diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
index d690156a..70d68420 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
@@ -393,6 +393,11 @@ class Starbound : ISBFileLocator {
 			1
 		}
 
+		state.setTableFunction("imageSpaces", this) { args ->
+			// List<Vec2I> root.imageSpaces(String imagePath, Vec2F worldPosition, float spaceScan, bool flip)
+			TODO()
+		}
+
 		state.pop()
 
 		state.load(polyfill, "@starbound.jar!/scripts/polyfill.lua")
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/JsonFunction.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/JsonFunction.kt
index 0508a039..cee00c41 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/JsonFunction.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/JsonFunction.kt
@@ -83,8 +83,10 @@ class JsonFunction(
 
 		when (interpolation) {
 			JsonFunctionInterpolation.LINEAR -> {
-				if (x < ranges[0].x) {
+				if (x <= lowerBound) {
 					return ranges[0].y
+				} else if (x >= upperBound) {
+					return ranges.last().y
 				}
 
 				for (i in 0 until ranges.size - 1) {
diff --git a/src/test/java/ru/dbotthepony/kstarbound/test/JsonFunctionTest.java b/src/test/java/ru/dbotthepony/kstarbound/test/JsonFunctionTest.java
new file mode 100644
index 00000000..80d09c46
--- /dev/null
+++ b/src/test/java/ru/dbotthepony/kstarbound/test/JsonFunctionTest.java
@@ -0,0 +1,306 @@
+package ru.dbotthepony.kstarbound.test;
+
+import com.google.gson.JsonObject;
+import com.google.gson.internal.bind.JsonTreeReader;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import ru.dbotthepony.kstarbound.Starbound;
+import ru.dbotthepony.kstarbound.defs.JsonFunction;
+
+import java.util.HashMap;
+import java.util.Locale;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class JsonFunctionTest {
+	private double[] drawData() {
+		return new double[] {
+			0.000000, 0.000000,
+			0.000500, 0.005000,
+			0.001000, 0.010000,
+			0.001500, 0.015000,
+			0.002000, 0.020000,
+			0.002500, 0.025000,
+			0.003000, 0.030000,
+			0.003500, 0.035000,
+			0.004000, 0.040000,
+			0.004500, 0.045000,
+			0.005000, 0.050000,
+			0.005500, 0.055000,
+			0.006000, 0.060000,
+			0.006500, 0.065000,
+			0.007000, 0.070000,
+			0.007500, 0.075000,
+			0.008000, 0.080000,
+			0.008500, 0.085000,
+			0.009000, 0.090000,
+			0.009500, 0.095000,
+			0.010000, 0.100000,
+			0.022000, 0.105000,
+			0.034000, 0.110000,
+			0.046000, 0.115000,
+			0.058000, 0.120000,
+			0.070000, 0.125000,
+			0.082000, 0.130000,
+			0.094000, 0.135000,
+			0.106000, 0.140000,
+			0.118000, 0.145000,
+			0.130000, 0.150000,
+			0.142000, 0.155000,
+			0.154000, 0.160000,
+			0.166000, 0.165000,
+			0.178000, 0.170000,
+			0.190000, 0.175000,
+			0.202000, 0.180000,
+			0.214000, 0.185000,
+			0.226000, 0.190000,
+			0.238000, 0.195000,
+			0.250000, 0.200000,
+			0.255435, 0.205000,
+			0.260870, 0.210000,
+			0.266304, 0.215000,
+			0.271739, 0.220000,
+			0.277174, 0.225000,
+			0.282609, 0.230000,
+			0.288043, 0.235000,
+			0.293478, 0.240000,
+			0.298913, 0.245000,
+			0.304348, 0.250000,
+			0.309783, 0.255000,
+			0.315217, 0.260000,
+			0.320652, 0.265000,
+			0.326087, 0.270000,
+			0.331522, 0.275000,
