Starting working on area lights.

tests/light_test.cpp

@@ -11,6 +11,8 @@
 #include <colour.h>
 #include <tuple.h>
 #include <gtest/gtest.h>
+#include <world.h>
+#include <worldbuilder.h>
 
 TEST(LightTest, A_point_lighthas_a_position_and_intensity)
 {
@@ -21,4 +23,127 @@ TEST(LightTest, A_point_lighthas_a_position_and_intensity)
 
     ASSERT_EQ(light.position, position);
     ASSERT_EQ(light.intensity, intensity);
+}
+
+TEST(LightTest, Point_lights_evaluate_the_lights_intensity_at_a_given_point)
+{
+    World w = DefaultWorld();
+    Light *light = w.getLight(0);
+
+    Tuple testList[] = {
+            Point(0, 1.0001, 0),
+            Point(-1.0001, 0, 0),
+            Point(0, 0, -1.0001),
+            Point(0, 0, 1.0001),
+            Point(1.0001, 0, 0),
+            Point(0, -1.0001, 0),
+            Point(0, 0, 0),
+    };
+
+    double testResult[] = {
+            1.0,
+            1.0,
+            1.0,
+            0.0,
+            0.0,
+            0.0,
+            0.0,
+    };
+
+    int testCount = sizeof(testList)/sizeof((testList)[0]);
+    int i;
+
+    for(i = 0; i < testCount; i++)
+    {
+        ASSERT_TRUE(double_equal(light->intensityAt(w, testList[i]), testResult[i]));
+    }
+}
+
+TEST(LightTest, Creating_an_area_light)
+{
+    Tuple corner = Point(0, 0, 0);
+    Tuple v1 = Vector(2, 0, 0);
+    Tuple v2 = Vector(0, 0, 1);
+
+    Light light = Light(AREA_LIGHT, corner, v1, 4, v2, 2, Colour(1, 1, 1));
+
+    /* Position is used to store the corner in area lights */
+    ASSERT_EQ(light.corner, corner);
+    ASSERT_EQ(light.uVec, Vector(0.5, 0, 0));
+    ASSERT_EQ(light.uSteps, 4);
+    ASSERT_EQ(light.vVec, Vector(0, 0, 0.5));
+    ASSERT_EQ(light.vSteps, 2);
+    ASSERT_EQ(light.samples, 8);
+    ASSERT_EQ(light.position, Point(1, 0, 0.5));
+}
+
+TEST(LightTest, Finding_a_single_point_on_an_area_light)
+{
+    Tuple corner = Point(0, 0, 0);
+    Tuple v1 = Vector(2, 0, 0);
+    Tuple v2 = Vector(0, 0, 1);
+
+    Light light = Light(AREA_LIGHT, corner, v1, 4, v2, 2, Colour(1, 1, 1));
+
+    uint32_t testList[][2] = {
+            {0, 0},
+            {1, 0},
+            {0, 1},
+            {2, 0},
+            {3, 1},
+    };
+
+    Point testResults[] {
+        Point(0.25, 0, 0.25),
+        Point(0.75, 0, 0.25),
+        Point(0.25, 0, 0.75),
+        Point(1.25, 0, 0.25),
+        Point(1.75, 0, 0.75),
+    };
+
+    int testCount = sizeof(testList)/sizeof((testList)[0]);
+    int i;
+
+    for(i = 0; i < testCount; i++)
+    {
+        Tuple tp = light.pointOnLight(testList[i][0], testList[i][1]);
+        ASSERT_EQ(tp, testResults[i]);
+    }
+
+}
+
+TEST(LightTest, The_area_light_intensity_function)
+{
+    World w = DefaultWorld();
+    Tuple corner = Point(-0.5, -0.5, -5);
+    Tuple v1 = Vector(1, 0, 0);
+    Tuple v2 = Vector(0, 1, 0);
+
+    Light light = Light(AREA_LIGHT, corner, v1, 2, v2, 2, Colour(1, 1, 1));
+
+    Point testList[] = {
+            Point(0, 0, 2),
+            Point(1, -1, 2),
+            Point(1.5, 0, 2),
+            Point(1.25, 1.25, 3),
+            Point(0, 0, -2),
+    };
+
+    double testResults[] {
+        0.0,
+        0.25,
+        0.5,
+        0.75,
+        1,
+    };
+
+    int testCount = sizeof(testList)/sizeof((testList)[0]);
+    int i;
+
+    for(i = 0; i < testCount; i++)
+    {
+        double intensity = light.intensityAt(w, testList[i]);
+        ASSERT_TRUE(double_equal(intensity, testResults[i]));
+    }
+
 }