diff --git a/h2d/col/Segments.hx b/h2d/col/Segments.hx
index 64327223de..167a107d4c 100644
--- a/h2d/col/Segments.hx
+++ b/h2d/col/Segments.hx
@@ -40,7 +40,20 @@ abstract Segments(Array<Segment>) from Array<Segment> to Array<Segment> {
 				if( s.side(p) < 0 )
 					return false;
 		} else {
-			throw "TODO";
+			// Ray-casting (winding number) algorithm for arbitrary polygons.
+			// Counts intersections of a horizontal ray starting from point p and going right.
+			var w = 0;
+			for( s in segments ) {
+				var startY = s.y;
+				var endY = s.y + s.dy;
+				if( endY <= p.y ) {
+					if( startY > p.y && s.side(p) < 0 )
+						w++;
+				} else if( startY <= p.y && s.side(p) > 0 ) {
+					w--;
+				}
+			}
+			return w != 0;
 		}
 		return true;
 	}
diff --git a/test.hxml b/test.hxml
new file mode 100644
index 0000000000..286dd68db7
--- /dev/null
+++ b/test.hxml
@@ -0,0 +1,4 @@
+-cp test
+-main test.TestRunner
+-lib heaps
+--interp
diff --git a/test/Assert.hx b/test/Assert.hx
new file mode 100644
index 0000000000..78b2f7d6be
--- /dev/null
+++ b/test/Assert.hx
@@ -0,0 +1,44 @@
+package test;
+
+class Assert {
+    public static var failures:Int = 0;
+    public static var successes:Int = 0;
+
+    public static function isTrue(value:Bool, ?pos:haxe.PosInfos) {
+        if (!value) {
+            failures++;
+            trace("FAIL: Expected true, got false at " + pos.fileName + ":" + pos.lineNumber);
+        } else {
+            successes++;
+        }
+    }
+
+    public static function isFalse(value:Bool, ?pos:haxe.PosInfos) {
+        if (value) {
+            failures++;
+            trace("FAIL: Expected false, got true at " + pos.fileName + ":" + pos.lineNumber);
+        } else {
+            successes++;
+        }
+    }
+
+    public static function equals<T>(expected:T, actual:T, ?pos:haxe.PosInfos) {
+        if (expected != actual) {
+            failures++;
+            trace("FAIL: Expected " + expected + ", got " + actual + " at " + pos.fileName + ":" + pos.lineNumber);
+        } else {
+            successes++;
+        }
+    }
+
+    public static function floatEquals(expected:Float, actual:Float, epsilon:Float = 1e-6, ?pos:haxe.PosInfos) {
+        var diff = expected - actual;
+        if (diff < 0) diff = -diff;
+        if (diff > epsilon) {
+            failures++;
+            trace("FAIL: Expected " + expected + ", got " + actual + " (diff " + diff + " > epsilon " + epsilon + ") at " + pos.fileName + ":" + pos.lineNumber);
+        } else {
+            successes++;
+        }
+    }
+}
diff --git a/test/TestMath.hx b/test/TestMath.hx
new file mode 100644
index 0000000000..02040057f8
--- /dev/null
+++ b/test/TestMath.hx
@@ -0,0 +1,64 @@
+package test;
+
+class TestMath {
+    public function new() {}
+
+    public function run() {
+        testClamp();
+        testIsPOT();
+        testNextPOT();
+        testLerp();
+        testInverseLerp();
+        testFmt();
+    }
+
+    function testClamp() {
+        Assert.equals(5.0, hxd.Math.clamp(5.0, 0.0, 10.0));
+        Assert.equals(0.0, hxd.Math.clamp(-1.0, 0.0, 10.0));
+        Assert.equals(10.0, hxd.Math.clamp(15.0, 0.0, 10.0));
+        Assert.equals(0.5, hxd.Math.clamp(0.5)); // Default range: 0 to 1
+        Assert.equals(0.0, hxd.Math.clamp(-0.2));
