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#include <mbgl/style/function_properties.hpp>
#include <mbgl/style/types.hpp>
#include <mbgl/util/interpolate.hpp>
#include <cmath>
namespace mbgl {
template <typename T>
inline T defaultStopsValue();
template <> inline bool defaultStopsValue() { return true; }
template <> inline float defaultStopsValue() { return 1.0f; }
template <> inline Color defaultStopsValue() { return {{ 0, 0, 0, 1 }}; }
template <typename T>
T StopsFunction<T>::evaluate(float z) const {
bool smaller = false;
float smaller_z = 0.0f;
T smaller_val = T();
bool larger = false;
float larger_z = 0.0f;
T larger_val = T();
for (uint32_t i = 0; i < values.size(); i++) {
float stop_z = values[i].first;
T stop_val = values[i].second;
if (stop_z <= z && (!smaller || smaller_z < stop_z)) {
smaller = true;
smaller_z = stop_z;
smaller_val = stop_val;
}
if (stop_z >= z && (!larger || larger_z > stop_z)) {
larger = true;
larger_z = stop_z;
larger_val = stop_val;
}
}
if (smaller && larger) {
if (larger_z == smaller_z || larger_val == smaller_val) {
return smaller_val;
}
const float zoomDiff = larger_z - smaller_z;
const float zoomProgress = z - smaller_z;
if (base == 1.0f) {
const float t = zoomProgress / zoomDiff;
return util::interpolate(smaller_val, larger_val, t);
} else {
const float t = (std::pow(base, zoomProgress) - 1) / (std::pow(base, zoomDiff) - 1);
return util::interpolate(smaller_val, larger_val, t);
}
} else if (larger) {
return larger_val;
} else if (smaller) {
return smaller_val;
} else {
// No stop defined.
return defaultStopsValue<T>();
}
}
template bool StopsFunction<bool>::evaluate(float z) const;
template float StopsFunction<float>::evaluate(float z) const;
template Color StopsFunction<Color>::evaluate(float z) const;
}
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