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b0533e6836
This fixes a bug where, when drawing 1/x, a vertical bar would appear on 0, because of false positive cache hits. Change-Id: I2eafeac5e254c8a556769a41c8edc532db44383a
57 lines
2.2 KiB
C++
57 lines
2.2 KiB
C++
#ifndef SHARED_CONTINUOUS_FUNCTION_CACHE_H
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#define SHARED_CONTINUOUS_FUNCTION_CACHE_H
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#include "../graph/graph/graph_view.h"
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#include <ion/display.h>
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#include <poincare/context.h>
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#include <poincare/coordinate_2D.h>
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namespace Shared {
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class ContinuousFunction;
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class ContinuousFunctionCache {
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private:
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/* The size of the cache is chosen to optimize the display of cartesian
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* functions */
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static constexpr int k_sizeOfCache = Ion::Display::Width;
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public:
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static constexpr int k_numberOfAvailableCaches = 2;
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static constexpr int k_parametricStepFactor = k_sizeOfCache / int(Graph::GraphView::k_graphStepDenominator);
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static void PrepareForCaching(void * fun, ContinuousFunctionCache * cache, float tMin, float tStep);
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ContinuousFunctionCache() { clear(); }
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float step() const { return m_tStep; }
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void clear();
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Poincare::Coordinate2D<float> valueForParameter(const ContinuousFunction * function, Poincare::Context * context, float t);
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private:
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/* We need a certain amount of tolerance since we try to evaluate the
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* equality of floats. But the value has to be chosen carefully. Too high of
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* a tolerance causes false positives, which lead to errors in curves
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* (ex : 1/x with a vertical line at 0). Too low of a tolerance causes false
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* negatives, which slows down the drawing.
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*
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* The value 128*FLT_EPSILON has been found to be the lowest for which all
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* indices verify indexForParameter(tMin + index * tStep) = index. */
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static constexpr float k_cacheHitTolerance = 128 * FLT_EPSILON;
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void invalidateBetween(int iInf, int iSup);
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void setRange(ContinuousFunction * function, float tMin, float tStep);
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int indexForParameter(const ContinuousFunction * function, float t) const;
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Poincare::Coordinate2D<float> valuesAtIndex(const ContinuousFunction * function, Poincare::Context * context, float t, int i);
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void pan(ContinuousFunction * function, float newTMin);
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float m_tMin, m_tStep;
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float m_cache[k_sizeOfCache];
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/* m_startOfCache is used to implement a circular buffer for easy panning
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* with cartesian functions. When dealing with parametric or polar functions,
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* m_startOfCache should be zero.*/
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int m_startOfCache;
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};
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}
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#endif
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