+			0.336957, 0.280000,
+			0.342391, 0.285000,
+			0.347826, 0.290000,
+			0.353261, 0.295000,
+			0.358696, 0.300000,
+			0.364130, 0.305000,
+			0.369565, 0.310000,
+			0.375000, 0.315000,
+			0.380435, 0.320000,
+			0.385870, 0.325000,
+			0.391304, 0.330000,
+			0.396739, 0.335000,
+			0.402174, 0.340000,
+			0.407609, 0.345000,
+			0.413043, 0.350000,
+			0.418478, 0.355000,
+			0.423913, 0.360000,
+			0.429348, 0.365000,
+			0.434783, 0.370000,
+			0.440217, 0.375000,
+			0.445652, 0.380000,
+			0.451087, 0.385000,
+			0.456522, 0.390000,
+			0.461957, 0.395000,
+			0.467391, 0.400000,
+			0.472826, 0.405000,
+			0.478261, 0.410000,
+			0.483696, 0.415000,
+			0.489130, 0.420000,
+			0.494565, 0.425000,
+			0.500000, 0.430000,
+			0.505435, 0.435000,
+			0.510870, 0.440000,
+			0.516304, 0.445000,
+			0.521739, 0.450000,
+			0.527174, 0.455000,
+			0.532609, 0.460000,
+			0.538043, 0.465000,
+			0.543478, 0.470000,
+			0.548913, 0.475000,
+			0.554348, 0.480000,
+			0.559783, 0.485000,
+			0.565217, 0.490000,
+			0.570652, 0.495000,
+			0.576087, 0.500000,
+			0.581522, 0.505000,
+			0.586957, 0.510000,
+			0.592391, 0.515000,
+			0.597826, 0.520000,
+			0.603261, 0.525000,
+			0.608696, 0.530000,
+			0.614130, 0.535000,
+			0.619565, 0.540000,
+			0.625000, 0.545000,
+			0.630435, 0.550000,
+			0.635870, 0.555000,
+			0.641304, 0.560000,
+			0.646739, 0.565000,
+			0.652174, 0.570000,
+			0.657609, 0.575000,
+			0.663043, 0.580000,
+			0.668478, 0.585000,
+			0.673913, 0.590000,
+			0.679348, 0.595000,
+			0.684783, 0.600000,
+			0.690217, 0.605000,
+			0.695652, 0.610000,
+			0.701087, 0.615000,
+			0.706522, 0.620000,
+			0.711957, 0.625000,
+			0.717391, 0.630000,
+			0.722826, 0.635000,
+			0.728261, 0.640000,
+			0.733696, 0.645000,
+			0.739130, 0.650000,
+			0.744565, 0.655000,
+			0.750000, 0.660000,
+			0.755435, 0.665000,
+			0.760870, 0.670000,
+			0.766304, 0.675000,
+			0.771739, 0.680000,
+			0.777174, 0.685000,
+			0.782609, 0.690000,
+			0.788043, 0.695000,
+			0.793478, 0.700000,
+			0.798913, 0.705000,
+			0.804348, 0.710000,
+			0.809783, 0.715000,
+			0.815217, 0.720000,
+			0.820652, 0.725000,
+			0.826087, 0.730000,
+			0.831522, 0.735000,
+			0.836957, 0.740000,
+			0.842391, 0.745000,
+			0.847826, 0.750000,
+			0.853261, 0.755000,
+			0.858696, 0.760000,
+			0.864130, 0.765000,
+			0.869565, 0.770000,
+			0.875000, 0.775000,
+			0.880435, 0.780000,
+			0.885870, 0.785000,
+			0.891304, 0.790000,
+			0.896739, 0.795000,
+			0.902174, 0.800000,
+			0.907609, 0.805000,
+			0.913043, 0.810000,
+			0.918478, 0.815000,
+			0.923913, 0.820000,
+			0.929348, 0.825000,
+			0.934783, 0.830000,
+			0.940217, 0.835000,
+			0.945652, 0.840000,
+			0.951087, 0.845000,
+			0.956522, 0.850000,
+			0.961957, 0.855000,
+			0.967391, 0.860000,
+			0.972826, 0.865000,
+			0.978261, 0.870000,
+			0.983696, 0.875000,
+			0.989130, 0.880000,
+			0.994565, 0.885000,
+			1.000000, 0.890000,
+			1.125000, 0.895000,
+			1.250000, 0.900000,
+			1.250000, 0.905000,
+			1.250000, 0.910000,
+			1.250000, 0.915000,
+			1.250000, 0.920000,
+			1.250000, 0.925000,
+			1.250000, 0.930000,
+			1.250000, 0.935000,
+			1.250000, 0.940000,
