From ee14cee226029e424e99120b9099dd1f938c2a3a Mon Sep 17 00:00:00 2001
From: RaveYard <29225776+MrRaveYard@users.noreply.github.com>
Date: Fri, 11 Apr 2025 14:46:03 +0200
Subject: [PATCH] SoftShadowRadius for 1 sample RT lights via dithering effect

---
 wadsrc/static/shaders/scene/light_trace.glsl | 46 +++++++++++++-------
 1 file changed, 30 insertions(+), 16 deletions(-)

diff --git a/wadsrc/static/shaders/scene/light_trace.glsl b/wadsrc/static/shaders/scene/light_trace.glsl
index bac9e2482..630879038 100644
--- a/wadsrc/static/shaders/scene/light_trace.glsl
+++ b/wadsrc/static/shaders/scene/light_trace.glsl
@@ -153,7 +153,7 @@ float traceShadow(vec3 lightpos, float softShadowRadius)
 #if defined(SHADE_VERTEX)
 	return traceHit(origin, direction, dist);
 #else
-	if(SHADOWMAP_FILTER == 0 || softShadowRadius == 0)
+	if(softShadowRadius == 0)
 	{
 		return traceHit(origin, direction, dist);
 	}
@@ -163,28 +163,42 @@ float traceShadow(vec3 lightpos, float softShadowRadius)
 		vec3 xdir = normalize(cross(direction, v));
 		vec3 ydir = cross(direction, xdir);
 
-		float sum = 0.0;
-		const int step_count = SHADOWMAP_FILTER * 4;
-
-		if(USE_RAYTRACE_PRECISE)
+		if (SHADOWMAP_FILTER > 0)
 		{
-			for (int i = 0; i < step_count; i++)
+			float sum = 0.0;
+			const int step_count = SHADOWMAP_FILTER * 4;
+
+			if (USE_RAYTRACE_PRECISE)
 			{
-				vec2 gridoffset = getVogelDiskSample(i, step_count, gl_FragCoord.x + gl_FragCoord.y * 13.37) * softShadowRadius;
-				vec3 pos = target + xdir * gridoffset.x + ydir * gridoffset.y;
-				sum += TraceDynLightRay(origin, 0.01f, normalize(pos - origin), dist);
+				for (int i = 0; i < step_count; i++)
+				{
+					vec2 gridoffset = getVogelDiskSample(i, step_count, gl_FragCoord.x + gl_FragCoord.y * 13.37) * softShadowRadius;
+					vec3 pos = target + xdir * gridoffset.x + ydir * gridoffset.y;
+					sum += TraceDynLightRay(origin, 0.01f, normalize(pos - origin), dist);
+				}
 			}
+			else
+			{
+				for (int i = 0; i < step_count; i++)
+				{
+					vec2 gridoffset = getVogelDiskSample(i, step_count, gl_FragCoord.x + gl_FragCoord.y * 13.37) * softShadowRadius;
+					vec3 pos = target + xdir * gridoffset.x + ydir * gridoffset.y;
+					sum += TraceAnyHit(origin, 0.01f, normalize(pos - origin), dist) ? 0.0 : 1.0;
+				}
+			}
+
+			return (sum / step_count);
 		}
 		else
 		{
-			for (int i = 0; i < step_count; i++)
-			{
-				vec2 gridoffset = getVogelDiskSample(i, step_count, gl_FragCoord.x + gl_FragCoord.y * 13.37) * softShadowRadius;
-				vec3 pos = target + xdir * gridoffset.x + ydir * gridoffset.y;
-				sum += TraceAnyHit(origin, 0.01f, normalize(pos - origin), dist) ? 0.0 : 1.0;
-			}
+			const int samples_per_dimension = 4;
+			const int sample_count = samples_per_dimension * samples_per_dimension;
+			const int index = (int(int(gl_FragCoord.x) % samples_per_dimension + gl_FragCoord.y * samples_per_dimension)) % sample_count;
+
+			vec2 gridoffset = getVogelDiskSample(index, sample_count, 0) * softShadowRadius;
+			vec3 pos = target + xdir * gridoffset.x + ydir * gridoffset.y;
+			return traceHit(origin, normalize(pos - origin), dist);
 		}
-		return (sum / step_count);
 	}
 #endif
 }