Add lightmapped water

KeepersCompound.Lightmapper/LightMapper.cs

@@ -8,12 +8,20 @@ namespace KeepersCompound.Lightmapper;
 
 public class LightMapper
 {
+    private enum SurfaceType
+    {
+        Solid,
+        Sky,
+        Water,
+    }
+    
     private class Settings
     {
         public Vector3 AmbientLight;
         public bool Hdr;
         public SoftnessMode MultiSampling;
         public float MultiSamplingCenterWeight;
+        public bool LightmappedWater;
     }
 
     private ResourcePathManager.CampaignResources _campaign;
@@ -22,6 +30,7 @@ public class LightMapper
     private ObjectHierarchy _hierarchy;
     private Raytracer _scene;
     private List<Light> _lights;
+    private List<SurfaceType> _triangleTypeMap;
 
     public LightMapper(
         string installPath,
@@ -33,6 +42,7 @@ public class LightMapper
         _misPath = _campaign.GetResourcePath(ResourceType.Mission, missionName);
         _mission = Timing.TimeStage("Parse DB", () => new DbFile(_misPath));
         _hierarchy = Timing.TimeStage("Build Hierarchy", BuildHierarchy);
+        _triangleTypeMap = [];
         _scene = Timing.TimeStage("Build Scene", BuildRaytracingScene);
         _lights = [];
     }
@@ -47,12 +57,14 @@ public class LightMapper
             return;
         }
 
+        // TODO: lmParams LightmappedWater doesn't mean the game will actually *use* the lightmapped water hmm
         var settings = new Settings
         {
             Hdr = worldRep.DataHeader.LightmapFormat == 2,
             AmbientLight = rendParams.ambientLight * 255,
             MultiSampling = lmParams.ShadowSoftness,
             MultiSamplingCenterWeight = lmParams.CenterWeight,
+            LightmappedWater = lmParams.LightmappedWater,
         };
         
         Timing.TimeStage("Gather Lights", BuildLightList);
@@ -119,9 +131,9 @@ public class LightMapper
                 continue;
             }
 
-            var maxPolyIdx = Math.Min(numRenderPolys, numPolys - numPortalPolys);
+            var solidPolys = numPolys - numPortalPolys;
             var cellIdxOffset = 0;
-            for (var polyIdx = 0; polyIdx < maxPolyIdx; polyIdx++)
+            for (var polyIdx = 0; polyIdx < numRenderPolys; polyIdx++)
             {
                 var poly = cell.Polys[polyIdx];
                 var meshIndexOffset = vertices.Count;
@@ -132,12 +144,25 @@ public class LightMapper
                     vertices.Add(vertex);
                 }
 
+                // We need to know what type of surface this poly is so we can map Embree primitive IDs to surface
+                // types
+                var renderPoly = cell.RenderPolys[polyIdx];
+                var primType = SurfaceType.Solid;
+                if (renderPoly.TextureId == 249)
+                {
+                    primType = SurfaceType.Sky;
+                } else if (polyIdx >= solidPolys)
+                {
+                    primType = SurfaceType.Water;
+                }
+                
                 // Cell polygons are n-sided, but fortunately they're convex so we can just do a fan triangulation
                 for (var j = 1; j < numPolyVertices - 1; j++)
                 {
                     indices.Add(meshIndexOffset);
                     indices.Add(meshIndexOffset + j);
                     indices.Add(meshIndexOffset + j + 1);
+                    _triangleTypeMap.Add(primType);
                 }
 
                 cellIdxOffset += cell.Polys[polyIdx].VertexCount;
@@ -368,9 +393,9 @@ public class LightMapper
                 return;
             }
 
-            var maxPolyIdx = Math.Min(numRenderPolys, numPolys - numPortalPolys);
+            var solidPolys = numPolys - numPortalPolys;
             var cellIdxOffset = 0;
-            for (var polyIdx = 0; polyIdx < maxPolyIdx; polyIdx++)
+            for (var polyIdx = 0; polyIdx < numRenderPolys; polyIdx++)
             {
                 var poly = cell.Polys[polyIdx];
                 var plane = cell.Planes[poly.PlaneId];
@@ -379,6 +404,14 @@ public class LightMapper
                 var lightmap = cell.Lightmaps[polyIdx];
 
                 info.AnimLightBitmask = 0;
+                
+                // We have to reset the lightmaps for water, but we don't want to do anything else
+                var waterPoly = polyIdx >= solidPolys;
+                if (!settings.LightmappedWater && waterPoly)
+                {
+                    lightmap.Reset(Vector3.One * 255f, settings.Hdr);
+                    continue;
+                }
                 lightmap.Reset(settings.AmbientLight, settings.Hdr);
 
                 // Get world position of lightmap (0, 0) (+0.5 so we cast from the center of a pixel)
@@ -598,13 +631,23 @@ public class LightMapper
     
     private bool TraceRay(Vector3 origin, Vector3 target)
     {
-        var direction = target - origin;
-        var hitResult = _scene.Trace(new Ray
+        var hitDistanceFromTarget = float.MinValue;
+        var hitSurfaceType = SurfaceType.Water;
+        while (hitDistanceFromTarget < -MathUtils.Epsilon && hitSurfaceType == SurfaceType.Water)
         {
-            Origin = origin,
-            Direction = Vector3.Normalize(direction),
-        });
-        return hitResult && Math.Abs(hitResult.Distance - direction.Length()) < MathUtils.Epsilon;
+            var direction = target - origin;
+            var hitResult = _scene.Trace(new Ray
+            {
+                Origin = origin,
+                Direction = Vector3.Normalize(direction),
+            });
+
+            hitDistanceFromTarget = hitResult.Distance - direction.Length();
+            hitSurfaceType = _triangleTypeMap[(int)hitResult.PrimId];
+            origin = hitResult.Position += direction * MathUtils.Epsilon;
+        }
+
+        return Math.Abs(hitDistanceFromTarget) < MathUtils.Epsilon;
     }
 
     private void SetAnimLightCellMaps()