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#include <mbgl/style/function_properties.hpp>
#include <mbgl/style/types.hpp>
#include <cmath>
namespace mbgl {
template <typename T>
inline T interpolate(T smaller, T larger, const float factor);
template <>
inline float interpolate(const float smaller, const float larger, const float factor) {
return (smaller * (1 - factor)) + (larger * factor);
}
template <>
inline bool interpolate(const bool smaller, const bool larger, const float factor) {
return interpolate(float(smaller), float(larger), factor);
}
template <>
inline Color interpolate(const Color smaller, const Color larger, const float factor) {
return {{
interpolate(smaller[0], larger[0], factor),
interpolate(smaller[1], larger[1], factor),
interpolate(smaller[2], larger[2], factor),
interpolate(smaller[3], larger[3], factor)
}};
}
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 {};
bool larger = false;
float larger_z = 0.0f;
T larger_val {};
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 interpolate<T>(smaller_val, larger_val, t);
} else {
const float t = (std::pow(base, zoomProgress) - 1) / (std::pow(base, zoomDiff) - 1);
return interpolate<T>(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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