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/*
Minetest
Copyright (C) 2010-2013 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 Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser 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 "numeric.h"
#include "../log.h"
#include "../constants.h" // BS, MAP_BLOCKSIZE
#include <iostream>
// Calculate the borders of a "d-radius" cube
void getFacePositions(std::list<v3s16> &list, u16 d)
{
if(d == 0)
{
list.push_back(v3s16(0,0,0));
return;
}
if(d == 1)
{
/*
This is an optimized sequence of coordinates.
*/
list.push_back(v3s16( 0, 1, 0)); // top
list.push_back(v3s16( 0, 0, 1)); // back
list.push_back(v3s16(-1, 0, 0)); // left
list.push_back(v3s16( 1, 0, 0)); // right
list.push_back(v3s16( 0, 0,-1)); // front
list.push_back(v3s16( 0,-1, 0)); // bottom
// 6
list.push_back(v3s16(-1, 0, 1)); // back left
list.push_back(v3s16( 1, 0, 1)); // back right
list.push_back(v3s16(-1, 0,-1)); // front left
list.push_back(v3s16( 1, 0,-1)); // front right
list.push_back(v3s16(-1,-1, 0)); // bottom left
list.push_back(v3s16( 1,-1, 0)); // bottom right
list.push_back(v3s16( 0,-1, 1)); // bottom back
list.push_back(v3s16( 0,-1,-1)); // bottom front
list.push_back(v3s16(-1, 1, 0)); // top left
list.push_back(v3s16( 1, 1, 0)); // top right
list.push_back(v3s16( 0, 1, 1)); // top back
list.push_back(v3s16( 0, 1,-1)); // top front
// 18
list.push_back(v3s16(-1, 1, 1)); // top back-left
list.push_back(v3s16( 1, 1, 1)); // top back-right
list.push_back(v3s16(-1, 1,-1)); // top front-left
list.push_back(v3s16( 1, 1,-1)); // top front-right
list.push_back(v3s16(-1,-1, 1)); // bottom back-left
list.push_back(v3s16( 1,-1, 1)); // bottom back-right
list.push_back(v3s16(-1,-1,-1)); // bottom front-left
list.push_back(v3s16( 1,-1,-1)); // bottom front-right
// 26
return;
}
// Take blocks in all sides, starting from y=0 and going +-y
for(s16 y=0; y<=d-1; y++)
{
// Left and right side, including borders
for(s16 z=-d; z<=d; z++)
{
list.push_back(v3s16(d,y,z));
list.push_back(v3s16(-d,y,z));
if(y != 0)
{
list.push_back(v3s16(d,-y,z));
list.push_back(v3s16(-d,-y,z));
}
}
// Back and front side, excluding borders
for(s16 x=-d+1; x<=d-1; x++)
{
list.push_back(v3s16(x,y,d));
list.push_back(v3s16(x,y,-d));
if(y != 0)
{
list.push_back(v3s16(x,-y,d));
list.push_back(v3s16(x,-y,-d));
}
}
}
// Take the bottom and top face with borders
// -d<x<d, y=+-d, -d<z<d
for(s16 x=-d; x<=d; x++)
for(s16 z=-d; z<=d; z++)
{
list.push_back(v3s16(x,-d,z));
list.push_back(v3s16(x,d,z));
}
}
/*
myrand
*/
static unsigned long next = 1;
/* RAND_MAX assumed to be 32767 */
int myrand(void)
{
next = next * 1103515245 + 12345;
return((unsigned)(next/65536) % 32768);
}
void mysrand(unsigned seed)
{
next = seed;
}
int myrand_range(int min, int max)
{
if(max-min > MYRAND_MAX)
{
errorstream<<"WARNING: myrand_range: max-min > MYRAND_MAX"<<std::endl;
max = min + MYRAND_MAX;
}
if(min > max)
{
errorstream<<"WARNING: myrand_range: min > max"<<std::endl;
return max;
}
return (myrand()%(max-min+1))+min;
}
/*
blockpos: position of block in block coordinates
camera_pos: position of camera in nodes
camera_dir: an unit vector pointing to camera direction
range: viewing range
*/
bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
f32 camera_fov, f32 range, f32 *distance_ptr)
{
v3s16 blockpos_nodes = blockpos_b * MAP_BLOCKSIZE;
// Block center position
v3f blockpos(
((float)blockpos_nodes.X + MAP_BLOCKSIZE/2) * BS,
((float)blockpos_nodes.Y + MAP_BLOCKSIZE/2) * BS,
((float)blockpos_nodes.Z + MAP_BLOCKSIZE/2) * BS
);
// Block position relative to camera
v3f blockpos_relative = blockpos - camera_pos;
// Distance in camera direction (+=front, -=back)
f32 dforward = blockpos_relative.dotProduct(camera_dir);
// Total distance
f32 d = blockpos_relative.getLength();
if(distance_ptr)
*distance_ptr = d;
// If block is very close, it is always in sight
if(d < 1.44*1.44*MAP_BLOCKSIZE*BS/2)
return true;
// If block is far away, it's not in sight
if(d > range)
return false;
// Maximum radius of a block
f32 block_max_radius = 0.5*1.44*1.44*MAP_BLOCKSIZE*BS;
// If block is (nearly) touching the camera, don't
// bother validating further (that is, render it anyway)
if(d < block_max_radius)
return true;
// Cosine of the angle between the camera direction
// and the block direction (camera_dir is an unit vector)
f32 cosangle = dforward / d;
// Compensate for the size of the block
// (as the block has to be shown even if it's a bit off FOV)
// This is an estimate, plus an arbitary factor
cosangle += block_max_radius / d * 0.5;
// If block is not in the field of view, skip it
if(cosangle < cos(camera_fov / 2))
return false;
return true;
}
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