Skip to content
This repository has been archived by the owner on Aug 8, 2023. It is now read-only.

Commit

Permalink
consolidate functions to only use stops
Browse files Browse the repository at this point in the history 
refs mapbox/mapbox-gl-style-spec#96
  • Loading branch information
@kkaefer
kkaefer committed Jul 17, 2014
1 parent d44742f commit 68f595a
Show file tree
Hide file tree
Showing 5 changed files with 72 additions and 195 deletions.
28 changes: 2 additions & 26 deletions include/mbgl/style/function_properties.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,44 +16,20 @@ struct ConstantFunction {
const T value;
};

template <typename T>
struct LinearFunction {
inline LinearFunction(const T &value, float z_base, float slope, const T &min, const T &max)
: value(value), min(min), max(max), z_base(z_base), slope(slope) {}
T evaluate(float z) const;

private:
const T value, min, max;
const float z_base, slope;
};

template <typename T>
struct ExponentialFunction {
inline ExponentialFunction(const T &value, float z_base, float exp_base, float slope, const T &min,
const T &max)
: value(value), min(min), max(max), z_base(z_base), exp_base(exp_base), slope(slope) {}
T evaluate(float z) const;

private:
const T value, min, max;
const float z_base, exp_base, slope;
};

template <typename T>
struct StopsFunction {
inline StopsFunction(const std::vector<std::pair<float, T>> &values) : values(values) {}
inline StopsFunction(const std::vector<std::pair<float, T>> &values, float base) : values(values), base(base) {}
T evaluate(float z) const;

private:
const std::vector<std::pair<float, T>> values;
const float base;
};

template <typename T>
using Function = util::variant<
std::false_type,
ConstantFunction<T>,
LinearFunction<T>,
ExponentialFunction<T>,
StopsFunction<T>
>;

Expand Down
87 changes: 24 additions & 63 deletions src/style/function_properties.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,82 +6,36 @@
namespace mbgl {


template <>
bool LinearFunction<bool>::evaluate(float z) const {
return z < z_base ? slope >= 0 : z > z_base ? slope >= 0 : value;
}

template <>
float LinearFunction<float>::evaluate(float z) const {
return std::fmin(std::fmax(min, value + (z - z_base) * slope), max);
}

template <>
Color LinearFunction<Color>::evaluate(float z) const {
return {{
std::fmin(std::fmax(min[0], value[0] + (z - z_base) * slope), max[0]),
std::fmin(std::fmax(min[1], value[1] + (z - z_base) * slope), max[1]),
std::fmin(std::fmax(min[2], value[2] + (z - z_base) * slope), max[2]),
std::fmin(std::fmax(min[3], value[3] + (z - z_base) * slope), max[3])
}};
}


template <>
bool ExponentialFunction<bool>::evaluate(float z) const {
return z < z_base ? slope >= 0 : z > z_base ? slope >= 0 : value;
}

template <>
float ExponentialFunction<float>::evaluate(float z) const {
return std::fmin(std::fmax(min, value + std::pow(exp_base, (z - z_base)) * slope), max);
}

template <>
Color ExponentialFunction<Color>::evaluate(float z) const {
return {{
std::fmin(std::fmax(min[0], value[0] + float(std::pow(exp_base, (z - z_base))) * slope), max[0]),
std::fmin(std::fmax(min[1], value[1] + float(std::pow(exp_base, (z - z_base))) * slope), max[1]),
std::fmin(std::fmax(min[2], value[2] + float(std::pow(exp_base, (z - z_base))) * slope), max[2]),
std::fmin(std::fmax(min[3], value[3] + float(std::pow(exp_base, (z - z_base))) * slope), max[3])
}};
}

template <typename T>
inline T exponentialInterpolate(T smaller, T larger, const float factor);
inline T interpolate(T smaller, T larger, const float factor);

template <>
inline float exponentialInterpolate(const float smaller, const float larger, const float factor) {
// Linear interpolation if base is 0
if (smaller == 0.0f) {
return factor * larger;
}
// Exponential interpolation between the values
return smaller * std::pow(larger / smaller, factor);
inline float interpolate(const float smaller, const float larger, const float factor) {
return (smaller * (1 - factor)) + (larger * factor);
}

