From bc500a7618f7be7eb46c199740f097d8c5918343 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Thu, 27 Aug 2026 17:49:19 +0200
Subject: [PATCH] test: add tests for sky and block light propagation

---
 tests/testLighting.cpp | 66 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 tests/testLighting.cpp

diff --git a/tests/testLighting.cpp b/tests/testLighting.cpp
new file mode 100644
index 0000000..ac206d6
--- /dev/null
+++ b/tests/testLighting.cpp
@@ -0,0 +1,66 @@
+#include "testHarness.h"
+#include "vf/Lighting.h"
+
+using namespace vf;
+
+namespace {
+
+void fillBox(World& world, Vec3i lo, Vec3i hi, Block block) {
+    for (int x = lo.x; x <= hi.x; ++x)
+        for (int y = lo.y; y <= hi.y; ++y)
+            for (int z = lo.z; z <= hi.z; ++z)
+                world.setBlock(x, y, z, block);
+}
+
+} // namespace
+
+VF_TEST(lightSunFloodsOpenColumnToFloor) {
+    World world;
+    fillBox(world, {0, 0, 0}, {7, 0, 7}, Block::Stone);   // single floor layer
+    LightField field = computeLight(world, {0, 0, 0}, {8, 8, 8});
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(3, 1, 3)), maxLight);   // air above floor
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(3, 7, 3)), maxLight);   // top of column
+}
+
+VF_TEST(lightSealedPocketStaysDark) {
+    World world;
+    fillBox(world, {10, 10, 10}, {12, 12, 12}, Block::Stone);
+    world.setBlock(11, 11, 11, Block::Air);   // sealed air cell in the core
+    LightField field = computeLight(world, {9, 9, 9}, {5, 5, 5});
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(11, 11, 11)), 0);
+    CHECK_EQ(static_cast<int>(field.blockAtWorld(11, 11, 11)), 0);
+}
+
+VF_TEST(lightSunAttenuatesAlongTunnel) {
+    World world;
+    fillBox(world, {0, 0, 0}, {11, 4, 2}, Block::Stone);
+    for (int y = 1; y <= 4; ++y) world.setBlock(0, y, 1, Block::Air);   // vertical shaft
+    for (int x = 1; x <= 9; ++x) world.setBlock(x, 1, 1, Block::Air);   // horizontal tunnel
+
+    LightField field = computeLight(world, {0, 0, 0}, {12, 5, 3});
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(0, 1, 1)), maxLight);       // shaft foot
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(1, 1, 1)), maxLight - 1);
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(3, 1, 1)), maxLight - 3);
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(6, 1, 1)), maxLight - 6);
+}
+
+VF_TEST(lightBlockEmitterFallsOffRadially) {
+    World world;
+    world.setBlock(5, 5, 5, Block::Glowstone);
+    LightField field = computeLight(world, {0, 0, 0}, {11, 11, 11});
+    CHECK_EQ(static_cast<int>(field.blockAtWorld(5, 5, 5)), maxLight);
+    CHECK_EQ(static_cast<int>(field.blockAtWorld(6, 5, 5)), maxLight - 1);
+    CHECK_EQ(static_cast<int>(field.blockAtWorld(8, 5, 5)), maxLight - 3);
+    CHECK_EQ(static_cast<int>(field.blockAtWorld(5, 5, 9)), maxLight - 4);
+}
+
+VF_TEST(lightCombinedTakesBrighterChannel) {
+    World world;
+    fillBox(world, {0, 0, 0}, {11, 11, 11}, Block::Stone);
+    world.setBlock(5, 5, 5, Block::Glowstone);
+    world.setBlock(6, 5, 5, Block::Air);   // lit only by the torch, no sky
+    LightField field = computeLight(world, {0, 0, 0}, {12, 12, 12});
+    CHECK_EQ(static_cast<int>(field.sunAtWorld(6, 5, 5)), 0);
+    CHECK_EQ(static_cast<int>(field.blockAtWorld(6, 5, 5)), maxLight - 1);
+    CHECK_NEAR(field.combinedAtWorld(6, 5, 5), static_cast<float>(maxLight - 1) / maxLight, 1e-4f);
+}