Working on a new generator class, nearly there

mapgen/map_generator.cpp

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+/* Copyright: (c) Kayne Ruse 2014
+ * 
+ * This software is provided 'as-is', without any express or implied
+ * warranty. In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ * 
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ * 
+ * 1. The origin of this software must not be misrepresented; you must not
+ * claim that you wrote the original software. If you use this software
+ * in a product, an acknowledgment in the product documentation would be
+ * appreciated but is not required.
+ * 
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ * misrepresented as being the original software.
+ * 
+ * 3. This notice may not be removed or altered from any source
+ * distribution.
+*/
+#include "map_generator.hpp"
+
+#include "maths.hpp"
+
+#include <cmath>
+
+//it's either this, or dealing with floating points
+struct Coord {
+	int x, y;
+};
+
+//std::abs() only uses floating points
+int absolute(int i) {
+	return i > 0 ? i : -i;
+}
+
+//calculate how far away a query point is from a grid point
+Coord calcDist(Coord gridPoint, Coord queryPoint) {
+	int i = absolute(queryPoint.x - gridPoint.x);
+	int j = absolute(queryPoint.y - gridPoint.y);
+	return {i, j};
+}
+
+//calculate the amount of influence a distance will have within a certain sized area
+int calcInfluence(Coord dist, int width, int height) {
+	//inverted distance
+	Coord i = {width - dist.x, height - dist.y};
+	//essentially calculating the length
+	return sqrt(i.x*i.x + i.y*i.y);
+}
+
+//determine the scaled value from the grid point
+int calcScale(int influence, int gridValue, int pointValue) {
+	/* TODO
+	 * (influence / {width, height}.Length()) //percentage to interpolate
+	 * poingValue - gridValue //difference
+	 * return percentage * difference //scale
+	*/
+	return gridValue;
+}
+
+int MapGenerator::Noise(int x, int y, int width, int height) {
+	Coord queryPoint = {x, y};
+
+	//the "grid points"
+	Coord tl = {snap(x, width), snap(y, height)};
+	Coord tr = {tl.x + width, tl.y};
+	Coord bl = {tl.x, tl.y + height};
+	Coord br = {tl.x + width, tl.y + height};
+
+	//get the distance from the query, and subsequently the influence
+	int tlInfluence = calcInfluence(calcDist(tl, queryPoint), width, height);
+	int trInfluence = calcInfluence(calcDist(tr, queryPoint), width, height);
+	int blInfluence = calcInfluence(calcDist(bl, queryPoint), width, height);
+	int brInfluence = calcInfluence(calcDist(br, queryPoint), width, height);
+
+	//now combine the grid's values with the influence values
+	int tlScale = calcScale(tlInfluence, RawNoise(tl.x, tl.y), RawNoise(queryPoint.x, queryPoint.y));
+	int trScale = calcScale(trInfluence, RawNoise(tr.x, tr.y), RawNoise(queryPoint.x, queryPoint.y));
+	int blScale = calcScale(blInfluence, RawNoise(bl.x, bl.y), RawNoise(queryPoint.x, queryPoint.y));
+	int brScale = calcScale(brInfluence, RawNoise(br.x, br.y), RawNoise(queryPoint.x, queryPoint.y));
+
+	//Finally, apply each scale to the raw value, resulting in the height map
+	return tlScale + trScale + blScale + brScale + RawNoise(queryPoint.x, queryPoint.y);
+}
+
+int MapGenerator::RawNoise(int x, int y) {
+	return (x * 11235 + y * 81321 + 3455) % 256;
+}