Merge pull request 'rework collision_t component into a more wholistic physics_t component' (#11) from object-physics into main

Reviewed-on: #11

CMakeLists.txt

@@ -17,14 +17,17 @@ find_package(SDL2)
 find_package(SDL2_image)
 find_package(SDL2_ttf)
 
-file(GLOB_RECURSE
+file(
+	GLOB_RECURSE
 	SOURCE_C
 	"${CMAKE_SOURCE_DIR}/src/**.c")
-file(GLOB_RECURSE
+file(
+	GLOB_RECURSE
 	SOURCE_CPP
 	"${CMAKE_SOURCE_DIR}/src/**.c*")
 
-add_executable(${PROJECT}
+add_executable(
+	${PROJECT}
 	${SOURCE_C}
 	${SOURCE_CPP})
 

src/corelib/object.c

@@ -4,7 +4,7 @@ object_t object_default() {
   return (object_t){
     .active = 1,
 	  .enabled = 1,
-	  .collider = collider_default(),
+	  .physics = physics_default(),
 	  .evt_draw = &object_draw_sprite,
 	  .evt_update = NULL,
     .sprite = sprite_default(),

src/corelib/object.h

@@ -5,7 +5,6 @@
 #include "physics.h"
 
 typedef struct object_t object_t;
-typedef struct collider_t collider_t;
 
 typedef void(*tick_fn)(struct object_t*);
 typedef void(*draw_fn)(struct object_t*);
@@ -14,7 +13,7 @@ struct object_t {
 	sprite_t sprite;
 	int active; // 1 if this object is in use and should not be overriden.
 	int enabled; // 1 if this object's events should be triggered.
-	collider_t collider; // the collider to use for this object's physics interaction.
+	physics_t physics; // the collider to use for this object's physics interaction.
 
 	uintptr_t timer; // free to use for whatever
 

src/corelib/physics.c

@@ -9,15 +9,18 @@ float fclampf(float x, float min_, float max_) {
 }
 
 
-collider_t collider_default() {
-	return (collider_t) {
-		.type=COLLIDERTYPE_NONE
+physics_t physics_default() {
+	return (physics_t) {
+		.type=COLLIDERTYPE_NONE,
+		.velocity_x = 0.f,
+		.velocity_y = 0.f,
+		.solver = &solve_collision_slide
 	};
 }
 
 void object_broadcast_collision(object_t* this, object_t* other) {
-	if(this->collider.evt_collision != NULL) {
-		this->collider.evt_collision(this, other);
+	if(this->physics.evt_collision != NULL) {
+		this->physics.evt_collision(this, other);
 	}
 }
 short can_collide(const object_t* this) {
@@ -40,21 +43,21 @@ int _rect_overlap(float aminx, float aminy, float amaxx, float amaxy, float bmin
 
 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;
+	const float aminx = a->physics.aabb.x + a->sprite.x, aminy = a->physics.aabb.y + a->sprite.x;
+	const float amaxx = aminx + a->physics.aabb.w, amaxy = aminy + a->physics.aabb.h;
+	const float bminx = b->physics.aabb.x, bminy = b->physics.aabb.y;
+	const float bmaxx = b->physics.aabb.x + b->physics.aabb.w, bmaxy = b->physics.aabb.y + b->physics.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,
-		  		bx = b->sprite.x + b->collider.circle.x, by = b->sprite.y + b->collider.circle.y;
+	const float ax = a->sprite.x + a->physics.circle.x, ay = a->sprite.y + a->physics.circle.y,
+		  		bx = b->sprite.x + b->physics.circle.x, by = b->sprite.y + b->physics.circle.y;
 	const float dx = fabsf(ax-bx), dy = fabsf(ay-by);
 	const float sqrdist = dx*dx+dy*dy;
-	const float mindist = a->collider.circle.radius + b->collider.circle.radius;
+	const float mindist = a->physics.circle.radius + b->physics.circle.radius;
 	const float mindistsqr = mindist*mindist;
 	return sqrdist < mindistsqr;
 }
@@ -62,17 +65,17 @@ short _collision_circle_circle(const object_t* a, const object_t* b) {
 static inline
 short _collision_circle_aabb(const object_t* circle, const object_t* aabb) {
 	// generate a point on the edge of the rectangle that is closest to the circle
-	const float bbminx = aabb->collider.aabb.x + aabb->sprite.x, bbmaxx = bbminx + aabb->collider.aabb.w,
-				bbminy = aabb->collider.aabb.y + aabb->sprite.y, bbmaxy = bbminy + aabb->collider.aabb.h;
-	const float cx = circle->sprite.x + circle->collider.circle.x,
-				cy = circle->sprite.y + circle->collider.circle.y;
+	const float bbminx = aabb->physics.aabb.x + aabb->sprite.x, bbmaxx = bbminx + aabb->physics.aabb.w,
+				bbminy = aabb->physics.aabb.y + aabb->sprite.y, bbmaxy = bbminy + aabb->physics.aabb.h;
+	const float cx = circle->sprite.x + circle->physics.circle.x,
+				cy = circle->sprite.y + circle->physics.circle.y;
 	const float x = fclampf(cx, bbminx, bbmaxx),
 				y = fclampf(cy, bbminy, bbmaxy);
 	const float dx = fabsf(cx - x), dy = fabsf(cy - y);
 
