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