init(float _aspect)
 
 	aspect = _aspect;
 	quit = false;
+	entity_count = shape_count = 0;
 
 	entity_t *ship = add_entity(&ship_entity_id);
 	ship->wrap = true;
+	ship->collision_radius = SHIP_COLLIDE_R;
+	ship->tag = COLLISION_SHIP;
 
 	shape_t *ship_shape = add_shape(ship_entity_id, &ship_shape_id);
 	ship_shape->visible = true;