First version of particle trail, supporting rocket trail, smoke trail and blood trail.

Assets/Scripts/Data/QConstants.cs

@@ -9,3 +9,25 @@
     public const int LightmapBlockWidth = 256;  // Should correspond to LMBLOCK_WIDTH
     public const int LightmapBlockHeight = 256; // Should correspond to LMBLOCK_HEIGHT
 }
+
+// Should correspond to particle_effect_t in game_uniquake.c
+public enum ParticleEffect
+{
+    Explosion = 0,
+    RogueExplosion,
+    BlobExplosion,
+    LavaSplash,
+    TeleportSplash,
+}
+
+// Should correspond to `int type` argument in R_RocketTrail
+public enum ParticleTrail
+{
+    Rocket = 0,
+    Smoke = 1,
+    Blood = 2,
+    Tracer = 3,
+    SlightBlood = 4,
+    Tracer2 = 5,
+    VoreBall = 6,
+}

Assets/Scripts/Modules/GameModule.Interop.cs

@@ -20,6 +20,7 @@ public partial class GameModule : CallbackHandler<GameModule>
             
             RunParticleEffect = CreateCallback<RunParticleEffectCallback>(Callback_RunParticleEffect),
             CreateParticleEffect = CreateCallback<CreateParticleEffectCallback>(Callback_CreateParticleEffect),
+            CreateParticleTrail = CreateCallback<CreateParticleTrailCallback>(Callback_CreateParticleTrail),
         };
         
         RegisterCallbacks(callbacks);
@@ -39,6 +40,7 @@ public partial class GameModule : CallbackHandler<GameModule>
         
         public IntPtr RunParticleEffect;
         public IntPtr CreateParticleEffect;
+        public IntPtr CreateParticleTrail;
     }
 
     [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
@@ -122,4 +124,15 @@ public partial class GameModule : CallbackHandler<GameModule>
         
         Profiler.EndSample();
     }
+
+    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+    private delegate void CreateParticleTrailCallback(IntPtr context, int type, ref QVec3 start, ref QVec3 end);
+
+    [MonoPInvokeCallback(typeof(CreateParticleTrailCallback))]
+    private static void Callback_CreateParticleTrail(IntPtr context, int type, ref QVec3 start, ref QVec3 end)
+    {
+        Profiler.BeginSample("CreateParticleTrail");
+        GetSelf(context).CreateParticleTrail(type, start.ToUnityPosition(), end.ToUnityPosition());
+        Profiler.EndSample();
+    }
 }

Assets/Scripts/Modules/GameModule.cs

@@ -97,25 +97,19 @@ public partial class GameModule
         uq.CurrentStyle.Particles.CreateRogueExplosion(position, colorMin, colorMax, uq.GameLayer);
     }
     
-    // Should correspond to particle_effect_t in game_uniquake.c
-    private enum ParticleEffect
-    {
-        Explosion = 0,
-        RogueExplosion,
-        BlobExplosion,
-        LavaSplash,
-        TeleportSplash,
-    }
-
-    // Should correspond to `int type` argument in R_RocketTrail
-    private enum ParticleTrail
-    {
-        Rocket = 0,
-        Smoke = 1,
-        Blood = 2,
-        Tracer = 3,
-        SlightBlood = 4,
-        Tracer2 = 5,
-        VoreBall = 6,
+    private void CreateParticleTrail(int type, Vector3 start, Vector3 end)
+    {
+        int dec;
+        if (type < 128)
+        {
+            dec = 3;
+        }
+        else
+        {
+            dec = 1;
+            type -= 128;
+        }
+        
+        uq.CurrentStyle.Particles.CreateParticleTrail((ParticleTrail)type, start, end, dec, uq.GameLayer);
     }
 }

