iOS: fix shaders fog issue

client/shaders/nodes_shader/opengl_fragment.glsl

@@ -3,12 +3,11 @@ uniform sampler2D normalTexture;
 uniform sampler2D textureFlags;
 
 uniform vec4 skyBgColor;
-uniform float fogDistance;
 uniform vec3 eyePosition;
 
 varying mediump vec4 varColor;
 varying mediump vec2 varTexCoord;
-varying mediump vec3 eyeVec;
+varying mediump vec3 eyeVec; // divided by fogDistance
 
 const float e = 2.718281828459;
 const float BS = 10.0;
@@ -75,7 +74,7 @@ void main(void)
 	// should be more efficient as well.
 	// Note: clarity = (1 - fogginess)
 	float clarity = clamp(fogShadingParameter
-		- fogShadingParameter * length(eyeVec) / fogDistance, 0.0, 1.0);
+		- fogShadingParameter * length(eyeVec), 0.0, 1.0);
 	col = mix(skyBgColor, col, clarity);
 	col = vec4(col.rgb, base.a);
 

client/shaders/nodes_shader/opengl_vertex.glsl

@@ -1,6 +1,7 @@
 // Color of the light emitted by the sun.
 uniform highp mat4 mWorld;
 uniform vec3 dayLight;
+uniform float fogDistance;
 uniform float animationTimer;
 
 varying mediump vec4 varColor;
@@ -74,7 +75,7 @@ float disp_z;
 	gl_Position = mWorldViewProj * inVertexPosition;
 #endif
 
-	eyeVec = -(mWorldView * inVertexPosition).xyz;
+	eyeVec = -(mWorldView * inVertexPosition).xyz / fogDistance;
 
 	// Calculate color.
 	// Red, green and blue components are pre-multiplied with