#version 120

varying mediump vec2 texture_coordinate;

uniform sampler2D heightTexture;

uniform sampler2D TerrainTexture1;
uniform sampler2D TerrainTexture2;
uniform sampler2D TerrainTexture3;
uniform sampler2D TerrainTexture4;
uniform sampler2D TerrainTexture5;

uniform float time;

void main (void)
{
	mediump float height = ((texture2D(heightTexture, texture_coordinate).r-0.5)*255.0);
	
	mediump float snow=0, rock=0, grass=0, dirt=0;
	
	mediump float x = height;
	
	dirt = -0.0008*(x-16)*(x-16)+1.0;
	grass = -0.0011*(x-48)*(x-48)+1.0;
	rock = -0.0011*(x-100)*(x-100)+1.0;
	snow = -0.0021*(x-120)*(x-120)+1.0;
	if(dirt<0) dirt = 0;
	if(grass<0) grass = 0;
	if(rock<0) rock = 0;
	if(snow<0) snow = 0;
	if(x>130) snow=1.0;
	
	mediump vec2 texCoords = texture_coordinate + vec2(time, time) ;

	if(texCoords.s >1 ) texCoords.s = texCoords.s-int(texCoords.s);
	if(texCoords.t >1 ) texCoords.t = texCoords.t-int(texCoords.t);
	
	//texCoords=normalize(texCoords);
	
	gl_FragColor = dirt * texture2D(TerrainTexture1, texture_coordinate);
	gl_FragColor += grass* texture2D(TerrainTexture2, texture_coordinate);
	gl_FragColor += rock * texture2D(TerrainTexture3, texture_coordinate);
	gl_FragColor += snow * texture2D(TerrainTexture4, texture_coordinate);

	//gl_FragColor = normalize(gl_FragColor);
	gl_FragColor.a = 1.0;
	
	if( height < 0 ) {
		gl_FragColor = texture2D(TerrainTexture5, texCoords );
	}	
	
	
}