RTSS: PSSM3 shadows - correctly handle sampling behind far plane

OGRECave · May 16, 2020 · e34f532 · e34f532
1 parent 1405bd6
commit e34f532
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Showing 2 changed files with 16 additions and 1 deletion.
diff --git a/Media/RTShaderLib/GLSL/SGXLib_IntegratedPSSM.glsl b/Media/RTShaderLib/GLSL/SGXLib_IntegratedPSSM.glsl
@@ -51,8 +51,16 @@ void SGX_ShadowPCF4(in sampler2D shadowMap, in vec4 shadowMapPos, in vec2 offset
 	vec2 uv = shadowMapPos.xy;
 	vec3 o = vec3(offset, -offset.x) * 0.3;
 
+	float depth = texture2D(shadowMap, uv.xy - o.xy).r;
+	if(depth >= 1.0)
+	{
+		// early out, if sampling behind far plane
+		c = 1.0;
+		return;
+	}
+
 	// Note: We using 2x2 PCF. Good enough and is a lot faster.
-	c =	 (shadowMapPos.z <= texture2D(shadowMap, uv.xy - o.xy).r) ? 1.0 : 0.0; // top left
+	c =	 (shadowMapPos.z <= depth) ? 1.0 : 0.0; // top left
 	c += (shadowMapPos.z <= texture2D(shadowMap, uv.xy + o.xy).r) ? 1.0 : 0.0; // bottom right
 	c += (shadowMapPos.z <= texture2D(shadowMap, uv.xy + o.zy).r) ? 1.0 : 0.0; // bottom left
 	c += (shadowMapPos.z <= texture2D(shadowMap, uv.xy - o.zy).r) ? 1.0 : 0.0; // top right

diff --git a/Media/RTShaderLib/HLSL_Cg/SGXLib_IntegratedPSSM.cg b/Media/RTShaderLib/HLSL_Cg/SGXLib_IntegratedPSSM.cg
@@ -46,6 +46,13 @@ void SGX_ShadowPCF4(sampler2D shadowMap, float4 shadowMapPos, float2 offset, out
     float2 uv = shadowMapPos.xy;
     float3 o = float3(offset, -offset.x) * 0.3f;
 
+    float depth = tex2D(shadowMap, uv.xy - o.xy).r;
+	if(depth >= 1.0)
+	{
+		// early out, if sampling behind far plane
+		c = 1.0;
+		return;
+	}
     // Note: We using 2x2 PCF. Good enough and is a lot faster.
     c =  (shadowMapPos.z <= tex2D(shadowMap, uv.xy - o.xy).r) ? 1 : 0; // top left
     c += (shadowMapPos.z <= tex2D(shadowMap, uv.xy + o.xy).r) ? 1 : 0; // bottom right