Restructuring of collision detection

git-svn-id: svn://cook.msm.cam.ac.uk:745/thrust3d/thrust3d@134 84d2e878-0bd5-11dd-ad15-13eda11d74c5

2 files changed, 70 insertions, 58 deletions

diff --git a/src/physics.c b/src/physics.c
index 7677a02..34e07da 100644
--- a/src/physics.c
+++ b/src/physics.c
@@ -142,7 +142,7 @@ int physics_will_collide_face(double sx, double sy, double sz, double vx, double
 /* Check for collision with all faces in a primitive */
 static int physics_check_collide_all_faces(ModelInstance *obj, ModelInstance *other, Uint32 dt, int a,
 						double sx, double sy, double sz, double vx, double vy, double vz,
-						double *ttc_lowest, double *nxc, double *nyc, double *nzc) {
+						CollisionSpec *coll) {
 
 	switch ( other->model->primitives[a]->type ) {
 	
@@ -172,12 +172,12 @@ static int physics_check_collide_all_faces(ModelInstance *obj, ModelInstance *ot
 				
 				if ( physics_will_collide_face(sx, sy, sz, vx, vy, vz, nx, ny, nz, face, 4, dt, other, &ttc) != 0 ) {
 					
-					if ( ttc < *ttc_lowest ) {
+					if ( ttc < coll->ttc ) {
 						printf("PH: collides with %s/%p in %5.2f ms\n", other->model->name, other, ttc);
-						*ttc_lowest = ttc;
-						*nxc = nx;
-						*nyc = ny;
-						*nzc = nz;
+						coll->ttc = ttc;
+						coll->nx = nx;
+						coll->ny = ny;
+						coll->nz = nz;
 					}
 					
 				}
@@ -193,7 +193,7 @@ static int physics_check_collide_all_faces(ModelInstance *obj, ModelInstance *ot
 }
 
 /* Return non-zero if 'obj' will collide with 'other' with 'dt' milliseconds */
-static int physics_check_collide(ModelInstance *obj, ModelInstance *other, Uint32 dt) {
+static int physics_check_collide(ModelInstance *obj, ModelInstance *other, double dt, CollisionSpec *coll) {
 
 	int i;
 	
@@ -202,13 +202,6 @@ static int physics_check_collide(ModelInstance *obj, ModelInstance *other, Uint3
 	const double vz = obj->vz;
 	
 	double ttc_lowest = +INFINITY;
-	double nxc = 0.0;
-	double nyc = 0.0;
-	double nzc = 0.0;
-	
-	if ( strcmp(other->model->name, "platform") ) {
-//		printf("Checking against platform\n");
-	}
 	
 	/* Consider all the primitives in 'obj' */
 	for ( i=0; i<obj->model->num_primitives; i++ ) {
@@ -225,8 +218,7 @@ static int physics_check_collide(ModelInstance *obj, ModelInstance *other, Uint3
 			
 			/* Consider all the primitives in 'other' */
 			for ( a=0; a<other->model->num_primitives; a++ ) {
-			//	printf("Primitive %i\n", a);
-				physics_check_collide_all_faces(obj, other, dt, a, sx, sy, sz, vx, vy, vz, &ttc_lowest, &nxc, &nyc, &nzc);
+				physics_check_collide_all_faces(obj, other, dt, a, sx, sy, sz, vx, vy, vz, coll);
 			}
 			
 		}
@@ -239,49 +231,37 @@ static int physics_check_collide(ModelInstance *obj, ModelInstance *other, Uint3
 		return 0;
 	}
 	
-	if ( (nxc == 0.0) && (nyc == 0.0) && (nzc == 1.0) ) {
-		obj->x += obj->vx * ttc_lowest;
-		obj->y += obj->vy * ttc_lowest;
-		obj->z += obj->vz * ttc_lowest;
-		obj->vz = 0.0;
-		obj->landed = 1;
-		printf("PH: Landed!\n");
-	} else {
-		obj->vx = -obj->vx;
-		obj->vy = -obj->vy;
-		obj->vz = -obj->vz;
-		obj->yawspeed = 0.0;
-		printf("PH: Bounce!\n");
-	}
-					
 	return 1;
 	
