// Shared helpers for the world shaders.
// Declares `noise_tex` (a seamless NoiseTexture2D set from terrain.gd) so every
// shader samples the same noise, which keeps grass, terrain and rock colour
// variation lined up with each other.

uniform sampler2D noise_tex : filter_linear_mipmap, repeat_enable;

float nz(vec2 p) {
	return texture(noise_tex, p).r;
}

// Triplanar noise: samples along all three axes so steep faces (cliffs, rock
// sides) don't show the stretched streaks a top-down projection would give.
float tri_nz(vec3 p, vec3 n, float s) {
	vec3 w = pow(abs(n), vec3(4.0));
	w /= (w.x + w.y + w.z);
	return nz(p.zy * s) * w.x + nz(p.xz * s) * w.y + nz(p.xy * s) * w.z;
}

// Vertex colours are authored as sRGB; lighting needs linear.
vec3 to_linear(vec3 c) {
	return pow(c, vec3(2.2));
}