From 3d68b1247362d1a261f848d3614723e6815d228b Mon Sep 17 00:00:00 2001
From: Eric Wasylishen <ewasylishen@gmail.com>
Date: Sat, 16 Mar 2024 15:07:18 -0600
Subject: [PATCH] light: never write .lit/.lux in Q2 mode

fixes `-dirtdebug` broken in lightpreview
---
 light/write.cc       | 33 ++++++++++++++++++---------------
 tests/test_ltface.cc | 23 +++++++++++++++++++++++
 2 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/light/write.cc b/light/write.cc
index 79d735f3..6d5c83ed 100644
--- a/light/write.cc
+++ b/light/write.cc
@@ -1094,19 +1094,22 @@ void SaveLightmapSurfaces(bspdata_t *bspdata, const fs::path &source)
     bspdata->bspx.entries.erase("RGBLIGHTING");
     bspdata->bspx.entries.erase("LIGHTINGDIR");
 
-    /*fixme: add a new per-surface offset+lmscale lump for compat/versitility?*/
-    if (light_options.write_litfile & lightfile::external) {
-        WriteLitFile(bsp, faces_sup, source, LIT_VERSION, lit_filebase, lux_filebase);
+    // lit/lux files (or their BSPX equivalents) - only write in games that lack RGB lightmaps.
+    // (technically we could allow .lux in Q2 mode, but no engines support it.)
+    if (!bsp->loadversion->game->has_rgb_lightmap) {
+        if (light_options.write_litfile & lightfile::external) {
+            WriteLitFile(bsp, faces_sup, source, LIT_VERSION, lit_filebase, lux_filebase);
+        }
+        if (light_options.write_litfile & lightfile::bspx) {
+            lit_filebase.resize(bsp->dlightdata.size() * 3);
+            bspdata->bspx.transfer("RGBLIGHTING", lit_filebase);
+        }
+        if (light_options.write_luxfile & lightfile::external) {
+            WriteLuxFile(bsp, source, LIT_VERSION, lux_filebase);
+        }
+        if (light_options.write_luxfile & lightfile::bspx) {
+            lux_filebase.resize(bsp->dlightdata.size() * 3);
+            bspdata->bspx.transfer("LIGHTINGDIR", lux_filebase);
+        }
     }
-    if (light_options.write_litfile & lightfile::bspx) {
-        lit_filebase.resize(bsp->dlightdata.size() * 3);
-        bspdata->bspx.transfer("RGBLIGHTING", lit_filebase);
-    }
-    if (light_options.write_luxfile & lightfile::external) {
-        WriteLuxFile(bsp, source, LIT_VERSION, lux_filebase);
-    }
-    if (light_options.write_luxfile & lightfile::bspx) {
-        lux_filebase.resize(bsp->dlightdata.size() * 3);
-        bspdata->bspx.transfer("LIGHTINGDIR", lux_filebase);
-    }
-}
\ No newline at end of file
+}
diff --git a/tests/test_ltface.cc b/tests/test_ltface.cc
index 5121250b..630b05e5 100644
--- a/tests/test_ltface.cc
+++ b/tests/test_ltface.cc
@@ -84,6 +84,13 @@ static testresults_t QbspVisLight_Common(const std::filesystem::path &name, std:
         light_args.push_back(bsp_path.string());
 
         light_main(light_args);
+
+        // ensure a .lit is never created in q2
+        if (is_q2) {
+            auto lit_check_path = bsp_path;
+            lit_check_path.replace_extension(".lit");
+            CHECK(!fs::exists(lit_check_path));
+        }
     }
 
     // serialize obj
@@ -336,6 +343,7 @@ static void CheckFaceLuxelAtPoint(const mbsp_t *bsp, const dmodelh2_t *model, co
     INFO("lm coord: ", coord[0], ", ", coord[1]);
     INFO("lm int_coord: ", int_coord[0], ", ", int_coord[1]);
     INFO("face num: ", Face_GetNum(bsp, face));
+    INFO("actual sample: ", sample[0], " ", sample[1], " ", sample[2]);
 
     qvec3i delta = qv::abs(qvec3i{sample} - qvec3i{expected_color});
     CHECK(delta[0] <= 1);
@@ -392,6 +400,21 @@ TEST_CASE("q2_dirt")
     CheckFaceLuxels(bsp, *face_under_lava, [](qvec3b sample) { CHECK(sample == qvec3b(96)); });
 }
 
+TEST_CASE("q2_dirtdebug")
+{
+    INFO("dirtdebug works in q2");
+
+    auto [bsp, bspx] = QbspVisLight_Q2("q2_dirt.map", {"-dirtdebug"});
+
+    auto *face_under_lava = BSP_FindFaceAtPoint(&bsp, &bsp.dmodels[0], {104, 112, 48});
+    REQUIRE(face_under_lava);
+
+    CheckFaceLuxels(bsp, *face_under_lava, [](qvec3b sample) { CHECK(sample == qvec3b(255)); });
+
+    // check floor in the corner
+    CheckFaceLuxelAtPoint(&bsp, &bsp.dmodels[0], {0, 0, 0}, {-124, 300, 32});
+}
+
 TEST_CASE("q2_light_translucency")
 {
     INFO("liquids cast translucent colored shadows (sampling texture) by default");