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path: root/src/libjin/math/ranged_value.cpp
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#include "ranged_value.h"

namespace JinEngine
{
	namespace Math
	{

		RangedValue::RangedValue()
			: mCount(0)
		{
		}

		RangedValue::RangedValue(float* points, uint n)
			: mCount(n)
		{
			for (uint i = 0; i < n; ++i)
			{
				float x = points[2*i];
				float y = points[2*i + 1];
				mXAxis.push_back(x);
				mYAxis.push_back(y);
			}
		}

		void RangedValue::addPoint(float x, float y)
		{
			mXAxis.push_back(x);
			mYAxis.push_back(y);
			++mCount;
		}

		void RangedValue::removePoint(uint i)
		{
			mXAxis.erase(mXAxis.begin() + i);
			mYAxis.erase(mYAxis.begin() + i);
			--mCount;
		}

		void RangedValue::insertPoint(uint i, float x, float y)
		{
			mXAxis.insert(mXAxis.begin() + i, x);
			mYAxis.insert(mYAxis.begin() + i, y);
			++mCount;
		}

		float RangedValue::getValue(float x)
		{
			int endIndex = -1;
			int n = mCount;
			for (int i = 1; i < n; i++) {
				float t = mXAxis[i];
				if (t > x) {
					endIndex = i;
					break;
				}
			}
			if (endIndex == -1) return mYAxis[n - 1];
			int startIndex = endIndex - 1;
			float startValue = mYAxis[startIndex];
			float startX = mXAxis[startIndex];
			return startValue + (mYAxis[endIndex] - startValue) * ((x - startX) / (mXAxis[endIndex] - startX));
		}

		void RangedValue::clear()
		{
			mXAxis.clear();
			mYAxis.clear();
		}

	}
}