Assets/Scripts/Support/ParticleTrailController.cs

@@ -0,0 +1,106 @@
+using System.Collections;
+using UnityEngine;
+
+public class ParticleTrailController : MonoBehaviour
+{
+    private Vector3 endPosition;
+
+    public void Initialize(ParticleSystem effect, ParticleTrail type, Vector3 end, int interval)
+    {
+        endPosition = end;
+
+        var main = effect.main;
+        var shape = effect.shape;
+        
+        var emission = effect.emission;
+        emission.rateOverDistance = 1.0f / interval;
+        
+        switch (type)
+        {
+            case ParticleTrail.Rocket:
+            {
+                main.startLifetime = new ParticleSystem.MinMaxCurve(0.6f, 1.2f);
+                shape.scale = new Vector3(6f, 6f, 6f);
+                
+                var colorOverLifetime = effect.colorOverLifetime;
+                colorOverLifetime.enabled = true;
+                colorOverLifetime.color = SetupGradients(RocketColorKeys, SmokeColorKeys);
+                break;
+            }
+            case ParticleTrail.Smoke:
+            {
+                main.startLifetime = new ParticleSystem.MinMaxCurve(0.2f, 0.8f);
+                shape.scale = new Vector3(6f, 6f, 6f);
+                
+                var colorOverLifetime = effect.colorOverLifetime;
+                colorOverLifetime.enabled = true;
+                colorOverLifetime.color = SetupGradients(SmokeColorKeys, SmokeColorKeys2);
+                break;
+            }
+            case ParticleTrail.Blood:
+            {
+                main.gravityModifierMultiplier = 0.05f;
+                main.startColor = new ParticleSystem.MinMaxGradient(
+                    new Color32(31, 0, 0, 255), 
+                    new Color32(55, 0, 0, 255));
+                
+                shape.scale = new Vector3(6f, 6f, 6f);
+                break;
+            }
+            case ParticleTrail.Tracer:
+            case ParticleTrail.Tracer2:
+            {
+                break;
+            }
+            case ParticleTrail.SlightBlood:
+            {
+                break;
+            }
+            case ParticleTrail.VoreBall:
+            {
+                break;
+            }
+        }
+    }
+
+    IEnumerator Start()
+    {
+        // Instantly move the particle emitter to its end position, to force it to emit all particles at once
+        yield return null;
+        transform.position = endPosition;
+    }
+
+    private static ParticleSystem.MinMaxGradient SetupGradients(GradientColorKey[] minKeys, GradientColorKey[] maxKeys)
+    {
+        return new ParticleSystem.MinMaxGradient
+        {
+            mode = ParticleSystemGradientMode.TwoGradients,
+            gradientMin = new Gradient { mode = GradientMode.Fixed, colorKeys = minKeys },
+            gradientMax = new Gradient { mode = GradientMode.Fixed, colorKeys = maxKeys },
+        };
+    }
+
+    private static readonly GradientColorKey[] RocketColorKeys = 
+    {
+        new GradientColorKey(new Color32(223, 171, 39, 255), 0.167f),
+        new GradientColorKey(new Color32(191, 119, 47, 255), 0.333f),
+        new GradientColorKey(new Color32(91, 91, 91, 255), 0.5f),
+        new GradientColorKey(new Color32(75, 75, 75, 255), 0.667f),
+        new GradientColorKey(new Color32(63, 63, 63, 255), 0.833f),
+        new GradientColorKey(new Color32(47, 47, 47, 255), 1.0f),
+    };
+
+    private static readonly GradientColorKey[] SmokeColorKeys = 
+    {
+        new GradientColorKey(new Color32(91, 91, 91, 255), 0.25f),
+        new GradientColorKey(new Color32(75, 75, 75, 255), 0.5f),
+        new GradientColorKey(new Color32(63, 63, 63, 255), 0.75f),
+        new GradientColorKey(new Color32(47, 47, 47, 255), 1.0f),
+    };
+
+    private static readonly GradientColorKey[] SmokeColorKeys2 = 
+    {
+        new GradientColorKey(new Color32(63, 63, 63, 255), 0.5f),
+        new GradientColorKey(new Color32(47, 47, 47, 255), 1.0f),
+    };
+}

Assets/Scripts/Support/ParticleTrailController.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 7220fa57562e4a48b6fc17e6bfc0a945
+timeCreated: 1628089994

Assets/Scripts/VisualStyle.cs

@@ -178,6 +178,9 @@ public class ParticleSystems
     [SerializeField]
     protected ParticleSystem lavaSplash;
 
