Added support for direct3d-like texture coords uv for shadow atlases

See http://thedev-log.blogspot.com/2012/07/texture-coordinates-tutorial-opengl-and.html,
the "opengl coordinates" where inverted for proper support of direct3d texture coordinate system.

Shaders/std/light.glsl

@@ -185,13 +185,17 @@ vec3 sampleLight(const vec3 p, const vec3 n, const vec3 v, const float dotNV, co
 				#ifdef _Clusters
 					vec4 lPos = LWVPSpotArray[index] * vec4(p + n * bias * 10, 1.0);
 					#ifdef _ShadowMapAtlas
+						vec3 uv = lPos.xyz / lPos.w;
+						#ifdef _InvY
+						uv.y = 1.0 - uv.y; // invert Y coordinates for direct3d coordinate system
+						#endif
 						direct *= shadowTest(
 							#ifndef _SingleAtlas
 							shadowMapAtlasSpot
 							#else
 							shadowMapAtlas
 							#endif
-							, lPos.xyz / lPos.w, bias
+							, uv, bias
 						);
 					#else
 							 if (index == 0) direct *= shadowTest(shadowMapSpot[0], lPos.xyz / lPos.w, bias);

Shaders/std/light_mobile.glsl

@@ -80,13 +80,17 @@ vec3 sampleLight(const vec3 p, const vec3 n, const vec3 v, const float dotNV, co
 				#ifdef _Clusters
 					vec4 lPos = LWVPSpotArray[index] * vec4(p + n * bias * 10, 1.0);
 					#ifdef _ShadowMapAtlas
+						vec3 uv = lPos.xyz / lPos.w;
+						#ifdef _InvY
+						uv.y = 1.0 - uv.y; // invert Y coordinates for direct3d coordinate system
+						#endif
 						direct *= shadowTest(
 							#ifndef _SingleAtlas
 							shadowMapAtlasSpot
 							#else
 							shadowMapAtlas
 							#endif
-							, lPos.xyz / lPos.w, bias
+							, uv, bias
 						);
 					#else
 							 if (index == 0) direct *= shadowTest(shadowMapSpot[0], lPos.xyz / lPos.w, bias);

Shaders/std/shadows.glsl

@@ -20,7 +20,6 @@ uniform vec2 smSizeUniform;
 #endif
 
 #ifdef _ShadowMapAtlas
-// https://www.khronos.org/registry/OpenGL/specs/gl/glspec20.pdf // p:168
 // https://www.gamedev.net/forums/topic/687535-implementing-a-cube-map-lookup-function/5337472/
 vec2 sampleCube(vec3 dir, out int faceIndex) {
 	vec3 dirAbs = abs(dir);
@@ -188,40 +187,77 @@ float PCFFakeCube(sampler2DShadow shadowMap, const vec3 lp, vec3 ml, const float
 	const vec2 uv = sampleCube(ml, faceIndex);
 
 	vec4 pointLightTile = pointLightDataArray[lightIndex + faceIndex]; // x: tile X offset, y: tile Y offset, z: tile size relative to atlas
-	float result = texture(shadowMap, vec3(pointLightTile.z * uv + pointLightTile.xy, compare));
+	vec2 uvtiled = pointLightTile.z * uv + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+
+	float result = texture(shadowMap, vec3(uvtiled, compare));
 	// soft shadowing
 	int newFaceIndex = 0;
-	vec2 uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(-1.0, 0.0) / smSize)));
+	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(-1.0, 0.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
 	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
 
 	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(-1.0, 1.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
-	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+	result += texture(shadowMap, vec3(uvtiled, compare));
 
 	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(0.0, -1.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
-	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+	result += texture(shadowMap, vec3(uvtiled, compare));
 
 	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(-1.0, -1.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
-	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+	result += texture(shadowMap, vec3(uvtiled, compare));
 
 	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(0.0, 1.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
-	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+	result += texture(shadowMap, vec3(uvtiled, compare));
 
 	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(1.0, -1.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
-	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+	result += texture(shadowMap, vec3(uvtiled, compare));
 
 	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(1.0, 0.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
-	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+	result += texture(shadowMap, vec3(uvtiled, compare));
 
 	uvtiled = transformOffsetedUV(faceIndex, newFaceIndex, vec2(uv + (vec2(1.0, 1.0) / smSize)));
 	pointLightTile = pointLightDataArray[lightIndex + newFaceIndex];
-	result += texture(shadowMap, vec3(pointLightTile.z * uvtiled + pointLightTile.xy, compare));
+	uvtiled = pointLightTile.z * uvtiled + pointLightTile.xy;
+	#ifdef _InvY
+	uvtiled.y = 1.0 - uvtiled.y; // invert Y coordinates for direct3d coordinate system
+	#endif
+	result += texture(shadowMap, vec3(uvtiled, compare));
 
 	return result / 9.0;
 }