uniform mat4 mWorld;

uniform vec3 eyePosition;
uniform float animationTimer;

varying vec3 vNormal;
varying vec3 vPosition;
varying vec3 worldPosition;
varying lowp vec4 varColor;
#ifdef GL_ES
varying mediump vec2 varTexCoord;
#else
centroid varying vec2 varTexCoord;
#endif

#ifdef ENABLE_DYNAMIC_SHADOWS
	// shadow uniforms
	uniform vec3 v_LightDirection;
	uniform float f_textureresolution;
	uniform mat4 m_ShadowViewProj;
	uniform float f_shadowfar;
	uniform float f_shadow_strength;
	uniform float f_timeofday;
	varying float cosLight;
	varying float normalOffsetScale;
	varying float adj_shadow_strength;
	varying float f_normal_length;
#endif

varying vec3 eyeVec;
varying float nightRatio;

varying float vIDiff;

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

#ifdef ENABLE_DYNAMIC_SHADOWS
// custom smoothstep implementation because it's not defined in glsl1.2
// https://docs.gl/sl4/smoothstep
float mtsmoothstep(in float edge0, in float edge1, in float x)
{
	float t = clamp((x - edge0) / (edge1 - edge0), 0.0, 1.0);
	return t * t * (3.0 - 2.0 * t);
}
#endif


float directional_ambient(vec3 normal)
{
	vec3 v = normal * normal;

	if (normal.y < 0.0)
		return dot(v, vec3(0.670820, 0.447213, 0.836660));

	return dot(v, vec3(0.670820, 1.000000, 0.836660));
}

void main(void)
{
	varTexCoord = (mTexture * inTexCoord0).st;
	gl_Position = mWorldViewProj * inVertexPosition;

	vPosition = gl_Position.xyz;
	vNormal = (mWorld * vec4(inVertexNormal, 0.0)).xyz;
	worldPosition = (mWorld * inVertexPosition).xyz;
	eyeVec = -(mWorldView * inVertexPosition).xyz;

#if (MATERIAL_TYPE == TILE_MATERIAL_PLAIN) || (MATERIAL_TYPE == TILE_MATERIAL_PLAIN_ALPHA)
	vIDiff = 1.0;
#else
	// This is intentional comparison with zero without any margin.
	// If normal is not equal to zero exactly, then we assume it's a valid, just not normalized vector
	vIDiff = length(inVertexNormal) == 0.0
		? 1.0
		: directional_ambient(normalize(inVertexNormal));
#endif
	nightRatio = 0.0;

#ifdef GL_ES
	varColor = inVertexColor.bgra;
#else
	varColor = inVertexColor;
#endif

#ifdef ENABLE_DYNAMIC_SHADOWS
	vec3 nNormal = normalize(vNormal);
	cosLight = dot(nNormal, -v_LightDirection);
	float texelSize = 767.0 / f_textureresolution;
	float slopeScale = clamp(1.0 - abs(cosLight), 0.0, 1.0);
	normalOffsetScale = texelSize * slopeScale;
	
	if (f_timeofday < 0.2) {
		adj_shadow_strength = f_shadow_strength * 0.5 *
			(1.0 - mtsmoothstep(0.18, 0.2, f_timeofday));
	} else if (f_timeofday >= 0.8) {
		adj_shadow_strength = f_shadow_strength * 0.5 *
			mtsmoothstep(0.8, 0.83, f_timeofday);
	} else {
		adj_shadow_strength = f_shadow_strength *
			mtsmoothstep(0.20, 0.25, f_timeofday) *
			(1.0 - mtsmoothstep(0.7, 0.8, f_timeofday));
	}
	f_normal_length = length(vNormal);
#endif
}