From 17eef0eb2049561739b5f81c78f43f3c359925b6 Mon Sep 17 00:00:00 2001
From: Sara <sara@saragerretsen.nl>
Date: Sun, 28 May 2023 23:59:24 +0200
Subject: [PATCH] added interpolate move

---
 src/corelib/world.c | 64 ++++++++++++++++++++++++++++++++++++++++-----
 src/corelib/world.h |  2 ++
 2 files changed, 59 insertions(+), 7 deletions(-)

diff --git a/src/corelib/world.c b/src/corelib/world.c
index 11a26f6..ce41dea 100644
--- a/src/corelib/world.c
+++ b/src/corelib/world.c
@@ -67,12 +67,7 @@ void draw_objects() {
 }
 
 static inline
-short _collision_aabb_aabb(const object_t* a, const object_t* b) {
-	const float aminx = a->collider.aabb.x + a->sprite.x, aminy = a->collider.aabb.y + a->sprite.x;
-	const float amaxx = aminx + a->collider.aabb.w, amaxy = aminy + a->collider.aabb.h;
-	const float bminx = b->collider.aabb.x, bminy = b->collider.aabb.y;
-	const float bmaxx = b->collider.aabb.x + b->collider.aabb.w, bmaxy = b->collider.aabb.y + b->collider.aabb.h;
-
+int _rect_overlap(float aminx, float aminy, float amaxx, float amaxy, float bminx, float bminy, float bmaxx, float bmaxy) {
 	return
 	(
 		(aminx < bmaxx && aminx > bmaxx) 
@@ -85,6 +80,16 @@ short _collision_aabb_aabb(const object_t* a, const object_t* b) {
 	);
 }
 
+static inline
+short _collision_aabb_aabb(const object_t* a, const object_t* b) {
+	const float aminx = a->collider.aabb.x + a->sprite.x, aminy = a->collider.aabb.y + a->sprite.x;
+	const float amaxx = aminx + a->collider.aabb.w, amaxy = aminy + a->collider.aabb.h;
+	const float bminx = b->collider.aabb.x, bminy = b->collider.aabb.y;
+	const float bmaxx = b->collider.aabb.x + b->collider.aabb.w, bmaxy = b->collider.aabb.y + b->collider.aabb.h;
+
+	return _rect_overlap(aminx, aminy, amaxx, amaxy, bminx, bminy, bmaxx, bmaxy);
+}
+
 static inline
 short _collision_circle_circle(const object_t* a, const object_t* b) {
 	const float ax = a->sprite.x + a->collider.circle.x, ay = a->sprite.y + a->collider.circle.y,
@@ -143,7 +148,7 @@ void update_collision() {
 	for(int outer = 0; outer < WORLD_NUM_OBJECTS; ++outer) {
 		object_t* oobject = g_objects + outer;
 		if(!_can_collide(oobject)) continue;
-		for(int inner = 0; inner < WORLD_NUM_OBJECTS/2; ++inner) {
+		for(int inner = 0; inner < WORLD_NUM_OBJECTS; ++inner) {
 			object_t* iobject = g_objects + inner;
 			if(!_can_collide(oobject)) continue;
 
@@ -154,3 +159,48 @@ void update_collision() {
 		}
 	}
 }
+
+object_t* interpolate_move(object_t* object, float target_x, float target_y, float max_step_size) {
+	// calculate step delta
+	float dx = target_x - object->sprite.x, dy = target_y - object->sprite.y;
+	// calculate direction x,y
+	float m = sqrtf(dx*dx + dy*dy);
+	dx /= m; dy /= m;
+	dx *= max_step_size; dy *= max_step_size;
+
+	// ensure this object would ever collide
+	// if it wouldn't collide anyway, just set position
+	if(_can_collide(object)) {
+		object->sprite.x = target_x;
+		object->sprite.y = target_y;
+		return NULL;
+	}
+
+	/*
+	 * 1. check collision with every other object
+	 * 2. move towards target
+	 */
+	while(object->sprite.x != target_x || object->sprite.y != target_y) {
+		for(int i = 0; i < WORLD_NUM_OBJECTS; ++i) {
+			object_t* other = g_objects + i;
+			if(!_can_collide(other)) continue;
+			if(object != other && _collision_check(other, object)) {
+				other->collider.evt_collision(other, object);
+				object->collider.evt_collision(object, other);
+				return other;
+			}
+		}
+
+		// move towards target, snap to target if distance is too low
+		float distx = fabsf(object->sprite.x - target_x), disty = fabsf(object->sprite.y - target_y);
+		if(distx < fabsf(dx) && disty < fabsf(dy)) {
+			object->sprite.x += dx; object->sprite.y += dy;
+		} else {
+			object->sprite.x = target_x;
+			object->sprite.y = target_y;
+		}
+	}
+
+	// no collision, return nothing
+	return NULL;
+}
diff --git a/src/corelib/world.h b/src/corelib/world.h
index 884b23f..d82287a 100644
--- a/src/corelib/world.h
+++ b/src/corelib/world.h
@@ -61,4 +61,6 @@ void draw_objects();
 
 void update_collision();
 
+object_t* interpolate_move(object_t* object, float target_x, float target_y, float max_step_size);
+
 #endif /* _world_h */