Restore collision detection, apparently fixing the 'drop through floors' problem

git-svn-id: svn://cook.msm.cam.ac.uk:745/thrust3d/thrust3d@138 84d2e878-0bd5-11dd-ad15-13eda11d74c5

1 files changed, 49 insertions, 52 deletions

diff --git a/src/physics.c b/src/physics.c
index 39a3e09..c6d4dd9 100644
--- a/src/physics.c
+++ b/src/physics.c
@@ -89,7 +89,7 @@ int physics_point_is_inside_hull(double cx, double cy, double cz, double *fvert,
 
 int physics_will_collide_face(double sx, double sy, double sz, double vx, double vy, double vz,
 					double nx, double ny, double nz, double *fvert, int nfvert, Uint32 dt,
-					ModelInstance *obj, double *ttc) {
+					double *ttc) {
 
 	double px, py, pz;
 	double pdotn, sdotn, vdotn;
@@ -115,24 +115,8 @@ int physics_will_collide_face(double sx, double sy, double sz, double vx, double
 	cy = sy + vy * t;
 	cz = sz + vz * t;
 	if ( physics_point_is_inside_hull(cx, cy, cz, fvert, nfvert, nx, ny, nz) == 1 ) {
-		
-		char *name;
-		
-		if ( obj == NULL ) {
-			name = "unknown";
-		} else {
-			name = obj->model->name;
-		}
-		
-	//	printf("Testing vertex %8f %8f %8f, velocity %8f %8f %8f against face %8f %8f %8f (%s/%p)\n",
-	//			sx, sy, sz, vx, vy, vz, px, py, pz, name, obj);
-	//	printf("(%f - %f) / %f\n", pdotn, sdotn, vdotn);
-	//	printf("Collision happens at t + %f\n", t);
-	//	exit(0);
-		
 		*ttc = t;
 		return 1;
-	
 	}
 	
 	return 0;
@@ -141,9 +125,10 @@ 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,
-						CollisionSpec *coll) {
+						double sx, double sy, double sz, CollisionSpec *coll) {
 
+	int found = 0;
+	
 	switch ( other->model->primitives[a]->type ) {
 	
 		case PRIMITIVE_QUADS : {
@@ -162,7 +147,7 @@ static int physics_check_collide_all_faces(ModelInstance *obj, ModelInstance *ot
 				const double nz = other->model->primitives[a]->normals[3*(4*f)+2];
 				
 				/* Skip if moving from the back to the front of this quad */
-				if ( nx*vx + ny*vy + nz*vz > 0.0 ) continue;
+				if ( nx*obj->vx + ny*obj->vy + nz*obj->vz > 0.0 ) continue;
 				
 				for ( q=0; q<4; q++ ) {
 					face[3*q + 0] = other->x + other->model->primitives[a]->vertices[3*((4*f)+q) + 0];
@@ -170,14 +155,19 @@ static int physics_check_collide_all_faces(ModelInstance *obj, ModelInstance *ot
 					face[3*q + 2] = other->z + other->model->primitives[a]->vertices[3*((4*f)+q) + 2];
 				}
 				
-				if ( physics_will_collide_face(sx, sy, sz, vx, vy, vz, nx, ny, nz, face, 4, dt, other, &ttc) != 0 ) {
+				if ( physics_will_collide_face(obj->x+sx, obj->y+sy, obj->z+sz, obj->vx, obj->vy, obj->vz,
+								nx, ny, nz, face, 4, dt, &ttc) != 0 ) {
 					
+					/* Update 'coll' if this collision happens sooner than the current best */
 					if ( ttc < coll->ttc ) {
-						printf("PH: collides with %s/%p in %5.2f ms\n", other->model->name, other, ttc);
 						coll->ttc = ttc;
 						coll->nx = nx;
 						coll->ny = ny;
 						coll->nz = nz;
+						coll->cx = obj->x + ttc*obj->vx;
+						coll->cy = obj->y + ttc*obj->vy;
+						coll->cz = obj->z + ttc*obj->vz;
+						found = 1;
 					}
 					
 				}
@@ -188,73 +178,61 @@ static int physics_check_collide_all_faces(ModelInstance *obj, ModelInstance *ot
 	
 	}
 	
-	return 0;
+	return found;
 	
