// __multiversion__
// This signals the loading code to prepend either #version 100 or #version 300 es as apropriate.

// To use centroid sampling we need to have version 300 es shaders, which requires changing:
// attribute to in
// varying to out when in vertex shaders or in when in fragment shaders
// defining an out vec4 FragColor and replacing uses of gl_FragColor with FragColor
// texture2D to texture
#if __VERSION__ >= 300

#define attribute in
#define varying out
#ifdef MSAA_FRAMEBUFFER_ENABLED
#define _centroid centroid
#else
#define _centroid
#endif
_centroid out vec2 uv;

#else
varying vec2 uv;
#endif

uniform MAT4 WORLDVIEWPROJ;
uniform MAT4 WORLD;
uniform vec4 TILE_LIGHT_COLOR;
uniform vec4 OVERLAY_COLOR;
uniform vec4 CHANGE_COLOR;
uniform vec4 GLINT_COLOR;
uniform vec4 FOG_COLOR;
uniform vec2 FOG_CONTROL;
uniform float RENDER_DISTANCE;
uniform vec2 UV_ANIM;
uniform vec2 UV_OFFSET;
uniform vec2 UV_ROTATION;
uniform vec2 GLINT_UV_SCALE;

attribute mediump vec4 POSITION;
attribute vec2 TEXCOORD_0;
attribute vec4 NORMAL;

#ifdef COLOR_BASED
	attribute vec4 COLOR;
#endif

varying vec4 light;
varying vec4 fogColor;

#ifdef USE_OVERLAY
varying vec4 overlayColor;
#endif

#if defined(USE_COLOR_MASK) || defined(ITEM_IN_HAND) || defined(COLOR_SECOND_TEXTURE)
varying vec4 changeColor;
#endif

#ifdef GLINT
	varying vec2 layer1UV;
	varying vec2 layer2UV;
    varying vec4 tileLightColor;
	varying vec4 glintColor;
#endif

const float AMBIENT = 0.45;

const float XFAC = -0.1;
const float ZFAC = 0.1;

float lightIntensity() {
#ifdef FANCY
    vec3 N = normalize( WORLD * NORMAL ).xyz;

    N.y *= TILE_LIGHT_COLOR.w; //TILE_LIGHT_COLOR.w contains the direction of the light

    //take care of double sided polygons on materials without culling
#ifdef FLIP_BACKFACES
    vec3 viewDir = normalize((WORLD * POSITION).xyz);
    if( dot(N, viewDir) > 0.0 )
        N *= -1.0;
#endif

    float yLight = (1.0+N.y) * 0.5;
    return yLight * (1.0-AMBIENT) + N.x*N.x * XFAC + N.z*N.z * ZFAC + AMBIENT;
#else
    return 1.0;
#endif
}

#ifdef GLINT
vec2 calculateLayerUV(float offset, float rotation) {
	vec2 uv = TEXCOORD_0;
	uv -= 0.5;
	float rsin = sin(rotation);
	float rcos = cos(rotation);
	uv = mat2(rcos, -rsin, rsin, rcos) * uv;
	uv.x += offset;
	uv += 0.5;

	return uv * GLINT_UV_SCALE;
}
#endif

void main()
{
    POS4 pos = WORLDVIEWPROJ * POSITION;
    gl_Position = pos;

    float L = lightIntensity();

#ifdef USE_OVERLAY
	L += OVERLAY_COLOR.a * 0.35;
    overlayColor = OVERLAY_COLOR;
#endif

#if defined(USE_COLOR_MASK) || defined(ITEM_IN_HAND) || defined(COLOR_SECOND_TEXTURE)
    changeColor = CHANGE_COLOR;
#endif

    light = vec4(vec3(L) * TILE_LIGHT_COLOR.xyz, 1.0);

#ifdef COLOR_BASED
	light *= COLOR;
#endif
    
#ifndef NO_TEXTURE
    uv = TEXCOORD_0;
#endif

#ifdef USE_UV_ANIM
	uv.xy += UV_ANIM.xy;
#endif

#ifdef GLINT
	glintColor = GLINT_COLOR;
	layer1UV = calculateLayerUV(UV_OFFSET.x, UV_ROTATION.x);
	layer2UV = calculateLayerUV(UV_OFFSET.y, UV_ROTATION.y);
    tileLightColor = TILE_LIGHT_COLOR;
#endif


//fog
    fogColor.rgb = FOG_COLOR.rgb;
//    fogColor.a = clamp(((pos.z / RENDER_DISTANCE) - FOG_CONTROL.x) / (FOG_CONTROL.y - FOG_CONTROL.x), 0.0, 1.0);
    fogColor.a = clamp(((length((WORLD * POSITION).xyz) / RENDER_DISTANCE) - FOG_CONTROL.x) / (FOG_CONTROL.y - FOG_CONTROL.x), 0.0, 1.0);
}