tests: add test for q1 faces which receive no light

they're allowed to be written as style 255 / lightofs -1 in Q1 mode
including lit water.

testmaps/q1_light_black.map

@@ -0,0 +1,92 @@
+// Game: Quake
+// Format: Standard
+// entity 0
+{
+"classname" "worldspawn"
+"_tb_textures" "textures/e1u1"
+"_bounce" "0"
+"wad" "deprecated/free_wad.wad"
+// brush 0
+{
+( 480 1088 928 ) ( 480 1089 928 ) ( 480 1088 929 ) bolt14 0 32 0 1 1
+( 704 1088 928 ) ( 704 1088 929 ) ( 705 1088 928 ) bolt14 0 32 0 1 1
+( 704 1088 928 ) ( 705 1088 928 ) ( 704 1089 928 ) bolt14 0 0 0 1 1
+( 944 1472 944 ) ( 944 1473 944 ) ( 945 1472 944 ) bolt14 0 0 0 1 1
+( 944 1488 944 ) ( 945 1488 944 ) ( 944 1488 945 ) bolt14 0 32 0 1 1
+( 1056 1472 944 ) ( 1056 1472 945 ) ( 1056 1473 944 ) bolt14 0 32 0 1 1
+}
+// brush 1
+{
+( 480 1088 1248 ) ( 480 1089 1248 ) ( 480 1088 1249 ) bolt14 0 96 0 1 1
+( 704 1072 1248 ) ( 704 1072 1249 ) ( 705 1072 1248 ) bolt14 0 96 0 1 1
+( 704 1088 1248 ) ( 705 1088 1248 ) ( 704 1089 1248 ) bolt14 0 0 0 1 1
+( 944 1472 1264 ) ( 944 1473 1264 ) ( 945 1472 1264 ) bolt14 0 0 0 1 1
+( 944 1488 1264 ) ( 945 1488 1264 ) ( 944 1488 1265 ) bolt14 0 96 0 1 1
+( 1056 1472 1264 ) ( 1056 1472 1265 ) ( 1056 1473 1264 ) bolt14 0 96 0 1 1
+}
+// brush 2
+{
+( 480 1072 928 ) ( 480 1073 928 ) ( 480 1072 929 ) bolt14 16 32 0 1 1
+( 704 1072 928 ) ( 704 1072 929 ) ( 705 1072 928 ) bolt14 0 32 0 1 1
+( 704 1072 928 ) ( 705 1072 928 ) ( 704 1073 928 ) bolt14 0 -16 0 1 1
+( 944 1456 1248 ) ( 944 1457 1248 ) ( 945 1456 1248 ) bolt14 0 -16 0 1 1
+( 944 1088 944 ) ( 945 1088 944 ) ( 944 1088 945 ) bolt14 0 32 0 1 1
+( 1056 1456 944 ) ( 1056 1456 945 ) ( 1056 1457 944 ) bolt14 16 32 0 1 1
+}
+// brush 3
+{
+( 480 1392 928 ) ( 480 1393 928 ) ( 480 1392 929 ) bolt14 -48 32 0 1 1
+( 832 1488 928 ) ( 832 1488 929 ) ( 833 1488 928 ) bolt14 -128 32 0 1 1
+( 832 1392 928 ) ( 833 1392 928 ) ( 832 1393 928 ) bolt14 -128 48 0 1 1
+( 1072 1776 1248 ) ( 1072 1777 1248 ) ( 1073 1776 1248 ) bolt14 -128 48 0 1 1
+( 1072 1504 944 ) ( 1073 1504 944 ) ( 1072 1504 945 ) bolt14 -128 32 0 1 1
+( 1056 1392 928 ) ( 1056 1392 929 ) ( 1056 1393 928 ) bolt14 -48 32 0 1 1
+}
+// brush 4
+{
+( 1056 1088 1056 ) ( 1056 1089 1056 ) ( 1056 1088 1057 ) bolt14 0 32 0 1 1
+( 736 1088 1056 ) ( 736 1088 1057 ) ( 737 1088 1056 ) bolt14 -32 32 0 1 1
+( 736 1088 928 ) ( 737 1088 928 ) ( 736 1089 928 ) bolt14 -32 0 0 1 1
+( 976 1472 1248 ) ( 976 1473 1248 ) ( 977 1472 1248 ) bolt14 -32 0 0 1 1
+( 976 1488 1072 ) ( 977 1488 1072 ) ( 976 1488 1073 ) bolt14 -32 32 0 1 1
+( 1072 1472 1072 ) ( 1072 1472 1073 ) ( 1072 1473 1072 ) bolt14 0 32 0 1 1
+}
+// brush 5
+{
+( 464 1088 1056 ) ( 464 1089 1056 ) ( 464 1088 1057 ) bolt14 0 32 0 1 1
+( 144 1072 1056 ) ( 144 1072 1057 ) ( 145 1072 1056 ) bolt14 48 32 0 1 1
+( 144 1088 928 ) ( 145 1088 928 ) ( 144 1089 928 ) bolt14 48 0 0 1 1
+( 384 1472 1248 ) ( 384 1473 1248 ) ( 385 1472 1248 ) bolt14 48 0 0 1 1
+( 384 1488 1072 ) ( 385 1488 1072 ) ( 384 1488 1073 ) bolt14 48 32 0 1 1
+( 480 1472 1072 ) ( 480 1472 1073 ) ( 480 1473 1072 ) bolt14 0 32 0 1 1
+}
+// brush 6
+{
+( 480 1216 944 ) ( 480 1217 944 ) ( 480 1216 945 ) *swater4 0 0 0 1 1
+( 544 1088 944 ) ( 544 1088 945 ) ( 545 1088 944 ) *swater4 0 0 0 1 1
+( 544 1216 944 ) ( 545 1216 944 ) ( 544 1217 944 ) *swater4 0 0 0 1 1
+( 608 1312 976 ) ( 608 1313 976 ) ( 609 1312 976 ) *swater4 0 0 0 1 1
+( 608 1488 960 ) ( 609 1488 960 ) ( 608 1488 961 ) *swater4 0 0 0 1 1
+( 608 1312 960 ) ( 608 1312 961 ) ( 608 1313 960 ) *swater4 0 0 0 1 1
+}
+}
+// entity 1
+{
+"classname" "info_player_start"
+"origin" "976 1408 968"
+"angle" "180"
+}
+// entity 2
+{
+"classname" "light"
+"origin" "600 1288 1112"
+"light" "1000"
+"angle" "30"
+"target" "s1"
+}
+// entity 3
+{
+"classname" "info_null"
+"origin" "484 1284 1116"
+"targetname" "s1"
+}

