add sphere

src/test/java/eu/jonahbauer/raytracing/shape/SphereTest.java

@@ -0,0 +1,25 @@
+package eu.jonahbauer.raytracing.shape;
+
+import eu.jonahbauer.raytracing.math.Ray;
+import eu.jonahbauer.raytracing.math.Vec3;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class SphereTest {
+
+    @Test
+    void hit() {
+        var center = new Vec3(1, 2, 3);
+        var radius = 5;
+        var sphere = new Sphere(center, radius);
+
+        var origin = new Vec3(6, 7, 8);
+        var direction = new Vec3(-1, -1, -1);
+        var ray = new Ray(origin, direction);
+
+        var t = sphere.hit(ray);
+        assertFalse(Double.isNaN(t));
+        assertEquals(center.plus(new Vec3(1, 1, 1).unit().times(radius)), ray.at(t));
+    }
+}