// MinecraftPT — Water Waves
// Gerstner-style water wave normals with multi-octave detail.

#ifndef WATER_WAVES_GLSL
#define WATER_WAVES_GLSL

vec3 GetWaveNormal(vec3 worldPos, float lightmap){
	vec2 pos = worldPos.xz;

	float time = frameTimeCounter * 0.05 * WAVE_SPEED;

	// Multi-octave sine waves
	float wave1 = sin(pos.x * 0.1 * WAVE_SCALE + time) * cos(pos.y * 0.08 * WAVE_SCALE + time * 0.7);
	float wave2 = sin(pos.x * 0.2 * WAVE_SCALE + time * 1.3) * cos(pos.y * 0.15 * WAVE_SCALE - time * 0.9);
	float wave3 = sin((pos.x + pos.y) * 0.35 * WAVE_SCALE + time * 1.7) * 0.5;

	// Height field derivatives for normal
	float dx = cos(pos.x * 0.1 * WAVE_SCALE + time) * 0.1 * WAVE_SCALE * 0.5 * 0.05
		+ cos(pos.x * 0.2 * WAVE_SCALE + time * 1.3) * 0.2 * WAVE_SCALE * 0.5 * 0.04;
	float dz = -sin(pos.x * 0.1 * WAVE_SCALE + time) * sin(pos.y * 0.08 * WAVE_SCALE + time * 0.7) * 0.08 * WAVE_SCALE * 0.5 * 0.05
		- sin(pos.x * 0.2 * WAVE_SCALE + time * 1.3) * sin(pos.y * 0.15 * WAVE_SCALE - time * 0.9) * 0.15 * WAVE_SCALE * 0.5 * 0.04;

	vec3 normal = normalize(vec3(-dx, 1.0, -dz) * WAVE_NORMAL_STRENGTH + vec3(0.0, 1.0 - WAVE_NORMAL_STRENGTH, 0.0));

	return normal;
}

#endif