Fix crash when hovering the cursor in heightmap.sdf (#536)

Hovering the cursor while in the ign gui when heightmap.sdf is opened
would cause a shader compiler error.

The triggering condition was having a directional light without shadow
nodes.

This error is from upstream
OGRECave/ogre-next@e40bc53

Signed-off-by: Matias N. Goldberg <[email protected]>

Co-authored-by: Ian Chen <[email protected]>

Author: darksylinc

ogre2/src/media/Hlms/Terra/GLSL/PbsTerraShadows/PbsTerraShadows_piece_vs_piece_ps.glsl

@@ -34,7 +34,7 @@
     outVs.terrainShadow = mix( terraShadowData.x, 1.0, clamp( terraHeightWeight, 0.0, 1.0 ) );
 @end
 
-@property( hlms_lights_directional )
+@property( hlms_lights_directional && hlms_num_shadow_map_lights )
     @piece( custom_ps_preLights )fShadow *= inPs.terrainShadow;@end
 @else
     @piece( custom_ps_preLights )float fShadow = inPs.terrainShadow;@end

ogre2/src/media/Hlms/Terra/HLSL/PbsTerraShadows/PbsTerraShadows_piece_vs_piece_ps.hlsl

@@ -36,7 +36,7 @@
     outVs.terrainShadow = lerp( terraShadowData.x, 1.0, saturate( terraHeightWeight ) );
 @end
 
-@property( hlms_lights_directional )
+@property( hlms_lights_directional && hlms_num_shadow_map_lights )
     @piece( custom_ps_preLights )fShadow *= inPs.terrainShadow;@end
 @else
     @piece( custom_ps_preLights )float fShadow = inPs.terrainShadow;@end

ogre2/src/media/Hlms/Terra/Metal/PbsTerraShadows/PbsTerraShadows_piece_vs_piece_ps.metal

@@ -36,7 +36,7 @@
     outVs.terrainShadow = lerp( terraShadowData.x, 1.0, saturate( terraHeightWeight ) );
 @end
 
-@property( hlms_lights_directional )
+@property( hlms_lights_directional && hlms_num_shadow_map_lights )
     @piece( custom_ps_preLights )fShadow *= inPs.terrainShadow;@end
 @else
     @piece( custom_ps_preLights )float fShadow = inPs.terrainShadow;@end