template <>
inline bool exponentialInterpolate(const bool smaller, const bool larger, const float factor) {
return exponentialInterpolate(float(smaller), float(larger), factor);
inline bool interpolate(const bool smaller, const bool larger, const float factor) {
return interpolate(float(smaller), float(larger), factor);
}

template <>
inline Color exponentialInterpolate(const Color smaller, const Color larger, const float factor) {
inline Color interpolate(const Color smaller, const Color larger, const float factor) {
return {{
exponentialInterpolate(smaller[0], larger[0], factor),
exponentialInterpolate(smaller[1], larger[1], factor),
exponentialInterpolate(smaller[2], larger[2], factor),
exponentialInterpolate(smaller[3], larger[3], factor)
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>
T exponentialDefault();
inline T defaultStopsValue();

template <> bool exponentialDefault() { return true; }
template <> float exponentialDefault() { return 1.0f; }
template <> Color exponentialDefault() { return {{ 0, 0, 0, 1 }}; }
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>
Expand Down Expand Up @@ -112,15 +66,22 @@ T StopsFunction<T>::evaluate(float z) const {
if (larger_z == smaller_z || larger_val == smaller_val) {
return smaller_val;
}
float factor = (z - smaller_z) / (larger_z - smaller_z);
return exponentialInterpolate<T>(smaller_val, larger_val, factor);
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 exponentialDefault<T>();
return defaultStopsValue<T>();
}
}

Expand Down
107 changes: 34 additions & 73 deletions src/style/style_parser.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -230,95 +230,56 @@ Color StyleParser::parseFunctionArgument(JSVal value) {
return parseColor(rvalue);
}

template <typename T> inline float defaultBaseValue() { return 1.75; }
template <> inline float defaultBaseValue<Color>() { return 1.0; }

template <typename T>
std::tuple<bool, Function<T>> StyleParser::parseFunction(JSVal value) {
if (!value.HasMember("fn")) {
fprintf(stderr, "[WARNING] function must specify a function name\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}

JSVal value_fn = value["fn"];
if (!value_fn.IsString()) {
fprintf(stderr, "[WARNING] function must specify a function type\n");
if (!value.HasMember("stops")) {
fprintf(stderr, "[WARNING] stops function must specify a stops array\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}

const std::string type { value_fn.GetString(), value_fn.GetStringLength() };
float base = defaultBaseValue<T>();

if (type == "linear") {
if (!value.HasMember("z")) {
fprintf(stderr, "[WARNING] linear function must specify a base zoom level\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}
if (!value.HasMember("val")) {
fprintf(stderr, "[WARNING] linear function must specify a base value\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
if (value.HasMember("base")) {
JSVal value_base = value["base"];
if (value_base.IsNumber()) {
base = value_base.GetDouble();
} else {
fprintf(stderr, "[WARNING] base must be numeric\n");
}
const float z_base = parseFunctionArgument<float>(value["z"]);
const T val = parseFunctionArgument<T>(value["val"]);
const float slope = value.HasMember("slope") ? parseFunctionArgument<float>(value["slope"]) : 1;
const T min = value.HasMember("min") ? parseFunctionArgument<T>(value["min"]) : T();
const T max = value.HasMember("max") ? parseFunctionArgument<T>(value["max"]) : T();
return std::tuple<bool, Function<T>> { true, LinearFunction<T>(val, z_base, slope, min, max) };
}
else if (type == "exponential") {
if (!value.HasMember("z")) {
fprintf(stderr, "[WARNING] exponential function must specify a base zoom level\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}
if (!value.HasMember("val")) {
fprintf(stderr, "[WARNING] exponential function must specify a base value\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}
const float z_base = parseFunctionArgument<float>(value["z"]);
const float exp_base = value.HasMember("base") ? parseFunctionArgument<float>(value["base"]) : 1.75;
const T val = parseFunctionArgument<T>(value["val"]);
const float slope = value.HasMember("slope") ? parseFunctionArgument<float>(value["slope"]) : 1;
const T min = value.HasMember("min") ? parseFunctionArgument<T>(value["min"]) : T();
const T max = value.HasMember("max") ? parseFunctionArgument<T>(value["max"]) : T();
return std::tuple<bool, Function<T>> { true, ExponentialFunction<T>(val, z_base, exp_base, slope, min, max) };
}
else if (type == "stops") {
if (!value.HasMember("stops")) {
fprintf(stderr, "[WARNING] stops function must specify a stops array\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}