 	// calculate the square distance from the centre of the circle to the edge of the aabb
 	const float distsqr = dx*dx+dy*dy;
-	const float rsqr = circle->collider.circle.radius*circle->collider.circle.radius;
+	const float rsqr = circle->physics.circle.radius*circle->physics.circle.radius;
 
 	// return if the square distance is larger than the square of the radius
 	return distsqr < rsqr;
@@ -80,13 +83,13 @@ short _collision_circle_aabb(const object_t* circle, const object_t* aabb) {
 
 static inline
 short _collision_check(const object_t* a, const object_t* b) {
-	if(a->collider.type == COLLIDERTYPE_AABB && b->collider.type == COLLIDERTYPE_AABB) {
+	if(a->physics.type == COLLIDERTYPE_AABB && b->physics.type == COLLIDERTYPE_AABB) {
 		return _collision_aabb_aabb(a, b);
-	} else if(a->collider.type == COLLIDERTYPE_CIRCLE && b->collider.type == COLLIDERTYPE_CIRCLE) {
+	} else if(a->physics.type == COLLIDERTYPE_CIRCLE && b->physics.type == COLLIDERTYPE_CIRCLE) {
 		return _collision_circle_circle(a, b);
-	} else if(a->collider.type == COLLIDERTYPE_CIRCLE && b->collider.type == COLLIDERTYPE_AABB) {
+	} else if(a->physics.type == COLLIDERTYPE_CIRCLE && b->physics.type == COLLIDERTYPE_AABB) {
 		return _collision_circle_aabb(a, b);
-	} else if(a->collider.type == COLLIDERTYPE_AABB && b->collider.type == COLLIDERTYPE_CIRCLE) {
+	} else if(a->physics.type == COLLIDERTYPE_AABB && b->physics.type == COLLIDERTYPE_CIRCLE) {
 		return _collision_circle_aabb(b, a);
 	}
 	return 0;
@@ -95,11 +98,11 @@ short _collision_check(const object_t* a, const object_t* b) {
 static inline
 float _solve_circle_aabb(const object_t* circle, const object_t* aabb, float* out_px, float* out_py) {
 	// generate a point on the edge of the rectangle that is closest to the circle
-	const float bbminx = aabb->collider.aabb.x + aabb->sprite.x, bbmaxx = bbminx + aabb->collider.aabb.w,
-	            bbminy = aabb->collider.aabb.y + aabb->sprite.y, bbmaxy = bbminy + aabb->collider.aabb.h;
+	const float bbminx = aabb->physics.aabb.x + aabb->sprite.x, bbmaxx = bbminx + aabb->physics.aabb.w,
+	            bbminy = aabb->physics.aabb.y + aabb->sprite.y, bbmaxy = bbminy + aabb->physics.aabb.h;
 	// the centre of the circle in world space
-	const float cx = circle->sprite.x + circle->collider.circle.x,
-	            cy = circle->sprite.y + circle->collider.circle.y;
+	const float cx = circle->sprite.x + circle->physics.circle.x,
+	            cy = circle->sprite.y + circle->physics.circle.y;
 	// the point on the rectangle closest to the centre of the circle
 	const float x = fclampf(cx, bbminx, bbmaxx),
 	            y = fclampf(cy, bbminy, bbmaxy);
@@ -111,7 +114,7 @@ float _solve_circle_aabb(const object_t* circle, const object_t* aabb, float* ou
 	            dist_y = fabsf(dif_y);
 	// euclidean distance
 	const float dist = sqrt(dist_x*dist_x + dist_y*dist_y);
-	const float solve_distance = circle->collider.circle.radius - dist;
+	const float solve_distance = circle->physics.circle.radius - dist;
 	// distance to solve collision
 	float solve_x, solve_y;
 	normalize(dif_x, dif_y, &solve_x, &solve_y);
@@ -122,11 +125,11 @@ float _solve_circle_aabb(const object_t* circle, const object_t* aabb, float* ou
 