+        Assert.equals(1.0, hxd.Math.clamp(1.5));
+    }
+
+    function testIsPOT() {
+        Assert.isTrue(hxd.Math.isPOT(1));
+        Assert.isTrue(hxd.Math.isPOT(2));
+        Assert.isTrue(hxd.Math.isPOT(4));
+        Assert.isTrue(hxd.Math.isPOT(1024));
+        Assert.isFalse(hxd.Math.isPOT(3));
+        Assert.isFalse(hxd.Math.isPOT(5));
+        Assert.isFalse(hxd.Math.isPOT(1000));
+    }
+
+    function testNextPOT() {
+        Assert.equals(0, hxd.Math.nextPOT(0));
+        Assert.equals(1, hxd.Math.nextPOT(1));
+        Assert.equals(2, hxd.Math.nextPOT(2));
+        Assert.equals(4, hxd.Math.nextPOT(3));
+        Assert.equals(4, hxd.Math.nextPOT(4));
+        Assert.equals(8, hxd.Math.nextPOT(5));
+        Assert.equals(1024, hxd.Math.nextPOT(1000));
+    }
+
+    function testLerp() {
+        Assert.floatEquals(5.0, hxd.Math.lerp(0.0, 10.0, 0.5));
+        Assert.floatEquals(0.0, hxd.Math.lerp(0.0, 10.0, 0.0));
+        Assert.floatEquals(10.0, hxd.Math.lerp(0.0, 10.0, 1.0));
+        Assert.floatEquals(2.5, hxd.Math.lerp(0.0, 10.0, 0.25));
+    }
+
+    function testInverseLerp() {
+        Assert.floatEquals(0.5, hxd.Math.inverseLerp(0.0, 10.0, 5.0));
+        Assert.floatEquals(0.0, hxd.Math.inverseLerp(0.0, 10.0, 0.0));
+        Assert.floatEquals(1.0, hxd.Math.inverseLerp(0.0, 10.0, 10.0));
+        Assert.floatEquals(0.25, hxd.Math.inverseLerp(0.0, 10.0, 2.5));
+    }
+
+    function testFmt() {
+        // fmt rounds to 4 significant digits (or standard forms)
+        Assert.floatEquals(1.234, hxd.Math.fmt(1.234));
+        Assert.floatEquals(1.234, hxd.Math.fmt(1.2343));
+        Assert.floatEquals(0.0, hxd.Math.fmt(1e-12));
+    }
+}
diff --git a/test/TestRunner.hx b/test/TestRunner.hx
new file mode 100644
index 0000000000..f75bb1e307
--- /dev/null
+++ b/test/TestRunner.hx
@@ -0,0 +1,25 @@
+package test;
+
+class TestRunner {
+    public static function main() {
+        Sys.println("Starting test execution...");
+        
+        var mathTests = new TestMath();
+        mathTests.run();
+
+        var segmentsTests = new TestSegments();
+        segmentsTests.run();
+
+        var shaderCacheTests = new TestShaderCache();
+        shaderCacheTests.run();
+        
+        Sys.println("Successes: " + Assert.successes);
+        if (Assert.failures > 0) {
+            Sys.println("Failures: " + Assert.failures);
+            Sys.exit(1);
+        } else {
+            Sys.println("All tests passed!");
+            Sys.exit(0);
+        }
+    }
+}
diff --git a/test/TestSegments.hx b/test/TestSegments.hx
new file mode 100644
index 0000000000..c0e9ab6d35
--- /dev/null
+++ b/test/TestSegments.hx
@@ -0,0 +1,91 @@
+package test;
+
+import h2d.col.Point;
+import h2d.col.Segment;
+import h2d.col.Segments;
+
+class TestSegments {
+    public function new() {}
+
+    public function run() {
+        testConvexContains();
+        testConcaveContains();
+        testDistanceAndProject();
+    }
+
+    function testConvexContains() {
+        var p1 = new Point(0, 0);
+        var p2 = new Point(0, 10);
+        var p3 = new Point(10, 10);
+        var p4 = new Point(10, 0);
+
+        // For containsPoint(p, true) to succeed, the segments must be counter-clockwise
+        // so that the point is on the inside side of all segment axes (s.side(p) >= 0).
