output: improve vertex movement (LostArtefacts#1496)

This allows locking specific vertices such that they don't move when
looked at through a water portal. We make use of an unused bit in
vertex shading, and ensure shading is clamped to the max value.

Resolves LostArtefacts#1493.

CHANGELOG.md

@@ -20,6 +20,7 @@
 - improved level load times
 - improved logs module names readability
 - improved crash debug information on Windows
+- improved vertex movement when looking through water portals (#1493)
 
 ## [4.3](https://github.com/LostArtefacts/TR1X/compare/4.2...4.3) - 2024-08-15
 - added deadly water feature from TR2+ for custom levels (#1404)

README.md

@@ -600,6 +600,7 @@ Not all options are turned on by default. Refer to `TR1X_ConfigTool.exe` for det
     - **Temple of the Cat**: incorrect textures in rooms 50, 70, 71, 76, 78, 87 and 96, and a missing texture in 75
     - **Atlantean Stronghold**: incorrect textures in rooms 2, 6, 7 and 75, and missing textures in rooms 5, 13, 19, 63 and 74
     - **The Hive**: incorrect textures in room 8, 13 and 18
+- improved vertex movement when looking through water portals
 
 #### Audio
 - added music during the credits

src/game/inject.c

@@ -1447,6 +1447,7 @@ static void Inject_AlterRoomVertex(INJECTION *injection)
     *(data_ptr + 2) += y_change;
     *(data_ptr + 3) += z_change;
     *(data_ptr + 4) += shade_change;
+    CLAMPG(*(data_ptr + 4), MAX_LIGHTING);
 }
 
 static void Inject_RotateRoomFace(INJECTION *injection)

src/game/level.c

@@ -65,6 +65,7 @@ static void Level_LoadCinematic(VFILE *file);
 static void Level_LoadDemo(VFILE *file);
 static void Level_LoadSamples(VFILE *file);
 static void Level_CompleteSetup(int32_t level_num);
+static void Level_MarkWaterEdgeVertices(void);
 static size_t Level_CalculateMaxVertices(void);
 
 static void Level_LoadFromFile(
@@ -898,6 +899,8 @@ static void Level_CompleteSetup(int32_t level_num)
 
     Inject_AllInjections(&m_LevelInfo);
 
+    Level_MarkWaterEdgeVertices();
+
     // Must be called post-injection to allow for floor data changes.
     Stats_ObserveRoomsLoad();
 
@@ -954,6 +957,30 @@ static void Level_CompleteSetup(int32_t level_num)
     Benchmark_End(benchmark, NULL);
 }
 
+static void Level_MarkWaterEdgeVertices(void)
+{
+    if (!g_Config.fix_texture_issues) {
+        return;
+    }
+
+    BENCHMARK *const benchmark = Benchmark_Start();
+    for (int32_t i = 0; i < g_RoomCount; i++) {
+        const ROOM_INFO *const room = &g_RoomInfo[i];
+        const int32_t y_test =
+            (room->flags & RF_UNDERWATER) ? room->max_ceiling : room->min_floor;
+        int16_t *data = room->data;
+        const int16_t num_vertices = *data++;
+        for (int32_t j = 0; j < num_vertices; j++) {
+            if (data[1] == y_test) {
+                data[3] |= NO_VERT_MOVE;
+            }
+            data += 4;
+        }
+    }
+
+    Benchmark_End(benchmark, NULL);
+}
+
 static size_t Level_CalculateMaxVertices(void)
 {
     BENCHMARK *const benchmark = Benchmark_Start();

src/game/output.c

@@ -342,29 +342,29 @@ static const int16_t *Output_CalcRoomVertices(const int16_t *obj_ptr)
         m_VBuf[i].xv = xv;
         m_VBuf[i].yv = yv;
         m_VBuf[i].zv = zv;
-        m_VBuf[i].g = obj_ptr[3];
+        m_VBuf[i].g = obj_ptr[3] & MAX_LIGHTING;
 
         if (zv < Output_GetNearZ()) {
             m_VBuf[i].clip = 0x8000;
         } else {
             int16_t clip_flags = 0;
             int32_t depth = zv_int >> W2V_SHIFT;
             if (depth > Output_GetDrawDistMax()) {
-                m_VBuf[i].g = 0x1FFF;
+                m_VBuf[i].g = MAX_LIGHTING;
                 if (!m_IsSkyboxEnabled) {
                     clip_flags |= 16;
                 }
             } else if (depth) {
                 m_VBuf[i].g += Output_CalcFogShade(depth);
                 if (!m_IsWaterEffect) {
-                    CLAMPG(m_VBuf[i].g, 0x1FFF);
+                    CLAMPG(m_VBuf[i].g, MAX_LIGHTING);
                 }
             }
 
             double persp = g_PhdPersp / zv;
             double xs = Viewport_GetCenterX() + xv * persp;
             double ys = Viewport_GetCenterY() + yv * persp;
-            if (m_IsWibbleEffect) {
+            if (m_IsWibbleEffect && !(obj_ptr[3] & NO_VERT_MOVE)) {
                 xs += m_WibbleTable[(m_WibbleOffset + (int)ys) & 0x1F];
                 ys += m_WibbleTable[(m_WibbleOffset + (int)xs) & 0x1F];
             }

src/global/const.h

@@ -130,6 +130,8 @@
 #define WIBBLE_SIZE 32
 #define MAX_WIBBLE 2
 #define MAX_SHADE 0x300
+#define MAX_LIGHTING 0x1FFF
+#define NO_VERT_MOVE 0x2000
 #define MAX_EXPANSION 5
 #define NO_BOX (-1)
 #define BOX_NUMBER 0x7FFF