+    [SerializeField]
+    protected ParticleSystem particleTrail;
+
     public virtual void Init()
     {
         InitTemplate(particleEffect);
@@ -186,6 +189,7 @@ public class ParticleSystems
         InitTemplate(blobExplosion);
         InitTemplate(teleportSplash);
         InitTemplate(lavaSplash);
+        InitTemplate(particleTrail);
     }
 
     protected virtual void InitTemplate(ParticleSystem template)
@@ -255,6 +259,19 @@ public class ParticleSystems
         InstantiateEffect(lavaSplash, position, layer);
     }
 
+    public virtual void CreateParticleTrail(ParticleTrail type, Vector3 start, Vector3 end, int interval, Layers layer)
+    {
+        var effect = InstantiateEffect(particleTrail, start, layer);
+        if (effect == null)
+            return;
+
+        var controller = effect.gameObject.GetComponent<ParticleTrailController>();
+        if (controller == null)
+            return;
+        
+        controller.Initialize(effect, type, end, interval);
+    }
+
     protected virtual ParticleSystem InstantiateEffect(ParticleSystem template, Vector3 position, Layers layer)
     {
         if (template == null)

Assets/Styles/Original/GLQuake.asset

@@ -37,3 +37,5 @@ MonoBehaviour:
       type: 3}
     lavaSplash: {fileID: 9150008102338277659, guid: 4db0c926dce46fe4c90920ecd8c5df2e,
       type: 3}
+    particleTrail: {fileID: 9150008102338277659, guid: 6f6d855fe9d5e524b9293af4fd7caf21,
+      type: 3}

Assets/Styles/Original/Particles/ParticleTrail.prefab.meta

@@ -0,0 +1,7 @@
+fileFormatVersion: 2
+guid: 6f6d855fe9d5e524b9293af4fd7caf21
+PrefabImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/Styles/Original/Software.asset

@@ -37,3 +37,5 @@ MonoBehaviour:
       type: 3}
     lavaSplash: {fileID: 9150008102338277659, guid: 4db0c926dce46fe4c90920ecd8c5df2e,
       type: 3}
+    particleTrail: {fileID: 9150008102338277659, guid: 6f6d855fe9d5e524b9293af4fd7caf21,
+      type: 3}

engine/Quake/r_part.c

@@ -649,6 +649,8 @@ FIXME -- rename function and use #defined types instead of numbers
 */
 void R_RocketTrail (vec3_t start, vec3_t end, int type)
 {
+	UQ_Game_ParticleTrail(type, start, end);
+
 #ifdef USE_OPENGL
 	vec3_t		vec;
 	float		len;

engine/Quake/render.h

@@ -184,5 +184,6 @@ void UQ_Game_ParticleExplosion2(vec3_t origin, int colorStart, int colorLength);
 void UQ_Game_BlobExplosion(vec3_t origin);
 void UQ_Game_TeleportSplash(vec3_t origin);
 void UQ_Game_LavaSplash(vec3_t origin);
+void UQ_Game_ParticleTrail(int type, vec3_t start, vec3_t end);
 
 #endif	/* _QUAKE_RENDER_H */

engine/UniQuake/game_uniquake.c

@@ -12,6 +12,7 @@ typedef struct unity_gamecalls_s
 
 	void(*RunParticleEffect)(void *context, vec3_t origin, vec3_t direction, unsigned int colorMin, unsigned int colorMax, int count);
 	void(*CreateParticleEffect)(void *context, int type, vec3_t origin, unsigned int colorMin, unsigned int colorMax);
+	void(*CreateParticleTrail)(void *context, int type, vec3_t start, vec3_t end);
 } unity_gamecalls_t;
 
 static void *unity_context;
@@ -92,3 +93,8 @@ void UQ_Game_LavaSplash(vec3_t origin)
 {
 	unity_gamecalls->CreateParticleEffect(unity_context, PARTFX_LAVA_SPLASH, origin, 0, 0);
 }
+
+void UQ_Game_ParticleTrail(int type, vec3_t start, vec3_t end)
+{
+	unity_gamecalls->CreateParticleTrail(unity_context, type, start, end);
+}