96 lines
2.8 KiB
C++
96 lines
2.8 KiB
C++
#include <llmr/style/properties.hpp>
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#include <llmr/util/constants.hpp>
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#include <cassert>
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#include <cmath>
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using namespace llmr;
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float functions::null(float, const std::vector<float>&) {
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return 0;
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}
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float functions::constant(float, const std::vector<float>& values) {
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assert(values.size() == 1);
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return values.front();
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}
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float functions::min(float z, const std::vector<float>& values) {
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assert(values.size() == 1);
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return z >= values.front();
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}
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float functions::max(float z, const std::vector<float>& values) {
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assert(values.size() == 1);
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return z <= values.front();
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}
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float functions::stops(float z, const std::vector<float>& stops) {
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// We need an even number of stop values.
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if (stops.size() % 2 != 0) return 0;
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// Accounts for us rendering tiles at another size, so our zoom levels are shifted appropriately.
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z += util::tileSize / 256.0f;
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bool smaller = false;
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float smaller_z, smaller_val;
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bool larger = false;
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float larger_z, larger_val;
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for (uint32_t i = 0; i < stops.size(); i += 2) {
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float stop_z = stops[i];
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float stop_val = stops[i + 1];
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if (stop_z <= z && (!smaller || smaller_z < stop_z)) { smaller = true; smaller_z = stop_z; smaller_val = stop_val; }
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if (stop_z >= z && (!larger || larger_z > stop_z)) { larger = true; larger_z = stop_z; larger_val = stop_val; }
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}
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if (smaller && larger) {
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if (larger_z == smaller_z || larger_val == smaller_val) return smaller_val;
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float factor = (z - smaller_z) / (larger_z - smaller_z);
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// Linear interpolation if base is 0
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if (smaller_val == 0) return factor * larger_val;
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// Exponential interpolation between the values
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return smaller_val * pow(larger_val / smaller_val, factor);
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} else if (larger || smaller) {
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// Do not draw a line.
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return -std::numeric_limits<float>::infinity();
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// Exponential extrapolation of the smaller or larger value
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//var edge = larger || smaller;
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//return Math.pow(2, z) * (edge.val / Math.pow(2, edge.z));
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} else {
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// No stop defined.
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return 1;
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}
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}
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float functions::linear(float z, const std::vector<float>& values) {
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if (values.size() != 5) {
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return 0;
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}
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const float z_base = values[0];
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const float val = values[1];
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const float slope = values[2];
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const float min = values[3];
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const float max = values[4];
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return fmin(fmax(min, val + (z - z_base) * slope), max);
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}
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float functions::exponential(float z, const std::vector<float>& values) {
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if (values.size() != 5) {
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return 0;
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}
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const float z_base = values[0];
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const float val = values[1];
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const float slope = values[2];
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const float min = values[3];
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const float max = values[4];
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return fmin(fmax(min, val + pow(1.75, (z - z_base)) * slope), max);
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}
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