uniform mat4 mWorldViewProj;
uniform mat4 mInvWorld;
uniform mat4 mTransWorld;
uniform mat4 mWorld;

uniform float dayNightRatio;

uniform vec3 eyePosition;

varying vec3 vPosition;
varying vec3 worldPosition;

varying vec3 eyeVec;
varying vec3 lightVec;

varying vec3 tsEyeVec;
varying vec3 tsLightVec;

const float BS = 10.0;

void main(void)
{
	gl_TexCoord[0] = gl_MultiTexCoord0;
	gl_Position = mWorldViewProj * gl_Vertex;
	vPosition = gl_Position.xyz;
	worldPosition = (mWorld * gl_Vertex).xyz;
	vec3 sunPosition = vec3 (0.0, eyePosition.y * BS + 900.0, 0.0);

	vec3 normal, tangent, binormal;
	normal = normalize(gl_NormalMatrix * gl_Normal);
	if (gl_Normal.x > 0.5) {
		//  1.0,  0.0,  0.0
		tangent  = normalize(gl_NormalMatrix * vec3( 0.0,  0.0, -1.0));
		binormal = normalize(gl_NormalMatrix * vec3( 0.0, -1.0,  0.0));
	} else if (gl_Normal.x < -0.5) {
		// -1.0,  0.0,  0.0
		tangent  = normalize(gl_NormalMatrix * vec3( 0.0,  0.0,  1.0));
		binormal = normalize(gl_NormalMatrix * vec3( 0.0, -1.0,  0.0));
	} else if (gl_Normal.y > 0.5) {
		//  0.0,  1.0,  0.0
		tangent  = normalize(gl_NormalMatrix * vec3( 1.0,  0.0,  0.0));
		binormal = normalize(gl_NormalMatrix * vec3( 0.0,  0.0,  1.0));
	} else if (gl_Normal.y < -0.5) {
		//  0.0, -1.0,  0.0
		tangent  = normalize(gl_NormalMatrix * vec3( 1.0,  0.0,  0.0));
		binormal = normalize(gl_NormalMatrix * vec3( 0.0,  0.0,  1.0));
	} else if (gl_Normal.z > 0.5) {
		//  0.0,  0.0,  1.0
		tangent  = normalize(gl_NormalMatrix * vec3( 1.0,  0.0,  0.0));
		binormal = normalize(gl_NormalMatrix * vec3( 0.0, -1.0,  0.0));
	} else if (gl_Normal.z < -0.5) {
		//  0.0,  0.0, -1.0
		tangent  = normalize(gl_NormalMatrix * vec3(-1.0,  0.0,  0.0));
		binormal = normalize(gl_NormalMatrix * vec3( 0.0, -1.0,  0.0));
	}
	mat3 tbnMatrix = mat3(	tangent.x, binormal.x, normal.x,
							tangent.y, binormal.y, normal.y,
							tangent.z, binormal.z, normal.z);

	lightVec = sunPosition - worldPosition;
	tsLightVec = lightVec * tbnMatrix;
	eyeVec = (gl_ModelViewMatrix * gl_Vertex).xyz;
	tsEyeVec = eyeVec * tbnMatrix;

	vec4 color;
	float day = gl_Color.r;
	float night = gl_Color.g;
	float light_source = gl_Color.b;

	float rg = mix(night, day, dayNightRatio);
	rg += light_source * 2.5; // Make light sources brighter
	float b = rg;

	// Moonlight is blue
	b += (day - night) / 13.0;
	rg -= (day - night) / 13.0;

	// Emphase blue a bit in darker places
	// See C++ implementation in mapblock_mesh.cpp finalColorBlend()
	b += max(0.0, (1.0 - abs(b - 0.13)/0.17) * 0.025);

	// Artificial light is yellow-ish
	// See C++ implementation in mapblock_mesh.cpp finalColorBlend()
	rg += max(0.0, (1.0 - abs(rg - 0.85)/0.15) * 0.065);

	color.r = clamp(rg,0.0,1.0);
	color.g = clamp(rg,0.0,1.0);
	color.b = clamp(b,0.0,1.0);

	// Make sides and bottom darker than the top
	color = color * color; // SRGB -> Linear
	if(gl_Normal.y <= 0.5)
		color *= 0.6;
	color = sqrt(color); // Linear -> SRGB
	color.a = gl_Color.a;

	gl_FrontColor = gl_BackColor = color;
}