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

uniform float dayNightRatio;
uniform vec3 eyePosition;
uniform float animationTimer;

varying vec3 vPosition;
varying vec3 worldPosition;

varying vec3 eyeVec;
varying vec3 lightVec;
varying vec3 tsEyeVec;
varying vec3 tsLightVec;
varying float area_enable_parallax;

const float e = 2.718281828459;
const float BS = 10.0;

float smoothCurve(float x)
{
	return x * x * (3.0 - 2.0 * x);
}
float triangleWave(float x)
{
	return abs(fract(x + 0.5) * 2.0 - 1.0);
}
float smoothTriangleWave(float x)
{
	return smoothCurve(triangleWave(x)) * 2.0 - 1.0;
}

void main(void)
{
	gl_TexCoord[0] = gl_MultiTexCoord0;
	//TODO: make offset depending on view angle and parallax uv displacement
	//thats for textures that doesnt align vertically, like dirt with grass
	//gl_TexCoord[0].y += 0.008;

	//Allow parallax/relief mapping only for certain kind of nodes
	//Variable is also used to control area of the effect
#if (DRAW_TYPE == NDT_NORMAL || DRAW_TYPE == NDT_LIQUID || DRAW_TYPE == NDT_FLOWINGLIQUID)
	area_enable_parallax = 1.0;
#else
	area_enable_parallax = 0.0;
#endif

#if ((MATERIAL_TYPE == TILE_MATERIAL_LIQUID_TRANSPARENT || MATERIAL_TYPE == TILE_MATERIAL_LIQUID_OPAQUE) && ENABLE_WAVING_WATER)
	vec4 pos = gl_Vertex;
	pos.y -= 2.0;

	float posYbuf = (pos.z / WATER_WAVE_LENGTH + animationTimer * WATER_WAVE_SPEED * WATER_WAVE_LENGTH);

	pos.y -= sin(posYbuf) * WATER_WAVE_HEIGHT + sin(posYbuf / 7.0) * WATER_WAVE_HEIGHT;
	gl_Position = mWorldViewProj * pos;
#elif MATERIAL_TYPE == TILE_MATERIAL_WAVING_LEAVES && ENABLE_WAVING_LEAVES
	vec4 pos = gl_Vertex;
	vec4 pos2 = mWorld * gl_Vertex;

	/*
	 * Mathematic optimization: pos2.x * A + pos2.z * A (2 multiplications + 1 addition)
	 * replaced with: (pos2.x + pos2.z) * A (1 addition + 1 multiplication)
	 * And bufferize calcul to a float
	 */
	float pos2XpZ = pos2.x + pos2.z;

	pos.x += (smoothTriangleWave(animationTimer*10.0 + pos2XpZ * 0.01) * 2.0 - 1.0) * 0.4;
	pos.y += (smoothTriangleWave(animationTimer*15.0 + pos2XpZ * -0.01) * 2.0 - 1.0) * 0.2;
	pos.z += (smoothTriangleWave(animationTimer*10.0 + pos2XpZ * -0.01) * 2.0 - 1.0) * 0.4;
	gl_Position = mWorldViewProj * pos;
#elif MATERIAL_TYPE == TILE_MATERIAL_WAVING_PLANTS && ENABLE_WAVING_PLANTS
	vec4 pos = gl_Vertex;
	vec4 pos2 = mWorld * gl_Vertex;
	if (gl_TexCoord[0].y < 0.05) {
		/*
		 * Mathematic optimization: pos2.x * A + pos2.z * A (2 multiplications + 1 addition)
		 * replaced with: (pos2.x + pos2.z) * A (1 addition + 1 multiplication)
		 * And bufferize calcul to a float
		 */
		float pos2XpZ = pos2.x + pos2.z;

		pos.x += (smoothTriangleWave(animationTimer * 20.0 + pos2XpZ * 0.1) * 2.0 - 1.0) * 0.8;
		pos.y -= (smoothTriangleWave(animationTimer * 10.0 + pos2XpZ * -0.5) * 2.0 - 1.0) * 0.4;
	}
	gl_Position = mWorldViewProj * pos;
#else
	gl_Position = mWorldViewProj * gl_Vertex;
#endif

	vPosition = gl_Position.xyz;
	worldPosition = (mWorld * gl_Vertex).xyz;

	// Don't generate heightmaps when too far from the eye
	float dist = distance (vec3(0.0, 0.0 ,0.0), vPosition);
	if (dist > 150.0) {
		area_enable_parallax = 0.0;
	}

	vec3 sunPosition = vec3 (0.0, eyePosition.y * BS + 900.0, 0.0);

	vec3 normal, tangent, binormal;
	normal = normalize(gl_NormalMatrix * gl_Normal);
	tangent = normalize(gl_NormalMatrix * gl_MultiTexCoord1.xyz);
	binormal = normalize(gl_NormalMatrix * gl_MultiTexCoord2.xyz);

	vec3 v;

	lightVec = sunPosition - worldPosition;
	v.x = dot(lightVec, tangent);
	v.y = dot(lightVec, binormal);
	v.z = dot(lightVec, normal);
	tsLightVec = normalize (v);

	eyeVec = -(gl_ModelViewMatrix * gl_Vertex).xyz;
	v.x = dot(eyeVec, tangent);
	v.y = dot(eyeVec, binormal);
	v.z = dot(eyeVec, normal);
	tsEyeVec = normalize (v);

	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) / 23.0;

	// 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 = rg;
	color.g = rg;
	color.b = b;

	color.a = gl_Color.a;
	gl_FrontColor = gl_BackColor = clamp(color,0.0,1.0);
}
