#version 330 core

#define FOV 24

#define EPSILON 0.01
#define MAX_STEPS 128
#define NEAR_D 0.1
#define FAR_D 120.

#define GRAD_EPSILON 0.0001

#define saturate(x) clamp(x, 0, 1)

uniform vec2 u_Resolution;
uniform vec4 u_Mouse;
uniform float u_Time;

out vec4 color;

#include "hg_sdf.glsl"
#include "utils.glsl"
#include "march_prolog.glsl"
#include "colormap_cool.glsl"

#define MAT_NORMALS 1.

vec3 ray_dir(float fov, vec2 uv) {
	float z = 1./tan(radians(fov)/2.);
	return normalize(vec3(uv, z));
}

SceneResult scene_f(vec3 p) {
	//SceneResult ball = SceneResult(length(p-vec3(0, 2, 0)) - 2, 3.);
	//SceneResult ball2 = SceneResult(length(p-vec3(2*sin(u_Time), 2-2*cos(u_Time), 0)) - 1, 3.);
	SceneResult plane = SceneResult(p.y+5, 2.);

	// SceneResult box = SceneResult(
	// 	fOpUnionRound(fBox(p, vec3(1)), fSphere(p-vec3(.8), 1.), .2), 0.);

	//SceneResult res = SceneResult(
	//	mix(fBox(p, vec3(1.)), fSphere(p, 1.),
	//		pow(sin(.5*TAU*u_Time), 0.8)),
	//	1.);

	// SceneResult res = SceneResult(-p.z, 1.);

	// SceneResult res = SceneResult(
	// 	fBox(p, vec3(1)),
	// 	1.);

	// SceneResult res = min_sr(min_sr(ball, ball2), plane);

	p -= vec3(0, 2, 0);
	//pR(p.yz, u_Time);

	//float d = max(abs(p.x), max(abs(p.y), abs(p.z))) - 2.;
	//float d = fBox(p, vec3(2));
	float d = fCircle(p, 3) - 1;

	SceneResult res = min_sr(plane, SceneResult(d, 3.));

	return res;
}

vec3 estimate_scene_normal(vec3 p) {
	vec3 dx = vec3(GRAD_EPSILON, 0, 0);
	vec3 dy = vec3(0, GRAD_EPSILON, 0);
	vec3 dz = vec3(0, 0, GRAD_EPSILON);

	return normalize(vec3(
		scene_f(p + dx).d - scene_f(p - dx).d,
		scene_f(p + dy).d - scene_f(p - dy).d,
		scene_f(p + dz).d - scene_f(p - dz).d
	));
}

vec3 raymarch(vec3 o, vec3 d, float start, float end) {
	float t = start;
	for (int i = 0; i < MAX_STEPS; i++) {
		SceneResult sr = scene_f(o + d*t);
		if (sr.d < EPSILON || t > end)
			return vec3(t, sr.mat_idx, i);

		t += sr.d;
	}
	return vec3(end, N_HIT_FAR_PLANE, MAX_STEPS);
}

float checker(vec2 uv) {
	return sign(mod(floor(uv.x) + floor(uv.y), 2.0));
}

vec4 shade_material(vec3 p, vec3 norm, float mat_idx) {
	if (mat_idx <= 0.0) {
		return vec4(0);
	}
	if (mat_idx <= 1.0) {
		// return colormap((mod(p.x, 3.) + 1)/2.5);
		return vec4(norm, 1.0);
	}
	if (mat_idx <= 2.0) {
		return vec4(vec3(mix(0.8, 1.0, checker(p.xz))), 1);
	}
	if (mat_idx <= 3.0) {
		return mix(vec4(vec3(0), 1), vec4(0.05, 0, 0.1, 1), dot(vec3(3, 3, 3), norm));
	}

	return vec4(1, 0, 0, 1);
	//return
}

vec4 shade(vec3 p, float mat_idx) {
	vec3 norm = estimate_scene_normal(p);
	vec4 color_mat = shade_material(p, norm, mat_idx);

	return color_mat;
}

void main() {
	vec2 mouse_uv = u_Mouse.xy * 2.0 / u_Resolution.xy - 1.0;

	vec2 uv = gl_FragCoord.xy * 2.0 / u_Resolution.xy - 1.0;
	uv.x *= u_Resolution.x/u_Resolution.y;

	float an = 0.;
	float d = 5.;
	vec3 eye = vec3(3. * sin(an), 3., 3. * cos(an)) * d;
	vec3 target = vec3(0., 2., 0.);
	mat3 lookAt = look_mat(eye, target, 0);
	vec3 dir = normalize(lookAt * ray_dir(FOV, uv));

	color = vec4(0.);

	vec3 result = raymarch(eye, dir, NEAR_D, FAR_D);
	float depth = result.x;
	float mat_idx = result.y;
	float iters = result.z;
	if (depth >= FAR_D) {
	//	color = vec4(.1, .3, .9, 1.);
		return;
	}

	//color = colormap(iters/MAX_STEPS+0.5);
	vec3 p = eye + dir * depth; // recast the ray
	color = shade(p, mat_idx);
	//color = vec4(vec3(depth/FAR_D), 1);

	// gamma
  	color = vec4(pow(clamp(color.xyz, 0.0, 1.0), vec3(0.4545)), 1.0);
}