Improvements to colored shadows (#11516)

Author: x2048

client/shaders/nodes_shader/opengl_fragment.glsl

@@ -489,7 +489,11 @@ void main(void)
 	if (distance_rate > 1e-7) {
 
 #ifdef COLORED_SHADOWS
-		vec4 visibility = getShadowColor(ShadowMapSampler, posLightSpace.xy, posLightSpace.z);
+		vec4 visibility;
+		if (cosLight > 0.0)
+			visibility = getShadowColor(ShadowMapSampler, posLightSpace.xy, posLightSpace.z);
+		else
+			visibility = vec4(1.0, 0.0, 0.0, 0.0);
 		shadow_int = visibility.r;
 		shadow_color = visibility.gba;
 #else
@@ -507,7 +511,8 @@ void main(void)
 
 	shadow_int = 1.0 - (shadow_int * f_adj_shadow_strength);
 
-	col.rgb = mix(shadow_color,col.rgb,shadow_int)*shadow_int;
+	// apply shadow (+color) as a factor to the material color
+	col.rgb = col.rgb * (1.0 - (1.0 - shadow_color) * (1.0 - pow(shadow_int, 2.0)));
 	// col.r = 0.5 * clamp(getPenumbraRadius(ShadowMapSampler, posLightSpace.xy, posLightSpace.z, 1.0) / SOFTSHADOWRADIUS, 0.0, 1.0) + 0.5 * col.r;
 #endif
 

client/shaders/object_shader/opengl_fragment.glsl

@@ -351,7 +351,11 @@ void main(void)
 	vec3 posLightSpace = getLightSpacePosition();
 
 #ifdef COLORED_SHADOWS
-	vec4 visibility = getShadowColor(ShadowMapSampler, posLightSpace.xy, posLightSpace.z);
+	vec4 visibility;
+	if (cosLight > 0.0)
+		visibility = getShadowColor(ShadowMapSampler, posLightSpace.xy, posLightSpace.z);
+	else
+		visibility = vec4(1.0, 0.0, 0.0, 0.0);
 	shadow_int = visibility.r;
 	shadow_color = visibility.gba;
 #else

client/shaders/shadow_shaders/pass1_trans_fragment.glsl

@@ -2,6 +2,8 @@ uniform sampler2D ColorMapSampler;
 varying vec4 tPos;
 
 #ifdef COLORED_SHADOWS
+varying vec3 varColor;
+
 // c_precision of 128 fits within 7 base-10 digits
 const float c_precision = 128.0;
 const float c_precisionp1 = c_precision + 1.0;
@@ -30,7 +32,10 @@ void main()
 
 	//col.rgb = col.a == 1.0 ? vec3(1.0) : col.rgb;
 #ifdef COLORED_SHADOWS
-	float packedColor = packColor(mix(col.rgb, black, col.a));
+	col.rgb *= varColor.rgb;
+	// alpha 0.0 results in all-white, 0.5 means full color, 1.0 means all black
+	// resulting color is used as a factor in the final shader
+	float packedColor = packColor(mix(mix(vec3(1.0), col.rgb, 2.0 * clamp(col.a, 0.0, 0.5)), black, 2.0 * clamp(col.a - 0.5, 0.0, 0.5)));
 	gl_FragColor = vec4(depth, packedColor, 0.0,1.0);
 #else
 	gl_FragColor = vec4(depth, 0.0, 0.0, 1.0);

client/shaders/shadow_shaders/pass1_trans_vertex.glsl

@@ -1,5 +1,8 @@
 uniform mat4 LightMVP; // world matrix
 varying vec4 tPos;
+#ifdef COLORED_SHADOWS
+varying vec3 varColor;
+#endif
 
 const float bias0 = 0.9;
 const float zPersFactor = 0.5;
@@ -23,4 +26,8 @@ void main()
 
 	gl_Position = vec4(tPos.xyz, 1.0);
 	gl_TexCoord[0].st = gl_MultiTexCoord0.st;
+
+#ifdef COLORED_SHADOWS
+	varColor = gl_Color.rgb;
+#endif
 }

src/client/clientmap.cpp

@@ -461,7 +461,10 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 				layer.Texture = shadow->get_texture();
 				layer.TextureWrapU = video::E_TEXTURE_CLAMP::ETC_CLAMP_TO_EDGE;
 				layer.TextureWrapV = video::E_TEXTURE_CLAMP::ETC_CLAMP_TO_EDGE;
-				layer.TrilinearFilter = true;
+				// Do not enable filter on shadow texture to avoid visual artifacts
+				// with colored shadows.
+				// Filtering is done in shader code anyway
+				layer.TrilinearFilter = false;
 			}
 			driver->setMaterial(material);
 			++material_swaps;