<@include gpu/Config.slh@>
<$VERSION_HEADER$>
//  Generated on <$_SCRIBE_DATE$>
//
//  Created by Sam Gateau on 6/3/16.
//  Copyright 2016 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//

<@include DeferredTransform.slh@>
<$declareDeferredFrameTransform()$>

in vec2 varTexCoord0;
out vec4 outFragColor;

uniform sampler2D depthMap;


void main(void) {
    // Pixel being shaded
    ivec2 pixelPos;
    vec2 texcoordPos;
    ivec4 stereoSide;
    ivec2 framePixelPos = getPixelPosTexcoordPosAndSide(gl_FragCoord.xy, pixelPos, texcoordPos, stereoSide);
    
	float Zdb = texelFetch(depthMap, ivec2(gl_FragCoord.xy), 0).x;

	// The position of the pixel fragment in Eye space then in world space
    vec3 eyePos = evalUnjitteredEyePositionFromZdb(stereoSide.x, Zdb, texcoordPos);
	vec3 worldPos = (getViewInverse() * vec4(eyePos, 1.0)).xyz;
    
    vec3 prevEyePos = (getPreviousView() * vec4(worldPos, 1.0)).xyz;
    vec4 prevClipPos = (getUnjitteredProjection(stereoSide.x) * vec4(prevEyePos, 1.0));
    vec2 prevUV =  0.5 * (prevClipPos.xy / prevClipPos.w) + vec2(0.5);

    //vec2 imageSize = getWidthHeight(0);
    vec2 imageSize = vec2(1.0, 1.0);
    outFragColor = vec4( ((texcoordPos - prevUV) * imageSize), 0.0, 0.0);
}