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/*
Minetest-c55
Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "collision.h"
#include "mapblock.h"
#include "map.h"
collisionMoveResult collisionMoveSimple(Map *map, f32 pos_max_d,
const core::aabbox3d<f32> &box_0,
f32 dtime, v3f &pos_f, v3f &speed_f)
{
collisionMoveResult result;
v3f oldpos_f = pos_f;
v3s16 oldpos_i = floatToInt(oldpos_f, BS);
/*
Calculate new position
*/
pos_f += speed_f * dtime;
/*
Collision detection
*/
// position in nodes
v3s16 pos_i = floatToInt(pos_f, BS);
/*
Collision uncertainty radius
Make it a bit larger than the maximum distance of movement
*/
f32 d = pos_max_d * 1.1;
// A fairly large value in here makes moving smoother
//f32 d = 0.15*BS;
// This should always apply, otherwise there are glitches
assert(d > pos_max_d);
/*
Calculate collision box
*/
core::aabbox3d<f32> box = box_0;
box.MaxEdge += pos_f;
box.MinEdge += pos_f;
core::aabbox3d<f32> oldbox = box_0;
oldbox.MaxEdge += oldpos_f;
oldbox.MinEdge += oldpos_f;
/*
If the object lies on a walkable node, this is set to true.
*/
result.touching_ground = false;
/*
Go through every node around the object
TODO: Calculate the range of nodes that need to be checked
*/
for(s16 y = oldpos_i.Y - 1; y <= oldpos_i.Y + 2; y++)
for(s16 z = oldpos_i.Z - 1; z <= oldpos_i.Z + 1; z++)
for(s16 x = oldpos_i.X - 1; x <= oldpos_i.X + 1; x++)
{
try{
// Object collides into walkable nodes
MapNode n = map->getNode(v3s16(x,y,z));
if(content_features(n).walkable == false)
continue;
}
catch(InvalidPositionException &e)
{
// Doing nothing here will block the object from
// walking over map borders
}
core::aabbox3d<f32> nodebox = getNodeBox(v3s16(x,y,z), BS);
/*
See if the object is touching ground.
Object touches ground if object's minimum Y is near node's
maximum Y and object's X-Z-area overlaps with the node's
X-Z-area.
Use 0.15*BS so that it is easier to get on a node.
*/
if(
//fabs(nodebox.MaxEdge.Y-box.MinEdge.Y) < d
fabs(nodebox.MaxEdge.Y-box.MinEdge.Y) < 0.15*BS
&& nodebox.MaxEdge.X-d > box.MinEdge.X
&& nodebox.MinEdge.X+d < box.MaxEdge.X
&& nodebox.MaxEdge.Z-d > box.MinEdge.Z
&& nodebox.MinEdge.Z+d < box.MaxEdge.Z
){
result.touching_ground = true;
}
// If object doesn't intersect with node, ignore node.
if(box.intersectsWithBox(nodebox) == false)
continue;
/*
Go through every axis
*/
v3f dirs[3] = {
v3f(0,0,1), // back-front
v3f(0,1,0), // top-bottom
v3f(1,0,0), // right-left
};
for(u16 i=0; i<3; i++)
{
/*
Calculate values along the axis
*/
f32 nodemax = nodebox.MaxEdge.dotProduct(dirs[i]);
f32 nodemin = nodebox.MinEdge.dotProduct(dirs[i]);
f32 objectmax = box.MaxEdge.dotProduct(dirs[i]);
f32 objectmin = box.MinEdge.dotProduct(dirs[i]);
f32 objectmax_old = oldbox.MaxEdge.dotProduct(dirs[i]);
f32 objectmin_old = oldbox.MinEdge.dotProduct(dirs[i]);
/*
Check collision for the axis.
Collision happens when object is going through a surface.
*/
bool negative_axis_collides =
(nodemax > objectmin && nodemax <= objectmin_old + d
&& speed_f.dotProduct(dirs[i]) < 0);
bool positive_axis_collides =
(nodemin < objectmax && nodemin >= objectmax_old - d
&& speed_f.dotProduct(dirs[i]) > 0);
bool main_axis_collides =
negative_axis_collides || positive_axis_collides;
/*
Check overlap of object and node in other axes
*/
bool other_axes_overlap = true;
for(u16 j=0; j<3; j++)
{
if(j == i)
continue;
f32 nodemax = nodebox.MaxEdge.dotProduct(dirs[j]);
f32 nodemin = nodebox.MinEdge.dotProduct(dirs[j]);
f32 objectmax = box.MaxEdge.dotProduct(dirs[j]);
f32 objectmin = box.MinEdge.dotProduct(dirs[j]);
if(!(nodemax - d > objectmin && nodemin + d < objectmax))
{
other_axes_overlap = false;
break;
}
}
/*
If this is a collision, revert the pos_f in the main
direction.
*/
if(other_axes_overlap && main_axis_collides)
{
speed_f -= speed_f.dotProduct(dirs[i]) * dirs[i];
pos_f -= pos_f.dotProduct(dirs[i]) * dirs[i];
pos_f += oldpos_f.dotProduct(dirs[i]) * dirs[i];
}
}
} // xyz
return result;
}
collisionMoveResult collisionMovePrecise(Map *map, f32 pos_max_d,
const core::aabbox3d<f32> &box_0,
f32 dtime, v3f &pos_f, v3f &speed_f)
{
collisionMoveResult final_result;
// Maximum time increment (for collision detection etc)
// time = distance / speed
f32 dtime_max_increment = pos_max_d / speed_f.getLength();
// Maximum time increment is 10ms or lower
if(dtime_max_increment > 0.01)
dtime_max_increment = 0.01;
// Don't allow overly huge dtime
if(dtime > 2.0)
dtime = 2.0;
f32 dtime_downcount = dtime;
u32 loopcount = 0;
do
{
loopcount++;
f32 dtime_part;
if(dtime_downcount > dtime_max_increment)
{
dtime_part = dtime_max_increment;
dtime_downcount -= dtime_part;
}
else
{
dtime_part = dtime_downcount;
/*
Setting this to 0 (no -=dtime_part) disables an infinite loop
when dtime_part is so small that dtime_downcount -= dtime_part
does nothing
*/
dtime_downcount = 0;
}
collisionMoveResult result = collisionMoveSimple(map, pos_max_d,
box_0, dtime_part, pos_f, speed_f);
if(result.touching_ground)
final_result.touching_ground = true;
}
while(dtime_downcount > 0.001);
return final_result;
}
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