JSVal value_stops = value["stops"];
if (!value_stops.IsArray()) {
fprintf(stderr, "[WARNING] stops function must specify a stops array\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}

std::vector<std::pair<float, T>> stops;
for (rapidjson::SizeType i = 0; i < value_stops.Size(); ++i) {
JSVal stop = value_stops[i];
if (stop.IsArray()) {
if (stop.Size() != 2) {
fprintf(stderr, "[WARNING] stop must have zoom level and value specification\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}
JSVal value_stops = value["stops"];
if (!value_stops.IsArray()) {
fprintf(stderr, "[WARNING] stops function must specify a stops array\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}

JSVal z = stop[rapidjson::SizeType(0)];
if (!z.IsNumber()) {
fprintf(stderr, "[WARNING] zoom level in stop must be a number\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}
std::vector<std::pair<float, T>> stops;
for (rapidjson::SizeType i = 0; i < value_stops.Size(); ++i) {
JSVal stop = value_stops[i];
if (stop.IsArray()) {
if (stop.Size() != 2) {
fprintf(stderr, "[WARNING] stop must have zoom level and value specification\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}

stops.emplace_back(z.GetDouble(), parseFunctionArgument<T>(stop[rapidjson::SizeType(1)]));
} else {
fprintf(stderr, "[WARNING] function argument must be a numeric value\n");
JSVal z = stop[rapidjson::SizeType(0)];
if (!z.IsNumber()) {
fprintf(stderr, "[WARNING] zoom level in stop must be a number\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}
}

return std::tuple<bool, Function<T>> { true, StopsFunction<T>(stops) };
}
else {
fprintf(stderr, "[WARNING] function type '%s' is unknown\n", type.c_str());
stops.emplace_back(z.GetDouble(), parseFunctionArgument<T>(stop[rapidjson::SizeType(1)]));
} else {
fprintf(stderr, "[WARNING] function argument must be a numeric value\n");
return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
}
}

return std::tuple<bool, Function<T>> { false, ConstantFunction<T>(T()) };
return std::tuple<bool, Function<T>> { true, StopsFunction<T>(stops, base) };
}


Expand Down
1 change: 0 additions & 1 deletion test/fixtures/styles/road-width.style.json
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@
"type": "line",
"style": {
"line-width": {
"fn": "stops",
"stops": [[13, 0], [13.999, 0], [14, 4], [14.1, 10], [14.2, 20]]
}
}
Expand Down
44 changes: 12 additions & 32 deletions test/functions.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,60 +19,40 @@ TEST(Function, Constant) {

TEST(Function, Stops) {
// Explicit constant slope in fringe regions.
mbgl::StopsFunction<float> slope_1({ { 0, 1.5 }, { 6, 1.5 }, { 8, 3 }, { 22, 3 } });
mbgl::StopsFunction<float> slope_1({ { 0, 1.5 }, { 6, 1.5 }, { 8, 3 }, { 22, 3 } }, 1.75);
EXPECT_EQ(1.5, slope_1.evaluate(0));
EXPECT_EQ(1.5, slope_1.evaluate(4));
EXPECT_EQ(1.5, slope_1.evaluate(6));
ASSERT_FLOAT_EQ(2.12132, slope_1.evaluate(7));
ASSERT_FLOAT_EQ(2.0454545454545454, slope_1.evaluate(7));
EXPECT_EQ(3.0, slope_1.evaluate(8));
EXPECT_EQ(3.0, slope_1.evaluate(9));
EXPECT_EQ(3.0, slope_1.evaluate(15));
EXPECT_EQ(3.0, slope_1.evaluate(22));