 static inline
 float _solve_circle_circle(const object_t* a, const object_t* b, float* out_px, float* out_py) {
-	const float x1 = a->collider.circle.x + a->sprite.x, y1 = a->collider.circle.y + a->sprite.y;
-	const float x2 = b->collider.circle.x + b->sprite.x, y2 = b->collider.circle.y + b->sprite.y;
+	const float x1 = a->physics.circle.x + a->sprite.x, y1 = a->physics.circle.y + a->sprite.y;
+	const float x2 = b->physics.circle.x + b->sprite.x, y2 = b->physics.circle.y + b->sprite.y;
 	const float dif_x = x1 - x2, dif_y = y1 - y2;
 	const float difference = sqrtf(fabsf(dif_x*dif_x) + fabsf(dif_y*dif_y));
-	const float target_difference = a->collider.circle.radius + b->collider.circle.radius;
+	const float target_difference = a->physics.circle.radius + b->physics.circle.radius;
 	float dir_x, dir_y;
 	normalize(dif_x, dif_y, &dir_x, &dir_y);
 	*out_px = dir_x * target_difference;
@@ -136,10 +139,10 @@ float _solve_circle_circle(const object_t* a, const object_t* b, float* out_px,
 
 static inline
 float _solve_aabb_aabb(const object_t* a, const object_t* b, float* out_px, float* out_py) {
-	float right = (a->collider.aabb.x + a->collider.aabb.w + a->sprite.x) - (b->collider.aabb.x + b->sprite.x);
-	float left = (a->collider.aabb.x + a->sprite.x) - (b->collider.aabb.x + b->collider.aabb.w + b->sprite.x);
-	float top = (a->collider.aabb.y + a->sprite.y) - (b->collider.aabb.y + b->collider.aabb.w + b->sprite.y);
-	float bottom = (a->collider.aabb.y + a->collider.aabb.h) - (b->collider.aabb.y + b->sprite.y);
+	float right = (a->physics.aabb.x + a->physics.aabb.w + a->sprite.x) - (b->physics.aabb.x + b->sprite.x);
+	float left = (a->physics.aabb.x + a->sprite.x) - (b->physics.aabb.x + b->physics.aabb.w + b->sprite.x);
+	float top = (a->physics.aabb.y + a->sprite.y) - (b->physics.aabb.y + b->physics.aabb.w + b->sprite.y);
+	float bottom = (a->physics.aabb.y + a->physics.aabb.h) - (b->physics.aabb.y + b->sprite.y);
 
 	float ret = right;
 	*out_px = right;
@@ -165,25 +168,24 @@ float _solve_aabb_aabb(const object_t* a, const object_t* b, float* out_px, floa
 }
 
 float get_solve_force(const object_t* a, const object_t* b, float* out_px, float* out_py) {
-	if(a->collider.type == COLLIDERTYPE_AABB && b->collider.type == COLLIDERTYPE_AABB) {
+	if(a->physics.type == COLLIDERTYPE_AABB && b->physics.type == COLLIDERTYPE_AABB) {
 		return _solve_aabb_aabb(a, b, out_px, out_py);
-	} else if(a->collider.type == COLLIDERTYPE_AABB && b->collider.type == COLLIDERTYPE_CIRCLE) {
+	} else if(a->physics.type == COLLIDERTYPE_AABB && b->physics.type == COLLIDERTYPE_CIRCLE) {
 		float penetration_distance = _solve_circle_aabb(b, a, out_px, out_py);
 		*out_px = -(*out_px);
 		*out_py = -(*out_py);
-	} else if(a->collider.type == COLLIDERTYPE_CIRCLE && b->collider.type == COLLIDERTYPE_AABB) {
+	} else if(a->physics.type == COLLIDERTYPE_CIRCLE && b->physics.type == COLLIDERTYPE_AABB) {
 		return _solve_circle_aabb(a, b, out_px, out_py);
-	} else if(a->collider.type == COLLIDERTYPE_CIRCLE && b->collider.type == COLLIDERTYPE_CIRCLE) {
+	} else if(a->physics.type == COLLIDERTYPE_CIRCLE && b->physics.type == COLLIDERTYPE_CIRCLE) {
 		return _solve_circle_circle(a, b, out_px, out_py);
 	}
 }
 