tests/test_ltface.cc

@@ -892,3 +892,45 @@ TEST_CASE("q2_light_black")
 
     CheckFaceLuxelAtPoint(&bsp, &bsp.dmodels[0], {0, 0, 0}, point, {-1, 0, 0});
 }
+
+TEST_CASE("q1_light_black")
+{
+    auto [bsp, bspx, lit] = QbspVisLight_Q1("q1_light_black.map", {"-lit"});
+
+    {
+        const qvec3d point{1056, 1300, 972};
+
+        INFO("ensure completely black lightmaps are written out as style 255 / lightofs -1 in Q1 mode");
+
+        const mface_t *face = BSP_FindFaceAtPoint(&bsp, &bsp.dmodels[0], point, {-1, 0, 0});
+        REQUIRE(face);
+        CHECK(face->styles[0] == 255);
+        CHECK(face->styles[1] == 255);
+        CHECK(face->styles[2] == 255);
+        CHECK(face->styles[3] == 255);
+        CHECK(face->lightofs == -1);
+
+        // this is consistent with original tools, see:
+        // https://github.com/id-Software/Quake-Tools/blob/master/qutils/LIGHT/LTFACE.C#L542
+    }
+    {
+        INFO("ensure lit water receiving no light is also written out as style 255 / lightofs -1");
+
+        const qvec3d point{568, 1288, 976};
+
+        const mface_t *face = BSP_FindFaceAtPoint(&bsp, &bsp.dmodels[0], point, {0, 0, 1});
+        REQUIRE(face);
+        auto *texinfo = Face_Texinfo(&bsp, face);
+        REQUIRE(texinfo);
+
+        CHECK(texinfo->flags.native == 0); // i.e. TEX_SPECIAL is not set because it's lit water
+        CHECK(face->styles[0] == 255);
+        CHECK(face->styles[1] == 255);
+        CHECK(face->styles[2] == 255);
+        CHECK(face->styles[3] == 255);
+        CHECK(face->lightofs == -1);
+
+        // Note, this liquid face is rendering as fullbright (incorrect) in: QS 0.96.0 and Ironwail 0.7.0
+        // and rendering as solid black (correct) in vkQuake 1.30.1, FTEQW Mar 1 2022
+    }
+}