// Test constant values in fringe regions.
mbgl::StopsFunction<float> slope_2({ { 6, 1.5 }, { 8, 3 } });
mbgl::StopsFunction<float> slope_2({ { 6, 1.5 }, { 8, 3 } }, 1.75);
EXPECT_EQ(1.5, slope_2.evaluate(0));
EXPECT_EQ(1.5, slope_2.evaluate(4));
EXPECT_EQ(1.5, slope_2.evaluate(6));
ASSERT_FLOAT_EQ(2.12132, slope_2.evaluate(7));
ASSERT_FLOAT_EQ(2.0454545454545454, slope_2.evaluate(7));
EXPECT_EQ(3.0, slope_2.evaluate(8));
EXPECT_EQ(3.0, slope_2.evaluate(9));
EXPECT_EQ(3.0, slope_2.evaluate(15));
EXPECT_EQ(3.0, slope_2.evaluate(22));

// Test no values.
mbgl::StopsFunction<float> slope_3({});
mbgl::StopsFunction<float> slope_3({}, 1.75);
EXPECT_EQ(1, slope_3.evaluate(2));
EXPECT_EQ(1, slope_3.evaluate(6));
EXPECT_EQ(1, slope_3.evaluate(12));
}


TEST(Function, Linear) {
mbgl::LinearFunction<float> slope_1(/* val */ 7.5, /* z_base */ 4, /* slope */ 2, /* min */ 7.5, /* max */ 20);
ASSERT_FLOAT_EQ(7.5, slope_1.evaluate(3));
ASSERT_FLOAT_EQ(7.5, slope_1.evaluate(4));
ASSERT_FLOAT_EQ(8.5, slope_1.evaluate(4.5));
ASSERT_FLOAT_EQ(9.5, slope_1.evaluate(5));
ASSERT_FLOAT_EQ(11.5, slope_1.evaluate(6));
ASSERT_FLOAT_EQ(19.5, slope_1.evaluate(10));
ASSERT_FLOAT_EQ(20, slope_1.evaluate(11));
ASSERT_FLOAT_EQ(20, slope_1.evaluate(20));
}


TEST(Function, Exponential) {
mbgl::ExponentialFunction<float> slope_1(/* val */ 7.5, /* z_base */ 4, /* exp_base */ 1.75, /* slope */ 2, /* min */ 7.5, /* max */ 20);
ASSERT_FLOAT_EQ(8.6428576, slope_1.evaluate(3)); // 7.5 + 1.75^(3 - 4) * 2
ASSERT_FLOAT_EQ(9.5, slope_1.evaluate(4)); // 7.5 + 1.75^(4 - 4) * 2
ASSERT_FLOAT_EQ(10.145751, slope_1.evaluate(4.5)); // 7.5 + 1.75^(4.5 - 4) * 2
ASSERT_FLOAT_EQ(11, slope_1.evaluate(5)); // 7.5 + 1.75^(5 - 4) * 2
ASSERT_FLOAT_EQ(13.625, slope_1.evaluate(6)); // 7.5 + 1.75^(6 - 4) * 2
ASSERT_FLOAT_EQ(18.21875, slope_1.evaluate(7)); // 7.5 + 1.75^(7 - 4) * 2
ASSERT_FLOAT_EQ(20, slope_1.evaluate(8)); // 7.5 + 1.75^(8 - 4) * 2 ==> clamped to 20
ASSERT_FLOAT_EQ(20, slope_1.evaluate(20)); // 7.5 + 1.75^(20 - 4) * 2 ==> clamped to 20
// Explicit constant slope in fringe regions.
mbgl::StopsFunction<float> slope_4({ { 0, 2 }, { 8, 10 } }, 1);
EXPECT_EQ(2, slope_4.evaluate(0));
EXPECT_EQ(3, slope_4.evaluate(1));
EXPECT_EQ(4, slope_4.evaluate(2));
EXPECT_EQ(4.75, slope_4.evaluate(2.75));
EXPECT_EQ(10, slope_4.evaluate(8));
}



0 comments on commit 68f595a

Please sign in to comment.