From 1bc37d576ce790c1169c5f9996be7bbc8026db2c Mon Sep 17 00:00:00 2001
From: Perttu Ahola <celeron55@gmail.com>
Date: Sun, 17 Jun 2012 01:29:13 +0300
Subject: Initially split utility.h to multiple files in util/

---
 src/util/numeric.cpp | 202 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 202 insertions(+)
 create mode 100644 src/util/numeric.cpp

(limited to 'src/util/numeric.cpp')

diff --git a/src/util/numeric.cpp b/src/util/numeric.cpp
new file mode 100644
index 000000000..d082cdb76
--- /dev/null
+++ b/src/util/numeric.cpp
@@ -0,0 +1,202 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2012 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(core::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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