mirror of https://github.com/minetest/minetest.git
203 lines
5.4 KiB
C++
203 lines
5.4 KiB
C++
/*
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Minetest
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Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "numeric.h"
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#include "../log.h"
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#include "../constants.h" // BS, MAP_BLOCKSIZE
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#include <iostream>
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// Calculate the borders of a "d-radius" cube
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void getFacePositions(std::list<v3s16> &list, u16 d)
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{
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if(d == 0)
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{
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list.push_back(v3s16(0,0,0));
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return;
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}
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if(d == 1)
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{
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/*
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This is an optimized sequence of coordinates.
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*/
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list.push_back(v3s16( 0, 1, 0)); // top
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list.push_back(v3s16( 0, 0, 1)); // back
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list.push_back(v3s16(-1, 0, 0)); // left
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list.push_back(v3s16( 1, 0, 0)); // right
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list.push_back(v3s16( 0, 0,-1)); // front
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list.push_back(v3s16( 0,-1, 0)); // bottom
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// 6
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list.push_back(v3s16(-1, 0, 1)); // back left
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list.push_back(v3s16( 1, 0, 1)); // back right
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list.push_back(v3s16(-1, 0,-1)); // front left
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list.push_back(v3s16( 1, 0,-1)); // front right
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list.push_back(v3s16(-1,-1, 0)); // bottom left
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list.push_back(v3s16( 1,-1, 0)); // bottom right
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list.push_back(v3s16( 0,-1, 1)); // bottom back
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list.push_back(v3s16( 0,-1,-1)); // bottom front
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list.push_back(v3s16(-1, 1, 0)); // top left
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list.push_back(v3s16( 1, 1, 0)); // top right
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list.push_back(v3s16( 0, 1, 1)); // top back
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list.push_back(v3s16( 0, 1,-1)); // top front
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// 18
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list.push_back(v3s16(-1, 1, 1)); // top back-left
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list.push_back(v3s16( 1, 1, 1)); // top back-right
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list.push_back(v3s16(-1, 1,-1)); // top front-left
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list.push_back(v3s16( 1, 1,-1)); // top front-right
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list.push_back(v3s16(-1,-1, 1)); // bottom back-left
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list.push_back(v3s16( 1,-1, 1)); // bottom back-right
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list.push_back(v3s16(-1,-1,-1)); // bottom front-left
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list.push_back(v3s16( 1,-1,-1)); // bottom front-right
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// 26
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return;
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}
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// Take blocks in all sides, starting from y=0 and going +-y
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for(s16 y=0; y<=d-1; y++)
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{
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// Left and right side, including borders
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for(s16 z=-d; z<=d; z++)
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{
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list.push_back(v3s16(d,y,z));
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list.push_back(v3s16(-d,y,z));
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if(y != 0)
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{
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list.push_back(v3s16(d,-y,z));
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list.push_back(v3s16(-d,-y,z));
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}
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}
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// Back and front side, excluding borders
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for(s16 x=-d+1; x<=d-1; x++)
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{
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list.push_back(v3s16(x,y,d));
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list.push_back(v3s16(x,y,-d));
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if(y != 0)
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{
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list.push_back(v3s16(x,-y,d));
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list.push_back(v3s16(x,-y,-d));
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}
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}
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}
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// Take the bottom and top face with borders
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// -d<x<d, y=+-d, -d<z<d
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for(s16 x=-d; x<=d; x++)
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for(s16 z=-d; z<=d; z++)
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{
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list.push_back(v3s16(x,-d,z));
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list.push_back(v3s16(x,d,z));
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}
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}
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/*
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myrand
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*/
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static unsigned long next = 1;
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/* RAND_MAX assumed to be 32767 */
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int myrand(void)
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{
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next = next * 1103515245 + 12345;
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return((unsigned)(next/65536) % 32768);
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}
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void mysrand(unsigned seed)
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{
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next = seed;
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}
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int myrand_range(int min, int max)
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{
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if(max-min > MYRAND_MAX)
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{
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errorstream<<"WARNING: myrand_range: max-min > MYRAND_MAX"<<std::endl;
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max = min + MYRAND_MAX;
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}
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if(min > max)
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{
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errorstream<<"WARNING: myrand_range: min > max"<<std::endl;
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return max;
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}
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return (myrand()%(max-min+1))+min;
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}
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/*
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blockpos: position of block in block coordinates
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camera_pos: position of camera in nodes
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camera_dir: an unit vector pointing to camera direction
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range: viewing range
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*/
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bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
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f32 camera_fov, f32 range, f32 *distance_ptr)
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{
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v3s16 blockpos_nodes = blockpos_b * MAP_BLOCKSIZE;
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// Block center position
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v3f blockpos(
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((float)blockpos_nodes.X + MAP_BLOCKSIZE/2) * BS,
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((float)blockpos_nodes.Y + MAP_BLOCKSIZE/2) * BS,
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((float)blockpos_nodes.Z + MAP_BLOCKSIZE/2) * BS
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);
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// Block position relative to camera
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v3f blockpos_relative = blockpos - camera_pos;
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// Distance in camera direction (+=front, -=back)
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f32 dforward = blockpos_relative.dotProduct(camera_dir);
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// Total distance
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f32 d = blockpos_relative.getLength();
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if(distance_ptr)
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*distance_ptr = d;
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// If block is very close, it is always in sight
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if(d < 1.44*1.44*MAP_BLOCKSIZE*BS/2)
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return true;
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// If block is far away, it's not in sight
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if(d > range)
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return false;
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// Maximum radius of a block
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f32 block_max_radius = 0.5*1.44*1.44*MAP_BLOCKSIZE*BS;
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// If block is (nearly) touching the camera, don't
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// bother validating further (that is, render it anyway)
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if(d < block_max_radius)
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return true;
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// Cosine of the angle between the camera direction
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// and the block direction (camera_dir is an unit vector)
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f32 cosangle = dforward / d;
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// Compensate for the size of the block
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// (as the block has to be shown even if it's a bit off FOV)
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// This is an estimate, plus an arbitary factor
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cosangle += block_max_radius / d * 0.5;
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// If block is not in the field of view, skip it
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if(cosangle < cos(camera_fov / 2))
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return false;
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return true;
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}
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