+        var ccw_s1 = new Segment(p1, p4);
+        var ccw_s2 = new Segment(p4, p3);
+        var ccw_s3 = new Segment(p3, p2);
+        var ccw_s4 = new Segment(p2, p1);
+
+        var ccw_segments:Segments = [ccw_s1, ccw_s2, ccw_s3, ccw_s4];
+
+        Assert.isTrue(ccw_segments.containsPoint(new Point(5, 5), true));
+        Assert.isFalse(ccw_segments.containsPoint(new Point(15, 5), true));
+        Assert.isFalse(ccw_segments.containsPoint(new Point(-5, 5), true));
+    }
+
+    function testConcaveContains() {
+        // Create an L-shaped concave polygon
+        // Vertices: (0,0) -> (10,0) -> (10,5) -> (5,5) -> (5,10) -> (0,10) -> (0,0)
+        var pts = [
+            new Point(0, 0),
+            new Point(10, 0),
+            new Point(10, 5),
+            new Point(5, 5),
+            new Point(5, 10),
+            new Point(0, 10)
+        ];
+        
+        var segmentsList = [];
+        var prev = pts[pts.length - 1];
+        for (p in pts) {
+            segmentsList.push(new Segment(prev, p));
+            prev = p;
+        }
+        var segments:Segments = segmentsList;
+
+        // Try containsPoint with isConvex = false.
+        // This should run our implementation without throwing "TODO".
+        try {
+            var inside1 = segments.containsPoint(new Point(2, 2), false); // inside
+            var inside2 = segments.containsPoint(new Point(8, 2), false); // inside
+            var inside3 = segments.containsPoint(new Point(8, 8), false); // outside (in the hollow of the L)
+            var inside4 = segments.containsPoint(new Point(2, 8), false); // inside
+            var outside = segments.containsPoint(new Point(12, 12), false); // outside
+
+            Assert.isTrue(inside1);
+            Assert.isTrue(inside2);
+            Assert.isFalse(inside3);
+            Assert.isTrue(inside4);
+            Assert.isFalse(outside);
+        } catch (e:Dynamic) {
+            Assert.isTrue(false);
+            trace("Exception in containsPoint(..., false): " + e);
+        }
+    }
+
+    function testDistanceAndProject() {
+        var p1 = new Point(0, 0);
+        var p2 = new Point(10, 0);
+        var s = new Segment(p1, p2);
+        var segments:Segments = [s];
+
+        // test distance
+        Assert.floatEquals(5.0, segments.distance(new Point(5, 5)));
+        Assert.floatEquals(25.0, segments.distanceSq(new Point(5, 5)));
+
+        // test project
+        var proj = segments.project(new Point(5, 5));
+        Assert.floatEquals(5.0, proj.x);
+        Assert.floatEquals(0.0, proj.y);
+    }
+}
diff --git a/test/TestShaderCache.hx b/test/TestShaderCache.hx
new file mode 100644
index 0000000000..a6d1c3c308
--- /dev/null
+++ b/test/TestShaderCache.hx
@@ -0,0 +1,41 @@
+package test;
+
+import h3d.impl.ShaderCache;
+import haxe.io.Bytes;
+
+class TestShaderCache {
+    public function new() {}
+
+    public function run() {
+        testShaderCacheInMemoryWithAllowSaveFalse();
+    }
+
+    function testShaderCacheInMemoryWithAllowSaveFalse() {
+        // Create a mock/temporary cache file path.
+        var cacheFile = "temp_shader_cache.data";
+        var cache = new ShaderCache(cacheFile);
+        
+        // Turn off disk persistence.
+        cache.allowSave = false;
+        cache.keepSource = true;
+
+        var shaderSource = "
+            @input float4 position;
+            void main() {
+                output.position = position;
+            }
+        ";
+        var compiledBinary = Bytes.ofString("MOCK_COMPILED_SHADER_BINARY");
+
+        // Save the compiled shader. It should cache in-memory.
+        cache.saveCompiledShader(shaderSource, compiledBinary);
+
+        // Try to resolve the shader binary from the cache.
+        var resolved = cache.resolveShaderBinary(shaderSource);
+
+        Assert.isTrue(resolved != null);
+        if (resolved != null) {
+            Assert.equals(compiledBinary.toString(), resolved.toString());
+        }
+    }
+}