#version 460 core
#define STAGE_FRAGMENT 1
#include "common.glsl"
// rain and snow of the gpu (gfx::gpu_particles, particles_precipitation.vert): a streak rounded at its ends, fainter towards
// its tail, in the colour the compute pass lit it with, faded in front of the scene, fogged

layout(location = 3) in vec4 f_pos;
layout(location = 13) in vec4 f_color;
layout(location = 17) in vec4 f_streak;
layout(location = 16) in float f_soft;

layout(location = 4) in vec4 f_clip_pos;
layout(location = 5) in vec4 f_clip_future_pos;

#include "common.glsl"
#include "apply_fog.glsl"
#include "tonemapping.glsl"
#include "particle_soft.glsl"

layout(location = 0) out vec4 out_color;
#ifdef NO_MOTION_OUTPUT
// a pass without the velocity target: the writes go nowhere
vec4 out_motion;
#else
layout(location = 1) out vec4 out_motion;
#endif

void main()
{
	// distance from the axis of the streak, in its radii
	float along = clamp(f_streak.y, 0.0, f_streak.w);
	float offaxis = length(vec2(f_streak.x, f_streak.y - along)) / max(f_streak.z, 1e-6);
	float alpha = f_color.a * (1.0 - smoothstep(0.35, 1.0, offaxis));
	alpha *= mix(1.0, 0.4, along / max(f_streak.w, 1e-6));
	alpha *= particle_soft_fade(f_soft, -f_pos.z);
	if (alpha <= 0.0)
		discard;
	vec4 color = vec4(apply_fog(f_color.rgb), alpha);
	if (POSTFX_ENABLED)
	{
		out_color = color;
	}
	else
	{
		out_color = tonemap(color);
	}
	if (MOTIONBLUR_ENABLED)
	{
		vec2 a = (f_clip_future_pos.xy / f_clip_future_pos.w) * 0.5 + 0.5;
		vec2 b = (f_clip_pos.xy / f_clip_pos.w) * 0.5 + 0.5;

		out_motion = vec4(a - b, 0.0f, alpha * alpha_mult);
	}
}