shader_type spatial;

uniform float slope_factor = 8.0;
uniform float blend_value = 0.5;

uniform sampler2D light_map;

uniform sampler2D grass_tex;
uniform vec2 grass_scale;

uniform sampler2D dirt_tex;
uniform vec2 dirt_scale;

varying float height_val;
varying vec3 normal;

void vertex(){
	height_val = VERTEX.y;
	normal = NORMAL;
}

float get_slope_of_terrain(float height_normal){
	float slope = 1.0-height_normal;
	slope *= slope;
	return (slope*slope_factor);
}

void fragment(){
	vec3 dirt = vec3(texture(dirt_tex, UV*dirt_scale).rgb);
	vec3 grass = vec3(texture(grass_tex, UV*grass_scale).rgb);
	
	float slope = clamp(get_slope_of_terrain(normal.y), 0.0, 1.0);
	
	vec3 mixin = mix(grass, dirt, slope);
	vec3 lightmap = vec3(texture(light_map, UV).rgb)*0.5;
	vec3 final_mix = mix(lightmap, mixin, vec3(blend_value, blend_value, blend_value));

	ALBEDO = final_mix;
}