-static inline
-void _solve_collision_slide(object_t* this, object_t* other) {
+void solve_collision_slide(object_t* left, object_t* right) {
 	float dx, dy;
-	const float d = get_solve_force(this, other, &dx, &dy);
-	this->sprite.x += dx;
-	this->sprite.y += dy;
+	const float d = get_solve_force(left, right, &dx, &dy);
+	left->sprite.x += dx;
+	left->sprite.y += dy;
 }
 
 static inline
@@ -196,22 +198,26 @@ void _solve_move(object_t* this) {
 		if(can_collide(other) && this != other && _collision_check(other, this)) {
 			object_broadcast_collision(other, this);
 			object_broadcast_collision(this, other);
-			_solve_collision_slide(this, other);
+			this->physics.solver(this, other);
 		}
 	}
 }
 
-void interpolate_move(object_t* this, const float target_x, const float target_y, const float max_step_size, const int slide) {
+void physics_move(object_t* this, float delta_time) {
+	const float max_step_size = this->physics.max_interpolate_step_size;
 	// calculate step delta
-	float dx = target_x - this->sprite.x, dy = target_y - this->sprite.y;
+	float dx = this->physics.velocity_x * delta_time, dy = this->physics.velocity_y * delta_time;
+	const float target_x = this->sprite.x + dx,
+	            target_y = this->sprite.y + dy;
 	if(dx == 0 && dy == 0)
 		return;
+
 	// calculate direction x,y
 	float m = sqrtf(dx*dx + dy*dy);
-	dx /= m;
-	dy /= m;
-	dx *= max_step_size; dy *= max_step_size;
-	int step_count = max_step_size / m;
+	dx = dx / m * max_step_size;
+	dy = dy / m * max_step_size;
+
+	const int step_count = max_step_size / m;
 
 	// ensure this object would ever collide
 	// if it wouldn't collide anyway, just set position
@@ -225,6 +231,7 @@ void interpolate_move(object_t* this, const float target_x, const float target_y
 		this->sprite.x = target_x;
 		this->sprite.y = target_y;
 		_solve_move(this);
+		return;
 	}
 
 	/*
@@ -233,21 +240,14 @@ void interpolate_move(object_t* this, const float target_x, const float target_y
 	 */
 	for(int steps = 0; steps <= step_count && (this->sprite.x != target_x || this->sprite.y != target_y); ++steps) {
 		// move towards target, snap to target if distance is too low
-		const float old_x = this->sprite.x, old_y = this->sprite.y;
-		float new_x, new_y;
-
 		const float distx = fabsf(this->sprite.x - target_x), disty = fabsf(this->sprite.y - target_y);
 		const float sqdist = distx*distx + disty*disty;
 		if(sqdist > max_step_size*max_step_size) {
 			this->sprite.x += dx;
 			this->sprite.y += dy;
-			new_x = this->sprite.x;
-			new_y = this->sprite.y;
 		} else {
 			this->sprite.x = target_x;
 			this->sprite.y = target_y;
-			new_x = target_x;
-			new_y = target_y;
 		}
 
 		_solve_move(this);

src/corelib/physics.h

@@ -5,7 +5,8 @@
 
 typedef struct object_t object_t;
 
-typedef void(*collided_fn)(object_t*, struct object_t*);
+typedef void(*collided_fn)(object_t*, object_t*);
+typedef void(*solver_fn)(object_t* left, object_t* right);
 
 typedef enum collider_type_t {
 	COLLIDERTYPE_MIN,
@@ -15,27 +16,34 @@ typedef enum collider_type_t {
 	COLLIDERTYPE_MAX,
 } collider_type_t;
 
-typedef struct collider_t {
+typedef struct circle_t {
+	float x, y;
+	float radius;
+} circle_t;
+
+typedef struct physics_t {
 	collider_type_t type;
 	collided_fn evt_collision;
+	solver_fn solver;
+	float velocity_x, velocity_y;
+	float max_interpolate_step_size;
 	union {
-		struct {
-			float x, y;
-			float radius;
-		} circle;
+		circle_t circle;
 		SDL_FRect aabb;
 	};
-} collider_t;
+} physics_t;
 
-collider_t collider_default();
+extern physics_t physics_default();
 
-void object_broadcast_evt_collision(object_t* this, object_t* other);
+extern void object_broadcast_evt_collision(object_t* this, object_t* other);
 
-void physics_update();
+extern void physics_update();
 
-void interpolate_move(object_t* object, float target_x, float target_y, float max_step_size, int slide);
+extern void physics_move(object_t* this, float delta_time);
 
 extern short can_collide(const object_t* this);
+
+extern void solve_collision_slide(object_t* left, object_t* right);
 extern float get_solve_force(const object_t* this, const object_t* other, float* solve_x, float* solve_y);
 
 #endif /* _physics_h */