// Per-Object Motion Blur
// http://john-chapman-graphics.blogspot.com/2013/01/per-object-motion-blur.html
#version 450

#include "compiled.glsl"

uniform sampler2D gbuffer0;
uniform sampler2D sveloc;
uniform sampler2D tex;
// uniform vec2 texStep;
uniform float frameScale;

in vec2 texCoord;
out vec4 fragColor;

void main() {
	vec2 velocity = texture(sveloc, texCoord).rg * motionBlurIntensity * frameScale;
	
	fragColor.rgb = texture(tex, texCoord).rgb;

	// Do not blur masked objects
	if (texture(gbuffer0, texCoord).a == 1.0) {
		return;
	}

	// float speed = length(velocity / texStep);
	// const int MAX_SAMPLES = 8;
	// int samples = clamp(int(speed), 1, MAX_SAMPLES);
	const int samples = 8;
	// for (int i = 1; i < samples; ++i) {
		vec2 offset = velocity * (float(0) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
		//
		offset = velocity * (float(1) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
		offset = velocity * (float(2) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
		offset = velocity * (float(3) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
		offset = velocity * (float(4) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
		offset = velocity * (float(5) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
		offset = velocity * (float(6) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
		offset = velocity * (float(7) / float(samples - 1) - 0.5);
		fragColor.rgb += texture(tex, texCoord + offset).rgb;
	// }
	fragColor.rgb /= float(samples + 1);
}