 }
 
-/* Return non-zero if 'obj' will collide with 'other' with 'dt' milliseconds */
+/* Return non-zero if 'obj' will collide with 'other' within 'dt' milliseconds */
 static int physics_check_collide(ModelInstance *obj, ModelInstance *other, double dt, CollisionSpec *coll) {
 
 	int i;
+	int found = 0;
 	
-	const double vx = obj->vx;
-	const double vy = obj->vy;
-	const double vz = obj->vz;
-	
-	double ttc_lowest = +INFINITY;
-	
-	/* Consider all the primitives in 'obj' */
+	/* Check all the vertices in the moving object... */
 	for ( i=0; i<obj->model->num_primitives; i++ ) {
-		
 		int j;
-		
-		/* Consider all the vertices in this primitive */
 		for ( j=0; j<obj->model->primitives[i]->num_vertices; j++ ) {
 		
 			int a;
-			const double sx = obj->x + obj->model->primitives[i]->vertices[3*j+0];
-			const double sy = obj->y + obj->model->primitives[i]->vertices[3*j+1];
-			const double sz = obj->z + obj->model->primitives[i]->vertices[3*j+2];
+			const double sx = obj->model->primitives[i]->vertices[3*j+0];
+			const double sy = obj->model->primitives[i]->vertices[3*j+1];
+			const double sz = obj->model->primitives[i]->vertices[3*j+2];
 			
-			/* Consider all the primitives in 'other' */
+			/* ...against all primitives in the static object */
 			for ( a=0; a<other->model->num_primitives; a++ ) {
-				physics_check_collide_all_faces(obj, other, dt, a, sx, sy, sz, vx, vy, vz, coll);
+				if ( physics_check_collide_all_faces(obj, other, dt, a, sx, sy, sz, coll) ) {
+					found = 1;
+				}
 			}
 			
 		}
 	}
 	
-	if ( ttc_lowest == +INFINITY ) return 0;
-	
-	if ( ttc_lowest > dt ) {
-		printf("PH: will collide with %s/%8p, but too far in the future at %5.2f ms\n", other->model->name, other, ttc_lowest);
-		return 0;
-	}
-	
-	return 1;
+	return found;
 	
 }
 
+/* Find the earliest collision for 'obj'.  Fill out 'coll' and return 1 if any */
 static int physics_find_earliest_collision(ModelInstance *obj, Game *game, double dt, CollisionSpec *coll) {
 
 	Room *room;
+	int found = 0;
 	
 	/* 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 ) {
 		
-		/* Consider all the objects in this room */
+		/* Check for collision of this object with all other objects in the room */
 		int j;
-		
 		for ( j=0; j<room->num_objects; j++ ) {
 			if ( physics_check_collide(obj, room->objects[j], dt, coll) ) {
-				return 1;
+				found = 1;
 			}
 		}
 		
 	}
 
-	return 0;
+	return found;
 
 }
 
@@ -306,19 +284,38 @@ static void physics_process(ModelInstance *obj, Uint32 dt, Game *game) {
 	do {
 	
 		CollisionSpec coll;
-		collided = physics_find_earliest_collision(obj, game, dt, &coll);
+		coll.ttc = +HUGE_VAL;
+		coll.nx = 0.0;  coll.ny = 0.0;  coll.nz = 0.0;
+		coll.cx = 0.0;  coll.cy = 0.0;  coll.cz = 0.0;
+		collided = physics_find_earliest_collision(obj, game, dt-sttc, &coll);
 		
 		if ( collided ) {
 		
+			/* Step forward to the point of collision */
+			obj->x = coll.cx;
+			obj->y = coll.cy;
+			obj->z = coll.cz;
+			
+			sttc += coll.ttc;
+			
+			/* Can we land here? */
 			if ( (coll.nx==0) && (coll.ny==0) && (coll.nz==1.0) ) {
+				/* Yes - land (already moved to this position */
 				obj->landed = 1;
 				obj->vx = 0.0;
 				obj->vy = 0.0;
 				obj->vz = 0.0;
+			} else {
+				/* No - bounce */
+				audio_play(game->audio, "clang", 1.0, 0);
+				obj->vx = -obj->vx;
+				obj->vy = -obj->vy;
+				obj->vz = -obj->vz;
 			}
 		
 		} else {
 			
+			/* No further collision - perform the 'end step' */
 			obj->x += obj->vx * (dt-sttc);
 			obj->y += obj->vy * (dt-sttc);
 			obj->z += obj->vz * (dt-sttc);