+			1.250000, 0.945000,
+			1.250000, 0.950000,
+			1.250000, 0.955000,
+			1.250000, 0.960000,
+			1.250000, 0.965000,
+			1.250000, 0.970000,
+			1.250000, 0.975000,
+			1.250000, 0.980000,
+			1.250000, 0.985000,
+			1.250000, 0.990000,
+			1.250000, 0.995000,
+			1.250000, 1.000000,
+			1.250000, 1.005000,
+			1.250000, 1.010000,
+			1.250000, 1.015000,
+			1.250000, 1.020000,
+			1.250000, 1.025000,
+			1.250000, 1.030000,
+			1.250000, 1.035000,
+			1.250000, 1.040000,
+			1.250000, 1.045000,
+			1.250000, 1.050000,
+			1.250000, 1.055000,
+			1.250000, 1.060000,
+			1.250000, 1.065000,
+			1.250000, 1.070000,
+			1.250000, 1.075000,
+			1.250000, 1.080000,
+			1.250000, 1.085000,
+			1.250000, 1.090000,
+			1.250000, 1.095000,
+			1.250000, 1.100000,
+			1.125000, 1.105000,
+			1.000000, 1.110000,
+			1.000000, 1.115000,
+			1.000000, 1.120000,
+			1.000000, 1.125000,
+			1.000000, 1.130000,
+			1.000000, 1.135000,
+			1.000000, 1.140000,
+			1.000000, 1.145000,
+			1.000000, 1.150000,
+			1.000000, 1.155000,
+			1.000000, 1.160000,
+			1.000000, 1.165000,
+			1.000000, 1.170000,
+			1.000000, 1.175000,
+			1.000000, 1.180000,
+			1.000000, 1.185000,
+			1.000000, 1.190000,
+			1.000000, 1.195000,
+			1.000000, 1.200000,
+		};
+	}
+
+	@Test
+	@DisplayName("Json functions")
+	public void test() {
+		var sb = new Starbound();
+
+		var fnData = """
+			{
+			  "drawTimeMultiplier" : [ "linear", "clamp", [0, 0], [0.1, 0.01], [0.2, 0.25], [0.89, 1.0], [0.9, 1.25], [1.1, 1.25], [1.11, 1.0], [1.2, 1.0] ],
+			  "normalizedDrawTimeMultiplier" : [ "linear", "clamp", [0, 0], [0.1, 0.01], [0.2, 0.25], [0.89, 0.9], [0.9, 1.0] ],
+			  "bowImageSelector" : [ "linear", "clamp", [0, 0], [0.9, 4.0], [1.1, 4.0], [1.11, 3.9], [1.2, 3.9] ],
+			  "bowImageSelectorNoPower" : [ "linear", "clamp", [0, 0], [0.9, 3.0] ],
+			  "poisonBowImageSelector" : [ "linear", "clamp", [0, 0], [0.9, 4.0], [1.1, 4.0], [1.11, 5.0], [1.2, 5.0] ],
+			  "poisonBowImageSelectorNoPower" : [ "linear", "clamp", [0, 0], [0.9, 3.0], [0.9001, 5.0] ],
+			  "constant" : [ "linear", "clamp", [0, 1.0] ]
+			}
+			""";
+
+		var data = sb.getGson().fromJson(fnData, JsonObject.class);
+
+		var funcs = new HashMap<String, JsonFunction>();
+
+		for (var entry : data.entrySet()) {
+			funcs.put(entry.getKey(), sb.getGson().fromJson(new JsonTreeReader(entry.getValue()), JsonFunction.class));
+		}
+
+		var constant = funcs.get("constant");
+
+		for (int i = -10; i <= 10; i++) {
+			assertEquals(1.0, constant.evaluate(i));
+		}
+
+		var drawTimeMultiplier = funcs.get("drawTimeMultiplier");
+		var drawTimeMultiplierData = drawData();
+
+		for (int i = 0; i < drawTimeMultiplierData.length; i += 2) {
+			double result = drawTimeMultiplierData[i];
+			double x = drawTimeMultiplierData[i + 1];
+			double evaluated = drawTimeMultiplier.evaluate(x);
+
+			if (!String.format(Locale.ROOT, "%.4f", result).equals(String.format(Locale.ROOT, "%.4f", evaluated))) {
+				throw new RuntimeException("Evaluation of function returned " + String.format(Locale.ROOT, "%.4f", evaluated) + " while " + String.format(Locale.ROOT, "%.4f", result) + " was expected for input " + x);
+			}
+		}
+	}
+}