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#include <llmr/style/properties.hpp>
#include <cassert>
#include <cmath>
using namespace llmr;
float functions::null(float z, const std::vector<float>&) {
return 0;
}
bool functions::null(float z, const std::vector<bool>&) {
return false;
}
float functions::constant(float z, const std::vector<float>& values) {
assert(values.size() == 1);
return values.front();
}
bool functions::constant(float z, const std::vector<bool>& values) {
assert(values.size() == 1);
return values.front();
}
float functions::stops(float z, const std::vector<float>& stops) {
// We need an even number of stop values.
if (stops.size() % 2 != 0) return 0;
// Accounts for us rendering tiles at 512x512, so our zoom levels are shifted by 1.
z += 1;
bool smaller = false;
float smaller_z, smaller_val;
bool larger = false;
float larger_z, larger_val;
for (uint32_t i = 0; i < stops.size(); i += 2) {
float stop_z = stops[i];
float stop_val = stops[i + 1];
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;
float factor = (z - smaller_z) / (larger_z - smaller_z);
// Linear interpolation if base is 0
if (smaller_val == 0) return factor * larger_val;
// Exponential interpolation between the values
return smaller_val * pow(larger_val / smaller_val, factor);
} else if (larger || smaller) {
// Do not draw a line.
return -std::numeric_limits<float>::infinity();
// Exponential extrapolation of the smaller or larger value
//var edge = larger || smaller;
//return Math.pow(2, z) * (edge.val / Math.pow(2, edge.z));
} else {
// No stop defined.
return 1;
}
}
bool functions::stops(float z, const std::vector<bool>& values) {
// TODO
return false;
}
float functions::linear(float z, const std::vector<float>& values) {
if (values.size() != 5) {
return 0;
}
const float z_base = values[0];
const float val = values[1];
const float slope = values[2];
const float min = values[3];
const float max = values[4];
return fmin(fmax(min, val + (z - z_base) * slope), max);
}
bool functions::linear(float z, const std::vector<bool>&) {
// TODO
return false;
}
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