 }
 
-/* Called once for each object which isn't just "scenery" */
-static void physics_process(ModelInstance *obj, Uint32 dt, Game *game) {
-	
-	int collided = 0;
-	do {
+static int physics_find_earliest_collision(ModelInstance *obj, Game *game, double dt, CollisionSpec *coll) {
+
+	Room *room;
 	
-		Room *room;
+	/* Consider only the current room, for now */
+	room = game_find_room(game, game->cur_room_x, game->cur_room_y, game->cur_room_z);
+	if ( room != NULL ) {
 		
-		collided = 0;
-	
-		/* Consider only the current room */
-		room = game_find_room(game, game->cur_room_x, game->cur_room_y, game->cur_room_z);
-		if ( room != NULL ) {
-			/* Consider all the objects in this room */
-			int j;
-			for ( j=0; j<room->num_objects; j++ ) {
-				if ( physics_check_collide(obj, room->objects[j], dt) ) {  /* Should be dt - ttc */
-					collided = 1;
-					audio_play(game->audio, "clang", 0.7, 0);
-				}
+		/* Consider all the objects in this room */
+		int j;
+		
+		for ( j=0; j<room->num_objects; j++ ) {
+			if ( physics_check_collide(obj, room->objects[j], dt, coll) ) {
+				return 1;
 			}
 		}
+		
+	}
+
+	return 0;
+
+}
+
+/* Called once for each object which isn't just "scenery" */
+static void physics_process(ModelInstance *obj, Uint32 dt, Game *game) {
 	
-	} while ( collided );
+	int collided = 0;
 	
 	/* Air friction */
 	if ( obj->vx > 0.0 ) {
@@ -321,13 +301,32 @@ static void physics_process(ModelInstance *obj, Uint32 dt, Game *game) {
 		obj->vz -= GRAVITY * dt;
 	}
 	
-	/* Take a step */
-	if ( !obj->landed ) {
-		obj->x += obj->vx * dt;
-		obj->y += obj->vy * dt;
-		obj->z += obj->vz * dt;
-		obj->yaw += obj->yawspeed * dt;
-	}
+	/* Take a step, allowing for collisions and landing */
+	double sttc = 0.0;
+	do {
+	
+		CollisionSpec coll;
+		collided = physics_find_earliest_collision(obj, game, dt, &coll);
+		
+		if ( collided ) {
+		
+			if ( (coll.nx==0) && (coll.ny==0) && (coll.nz==1.0) ) {
+				obj->landed = 1;
+				obj->vx = 0.0;
+				obj->vy = 0.0;
+				obj->vz = 0.0;
+			}
+		
+		} else {
+			
+			obj->x += obj->vx * (dt-sttc);
+			obj->y += obj->vy * (dt-sttc);
+			obj->z += obj->vz * (dt-sttc);
+			obj->yaw += obj->yawspeed * (dt-sttc);
+			
+		}
+	
+	} while ( collided && !obj->landed );
 	
 	if ( obj->yaw < -M_PI ) obj->yaw += 2*M_PI;
 	if ( obj->yaw > M_PI ) obj->yaw -= 2*M_PI;
@@ -362,7 +361,6 @@ void physics_step(Game *game, Uint32 t) {
 		game->lander->yawspeed += YAWTHRUST *dt;	/* +ve yaw is "right" */
 	}
 	
-	/* The number of rooms to consider for physics purposes can probably be further reduced */
 	physics_process(game->lander, dt, game);
 	
 	game_check_handoff(game);
diff --git a/src/types.h b/src/types.h
index d489be7..dcbc097 100644
--- a/src/types.h
+++ b/src/types.h
@@ -255,5 +255,19 @@ typedef struct {
 		
 } Game;
 
+typedef struct {
+
+	double nx;
+	double ny;
+	double nz;	/* Normal of face being collided with */
+	
+	double cx;
+	double cy;
+	double cz;	/* Coordinates of object at the moment when it collides */
+	
+	double ttc;
+
+} CollisionSpec;
+
 #endif	/* TYPES_H */